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diff --git a/doc/bird.sgml b/doc/bird.sgml index bb88dc61..f2001e75 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -39,11 +39,12 @@ This document contains user documentation for the BIRD Internet Routing Daemon p <chapt>Introduction +<label id="intro"> <sect>What is BIRD +<label id="what-is-bird"> -<p><label id="intro"> -The name `BIRD' is actually an acronym standing for `BIRD Internet Routing +<p>The name `BIRD' is actually an acronym standing for `BIRD Internet Routing Daemon'. Let's take a closer look at the meaning of the name: <p><em/BIRD/: Well, we think we have already explained that. It's an acronym @@ -118,6 +119,7 @@ files, tools ...). <sect>Installing BIRD +<label id="install"> <p>On a recent UNIX system with GNU development tools (GCC, binutils, m4, make) and Perl, installing BIRD should be as easy as: @@ -138,45 +140,46 @@ BIRD executable by configuring out routing protocols you don't use, and <sect>Running BIRD +<label id="argv"> <p>You can pass several command-line options to bird: <descrip> - <tag>-c <m/config name/</tag> + <tag><label id="argv-config">-c <m/config name/</tag> use given configuration file instead of <it/prefix/<file>/etc/bird.conf</file>. - <tag>-d</tag> + <tag><label id="argv-debug">-d</tag> enable debug messages and run bird in foreground. - <tag>-D <m/filename of debug log/</tag> + <tag><label id="argv-log-file">-D <m/filename of debug log/</tag> log debugging information to given file instead of stderr. - <tag>-p</tag> + <tag><label id="argv-parse">-p</tag> just parse the config file and exit. Return value is zero if the config file is valid, nonzero if there are some errors. - <tag>-s <m/name of communication socket/</tag> + <tag><label id="argv-socket">-s <m/name of communication socket/</tag> use given filename for a socket for communications with the client, default is <it/prefix/<file>/var/run/bird.ctl</file>. - <tag>-P <m/name of PID file/</tag> + <tag><label id="argv-pid">-P <m/name of PID file/</tag> create a PID file with given filename. - <tag>-u <m/user/</tag> + <tag><label id="argv-user">-u <m/user/</tag> drop privileges and use that user ID, see the next section for details. - <tag>-g <m/group/</tag> + <tag><label id="argv-group">-g <m/group/</tag> use that group ID, see the next section for details. - <tag>-f</tag> + <tag><label id="argv-foreground">-f</tag> run bird in foreground. - <tag>-l</tag> + <tag><label id="argv-local">-l</tag> look for a configuration file and a communication socket in the current working directory instead of in default system locations. However, paths specified by options <cf/-c/, <cf/-s/ have higher priority. - <tag>-R</tag> + <tag><label id="argv-recovery">-R</tag> apply graceful restart recovery after start. </descrip> @@ -184,6 +187,7 @@ BIRD executable by configuring out routing protocols you don't use, and <sect>Privileges +<label id="privileges"> <p>BIRD, as a routing daemon, uses several privileged operations (like setting routing table and using raw sockets). Traditionally, BIRD is executed and runs @@ -208,6 +212,7 @@ the config file and create the control socket and the CAP_NET_* capabilities. <chapt>About routing tables +<label id="routing-tables"> <p>BIRD has one or more routing tables which may or may not be synchronized with OS kernel and which may or may not be synchronized with each other (see the Pipe @@ -245,7 +250,7 @@ network. Note that although most protocols are interested in receiving just selected routes, some protocols (e.g. the <cf/Pipe/ protocol) receive and process all entries in routing tables (accepted by filters). -<p><label id="dsc-sorted">Usually, a routing table just chooses a selected route +<p><label id="dsc-table-sorted">Usually, a routing table just chooses a selected route from a list of entries for one network. But if the <cf/sorted/ option is activated, these lists of entries are kept completely sorted (according to preference or some protocol-dependent metric). This is needed for some features @@ -259,6 +264,7 @@ is that it is slightly more computationally expensive. <sect>Graceful restart +<label id="graceful-restart"> <p>When BIRD is started after restart or crash, it repopulates routing tables in an uncoordinated manner, like after clean start. This may be impractical in some @@ -274,8 +280,10 @@ particular boot by option <cf/-R/. <chapt>Configuration +<label id="config"> <sect>Introduction +<label id="config-intro"> <p>BIRD is configured using a text configuration file. Upon startup, BIRD reads <it/prefix/<file>/etc/bird.conf</file> (unless the <tt/-c/ command line option @@ -319,15 +327,16 @@ protocol rip { <sect>Global options +<label id="global-opts"> <p><descrip> - <tag>include "<m/filename/"</tag> + <tag><label id="opt-include">include "<m/filename/"</tag> This statement causes inclusion of a new file. <m/Filename/ could also be a wildcard, in that case matching files are included in alphabetic order. The maximal depth is 8. Note that this statement could be used anywhere in the config file, not just as a top-level option. - <tag><label id="dsc-log">log "<m/filename/"|syslog [name <m/name/]|stderr all|{ <m/list of classes/ }</tag> + <tag><label id="opt-log">log "<m/filename/"|syslog [name <m/name/]|stderr all|{ <m/list of classes/ }</tag> Set logging of messages having the given class (either <cf/all/ or <cf/{ error, trace }/ etc.) into selected destination (a file specified as a filename string, syslog with optional name argument, or the stderr @@ -341,48 +350,48 @@ protocol rip { You may specify more than one <cf/log/ line to establish logging to multiple destinations. Default: log everything to the system log. - <tag>debug protocols all|off|{ states, routes, filters, interfaces, events, packets }</tag> + <tag><label id="opt-debug-protocols">debug protocols all|off|{ states, routes, filters, interfaces, events, packets }</tag> Set global defaults of protocol debugging options. See <cf/debug/ in the following section. Default: off. - <tag>debug commands <m/number/</tag> + <tag><label id="opt-debug-commands">debug commands <m/number/</tag> Control logging of client connections (0 for no logging, 1 for logging of connects and disconnects, 2 and higher for logging of all client commands). Default: 0. - <tag>debug latency <m/switch/</tag> + <tag><label id="opt-debug-latency">debug latency <m/switch/</tag> Activate tracking of elapsed time for internal events. Recent events could be examined using <cf/dump events/ command. Default: off. - <tag>debug latency limit <m/time/</tag> + <tag><label id="opt-debug-latency-limit">debug latency limit <m/time/</tag> If <cf/debug latency/ is enabled, this option allows to specify a limit for elapsed time. Events exceeding the limit are logged. Default: 1 s. - <tag>watchdog warning <m/time/</tag> + <tag><label id="opt-watchdog-warn">watchdog warning <m/time/</tag> Set time limit for I/O loop cycle. If one iteration took more time to complete, a warning is logged. Default: 5 s. - <tag>watchdog timeout <m/time/</tag> + <tag><label id="opt-watchdog-timeout">watchdog timeout <m/time/</tag> Set time limit for I/O loop cycle. If the limit is breached, BIRD is killed by abort signal. The timeout has effective granularity of seconds, zero means disabled. Default: disabled (0). - <tag>mrtdump "<m/filename/"</tag> + <tag><label id="opt-mrtdump">mrtdump "<m/filename/"</tag> Set MRTdump file name. This option must be specified to allow MRTdump feature. Default: no dump file. - <tag>mrtdump protocols all|off|{ states, messages }</tag> + <tag><label id="opt-mrtdump-protocols">mrtdump protocols all|off|{ states, messages }</tag> Set global defaults of MRTdump options. See <cf/mrtdump/ in the following section. Default: off. - <tag>filter <m/name local variables/{ <m/commands/ }</tag> + <tag><label id="opt-filter">filter <m/name local variables/{ <m/commands/ }</tag> Define a filter. You can learn more about filters in the following chapter. - <tag>function <m/name/ (<m/parameters/) <m/local variables/ { <m/commands/ }</tag> + <tag><label id="opt-function">function <m/name/ (<m/parameters/) <m/local variables/ { <m/commands/ }</tag> Define a function. You can learn more about functions in the following chapter. - <tag>protocol rip|ospf|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag> + <tag><label id="opt-protocol">protocol rip|ospf|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag> Define a protocol instance called <cf><m/name/</cf> (or with a name like "rip5" generated automatically if you don't specify any <cf><m/name/</cf>). You can learn more about configuring protocols in @@ -391,7 +400,7 @@ protocol rip { <cf><m/name2/</cf> You can run more than one instance of most protocols (like RIP or BGP). By default, no instances are configured. - <tag>template rip|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag> + <tag><label id="opt-template">template rip|bgp|... [<m/name/ [from <m/name2/]] { <m>protocol options</m> }</tag> Define a protocol template instance called <m/name/ (or with a name like "bgp1" generated automatically if you don't specify any <m/name/). Protocol templates can be used to group common options when many @@ -400,25 +409,25 @@ protocol rip { expression and the name of the template. At the moment templates (and <cf/from/ expression) are not implemented for OSPF protocol. - <tag>define <m/constant/ = <m/expression/</tag> + <tag><label id="opt-define">define <m/constant/ = <m/expression/</tag> Define a constant. You can use it later in every place you could use a value of the same type. Besides, there are some predefined numeric constants based on /etc/iproute2/rt_* files. A list of defined constants can be seen (together with other symbols) using 'show symbols' command. - <tag>router id <m/IPv4 address/</tag> - Set BIRD's router ID. It's a world-wide unique identification of your + <tag><label id="opt-router-id">router id <m/IPv4 address/</tag> + Set BIRD's router ID. It's a world-wide unique identification of your router, usually one of router's IPv4 addresses. Default: in IPv4 version, the lowest IP address of a non-loopback interface. In IPv6 version, this option is mandatory. - <tag>router id from [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...]</tag> + <tag><label id="opt-router-id-from">router id from [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...]</tag> Set BIRD's router ID based on an IP address of an interface specified by an interface pattern. The option is applicable for IPv4 version only. - See <ref id="dsc-iface" name="interface"> section for detailed + See <ref id="proto-iface" name="interface"> section for detailed description of interface patterns with extended clauses. - <tag>listen bgp [address <m/address/] [port <m/port/] [dual]</tag> + <tag><label id="opt-listen-bgp">listen bgp [address <m/address/] [port <m/port/] [dual]</tag> This option allows to specify address and port where BGP protocol should listen. It is global option as listening socket is common to all BGP instances. Default is to listen on all addresses (0.0.0.0) and port 179. @@ -427,13 +436,13 @@ protocol rip { BIRD would accept IPv6 routes only). Such behavior was default in older versions of BIRD. - <tag>graceful restart wait <m/number/</tag> + <tag><label id="opt-graceful-restart">graceful restart wait <m/number/</tag> During graceful restart recovery, BIRD waits for convergence of routing protocols. This option allows to specify a timeout for the recovery to prevent waiting indefinitely if some protocols cannot converge. Default: 240 seconds. - <tag>timeformat route|protocol|base|log "<m/format1/" [<m/limit/ "<m/format2/"]</tag> + <tag><label id="opt-timeformat">timeformat route|protocol|base|log "<m/format1/" [<m/limit/ "<m/format2/"]</tag> This option allows to specify a format of date/time used by BIRD. The first argument specifies for which purpose such format is used. <cf/route/ is a format used in 'show route' command output, @@ -459,13 +468,13 @@ protocol rip { hh:mm:ss) for <cf/base/ and <cf/log/. These timeformats could be set by <cf/old short/ and <cf/old long/ compatibility shorthands. - <tag>table <m/name/ [sorted]</tag> + <tag><label id="opt-table">table <m/name/ [sorted]</tag> Create a new routing table. The default routing table is created implicitly, other routing tables have to be added by this command. Option <cf/sorted/ can be used to enable sorting of routes, see - <ref id="dsc-sorted" name="sorted table"> description for details. + <ref id="dsc-table-sorted" name="sorted table"> description for details. - <tag>roa table <m/name/ [ { roa table options ... } ]</tag> + <tag><label id="opt-roa-table">roa table <m/name/ [ { roa table options ... } ]</tag> Create a new ROA (Route Origin Authorization) table. ROA tables can be used to validate route origination of BGP routes. A ROA table contains ROA entries, each consist of a network prefix, a max prefix length and @@ -479,12 +488,13 @@ protocol rip { ROA entries. The option may be used multiple times. Other entries can be added dynamically by <cf/add roa/ command. - <tag>eval <m/expr/</tag> + <tag><label id="opt-eval">eval <m/expr/</tag> Evaluates given filter expression. It is used by us for testing of filters. </descrip> <sect>Protocol options +<label id="protocol-opts"> <p>For each protocol instance, you can configure a bunch of options. Some of them (those described in this section) are generic, some are specific to the @@ -497,16 +507,16 @@ disable it. An empty <m/switch/ is equivalent to <cf/on/ ("silence means agreement"). <descrip> - <tag>preference <m/expr/</tag> + <tag><label id="proto-preference">preference <m/expr/</tag> Sets the preference of routes generated by this protocol. Default: protocol dependent. - <tag>disabled <m/switch/</tag> + <tag><label id="proto-disabled">disabled <m/switch/</tag> Disables the protocol. You can change the disable/enable status from the command line interface without needing to touch the configuration. Disabled protocols are not activated. Default: protocol is enabled. - <tag>debug all|off|{ states, routes, filters, interfaces, events, packets }</tag> + <tag><label id="proto-debug">debug all|off|{ states, routes, filters, interfaces, events, packets }</tag> Set protocol debugging options. If asked, each protocol is capable of writing trace messages about its work to the log (with category <cf/trace/). You can either request printing of <cf/all/ trace messages @@ -517,7 +527,7 @@ agreement"). protocol, <cf/events/ for events internal to the protocol and <cf/packets/ for packets sent and received by the protocol. Default: off. - <tag>mrtdump all|off|{ states, messages }</tag> + <tag><label id="proto-mrtdump">mrtdump all|off|{ states, messages }</tag> Set protocol MRTdump flags. MRTdump is a standard binary format for logging information from routing protocols and daemons. These flags control what kind of information is logged from the protocol to the @@ -527,27 +537,27 @@ agreement"). BGP protocol, <cf/states/ logs BGP state changes and <cf/messages/ logs received BGP messages. Other protocols does not support MRTdump yet. - <tag>router id <m/IPv4 address/</tag> + <tag><label id="proto-router-id">router id <m/IPv4 address/</tag> This option can be used to override global router id for a given protocol. Default: uses global router id. - <tag>import all | none | filter <m/name/ | filter { <m/filter commands/ } | where <m/filter expression/</tag> + <tag><label id="proto-import">import all | none | filter <m/name/ | filter { <m/filter commands/ } | where <m/filter expression/</tag> Specify a filter to be used for filtering routes coming from the protocol to the routing table. <cf/all/ is shorthand for <cf/where true/ and <cf/none/ is shorthand for <cf/where false/. Default: <cf/all/. - <tag>export <m/filter/</tag> + <tag><label id="proto-export">export <m/filter/</tag> This is similar to the <cf>import</cf> keyword, except that it works in the direction from the routing table to the protocol. Default: <cf/none/. - <tag>import keep filtered <m/switch/</tag> + <tag><label id="proto-import-keep-filtered">import keep filtered <m/switch/</tag> Usually, if an import filter rejects a route, the route is forgotten. When this option is active, these routes are kept in the routing table, but they are hidden and not propagated to other protocols. But it is possible to show them using <cf/show route filtered/. Note that this option does not work for the pipe protocol. Default: off. - <tag><label id="import-limit">import limit [<m/number/ | off ] [action warn | block | restart | disable]</tag> + <tag><label id="proto-import-limit">import limit [<m/number/ | off ] [action warn | block | restart | disable]</tag> Specify an import route limit (a maximum number of routes imported from the protocol) and optionally the action to be taken when the limit is hit. Warn action just prints warning log message. Block action discards @@ -556,7 +566,7 @@ agreement"). action if an action is not explicitly specified. Note that limits are reset during protocol reconfigure, reload or restart. Default: <cf/off/. - <tag>receive limit [<m/number/ | off ] [action warn | block | restart | disable]</tag> + <tag><label id="proto-receive-limit">receive limit [<m/number/ | off ] [action warn | block | restart | disable]</tag> Specify an receive route limit (a maximum number of routes received from the protocol and remembered). It works almost identically to <cf>import limit</cf> option, the only difference is that if <cf/import keep @@ -566,7 +576,7 @@ agreement"). on the contrary, counts accepted routes only and routes blocked by the limit are handled like filtered routes. Default: <cf/off/. - <tag>export limit [ <m/number/ | off ] [action warn | block | restart | disable]</tag> + <tag><label id="proto-export-limit">export limit [ <m/number/ | off ] [action warn | block | restart | disable]</tag> Specify an export route limit, works similarly to the <cf>import limit</cf> option, but for the routes exported to the protocol. This option is experimental, there are some problems in details of its @@ -576,18 +586,18 @@ agreement"). updates of already accepted routes -- and these details will probably change in the future. Default: <cf/off/. - <tag>description "<m/text/"</tag> + <tag><label id="proto-description">description "<m/text/"</tag> This is an optional description of the protocol. It is displayed as a part of the output of 'show route all' command. - <tag>table <m/name/</tag> + <tag><label id="proto-table">table <m/name/</tag> Connect this protocol to a non-default routing table. </descrip> <p>There are several options that give sense only with certain protocols: <descrip> - <tag><label id="dsc-iface">interface [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...] [ { <m/option/ ; [...] } ]</tag> + <tag><label id="proto-iface">interface [-] [ "<m/mask/" ] [ <m/prefix/ ] [, ...] [ { <m/option/ ; [...] } ]</tag> Specifies a set of interfaces on which the protocol is activated with given interface-specific options. A set of interfaces specified by one interface option is described using an interface pattern. The interface @@ -634,7 +644,7 @@ agreement"). <cf>interface "eth*" 192.168.1.0/24;</cf> - start the protocol on all ethernet interfaces that have address from 192.168.1.0/24. - <tag><label id="dsc-prio">tx class|dscp <m/num/</tag> + <tag><label id="proto-tx-class">tx class|dscp <m/num/</tag> This option specifies the value of ToS/DS/Class field in IP headers of the outgoing protocol packets. This may affect how the protocol packets are processed by the network relative to the other network traffic. With @@ -643,12 +653,12 @@ agreement"). keyword, the value (0-63) is used just for the DS field in the octet. Default value is 0xc0 (DSCP 0x30 - CS6). - <tag>tx priority <m/num/</tag> + <tag><label id="proto-tx-priority">tx priority <m/num/</tag> This option specifies the local packet priority. This may affect how the protocol packets are processed in the local TX queues. This option is Linux specific. Default value is 7 (highest priority, privileged traffic). - <tag><label id="dsc-pass">password "<m/password/" [ { id <m/num/; generate from <m/time/; generate to <m/time/; accept from <m/time/; accept to <m/time/; } ]</tag> + <tag><label id="proto-pass">password "<m/password/" [ { id <m/num/; generate from <m/time/; generate to <m/time/; accept from <m/time/; accept to <m/time/; } ]</tag> Specifies a password that can be used by the protocol. Password option can be used more times to specify more passwords. If more passwords are specified, it is a protocol-dependent decision which one is really @@ -659,35 +669,35 @@ agreement"). This option is allowed in OSPF and RIP protocols. BGP has also <cf/password/ option, but it is slightly different and described separately. - Default: none. </descrip> <p>Password option can contain section with some (not necessary all) password sub-options: <descrip> - <tag>id <M>num</M></tag> + <tag><label id="proto-pass-id">id <M>num</M></tag> ID of the password, (1-255). If it is not used, BIRD will choose ID based on an order of the password item in the interface. For example, second password item in one interface will have default ID 2. ID is used by some routing protocols to identify which password was used to authenticate protocol packets. - <tag>generate from "<m/time/"</tag> + <tag><label id="proto-pass-gen-from">generate from "<m/time/"</tag> The start time of the usage of the password for packet signing. The format of <cf><m/time/</cf> is <tt>dd-mm-yyyy HH:MM:SS</tt>. - <tag>generate to "<m/time/"</tag> + <tag><label id="proto-pass-gen-to">generate to "<m/time/"</tag> The last time of the usage of the password for packet signing. - <tag>accept from "<m/time/"</tag> + <tag><label id="proto-pass-accept-from">accept from "<m/time/"</tag> The start time of the usage of the password for packet verification. - <tag>accept to "<m/time/"</tag> + <tag><label id="proto-pass-accept-to">accept to "<m/time/"</tag> The last time of the usage of the password for packet verification. </descrip> <chapt>Remote control +<label id="remote-control"> <p>You can use the command-line client <file>birdc</file> to talk with a running BIRD. Communication is done using a <file/bird.ctl/ UNIX domain socket (unless @@ -713,26 +723,26 @@ This argument can be omitted if there exists only a single instance. <p>Here is a brief list of supported functions: <descrip> - <tag>show status</tag> + <tag><label id="cli-show-status">show status</tag> Show router status, that is BIRD version, uptime and time from last reconfiguration. - <tag>show interfaces [summary]</tag> + <tag><label id="cli-show-interfaces">show interfaces [summary]</tag> Show the list of interfaces. For each interface, print its type, state, MTU and addresses assigned. - <tag>show protocols [all]</tag> + <tag><label id="cli-show-protocols">show protocols [all]</tag> Show list of protocol instances along with tables they are connected to and protocol status, possibly giving verbose information, if <cf/all/ is specified. - <tag>show ospf interface [<m/name/] ["<m/interface/"]</tag> + <tag><label id="cli-show-ospf-iface">show ospf interface [<m/name/] ["<m/interface/"]</tag> Show detailed information about OSPF interfaces. - <tag>show ospf neighbors [<m/name/] ["<m/interface/"]</tag> + <tag><label id="cli-show-ospf-neighbors">show ospf neighbors [<m/name/] ["<m/interface/"]</tag> Show a list of OSPF neighbors and a state of adjacency to them. - <tag>show ospf state [all] [<m/name/]</tag> + <tag><label id="cli-show-ospf-state">show ospf state [all] [<m/name/]</tag> Show detailed information about OSPF areas based on a content of the link-state database. It shows network topology, stub networks, aggregated networks and routers from other areas and external routes. @@ -740,31 +750,31 @@ This argument can be omitted if there exists only a single instance. <cf/all/ to show information about all network nodes in the link-state database. - <tag>show ospf topology [all] [<m/name/]</tag> + <tag><label id="cli-show-ospf-topology">show ospf topology [all] [<m/name/]</tag> Show a topology of OSPF areas based on a content of the link-state database. It is just a stripped-down version of 'show ospf state'. - <tag>show ospf lsadb [global | area <m/id/ | link] [type <m/num/] [lsid <m/id/] [self | router <m/id/] [<m/name/] </tag> + <tag><label id="cli-show-ospf-lsadb">show ospf lsadb [global | area <m/id/ | link] [type <m/num/] [lsid <m/id/] [self | router <m/id/] [<m/name/] </tag> Show contents of an OSPF LSA database. Options could be used to filter entries. - <tag>show rip interfaces [<m/name/] ["<m/interface/"]</tag> + <tag><label id="cli-show-rip-interfaces">show rip interfaces [<m/name/] ["<m/interface/"]</tag> Show detailed information about RIP interfaces. - <tag>show rip neighbors [<m/name/] ["<m/interface/"]</tag> + <tag><label id="cli-show-rip-neighbors">show rip neighbors [<m/name/] ["<m/interface/"]</tag> Show a list of RIP neighbors and associated state. - <tag>show static [<m/name/]</tag> + <tag><label id="cli-show-static">show static [<m/name/]</tag> Show detailed information about static routes. - <tag>show bfd sessions [<m/name/]</tag> + <tag><label id="cli-show-bfd-sessions">show bfd sessions [<m/name/]</tag> Show information about BFD sessions. - <tag>show symbols [table|filter|function|protocol|template|roa|<m/symbol/]</tag> + <tag><label id="cli-show-symbols">show symbols [table|filter|function|protocol|template|roa|<m/symbol/]</tag> Show the list of symbols defined in the configuration (names of protocols, routing tables etc.). - <tag>show route [[for] <m/prefix/|<m/IP/] [table <m/sym/] [filter <m/f/|where <m/c/] [(export|preexport|noexport) <m/p/] [protocol <m/p/] [<m/options/]</tag> + <tag><label id="cli-show-route">show route [[for] <m/prefix/|<m/IP/] [table <m/sym/] [filter <m/f/|where <m/c/] [(export|preexport|noexport) <m/p/] [protocol <m/p/] [<m/options/]</tag> Show contents of a routing table (by default of the main one or the table attached to a respective protocol), that is routes, their metrics and (in case the <cf/all/ switch is given) all their attributes. @@ -799,7 +809,7 @@ This argument can be omitted if there exists only a single instance. number of networks, number of routes before and after filtering). If you use <cf/count/ instead, only the statistics will be printed. - <tag>show roa [<m/prefix/ | in <m/prefix/ | for <m/prefix/] [as <m/num/] [table <m/t/>]</tag> + <tag><label id="cli-show-roa">show roa [<m/prefix/ | in <m/prefix/ | for <m/prefix/] [as <m/num/] [table <m/t/>]</tag> Show contents of a ROA table (by default of the first one). You can specify a <m/prefix/ to print ROA entries for a specific network. If you use <cf>for <m/prefix/</cf>, you'll get all entries relevant for route @@ -808,19 +818,19 @@ This argument can be omitted if there exists only a single instance. entries covered by the network prefix. You could also use <cf/as/ option to show just entries for given AS. - <tag>add roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag> + <tag><label id="cli-add-roa">add roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag> Add a new ROA entry to a ROA table. Such entry is called <it/dynamic/ compared to <it/static/ entries specified in the config file. These dynamic entries survive reconfiguration. - <tag>delete roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag> + <tag><label id="cli-delete-roa">delete roa <m/prefix/ max <m/num/] as <m/num/ [table <m/t/>]</tag> Delete the specified ROA entry from a ROA table. Only dynamic ROA entries (i.e., the ones added by <cf/add roa/ command) can be deleted. - <tag>flush roa [table <m/t/>]</tag> + <tag><label id="cli-flush-roa">flush roa [table <m/t/>]</tag> Remove all dynamic ROA entries from a ROA table. - <tag>configure [soft] ["<m/config file/"] [timeout [<m/num/]]</tag> + <tag><label id="cli-configure">configure [soft] ["<m/config file/"] [timeout [<m/num/]]</tag> Reload configuration from a given file. BIRD will smoothly switch itself to the new configuration, protocols are reconfigured if possible, restarted otherwise. Changes in filters usually lead to restart of @@ -839,11 +849,11 @@ This argument can be omitted if there exists only a single instance. config timeout expiration is equivalent to <cf/configure undo/ command. The timeout duration could be specified, default is 300 s. - <tag>configure confirm</tag> + <tag><label id="cli-configure-confirm">configure confirm</tag> Deactivate the config undo timer and therefore confirm the current configuration. - <tag>configure undo</tag> + <tag><label id="cli-configure-undo">configure undo</tag> Undo the last configuration change and smoothly switch back to the previous (stored) configuration. If the last configuration change was soft, the undo change is also soft. There is only one level of undo, but @@ -851,15 +861,15 @@ This argument can be omitted if there exists only a single instance. immediately in a row and the intermediate ones are skipped then the undo also skips them back. - <tag>configure check ["<m/config file/"]</tag> + <tag><label id="cli-configure-check">configure check ["<m/config file/"]</tag> Read and parse given config file, but do not use it. useful for checking syntactic and some semantic validity of an config file. - <tag>enable|disable|restart <m/name/|"<m/pattern/"|all</tag> + <tag><label id="cli-enable-disable-restart">enable|disable|restart <m/name/|"<m/pattern/"|all</tag> Enable, disable or restart a given protocol instance, instances matching the <cf><m/pattern/</cf> or <cf/all/ instances. - <tag>reload [in|out] <m/name/|"<m/pattern/"|all</tag> + <tag><label id="cli-reload">reload [in|out] <m/name/|"<m/pattern/"|all</tag> Reload a given protocol instance, that means re-import routes from the protocol instance and re-export preferred routes to the instance. If <cf/in/ or <cf/out/ options are used, the command is restricted to one @@ -876,27 +886,29 @@ This argument can be omitted if there exists only a single instance. pipe protocol, both directions are always reloaded together (<cf/in/ or <cf/out/ options are ignored in that case). - <tag/down/ + <tag><label id="cli-down">down</tag> Shut BIRD down. - <tag>debug <m/protocol/|<m/pattern/|all all|off|{ states | routes | filters | events | packets }</tag> + <tag><label id="cli-debug">debug <m/protocol/|<m/pattern/|all all|off|{ states | routes | filters | events | packets }</tag> Control protocol debugging. - <tag>dump resources|sockets|interfaces|neighbors|attributes|routes|protocols</tag> + <tag><label id="cli-dump">dump resources|sockets|interfaces|neighbors|attributes|routes|protocols</tag> Dump contents of internal data structures to the debugging output. - <tag>echo all|off|{ <m/list of log classes/ } [ <m/buffer-size/ ]</tag> + <tag><label id="cli-echo">echo all|off|{ <m/list of log classes/ } [ <m/buffer-size/ ]</tag> Control echoing of log messages to the command-line output. - See <ref id="dsc-log" name="log option"> for a list of log classes. + See <ref id="opt-log" name="log option"> for a list of log classes. - <tag>eval <m/expr/</tag> + <tag><label id="cli-eval">eval <m/expr/</tag> Evaluate given expression. </descrip> <chapt>Filters +<label id="filters"> <sect>Introduction +<label id="filters-intro"> <p>BIRD contains a simple programming language. (No, it can't yet read mail :-). There are two objects in this language: filters and functions. Filters are @@ -984,33 +996,34 @@ bird> <sect>Data types +<label id="data-types"> <p>Each variable and each value has certain type. Booleans, integers and enums are incompatible with each other (that is to prevent you from shooting in the foot). <descrip> - <tag/bool/ + <tag><label id="type-bool">bool</tag> This is a boolean type, it can have only two values, <cf/true/ and <cf/false/. Boolean is the only type you can use in <cf/if/ statements. - <tag/int/ + <tag><label id="type-int">int</tag> This is a general integer type. It is an unsigned 32bit type; i.e., you can expect it to store values from 0 to 4294967295. Overflows are not checked. You can use <cf/0x1234/ syntax to write hexadecimal values. - <tag/pair/ + <tag><label id="type-pair">pair</tag> This is a pair of two short integers. Each component can have values from 0 to 65535. Literals of this type are written as <cf/(1234,5678)/. The same syntax can also be used to construct a pair from two arbitrary integer expressions (for example <cf/(1+2,a)/). - <tag/quad/ + <tag><label id="type-quad">quad</tag> This is a dotted quad of numbers used to represent router IDs (and others). Each component can have a value from 0 to 255. Literals of this type are written like IPv4 addresses. - <tag/string/ + <tag><label id="type-string">string</tag> This is a string of characters. There are no ways to modify strings in filters. You can pass them between functions, assign them to variables of type <cf/string/, print such variables, use standard string @@ -1020,7 +1033,7 @@ foot). !˜/) operators could be used to match a string value against a shell pattern (represented also as a string). - <tag/ip/ + <tag><label id="type-ip">ip</tag> This type can hold a single IP address. Depending on the compile-time configuration of BIRD you are using, it is either an IPv4 or IPv6 address. IP addresses are written in the standard notation @@ -1029,7 +1042,7 @@ foot). first <cf><M>num</M></cf> bits from the IP address. So <cf/1.2.3.4.mask(8) = 1.0.0.0/ is true. - <tag/prefix/ + <tag><label id="type-prefix">prefix</tag> This type can hold a network prefix consisting of IP address and prefix length. Prefix literals are written as <cf><m/ipaddress//<m/pxlen/</cf>, or <cf><m>ipaddress</m>/<m>netmask</m></cf>. There are two special @@ -1037,7 +1050,7 @@ foot). pair, and <cf/.len/, which separates prefix length from the pair. So <cf>1.2.0.0/16.len = 16</cf> is true. - <tag/ec/ + <tag><label id="type-ec">ec</tag> This is a specialized type used to represent BGP extended community values. It is essentially a 64bit value, literals of this type are usually written as <cf>(<m/kind/, <m/key/, <m/value/)</cf>, where @@ -1048,7 +1061,7 @@ foot). for <cf/key/ and <cf/value/ parts, (e.g. <cf/(ro, myas, 3*10)/, where <cf/myas/ is an integer variable). - <tag/lc/ + <tag><label id="type-lc">lc</tag> This is a specialized type used to represent BGP large community values. It is essentially a triplet of 32bit values, where the first value is reserved for the AS number of the issuer, while meaning of @@ -1057,7 +1070,7 @@ foot). pairs, LCs can be constructed using expressions for its parts, (e.g. <cf/(myas, 10+20, 3*10)/, where <cf/myas/ is an integer variable). - <tag/int|pair|quad|ip|prefix|ec|lc|enum set/ + <tag><label id="type-set">int|pair|quad|ip|prefix|ec|lc|enum set</tag> Filters recognize four types of sets. Sets are similar to strings: you can pass them around but you can't modify them. Literals of type <cf>int set</cf> look like <cf> [ 1, 2, 5..7 ]</cf>. As you can see, both simple @@ -1133,12 +1146,12 @@ foot). <cf>192.168.0.0/16{16,24}</cf> and <cf>192.168.0.0/16 ge 24</cf> as <cf>192.168.0.0/16{24,32}</cf>. - <tag/enum/ + <tag><label id="type-enum">enum</tag> Enumeration types are fixed sets of possibilities. You can't define your own variables of such type, but some route attributes are of enumeration type. Enumeration types are incompatible with each other. - <tag/bgppath/ + <tag><label id="type-bgppath">bgppath</tag> BGP path is a list of autonomous system numbers. You can't write literals of this type. There are several special operators on bgppaths: @@ -1171,7 +1184,7 @@ foot). <cf><m/P/.prepend(<m/A/);</cf> if <m/P/ is appropriate route attribute (for example <cf/bgp_path/). Similarly for <cf/delete/ and <cf/filter/. - <tag/bgpmask/ + <tag><label id="type-bgpmask">bgpmask</tag> BGP masks are patterns used for BGP path matching (using <cf>path ˜ [= 2 3 5 * =]</cf> syntax). The masks resemble wildcard patterns as used by UNIX shells. Autonomous system numbers match themselves, @@ -1185,7 +1198,7 @@ foot). There is also old (deprecated) syntax that uses / .. / instead of [= .. =] and ? instead of *. - <tag/clist/ + <tag><label id="type-clist">clist</tag> Clist is similar to a set, except that unlike other sets, it can be modified. The type is used for community list (a set of pairs) and for cluster list (a set of quads). There exist no literals of this type. @@ -1214,7 +1227,7 @@ foot). <cf><m/C/.add(<m/P/);</cf> if <m/C/ is appropriate route attribute (for example <cf/bgp_community/). Similarly for <cf/delete/ and <cf/filter/. - <tag/eclist/ + <tag><label id="type-eclist">eclist</tag> Eclist is a data type used for BGP extended community lists. Eclists are very similar to clists, but they are sets of ECs instead of pairs. The same operations (like <cf/add/, <cf/delete/ or <cf/˜/ and @@ -1231,6 +1244,7 @@ foot). <sect>Operators +<label id="operators"> <p>The filter language supports common integer operators <cf>(+,-,*,/)</cf>, parentheses <cf/(a*(b+c))/, comparison <cf/(a=b, a!=b, a<b, a>=b)/. @@ -1261,6 +1275,7 @@ prefix and an ASN as arguments. <sect>Control structures +<label id="control-structures"> <p>Filters support two control structures: conditions and case switches. @@ -1296,6 +1311,7 @@ if 1234 = i then printn "."; else { <sect>Route attributes +<label id="route-attributes"> <p>A filter is implicitly passed a route, and it can access its attributes just like it accesses variables. Attempts to access undefined attribute result in a @@ -1305,11 +1321,11 @@ rule are attributes of clist type, where undefined value is regarded as empty clist for most purposes. <descrip> - <tag><m/prefix/ net</tag> + <tag><label id="rta-net"><m/prefix/ net</tag> Network the route is talking about. Read-only. (See the chapter about routing tables.) - <tag><m/enum/ scope</tag> + <tag><label id="rta-scope"><m/enum/ scope</tag> The scope of the route. Possible values: <cf/SCOPE_HOST/ for routes local to this host, <cf/SCOPE_LINK/ for those specific for a physical link, <cf/SCOPE_SITE/ and <cf/SCOPE_ORGANIZATION/ for private routes and @@ -1317,33 +1333,33 @@ clist for most purposes. interpreted by BIRD and can be used to mark routes in filters. The default value for new routes is <cf/SCOPE_UNIVERSE/. - <tag><m/int/ preference</tag> + <tag><label id="rta-preference"><m/int/ preference</tag> Preference of the route. Valid values are 0-65535. (See the chapter about routing tables.) - <tag><m/ip/ from</tag> + <tag><label id="rta-from"><m/ip/ from</tag> The router which the route has originated from. - <tag><m/ip/ gw</tag> + <tag><label id="rta-gw"><m/ip/ gw</tag> Next hop packets routed using this route should be forwarded to. - <tag><m/string/ proto</tag> + <tag><label id="rta-proto"><m/string/ proto</tag> The name of the protocol which the route has been imported from. Read-only. - <tag><m/enum/ source</tag> + <tag><label id="rta-source"><m/enum/ source</tag> what protocol has told me about this route. Possible values: <cf/RTS_DUMMY/, <cf/RTS_STATIC/, <cf/RTS_INHERIT/, <cf/RTS_DEVICE/, <cf/RTS_STATIC_DEVICE/, <cf/RTS_REDIRECT/, <cf/RTS_RIP/, <cf/RTS_OSPF/, <cf/RTS_OSPF_IA/, <cf/RTS_OSPF_EXT1/, <cf/RTS_OSPF_EXT2/, <cf/RTS_BGP/, <cf/RTS_PIPE/, <cf/RTS_BABEL/. - <tag><m/enum/ cast</tag> + <tag><label id="rta-cast"><m/enum/ cast</tag> Route type (Currently <cf/RTC_UNICAST/ for normal routes, <cf/RTC_BROADCAST/, <cf/RTC_MULTICAST/, <cf/RTC_ANYCAST/ will be used in the future for broadcast, multicast and anycast routes). Read-only. - <tag><m/enum/ dest</tag> + <tag><label id="rta-dest"><m/enum/ dest</tag> Type of destination the packets should be sent to (<cf/RTD_ROUTER/ for forwarding to a neighboring router, <cf/RTD_DEVICE/ for routing to a directly-connected network, @@ -1354,18 +1370,18 @@ clist for most purposes. messages). Can be changed, but only to <cf/RTD_BLACKHOLE/, <cf/RTD_UNREACHABLE/ or <cf/RTD_PROHIBIT/. - <tag><m/string/ ifname</tag> + <tag><label id="rta-ifname"><m/string/ ifname</tag> Name of the outgoing interface. Sink routes (like blackhole, unreachable or prohibit) and multipath routes have no interface associated with them, so <cf/ifname/ returns an empty string for such routes. Read-only. - <tag><m/int/ ifindex</tag> + <tag><label id="rta-ifindex"><m/int/ ifindex</tag> Index of the outgoing interface. System wide index of the interface. May be used for interface matching, however indexes might change on interface creation/removal. Zero is returned for routes with undefined outgoing interfaces. Read-only. - <tag><m/int/ igp_metric</tag> + <tag><label id="rta-igp-metric"><m/int/ igp_metric</tag> The optional attribute that can be used to specify a distance to the network for routes that do not have a native protocol metric attribute (like <cf/ospf_metric1/ for OSPF routes). It is used mainly by BGP to @@ -1379,34 +1395,38 @@ corresponding protocol sections. <sect>Other statements +<label id="other-statements"> <p>The following statements are available: <descrip> - <tag><m/variable/ = <m/expr/</tag> + <tag><label id="assignment"><m/variable/ = <m/expr/</tag> Set variable to a given value. - <tag>accept|reject [ <m/expr/ ]</tag> + <tag><label id="filter-accept-reject">accept|reject [ <m/expr/ ]</tag> Accept or reject the route, possibly printing <cf><m>expr</m></cf>. - <tag>return <m/expr/</tag> + <tag><label id="return">return <m/expr/</tag> Return <cf><m>expr</m></cf> from the current function, the function ends at this point. - <tag>print|printn <m/expr/ [<m/, expr.../]</tag> + <tag><label id="print">print|printn <m/expr/ [<m/, expr.../]</tag> Prints given expressions; useful mainly while debugging filters. The <cf/printn/ variant does not terminate the line. - <tag>quitbird</tag> + <tag><label id="quitbird">quitbird</tag> Terminates BIRD. Useful when debugging the filter interpreter. </descrip> <chapt>Protocols +<label id="protocols"> <sect>Babel +<label id="babel"> <sect1>Introduction +<label id="babel-intro"> <p>The Babel protocol (RFC6126) is a loop-avoiding distance-vector routing protocol that is robust and efficient both in ordinary wired networks and in @@ -1423,6 +1443,7 @@ just ignore extension messages). <p>The Babel protocol implementation in BIRD is currently in alpha stage. <sect1>Configuration +<label id="babel-config"> <p>Babel supports no global configuration options apart from those common to all other protocols, but supports the following per-interface configuration options: @@ -1445,7 +1466,7 @@ protocol babel [<name>] { </code> <descrip> - <tag>type wired|wireless </tag> + <tag><label id="babel-type">type wired|wireless </tag> This option specifies the interface type: Wired or wireless. Wired interfaces are considered more reliable, and so the default hello interval is higher, and a neighbour is considered unreachable after only @@ -1456,41 +1477,41 @@ protocol babel [<name>] { when packets are lost rather than the more binary up/down mechanism of wired type links. Default: <cf/wired/. - <tag>rxcost <m/num/</tag> + <tag><label id="babel-rxcost">rxcost <m/num/</tag> This specifies the RX cost of the interface. The route metrics will be computed from this value with a mechanism determined by the interface <cf/type/. Default: 96 for wired interfaces, 256 for wireless. - <tag>hello interval <m/num/</tag> + <tag><label id="babel-hello">hello interval <m/num/</tag> Interval at which periodic "hello" messages are sent on this interface, in seconds. Default: 4 seconds. - <tag>update interval <m/num/</tag> + <tag><label id="babel-update">update interval <m/num/</tag> Interval at which periodic (full) updates are sent. Default: 4 times the hello interval. - <tag>port <m/number/</tag> + <tag><label id="babel-port">port <m/number/</tag> This option selects an UDP port to operate on. The default is to operate on port 6696 as specified in the Babel RFC. - <tag>tx class|dscp|priority <m/number/</tag> + <tag><label id="babel-tx-class">tx class|dscp|priority <m/number/</tag> These options specify the ToS/DiffServ/Traffic class/Priority of the - outgoing Babel packets. See <ref id="dsc-prio" name="tx class"> common + outgoing Babel packets. See <ref id="proto-tx-class" name="tx class"> common option for detailed description. - <tag>rx buffer <m/number/</tag> + <tag><label id="babel-rx-buffer">rx buffer <m/number/</tag> This option specifies the size of buffers used for packet processing. The buffer size should be bigger than maximal size of received packets. The default value is the interface MTU, and the value will be clamped to a minimum of 512 bytes + IP packet overhead. - <tag>tx length <m/number/</tag> + <tag><label id="babel-tx-length">tx length <m/number/</tag> This option specifies the maximum length of generated Babel packets. To avoid IP fragmentation, it should not exceed the interface MTU value. The default value is the interface MTU value, and the value will be clamped to a minimum of 512 bytes + IP packet overhead. - <tag>check link <m/switch/</tag> + <tag><label id="babel-check-link">check link <m/switch/</tag> If set, the hardware link state (as reported by OS) is taken into consideration. When the link disappears (e.g. an ethernet cable is unplugged), neighbors are immediately considered unreachable and all @@ -1500,12 +1521,14 @@ protocol babel [<name>] { </descrip> <sect1>Attributes +<label id="babel-attr"> <p>Babel defines just one attribute: the internal babel metric of the route. It is exposed as the <cf/babel_metric/ attribute and has range from 1 to infinity (65535). <sect1>Example +<label id="babel-exam"> <p><code> protocol babel { @@ -1529,9 +1552,10 @@ protocol babel { <sect>BFD -<label id="sect-bfd"> +<label id="bfd"> <sect1>Introduction +<label id="bfd-intro"> <p>Bidirectional Forwarding Detection (BFD) is not a routing protocol itself, it is an independent tool providing liveness and failure detection. Routing @@ -1569,6 +1593,7 @@ default a bit different dynamic port range than the IANA approved one <cf>/proc/sys/net/ipv4/ip_local_port_range</cf> <sect1>Configuration +<label id="bfd-config"> <p>BFD configuration consists mainly of multiple definitions of interfaces. Most BFD config options are session specific. When a new session is requested @@ -1610,22 +1635,22 @@ protocol bfd [<name>] { </code> <descrip> - <tag>interface <m/pattern [, ...]/ { <m/options/ }</tag> + <tag><label id="bfd-iface">interface <m/pattern [, ...]/ { <m/options/ }</tag> Interface definitions allow to specify options for sessions associated with such interfaces and also may contain interface specific options. - See <ref id="dsc-iface" name="interface"> common option for a detailed + See <ref id="proto-iface" name="interface"> common option for a detailed description of interface patterns. Note that contrary to the behavior of <cf/interface/ definitions of other protocols, BFD protocol would accept sessions (in default configuration) even on interfaces not covered by such definitions. - <tag>multihop { <m/options/ }</tag> + <tag><label id="bfd-multihop">multihop { <m/options/ }</tag> Multihop definitions allow to specify options for multihop BFD sessions, in the same manner as <cf/interface/ definitions are used for directly connected sessions. Currently only one such definition (for all multihop sessions) could be used. - <tag>neighbor <m/ip/ [dev "<m/interface/"] [local <m/ip/] [multihop <m/switch/]</tag> + <tag><label id="bfd-neighbor">neighbor <m/ip/ [dev "<m/interface/"] [local <m/ip/] [multihop <m/switch/]</tag> BFD sessions are usually created on demand as requested by other protocols (like OSPF or BGP). This option allows to explicitly add a BFD session to the specified neighbor regardless of such requests. @@ -1640,33 +1665,33 @@ protocol bfd [<name>] { <p>Session specific options (part of <cf/interface/ and <cf/multihop/ definitions): <descrip> - <tag>interval <m/time/</tag> + <tag><label id="bfd-interval">interval <m/time/</tag> BFD ensures availability of the forwarding path associated with the session by periodically sending BFD control packets in both directions. The rate of such packets is controlled by two options, <cf/min rx interval/ and <cf/min tx interval/ (see below). This option is just a shorthand to set both of these options together. - <tag>min rx interval <m/time/</tag> + <tag><label id="bfd-min-rx-interval">min rx interval <m/time/</tag> This option specifies the minimum RX interval, which is announced to the neighbor and used there to limit the neighbor's rate of generated BFD control packets. Default: 10 ms. - <tag>min tx interval <m/time/</tag> + <tag><label id="bfd-min-tx-interval">min tx interval <m/time/</tag> This option specifies the desired TX interval, which controls the rate of generated BFD control packets (together with <cf/min rx interval/ announced by the neighbor). Note that this value is used only if the BFD session is up, otherwise the value of <cf/idle tx interval/ is used instead. Default: 100 ms. - <tag>idle tx interval <m/time/</tag> + <tag><label id="bfd-idle-tx-interval">idle tx interval <m/time/</tag> In order to limit unnecessary traffic in cases where a neighbor is not available or not running BFD, the rate of generated BFD control packets is lower when the BFD session is not up. This option specifies the desired TX interval in such cases instead of <cf/min tx interval/. Default: 1 s. - <tag>multiplier <m/num/</tag> + <tag><label id="bfd-multiplier">multiplier <m/num/</tag> Failure detection time for BFD sessions is based on established rate of BFD control packets (<cf>min rx/tx interval</cf>) multiplied by this multiplier, which is essentially (ignoring jitter) a number of missed @@ -1674,7 +1699,7 @@ protocol bfd [<name>] { multipliers could be different in each direction of a BFD session. Default: 5. - <tag>passive <m/switch/</tag> + <tag><label id="bfd-passive">passive <m/switch/</tag> Generally, both BFD session endpoints try to establish the session by sending control packets to the other side. This option allows to enable passive mode, which means that the router does not send BFD packets @@ -1682,6 +1707,7 @@ protocol bfd [<name>] { </descrip> <sect1>Example +<label id="bfd-exam"> <p><code> protocol bfd { @@ -1708,6 +1734,7 @@ protocol bfd { <sect>BGP +<label id="bgp"> <p>The Border Gateway Protocol is the routing protocol used for backbone level routing in the today's Internet. Contrary to other protocols, its convergence @@ -1758,6 +1785,7 @@ and applied to IPv6 according to RFC 2545<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc2545.txt">. <sect1>Route selection rules +<label id="bgp-route-select-rules"> <p>BGP doesn't have any simple metric, so the rules for selection of an optimal route among multiple BGP routes with the same preference are a bit more complex @@ -1777,6 +1805,7 @@ choose among them and so on. </itemize> <sect1>IGP routing table +<label id="bgp-igp-routing-table"> <p>BGP is mainly concerned with global network reachability and with routes to other autonomous systems. When such routes are redistributed to routers in the @@ -1787,13 +1816,14 @@ boundary routers for the purpose of BGP route selection. In BIRD, there is usually one routing table used for both IGP routes and BGP routes. <sect1>Configuration +<label id="bgp-config"> <p>Each instance of the BGP corresponds to one neighboring router. This allows to set routing policy and all the other parameters differently for each neighbor using the following configuration parameters: <descrip> - <tag>local [<m/ip/] as <m/number/</tag> + <tag><label id="bgp-local">local [<m/ip/] as <m/number/</tag> Define which AS we are part of. (Note that contrary to other IP routers, BIRD is able to act as a router located in multiple AS'es simultaneously, but in such cases you need to tweak the BGP paths manually in the filters @@ -1801,7 +1831,7 @@ using the following configuration parameters: address, equivalent to the <cf/source address/ option (see below). This parameter is mandatory. - <tag>neighbor [<m/ip/] [port <m/number/] [as <m/number/]</tag> + <tag><label id="bgp-neighbor">neighbor [<m/ip/] [port <m/number/] [as <m/number/]</tag> Define neighboring router this instance will be talking to and what AS it is located in. In case the neighbor is in the same AS as we are, we automatically switch to iBGP. Optionally, the remote port may also be @@ -1810,20 +1840,20 @@ using the following configuration parameters: <cf/neighbor 10.0.0.1; neighbor as 65000;/ are valid). This parameter is mandatory. - <tag>interface <m/string/</tag> + <tag><label id="bgp-iface">interface <m/string/</tag> Define interface we should use for link-local BGP IPv6 sessions. Interface can also be specified as a part of <cf/neighbor address/ (e.g., <cf/neighbor fe80::1234%eth0 as 65000;/). It is an error to use this parameter for non link-local sessions. - <tag>direct</tag> + <tag><label id="bgp-direct">direct</tag> Specify that the neighbor is directly connected. The IP address of the neighbor must be from a directly reachable IP range (i.e. associated with one of your router's interfaces), otherwise the BGP session wouldn't start but it would wait for such interface to appear. The alternative is the <cf/multihop/ option. Default: enabled for eBGP. - <tag>multihop [<m/number/]</tag> + <tag><label id="bgp-multihop">multihop [<m/number/]</tag> Configure multihop BGP session to a neighbor that isn't directly connected. Accurately, this option should be used if the configured neighbor IP address does not match with any local network subnets. Such @@ -1835,22 +1865,22 @@ using the following configuration parameters: path is counted; i.e., if two BGP speakers are separated by one router, the number of hops is 2. Default: enabled for iBGP. - <tag>source address <m/ip/</tag> + <tag><label id="bgp-source-address">source address <m/ip/</tag> Define local address we should use for next hop calculation and as a source address for the BGP session. Default: the address of the local end of the interface our neighbor is connected to. - <tag>next hop self</tag> + <tag><label id="bgp-next-hop-self">next hop self</tag> Avoid calculation of the Next Hop attribute and always advertise our own source address as a next hop. This needs to be used only occasionally to circumvent misconfigurations of other routers. Default: disabled. - <tag>next hop keep</tag> + <tag><label id="bgp-next-hop-keep">next hop keep</tag> Forward the received Next Hop attribute even in situations where the local address should be used instead, like when the route is sent to an interface with a different subnet. Default: disabled. - <tag>missing lladdr self|drop|ignore</tag> + <tag><label id="bgp-missing-lladdr">missing lladdr self|drop|ignore</tag> Next Hop attribute in BGP-IPv6 sometimes contains just the global IPv6 address, but sometimes it has to contain both global and link-local IPv6 addresses. This option specifies what to do if BIRD have to send both @@ -1864,7 +1894,7 @@ using the following configuration parameters: route server (option <cf/rs client/), in that case default is <cf/ignore/, because route servers usually do not forward packets themselves. - <tag>gateway direct|recursive</tag> + <tag><label id="bgp-gateway">gateway direct|recursive</tag> For received routes, their <cf/gw/ (immediate next hop) attribute is computed from received <cf/bgp_next_hop/ attribute. This option specifies how it is computed. Direct mode means that the IP address from @@ -1879,31 +1909,31 @@ using the following configuration parameters: standard. Direct mode is simpler, does not require any routes in a routing table, and was used in older versions of BIRD, but does not handle well nontrivial iBGP setups and multihop. Recursive mode is - incompatible with <ref id="dsc-sorted" name="sorted tables">. Default: + incompatible with <ref id="dsc-table-sorted" name="sorted tables">. Default: <cf/direct/ for direct sessions, <cf/recursive/ for multihop sessions. - <tag>igp table <m/name/</tag> + <tag><label id="bgp-igp-table">igp table <m/name/</tag> Specifies a table that is used as an IGP routing table. Default: the same as the table BGP is connected to. - <tag>check link <M>switch</M></tag> + <tag><label id="bgp-check-link">check link <M>switch</M></tag> BGP could use hardware link state into consideration. If enabled, BIRD tracks the link state of the associated interface and when link disappears (e.g. an ethernet cable is unplugged), the BGP session is immediately shut down. Note that this option cannot be used with multihop BGP. Default: disabled. - <tag>bfd <M>switch</M></tag> + <tag><label id="bgp-bfd">bfd <M>switch</M></tag> BGP could use BFD protocol as an advisory mechanism for neighbor liveness and failure detection. If enabled, BIRD setups a BFD session for the BGP neighbor and tracks its liveness by it. This has an advantage of an order of magnitude lower detection times in case of failure. Note that BFD protocol also has to be configured, see - <ref id="sect-bfd" name="BFD"> section for details. Default: disabled. + <ref id="bfd" name="BFD"> section for details. Default: disabled. - <tag>ttl security <m/switch/</tag> + <tag><label id="bgp-ttl-security">ttl security <m/switch/</tag> Use GTSM (RFC 5082 - the generalized TTL security mechanism). GTSM - protects against spoofed packets by ignoring received packets with a + protects against spoofed packets by ignoring doc/bird.sgmlreceived packets with a smaller than expected TTL. To work properly, GTSM have to be enabled on both sides of a BGP session. If both <cf/ttl security/ and <cf/multihop/ options are enabled, <cf/multihop/ option should specify proper hop @@ -1912,12 +1942,12 @@ using the following configuration parameters: (ICMP protection, for example) RFC 5082 support is provided by Linux only. Default: disabled. - <tag>password <m/string/</tag> + <tag><label id="bgp-pass">password <m/string/</tag> Use this password for MD5 authentication of BGP sessions (RFC 2385). When used on BSD systems, see also <cf/setkey/ option below. Default: no authentication. - <tag>setkey <m/switch/</tag> + <tag><label id="bgp-setkey">setkey <m/switch/</tag> On BSD systems, keys for TCP MD5 authentication are stored in the global SA/SP database, which can be accessed by external utilities (e.g. setkey(8)). BIRD configures security associations in the SA/SP database @@ -1928,16 +1958,16 @@ using the following configuration parameters: set manually by an external utility on NetBSD and OpenBSD. Default: enabled (ignored on non-FreeBSD). - <tag>passive <m/switch/</tag> + <tag><label id="bgp-passive">passive <m/switch/</tag> Standard BGP behavior is both initiating outgoing connections and - accepting incoming connections. In passive mode, outgoing connections + accepting incoming connections. In passive modoc/bird.sgmlde, outgoing connections are not initiated. Default: off. - <tag>rr client</tag> + <tag><label id="bgp-rr-client">rr client</tag> Be a route reflector and treat the neighbor as a route reflection client. Default: disabled. - <tag>rr cluster id <m/IPv4 address/</tag> + <tag><label id="bgp-rr-cluster-id">rr cluster id <m/IPv4 address/</tag> Route reflectors use cluster id to avoid route reflection loops. When there is one route reflector in a cluster it usually uses its router id as a cluster id, but when there are more route reflectors in a cluster, @@ -1945,7 +1975,7 @@ using the following configuration parameters: id. Clients in a cluster need not know their cluster id and this option is not allowed for them. Default: the same as router id. - <tag>rs client</tag> + <tag><label id="bgp-rs-client">rs client</tag> Be a route server and treat the neighbor as a route server client. A route server is used as a replacement for full mesh EBGP routing in Internet exchange points in a similar way to route reflectors used in @@ -1955,16 +1985,16 @@ using the following configuration parameters: example does not prepend its AS number to AS PATH attribute and keeps MED attribute). Default: disabled. - <tag>secondary <m/switch/</tag> + <tag><label id="bgp-secondary">secondary <m/switch/</tag> Usually, if an export filter rejects a selected route, no other route is propagated for that network. This option allows to try the next route in order until one that is accepted is found or all routes for that network are rejected. This can be used for route servers that need to propagate different tables to each client but do not want to have these tables explicitly (to conserve memory). This option requires that the connected - routing table is <ref id="dsc-sorted" name="sorted">. Default: off. + routing table is <ref id="dsc-table-sorted" name="sorted">. Default: off. - <tag>add paths <m/switch/|rx|tx</tag> + <tag><label id="bgp-add-paths">add paths <m/switch/|rx|tx</tag> Standard BGP can propagate only one path (route) per destination network (usually the selected one). This option controls the add-path protocol extension, which allows to advertise any number of paths to a @@ -1973,7 +2003,7 @@ using the following configuration parameters: TX direction. When active, all available routes accepted by the export filter are advertised to the neighbor. Default: off. - <tag>allow local as [<m/number/]</tag> + <tag><label id="bgp-allow-local-as">allow local as [<m/number/]</tag> BGP prevents routing loops by rejecting received routes with the local AS number in the AS path. This option allows to loose or disable the check. Optional <cf/number/ argument can be used to specify the maximum @@ -1982,7 +2012,7 @@ using the following configuration parameters: completely disabled and you should ensure loop-free behavior by some other means. Default: 0 (no local AS number allowed). - <tag>enable route refresh <m/switch/</tag> + <tag><label id="bgp-enable-route-refresh">enable route refresh <m/switch/</tag> After the initial route exchange, BGP protocol uses incremental updates to keep BGP speakers synchronized. Sometimes (e.g., if BGP speaker changes its import filter, or if there is suspicion of inconsistency) it @@ -1995,7 +2025,7 @@ using the following configuration parameters: capabilities and supports related procedures. Note that even when disabled, BIRD can send route refresh requests. Default: on. - <tag>graceful restart <m/switch/|aware</tag> + <tag><label id="bgp-graceful-restart">graceful restart <m/switch/|aware</tag> When a BGP speaker restarts or crashes, neighbors will discard all received paths from the speaker, which disrupts packet forwarding even when the forwarding plane of the speaker remains intact. RFC 4724 @@ -2009,13 +2039,13 @@ using the following configuration parameters: local graceful restart requires also configuration of other protocols. Default: aware. - <tag>graceful restart time <m/number/</tag> + <tag><label id="bgp-graceful-restart-time">graceful restart time <m/number/</tag> The restart time is announced in the BGP graceful restart capability and specifies how long the neighbor would wait for the BGP session to re-establish after a restart before deleting stale routes. Default: 120 seconds. - <tag>interpret communities <m/switch/</tag> + <tag><label id="bgp-interpret-communities">interpret communities <m/switch/</tag> RFC 1997 demands that BGP speaker should process well-known communities like no-export (65535, 65281) or no-advertise (65535, 65282). For example, received route carrying a no-adverise community should not be @@ -2026,7 +2056,7 @@ using the following configuration parameters: disabled. In that case, similar behavior can be implemented in the export filter. Default: on. - <tag>enable as4 <m/switch/</tag> + <tag><label id="bgp-enable-as4">enable as4 <m/switch/</tag> BGP protocol was designed to use 2B AS numbers and was extended later to allow 4B AS number. BIRD supports 4B AS extension, but by disabling this option it can be persuaded not to advertise it and to maintain old-style @@ -2034,12 +2064,12 @@ using the following configuration parameters: in neighbor's implementation of 4B AS extension. Even when disabled (off), BIRD behaves internally as AS4-aware BGP router. Default: on. - <tag>enable extended messages <m/switch/</tag> + <tag><label id="bgp-enable-extended-messages">enable extended messages <m/switch/</tag> The BGP protocol uses maximum message length of 4096 bytes. This option provides an extension to allow extended messages with length up to 65535 bytes. Default: off. - <tag>capabilities <m/switch/</tag> + <tag><label id="bgp-capabilities">capabilities <m/switch/</tag> Use capability advertisement to advertise optional capabilities. This is standard behavior for newer BGP implementations, but there might be some older BGP implementations that reject such connection attempts. When @@ -2047,64 +2077,64 @@ using the following configuration parameters: disabled. Default: on, with automatic fallback to off when received capability-related error. - <tag>advertise ipv4 <m/switch/</tag> + <tag><label id="bgp-advertise-ipv4">advertise ipv4 <m/switch/</tag> Advertise IPv4 multiprotocol capability. This is not a correct behavior according to the strict interpretation of RFC 4760, but it is widespread and required by some BGP implementations (Cisco and Quagga). This option is relevant to IPv4 mode with enabled capability advertisement only. Default: on. - <tag>route limit <m/number/</tag> + <tag><label id="bgp-route-limit">route limit <m/number/</tag> The maximal number of routes that may be imported from the protocol. If the route limit is exceeded, the connection is closed with an error. Limit is currently implemented as <cf>import limit <m/number/ action restart</cf>. This option is obsolete and it is replaced by - <ref id="import-limit" name="import limit option">. Default: no limit. + <ref id="proto-import-limit" name="import limit option">. Default: no limit. - <tag>disable after error <m/switch/</tag> + <tag><label id="bgp-disable-after-error">disable after error <m/switch/</tag> When an error is encountered (either locally or by the other side), disable the instance automatically and wait for an administrator to fix the problem manually. Default: off. - <tag>hold time <m/number/</tag> + <tag><label id="bgp-hold-time">hold time <m/number/</tag> Time in seconds to wait for a Keepalive message from the other side before considering the connection stale. Default: depends on agreement with the neighboring router, we prefer 240 seconds if the other side is willing to accept it. - <tag>startup hold time <m/number/</tag> + <tag><label id="bgp-startup-hold-time">startup hold time <m/number/</tag> Value of the hold timer used before the routers have a chance to exchange open messages and agree on the real value. Default: 240 seconds. - <tag>keepalive time <m/number/</tag> + <tag><label id="bgp-keepalive-time">keepalive time <m/number/</tag> Delay in seconds between sending of two consecutive Keepalive messages. Default: One third of the hold time. - <tag>connect delay time <m/number/</tag> + <tag><label id="bgp-connect-delay-time">connect delay time <m/number/</tag> Delay in seconds between protocol startup and the first attempt to connect. Default: 5 seconds. - <tag>connect retry time <m/number/</tag> + <tag><label id="bgp-connect-retry-time">connect retry time <m/number/</tag> Time in seconds to wait before retrying a failed attempt to connect. Default: 120 seconds. - <tag>error wait time <m/number/,<m/number/</tag> + <tag><label id="bgp-error-wait-time">error wait time <m/number/,<m/number/</tag> Minimum and maximum delay in seconds between a protocol failure (either local or reported by the peer) and automatic restart. Doesn't apply when <cf/disable after error/ is configured. If consecutive errors happen, the delay is increased exponentially until it reaches the maximum. Default: 60, 300. - <tag>error forget time <m/number/</tag> + <tag><label id="bgp-error-forget-time">error forget time <m/number/</tag> Maximum time in seconds between two protocol failures to treat them as a error sequence which makes <cf/error wait time/ increase exponentially. Default: 300 seconds. - <tag>path metric <m/switch/</tag> + <tag><label id="bgp-path-metric">path metric <m/switch/</tag> Enable comparison of path lengths when deciding which BGP route is the best one. Default: on. - <tag>med metric <m/switch/</tag> + <tag><label id="bgp-med-metric">med metric <m/switch/</tag> Enable comparison of MED attributes (during best route selection) even between routes received from different ASes. This may be useful if all MED attributes contain some consistent metric, perhaps enforced in @@ -2112,7 +2142,7 @@ using the following configuration parameters: attributes are compared only if routes are received from the same AS (which is the standard behavior). Default: off. - <tag>deterministic med <m/switch/</tag> + <tag><label id="bgp-deterministic-med">deterministic med <m/switch/</tag> BGP route selection algorithm is often viewed as a comparison between individual routes (e.g. if a new route appears and is better than the current best one, it is chosen as the new best one). But the proper @@ -2124,23 +2154,23 @@ using the following configuration parameters: option enables a different (and slower) algorithm implementing proper RFC 4271 route selection, which is deterministic. Alternative way how to get deterministic behavior is to use <cf/med metric/ option. This option - is incompatible with <ref id="dsc-sorted" name="sorted tables">. + is incompatible with <ref id="dsc-table-sorted" name="sorted tables">. Default: off. - <tag>igp metric <m/switch/</tag> + <tag><label id="bgp-igp-metric">igp metric <m/switch/</tag> Enable comparison of internal distances to boundary routers during best route selection. Default: on. - <tag>prefer older <m/switch/</tag> + <tag><label id="bgp-prefer-older">prefer older <m/switch/</tag> Standard route selection algorithm breaks ties by comparing router IDs. This changes the behavior to prefer older routes (when both are external and from different peer). For details, see RFC 5004. Default: off. - <tag>default bgp_med <m/number/</tag> + <tag><label id="bgp-default-med">default bgp_med <m/number/</tag> Value of the Multiple Exit Discriminator to be used during route selection when the MED attribute is missing. Default: 0. - <tag>default bgp_local_pref <m/number/</tag> + <tag><label id="bgp-default-local-pref">default bgp_local_pref <m/number/</tag> A default value for the Local Preference attribute. It is used when a new Local Preference attribute is attached to a route by the BGP protocol itself (for example, if a route is received through eBGP and @@ -2149,23 +2179,24 @@ using the following configuration parameters: </descrip> <sect1>Attributes +<label id="bgp-attr"> <p>BGP defines several route attributes. Some of them (those marked with `<tt/I/' in the table below) are available on internal BGP connections only, some of them (marked with `<tt/O/') are optional. <descrip> - <tag>bgppath <cf/bgp_path/</tag> + <tag><label id="rta-bgp-path">bgppath bgp_path/</tag> Sequence of AS numbers describing the AS path the packet will travel through when forwarded according to the particular route. In case of internal BGP it doesn't contain the number of the local AS. - <tag>int <cf/bgp_local_pref/ [I]</tag> + <tag><label id="rta-bgp-local-pref">int bgp_local_pref/ [I]</tag> Local preference value used for selection among multiple BGP routes (see the selection rules above). It's used as an additional metric which is propagated through the whole local AS. - <tag>int <cf/bgp_med/ [O]</tag> + <tag><label id="rta-bgp-med">int bgp_med/ [O]</tag> The Multiple Exit Discriminator of the route is an optional attribute which is used on external (inter-AS) links to convey to an adjacent AS the optimal entry point into the local AS. The received attribute is @@ -2176,20 +2207,20 @@ some of them (marked with `<tt/O/') are optional. external BGP instance. See RFC 4451<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4451.txt"> for further discussion of BGP MED attribute. - <tag>enum <cf/bgp_origin/</tag> + <tag><label id="rta-bgp-origin">enum bgp_origin/</tag> Origin of the route: either <cf/ORIGIN_IGP/ if the route has originated in an interior routing protocol or <cf/ORIGIN_EGP/ if it's been imported from the <tt>EGP</tt> protocol (nowadays it seems to be obsolete) or <cf/ORIGIN_INCOMPLETE/ if the origin is unknown. - <tag>ip <cf/bgp_next_hop/</tag> + <tag><label id="rta-bgp-next-hop">ip bgp_next_hop/</tag> Next hop to be used for forwarding of packets to this destination. On internal BGP connections, it's an address of the originating router if it's inside the local AS or a boundary router the packet will leave the AS through if it's an exterior route, so each BGP speaker within the AS has a chance to use the shortest interior path possible to this point. - <tag>void <cf/bgp_atomic_aggr/ [O]</tag> + <tag><label id="rta-bgp-atomic-aggr">void bgp_atomic_aggr/ [O]</tag> This is an optional attribute which carries no value, but the sole presence of which indicates that the route has been aggregated from multiple routes by some router on the path from the originator. @@ -2197,7 +2228,7 @@ some of them (marked with `<tt/O/') are optional. <!-- we don't handle aggregators right since they are of a very obscure type <tag>bgp_aggregator</tag> --> - <tag>clist <cf/bgp_community/ [O]</tag> + <tag><label id="rta-bgp-community">clist bgp_community/ [O]</tag> List of community values associated with the route. Each such value is a pair (represented as a <cf/pair/ data type inside the filters) of 16-bit integers, the first of them containing the number of the AS which @@ -2208,14 +2239,14 @@ some of them (marked with `<tt/O/') are optional. freedom about which community attributes it defines and what will their semantics be. - <tag>eclist <cf/bgp_ext_community/ [O]</tag> + <tag><label id="rta-bgp-ext-community">eclist bgp_ext_community/ [O]</tag> List of extended community values associated with the route. Extended communities have similar usage as plain communities, but they have an extended range (to allow 4B ASNs) and a nontrivial structure with a type field. Individual community values are represented using an <cf/ec/ data type inside the filters. - <tag>lclist <cf/bgp_large_community/ [O]</tag> + <tag><label id="rta-bgp-large-community">lclist <cf/bgp_large_community/ [O]</tag> List of large community values associated with the route. Large BGP communities is another variant of communities, but contrary to extended communities they behave very much the same way as regular communities, @@ -2223,17 +2254,18 @@ some of them (marked with `<tt/O/') are optional. Individual community values are represented using an <cf/lc/ data type inside the filters. - <tag>quad <cf/bgp_originator_id/ [I, O]</tag> + <tag><label id="rta-bgp-originator-id">quad bgp_originator_id/ [I, O]</tag> This attribute is created by the route reflector when reflecting the route and contains the router ID of the originator of the route in the local AS. - <tag>clist <cf/bgp_cluster_list/ [I, O]</tag> + <tag><label id="rta-bgp-cluster-list">clist bgp_cluster_list/ [I, O]</tag> This attribute contains a list of cluster IDs of route reflectors. Each route reflector prepends its cluster ID when reflecting the route. </descrip> <sect1>Example +<label id="bgp-exam"> <p><code> protocol bgp { @@ -2259,6 +2291,7 @@ protocol bgp { <sect>Device +<label id="device"> <p>The Device protocol is not a real routing protocol. It doesn't generate any routes and it only serves as a module for getting information about network @@ -2269,17 +2302,18 @@ protocol in the configuration since almost all other protocols require network interfaces to be defined for them to work with. <sect1>Configuration +<label id="device-config"> <p><descrip> - <tag>scan time <m/number/</tag> + <tag><label id="device-scan-time">scan time <m/number/</tag> Time in seconds between two scans of the network interface list. On systems where we are notified about interface status changes asynchronously (such as newer versions of Linux), we need to scan the list only in order to avoid confusion by lost notification messages, so the default time is set to a large value. - <tag>primary [ "<m/mask/" ] <m/prefix/</tag> + <tag><label id="device-primary">primary [ "<m/mask/" ] <m/prefix/</tag> If a network interface has more than one network address, BIRD has to choose one of them as a primary one. By default, BIRD chooses the lexicographically smallest address as the primary one. @@ -2307,6 +2341,7 @@ protocol device { <sect>Direct +<label id="direct"> <p>The Direct protocol is a simple generator of device routes for all the directly connected networks according to the list of interfaces provided by the @@ -2332,16 +2367,16 @@ on Linux systems BIRD cannot change non-BIRD route in the kernel routing table. <p>There are just few configuration options for the Direct protocol: <p><descrip> - <tag>interface <m/pattern [, ...]/</tag> + <tag><label id="direct-iface">interface <m/pattern [, ...]/</tag> By default, the Direct protocol will generate device routes for all the interfaces available. If you want to restrict it to some subset of interfaces or addresses (e.g. if you're using multiple routing tables for policy routing and some of the policy domains don't contain all - interfaces), just use this clause. See <ref id="dsc-iface" name="interface"> + interfaces), just use this clause. See <ref id="proto-iface" name="interface"> common option for detailed description. The Direct protocol uses extended interface clauses. - <tag>check link <m/switch/</tag> + <tag><label id="direct-check-link">check link <m/switch/</tag> If enabled, a hardware link state (reported by OS) is taken into consideration. Routes for directly connected networks are generated only if link up is reported and they are withdrawn when link disappears @@ -2360,6 +2395,7 @@ protocol direct { <sect>Kernel +<label id="krt"> <p>The Kernel protocol is not a real routing protocol. Instead of communicating with other routers in the network, it performs synchronization of BIRD's routing @@ -2392,34 +2428,35 @@ kernel protocols to the same routing table and changing route destination limitations can be overcome using another routing table and the pipe protocol. <sect1>Configuration +<label id="krt-config"> <p><descrip> - <tag>persist <m/switch/</tag> + <tag><label id="krt-persist">persist <m/switch/</tag> Tell BIRD to leave all its routes in the routing tables when it exits (instead of cleaning them up). - <tag>scan time <m/number/</tag> + <tag><label id="krt-scan-time">scan time <m/number/</tag> Time in seconds between two consecutive scans of the kernel routing table. - <tag>learn <m/switch/</tag> + <tag><label id="krt-learn">learn <m/switch/</tag> Enable learning of routes added to the kernel routing tables by other routing daemons or by the system administrator. This is possible only on systems which support identification of route authorship. - <tag>device routes <m/switch/</tag> + <tag><label id="krt-device-routes">device routes <m/switch/</tag> Enable export of device routes to the kernel routing table. By default, such routes are rejected (with the exception of explicitly configured device routes from the static protocol) regardless of the export filter to protect device routes in kernel routing table (managed by OS itself) from accidental overwriting or erasing. - <tag>kernel table <m/number/</tag> + <tag><label id="krt-kernel-table">kernel table <m/number/</tag> Select which kernel table should this particular instance of the Kernel protocol work with. Available only on systems supporting multiple routing tables. - <tag>metric <m/number/</tag> (Linux) + <tag><label id="krt-metric">metric <m/number/</tag> (Linux) Use specified value as a kernel metric (priority) for all routes sent to the kernel. When multiple routes for the same network are in the kernel routing table, the Linux kernel chooses one with lower metric. Also, @@ -2430,13 +2467,13 @@ limitations can be overcome using another routing table and the pipe protocol. or per-route metric can be set using <cf/krt_metric/ attribute. Default: 0 (undefined). - <tag>graceful restart <m/switch/</tag> + <tag><label id="krt-graceful-restart">graceful restart <m/switch/</tag> Participate in graceful restart recovery. If this option is enabled and a graceful restart recovery is active, the Kernel protocol will defer synchronization of routing tables until the end of the recovery. Note that import of kernel routes to BIRD is not affected. - <tag>merge paths <M>switch</M> [limit <M>number</M>]</tag> + <tag><label id="krt-merge-paths">merge paths <M>switch</M> [limit <M>number</M>]</tag> Usually, only best routes are exported to the kernel protocol. With path merging enabled, both best routes and equivalent non-best routes are merged during export to generate one ECMP (equal-cost multipath) route @@ -2450,32 +2487,33 @@ limitations can be overcome using another routing table and the pipe protocol. </descrip> <sect1>Attributes +<label id="krt-attr"> <p>The Kernel protocol defines several attributes. These attributes are translated to appropriate system (and OS-specific) route attributes. We support these attributes: <descrip> - <tag>int <cf/krt_source/</tag> + <tag><label id="rta-krt-source">int krt_source/</tag> The original source of the imported kernel route. The value is system-dependent. On Linux, it is a value of the protocol field of the route. See /etc/iproute2/rt_protos for common values. On BSD, it is based on STATIC and PROTOx flags. The attribute is read-only. - <tag>int <cf/krt_metric/</tag> (Linux) + <tag><label id="rta-krt-metric">int krt_metric/</tag> (Linux) The kernel metric of the route. When multiple same routes are in a kernel routing table, the Linux kernel chooses one with lower metric. Note that preferred way to set kernel metric is to use protocol option <cf/metric/, unless per-route metric values are needed. - <tag>ip <cf/krt_prefsrc/</tag> (Linux) + <tag><label id="rta-krt-prefsrc">ip krt_prefsrc/</tag> (Linux) The preferred source address. Used in source address selection for outgoing packets. Has to be one of the IP addresses of the router. - <tag>int <cf/krt_realm/</tag> (Linux) + <tag><label id="rta-krt-realm">int krt_realm/</tag> (Linux) The realm of the route. Can be used for traffic classification. - <tag>int <cf/krt_scope/</tag> (Linux IPv4) + <tag><label id="rta-krt-scope">int krt_scope/</tag> (Linux IPv4) The scope of the route. Valid values are 0-254, although Linux kernel may reject some values depending on route type and nexthop. It is supposed to represent `indirectness' of the route, where nexthops of @@ -2500,6 +2538,7 @@ Supported attributes are: <cf/krt_feature_ecn/, <cf/krt_feature_allfrag/ <sect1>Example +<label id="krt-exam"> <p>A simple configuration can look this way: @@ -2529,8 +2568,10 @@ protocol kernel { # Secondary routing table <sect>OSPF +<label id="ospf"> <sect1>Introduction +<label id="ospf-intro"> <p>Open Shortest Path First (OSPF) is a quite complex interior gateway protocol. The current IPv4 version (OSPFv2) is defined in RFC 2328 @@ -2565,6 +2606,7 @@ identical by flooding updates. The flooding process is reliable and ensures that each router detects all changes. <sect1>Configuration +<label id="ospf-config"> <p>In the main part of configuration, there can be multiple definitions of OSPF areas, each with a different id. These definitions includes many other switches @@ -2658,12 +2700,12 @@ protocol ospf <name> { </code> <descrip> - <tag>rfc1583compat <M>switch</M></tag> + <tag><label id="ospf-rfc1583compat">rfc1583compat <M>switch</M></tag> This option controls compatibility of routing table calculation with RFC 1583 <htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc1583.txt">. Default value is no. - <tag>instance id <m/num/</tag> + <tag><label id="ospf-instance-id">instance id <m/num/</tag> When multiple OSPF protocol instances are active on the same links, they should use different instance IDs to distinguish their packets. Although it could be done on per-interface basis, it is often preferred to set @@ -2673,7 +2715,7 @@ protocol ospf <name> { interfaces of the OSPF instance. Note that this option, if used, must precede interface definitions. Default value is 0. - <tag>stub router <M>switch</M></tag> + <tag><label id="ospf-stub-router">stub router <M>switch</M></tag> This option configures the router to be a stub router, i.e., a router that participates in the OSPF topology but does not allow transit traffic. In OSPFv2, this is implemented by advertising maximum metric @@ -2682,13 +2724,13 @@ protocol ospf <name> { <htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc6987.txt"> for details. Default value is no. - <tag>tick <M>num</M></tag> + <tag><label id="ospf-tick">tick <M>num</M></tag> The routing table calculation and clean-up of areas' databases is not performed when a single link state change arrives. To lower the CPU utilization, it's processed later at periodical intervals of <m/num/ seconds. The default value is 1. - <tag>ecmp <M>switch</M> [limit <M>number</M>]</tag> + <tag><label id="ospf-ecmp">ecmp <M>switch</M> [limit <M>number</M>]</tag> This option specifies whether OSPF is allowed to generate ECMP (equal-cost multipath) routes. Such routes are used when there are several directions to the destination, each with the same (computed) @@ -2696,7 +2738,7 @@ protocol ospf <name> { nexthops in one route. By default, ECMP is disabled. If enabled, default value of the limit is 16. - <tag>merge external <M>switch</M></tag> + <tag><label id="ospf-merge-external">merge external <M>switch</M></tag> This option specifies whether OSPF should merge external routes from different routers/LSAs for the same destination. When enabled together with <cf/ecmp/, equal-cost external routes will be combined to multipath @@ -2704,18 +2746,18 @@ protocol ospf <name> { from different LSAs are treated as separate even if they represents the same destination. Default value is no. - <tag>area <M>id</M></tag> + <tag><label id="ospf-area">area <M>id</M></tag> This defines an OSPF area with given area ID (an integer or an IPv4 address, similarly to a router ID). The most important area is the backbone (ID 0) to which every other area must be connected. - <tag>stub</tag> + <tag><label id="ospf-stub">stub</tag> This option configures the area to be a stub area. External routes are not flooded into stub areas. Also summary LSAs can be limited in stub areas (see option <cf/summary/). By default, the area is not a stub area. - <tag>nssa</tag> + <tag><label id="ospf-nssa">nssa</tag> This option configures the area to be a NSSA (Not-So-Stubby Area). NSSA is a variant of a stub area which allows a limited way of external route propagation. Global external routes are not propagated into a NSSA, but @@ -2723,7 +2765,7 @@ protocol ospf <name> { (and possibly translated and/or aggregated on area boundary). By default, the area is not NSSA. - <tag>summary <M>switch</M></tag> + <tag><label id="ospf-summary">summary <M>switch</M></tag> This option controls propagation of summary LSAs into stub or NSSA areas. If enabled, summary LSAs are propagated as usual, otherwise just the default summary route (0.0.0.0/0) is propagated (this is sometimes @@ -2731,43 +2773,43 @@ protocol ospf <name> { routers, propagating summary LSAs could lead to more efficient routing at the cost of larger link state database. Default value is no. - <tag>default nssa <M>switch</M></tag> + <tag><label id="ospf-default-nssa">default nssa <M>switch</M></tag> When <cf/summary/ option is enabled, default summary route is no longer propagated to the NSSA. In that case, this option allows to originate default route as NSSA-LSA to the NSSA. Default value is no. - <tag>default cost <M>num</M></tag> + <tag><label id="ospf-default-cost">default cost <M>num</M></tag> This option controls the cost of a default route propagated to stub and NSSA areas. Default value is 1000. - <tag>default cost2 <M>num</M></tag> + <tag><label id="ospf-default-cost2">default cost2 <M>num</M></tag> When a default route is originated as NSSA-LSA, its cost can use either type 1 or type 2 metric. This option allows to specify the cost of a default route in type 2 metric. By default, type 1 metric (option <cf/default cost/) is used. - <tag>translator <M>switch</M></tag> + <tag><label id="ospf-translator">translator <M>switch</M></tag> This option controls translation of NSSA-LSAs into external LSAs. By default, one translator per NSSA is automatically elected from area boundary routers. If enabled, this area boundary router would unconditionally translate all NSSA-LSAs regardless of translator election. Default value is no. - <tag>translator stability <M>num</M></tag> + <tag><label id="ospf-translator-stability">translator stability <M>num</M></tag> This option controls the translator stability interval (in seconds). When the new translator is elected, the old one keeps translating until the interval is over. Default value is 40. - <tag>networks { <m/set/ }</tag> + <tag><label id="ospf-networks">networks { <m/set/ }</tag> Definition of area IP ranges. This is used in summary LSA origination. Hidden networks are not propagated into other areas. - <tag>external { <m/set/ }</tag> + <tag><label id="ospf-external">external { <m/set/ }</tag> Definition of external area IP ranges for NSSAs. This is used for NSSA-LSA translation. Hidden networks are not translated into external LSAs. Networks can have configured route tag. - <tag>stubnet <m/prefix/ { <m/options/ }</tag> + <tag><label id="ospf-stubnet">stubnet <m/prefix/ { <m/options/ }</tag> Stub networks are networks that are not transit networks between OSPF routers. They are also propagated through an OSPF area as a part of a link state database. By default, BIRD generates a stub network record @@ -2783,9 +2825,9 @@ protocol ospf <name> { that are subnetworks of given stub network are suppressed. This might be used, for example, to aggregate generated stub networks. - <tag>interface <M>pattern</M> [instance <m/num/]</tag> + <tag><label id="ospf-iface">interface <M>pattern</M> [instance <m/num/]</tag> Defines that the specified interfaces belong to the area being defined. - See <ref id="dsc-iface" name="interface"> common option for detailed + See <ref id="proto-iface" name="interface"> common option for detailed description. In OSPFv2, extended interface clauses are used, because each network prefix is handled as a separate virtual interface. @@ -2796,54 +2838,54 @@ protocol ospf <name> { <htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc6549.txt">) and is supposed to be set per-protocol. For OSPFv3, it is an integral feature. - <tag>virtual link <M>id</M> [instance <m/num/]</tag> + <tag><label id="ospf-virtual-link">virtual link <M>id</M> [instance <m/num/]</tag> Virtual link to router with the router id. Virtual link acts as a point-to-point interface belonging to backbone. The actual area is used as a transport area. This item cannot be in the backbone. Like with <cf/interface/ option, you could also use several virtual links to one destination with different instance IDs. - <tag>cost <M>num</M></tag> + <tag><label id="ospf-cost">cost <M>num</M></tag> Specifies output cost (metric) of an interface. Default value is 10. - <tag>stub <M>switch</M></tag> + <tag><label id="ospf-stub-iface">stub <M>switch</M></tag> If set to interface it does not listen to any packet and does not send any hello. Default value is no. - <tag>hello <M>num</M></tag> + <tag><label id="ospf-hello">hello <M>num</M></tag> Specifies interval in seconds between sending of Hello messages. Beware, all routers on the same network need to have the same hello interval. Default value is 10. - <tag>poll <M>num</M></tag> + <tag><label id="ospf-poll">poll <M>num</M></tag> Specifies interval in seconds between sending of Hello messages for some neighbors on NBMA network. Default value is 20. - <tag>retransmit <M>num</M></tag> + <tag><label id="ospf-retransmit">retransmit <M>num</M></tag> Specifies interval in seconds between retransmissions of unacknowledged updates. Default value is 5. - <tag>priority <M>num</M></tag> + <tag><label id="ospf-priority">priority <M>num</M></tag> On every multiple access network (e.g., the Ethernet) Designated Router and Backup Designated router are elected. These routers have some special functions in the flooding process. Higher priority increases preferences in this election. Routers with priority 0 are not eligible. Default value is 1. - <tag>wait <M>num</M></tag> + <tag><label id="ospf-wait">wait <M>num</M></tag> After start, router waits for the specified number of seconds between starting election and building adjacency. Default value is 4*<m/hello/. - <tag>dead count <M>num</M></tag> + <tag><label id="ospf-dead-count">dead count <M>num</M></tag> When the router does not receive any messages from a neighbor in <m/dead count/*<m/hello/ seconds, it will consider the neighbor down. - <tag>dead <M>num</M></tag> + <tag><label id="ospf-dead">dead <M>num</M></tag> When the router does not receive any messages from a neighbor in <m/dead/ seconds, it will consider the neighbor down. If both directives <cf/dead count/ and <cf/dead/ are used, <cf/dead/ has precedence. - <tag>secondary <M>switch</M></tag> + <tag><label id="ospf-secondary">secondary <M>switch</M></tag> On BSD systems, older versions of BIRD supported OSPFv2 only for the primary IP address of an interface, other IP ranges on the interface were handled as stub networks. Since v1.4.1, regular operation on @@ -2853,14 +2895,14 @@ protocol ospf <name> { behavior will be changed. On Linux systems, the option is irrelevant, as operation on non-primary addresses is already the regular behavior. - <tag>rx buffer <M>num</M></tag> + <tag><label id="ospf-rx-buffer">rx buffer <M>num</M></tag> This option allows to specify the size of buffers used for packet processing. The buffer size should be bigger than maximal size of any packets. By default, buffers are dynamically resized as needed, but a fixed value could be specified. Value <cf/large/ means maximal allowed packet size - 65535. - <tag>tx length <M>num</M></tag> + <tag><label id="ospf-tx-length">tx length <M>num</M></tag> Transmitted OSPF messages that contain large amount of information are segmented to separate OSPF packets to avoid IP fragmentation. This option specifies the soft ceiling for the length of generated OSPF @@ -2868,7 +2910,7 @@ protocol ospf <name> { larger OSPF packets may still be generated if underlying OSPF messages cannot be splitted (e.g. when one large LSA is propagated). - <tag>type broadcast|bcast</tag> + <tag><label id="ospf-type-bcast">type broadcast|bcast</tag> BIRD detects a type of a connected network automatically, but sometimes it's convenient to force use of a different type manually. On broadcast networks (like ethernet), flooding and Hello messages are sent using @@ -2878,7 +2920,7 @@ protocol ospf <name> { on physically NBMA networks and on unnumbered networks (networks without proper IP prefix). - <tag>type pointopoint|ptp</tag> + <tag><label id="ospf-type-ptp">type pointopoint|ptp</tag> Point-to-point networks connect just 2 routers together. No election is performed and no network LSA is originated, which makes it simpler and faster to establish. This network type is useful not only for physically @@ -2886,31 +2928,31 @@ protocol ospf <name> { as PtP links. This network type cannot be used on physically NBMA networks. - <tag>type nonbroadcast|nbma</tag> + <tag><label id="ospf-type-nbma">type nonbroadcast|nbma</tag> On NBMA networks, the packets are sent to each neighbor separately because of lack of multicast capabilities. Like on broadcast networks, a designated router is elected, which plays a central role in propagation of LSAs. This network type cannot be used on unnumbered networks. - <tag>type pointomultipoint|ptmp</tag> + <tag><label id="ospf-type-ptmp">type pointomultipoint|ptmp</tag> This is another network type designed to handle NBMA networks. In this case the NBMA network is treated as a collection of PtP links. This is useful if not every pair of routers on the NBMA network has direct communication, or if the NBMA network is used as an (possibly unnumbered) PtP link. - <tag>link lsa suppression <m/switch/</tag> + <tag><label id="ospf-link-lsa-suppression">link lsa suppression <m/switch/</tag> In OSPFv3, link LSAs are generated for each link, announcing link-local IPv6 address of the router to its local neighbors. These are useless on PtP or PtMP networks and this option allows to suppress the link LSA origination for such interfaces. The option is ignored on other than PtP or PtMP interfaces. Default value is no. - <tag>strict nonbroadcast <m/switch/</tag> + <tag><label id="ospf-strict-nonbroadcast">strict nonbroadcast <m/switch/</tag> If set, don't send hello to any undefined neighbor. This switch is ignored on other than NBMA or PtMP interfaces. Default value is no. - <tag>real broadcast <m/switch/</tag> + <tag><label id="ospf-real-broadcast">real broadcast <m/switch/</tag> In <cf/type broadcast/ or <cf/type ptp/ network configuration, OSPF packets are sent as IP multicast packets. This option changes the behavior to using old-fashioned IP broadcast packets. This may be useful @@ -2918,7 +2960,7 @@ protocol ospf <name> { not work reliably. This is a non-standard option and probably is not interoperable with other OSPF implementations. Default value is no. - <tag>ptp netmask <m/switch/</tag> + <tag><label id="ospf-ptp-netmask">ptp netmask <m/switch/</tag> In <cf/type ptp/ network configurations, OSPFv2 implementations should ignore received netmask field in hello packets and should send hello packets with zero netmask field on unnumbered PtP links. But some OSPFv2 @@ -2928,7 +2970,7 @@ protocol ospf <name> { compatibility problems related to this issue. Default value is no for unnumbered PtP links, yes otherwise. - <tag>check link <M>switch</M></tag> + <tag><label id="ospf-check-link">check link <M>switch</M></tag> If set, a hardware link state (reported by OS) is taken into consideration. When a link disappears (e.g. an ethernet cable is unplugged), neighbors are immediately considered unreachable and only the address of the iface @@ -2936,15 +2978,15 @@ protocol ospf <name> { some hardware drivers or platforms do not implement this feature. Default value is no. - <tag>bfd <M>switch</M></tag> + <tag><label id="ospf-bfd">bfd <M>switch</M></tag> OSPF could use BFD protocol as an advisory mechanism for neighbor liveness and failure detection. If enabled, BIRD setups a BFD session for each OSPF neighbor and tracks its liveness by it. This has an advantage of an order of magnitude lower detection times in case of failure. Note that BFD protocol also has to be configured, see - <ref id="sect-bfd" name="BFD"> section for details. Default value is no. + <ref id="bfd" name="BFD"> section for details. Default value is no. - <tag>ttl security [<m/switch/ | tx only]</tag> + <tag><label id="ospf-ttl-security">ttl security [<m/switch/ | tx only]</tag> TTL security is a feature that protects routing protocols from remote spoofed packets by using TTL 255 instead of TTL 1 for protocol packets destined to neighbors. Because TTL is decremented when packets are @@ -2957,35 +2999,35 @@ protocol ospf <name> { set to <cf/tx only/, TTL 255 is used for sent packets, but is not checked for received packets. Default value is no. - <tag>tx class|dscp|priority <m/num/</tag> + <tag><label id="ospf-tx-class">tx class|dscp|priority <m/num/</tag> These options specify the ToS/DiffServ/Traffic class/Priority of the - outgoing OSPF packets. See <ref id="dsc-prio" name="tx class"> common + outgoing OSPF packets. See <ref id="proto-tx-class" name="tx class"> common option for detailed description. - <tag>ecmp weight <M>num</M></tag> + <tag><label id="ospf-ecmp-weight">ecmp weight <M>num</M></tag> When ECMP (multipath) routes are allowed, this value specifies a relative weight used for nexthops going through the iface. Allowed values are 1-256. Default value is 1. - <tag>authentication none</tag> + <tag><label id="ospf-auth-none">authentication none</tag> No passwords are sent in OSPF packets. This is the default value. - <tag>authentication simple</tag> + <tag><label id="ospf-auth-simple">authentication simple</tag> Every packet carries 8 bytes of password. Received packets lacking this password are ignored. This authentication mechanism is very weak. - <tag>authentication cryptographic</tag> + <tag><label id="ospf-auth-cryptographic">authentication cryptographic</tag> 16-byte long MD5 digest is appended to every packet. For the digest generation 16-byte long passwords are used. Those passwords are not sent via network, so this mechanism is quite secure. Packets can still be read by an attacker. - <tag>password "<M>text</M>"</tag> + <tag><label id="ospf-pass">password "<M>text</M>"</tag> An 8-byte or 16-byte password used for authentication. See - <ref id="dsc-pass" name="password"> common option for detailed + <ref id="proto-pass" name="password"> common option for detailed description. - <tag>neighbors { <m/set/ } </tag> + <tag><label id="ospf-neighbors">neighbors { <m/set/ } </tag> A set of neighbors to which Hello messages on NBMA or PtMP networks are to be sent. For NBMA networks, some of them could be marked as eligible. In OSPFv3, link-local addresses should be used, using global ones is @@ -2994,6 +3036,7 @@ protocol ospf <name> { </descrip> <sect1>Attributes +<label id="ospf-attr"> <p>OSPF defines four route attributes. Each internal route has a <cf/metric/. @@ -3013,6 +3056,7 @@ network. This attribute is read-only. Default is <cf/ospf_metric2 = 10000/ and <cf/ospf_tag = 0/. <sect1>Example +<label id="ospf-exam"> <p><code> protocol ospf MyOSPF { @@ -3079,8 +3123,10 @@ protocol ospf MyOSPF { <sect>Pipe +<label id="pipe"> <sect1>Introduction +<label id="pipe-intro"> <p>The Pipe protocol serves as a link between two routing tables, allowing routes to be passed from a table declared as primary (i.e., the one the pipe is @@ -3115,21 +3161,24 @@ routes appear in which tables and also you can employ the Pipe protocol for exporting a selected subset of one table to another one. <sect1>Configuration +<label id="pipe-config"> <p><descrip> - <tag>peer table <m/table/</tag> + <tag><label id="pipe-peer-table">peer table <m/table/</tag> Defines secondary routing table to connect to. The primary one is selected by the <cf/table/ keyword. - <tag>mode opaque|transparent</tag> + <tag><label id="pipe-mode">mode opaque|transparent</tag> Specifies the mode for the pipe to work in. Default is transparent. </descrip> <sect1>Attributes +<label id="pipe-attr"> <p>The Pipe protocol doesn't define any route attributes. <sect1>Example +<label id="pipe-exam"> <p>Let's consider a router which serves as a boundary router of two different autonomous systems, each of them connected to a subset of interfaces of the @@ -3200,8 +3249,10 @@ protocol pipe { # The Pipe <sect>RAdv +<label id="radv"> <sect1>Introduction +<label id="radv-intro"> <p>The RAdv protocol is an implementation of Router Advertisements, which are used in the IPv6 stateless autoconfiguration. IPv6 routers send (in irregular @@ -3214,18 +3265,19 @@ and also the DNS extensions from RFC 6106<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc6106.txt">. <sect1>Configuration +<label id="radv-config"> <p>There are several classes of definitions in RAdv configuration -- interface definitions, prefix definitions and DNS definitions: <descrip> - <tag>interface <m/pattern [, ...]/ { <m/options/ }</tag> + <tag><label id="radv-iface">interface <m/pattern [, ...]/ { <m/options/ }</tag> Interface definitions specify a set of interfaces on which the protocol is activated and contain interface specific options. - See <ref id="dsc-iface" name="interface"> common options for + See <ref id="proto-iface" name="interface"> common options for detailed description. - <tag>prefix <m/prefix/ { <m/options/ }</tag> + <tag><label id="radv-prefix">prefix <m/prefix/ { <m/options/ }</tag> Prefix definitions allow to modify a list of advertised prefixes. By default, the advertised prefixes are the same as the network prefixes assigned to the interface. For each network prefix, the matching prefix @@ -3239,7 +3291,7 @@ definitions, prefix definitions and DNS definitions: prefix definition is matching if the network prefix is a subnet of the prefix in prefix definition. - <tag>rdnss { <m/options/ }</tag> + <tag><label id="radv-rdnss">rdnss { <m/options/ }</tag> RDNSS definitions allow to specify a list of advertised recursive DNS servers together with their options. As options are seldom necessary, there is also a short variant <cf>rdnss <m/address/</cf> that just @@ -3247,15 +3299,15 @@ definitions, prefix definitions and DNS definitions: definitions may also be interface-specific when used inside interface options. By default, interface uses both global and interface-specific options, but that can be changed by <cf/rdnss local/ option. - - <tag>dnssl { <m/options/ }</tag> +dsc-iface + <tag><label id="radv-dnssl">dnssl { <m/options/ }</tag> DNSSL definitions allow to specify a list of advertised DNS search domains together with their options. Like <cf/rdnss/ above, multiple definitions are cumulative, they can be used also as interface-specific options and there is a short variant <cf>dnssl <m/domain/</cf> that just specifies one DNS search domain. - <label id="dsc-trigger"> <tag>trigger <m/prefix/</tag> + <tag><label id="radv-trigger">trigger <m/prefix/</tag> RAdv protocol could be configured to change its behavior based on availability of routes. When this option is used, the protocol waits in suppressed state until a <it/trigger route/ (for the specified network) @@ -3277,99 +3329,99 @@ definitions, prefix definitions and DNS definitions: <p>Interface specific options: <descrip> - <tag>max ra interval <m/expr/</tag> + <tag><label id="radv-iface-max-ra-interval">max ra interval <m/expr/</tag> Unsolicited router advertisements are sent in irregular time intervals. This option specifies the maximum length of these intervals, in seconds. Valid values are 4-1800. Default: 600 - <tag>min ra interval <m/expr/</tag> + <tag><label id="radv-iface-min-ra-interval">min ra interval <m/expr/</tag> This option specifies the minimum length of that intervals, in seconds. Must be at least 3 and at most 3/4 * <cf/max ra interval/. Default: about 1/3 * <cf/max ra interval/. - <tag>min delay <m/expr/</tag> + <tag><label id="radv-iface-min-delay">min delay <m/expr/</tag> The minimum delay between two consecutive router advertisements, in seconds. Default: 3 - <tag>managed <m/switch/</tag> + <tag><label id="radv-iface-managed">managed <m/switch/</tag> This option specifies whether hosts should use DHCPv6 for IP address configuration. Default: no - <tag>other config <m/switch/</tag> + <tag><label id="radv-iface-other-config">other config <m/switch/</tag> This option specifies whether hosts should use DHCPv6 to receive other configuration information. Default: no - <tag>link mtu <m/expr/</tag> + <tag><label id="radv-iface-link-mtu">link mtu <m/expr/</tag> This option specifies which value of MTU should be used by hosts. 0 means unspecified. Default: 0 - <tag>reachable time <m/expr/</tag> + <tag><label id="radv-iface-reachable-time">reachable time <m/expr/</tag> This option specifies the time (in milliseconds) how long hosts should assume a neighbor is reachable (from the last confirmation). Maximum is 3600000, 0 means unspecified. Default 0. - <tag>retrans timer <m/expr/</tag> + <tag><label id="radv-iface-retrans-timer">retrans timer <m/expr/</tag> This option specifies the time (in milliseconds) how long hosts should wait before retransmitting Neighbor Solicitation messages. 0 means unspecified. Default 0. - <tag>current hop limit <m/expr/</tag> + <tag><label id="radv-iface-current-hop-limit">current hop limit <m/expr/</tag> This option specifies which value of Hop Limit should be used by hosts. Valid values are 0-255, 0 means unspecified. Default: 64 - <tag>default lifetime <m/expr/ [sensitive <m/switch/]</tag> + <tag><label id="radv-iface-default-lifetime">default lifetime <m/expr/ [sensitive <m/switch/]</tag> This option specifies the time (in seconds) how long (after the receipt of RA) hosts may use the router as a default router. 0 means do not use - as a default router. For <cf/sensitive/ option, see <ref id="dsc-trigger" name="trigger">. + as a default router. For <cf/sensitive/ option, see <ref id="radv-trigger" name="trigger">. Default: 3 * <cf/max ra interval/, <cf/sensitive/ yes. - <tag>default preference low|medium|high</tag> + <tag><label id="radv-iface-default-preference-low">default preference low|medium|high</tag> This option specifies the Default Router Preference value to advertise to hosts. Default: medium. - <tag>rdnss local <m/switch/</tag> + <tag><label id="radv-iface-rdnss-local">rdnss local <m/switch/</tag> Use only local (interface-specific) RDNSS definitions for this interface. Otherwise, both global and local definitions are used. Could also be used to disable RDNSS for given interface if no local definitons are specified. Default: no. - <tag>dnssl local <m/switch/</tag> + <tag><label id="radv-iface-dnssl-local">dnssl local <m/switch/</tag> Use only local DNSSL definitions for this interface. See <cf/rdnss local/ option above. Default: no. </descrip> -<p>Prefix specific options: +<p>Prefix specific options <descrip> - <tag>skip <m/switch/</tag> + <tag><label id="radv-prefix-skip">skip <m/switch/</tag> This option allows to specify that given prefix should not be advertised. This is useful for making exceptions from a default policy of advertising all prefixes. Note that for withdrawing an already advertised prefix it is more useful to advertise it with zero valid lifetime. Default: no - <tag>onlink <m/switch/</tag> + <tag><label id="radv-prefix-onlink">onlink <m/switch/</tag> This option specifies whether hosts may use the advertised prefix for onlink determination. Default: yes - <tag>autonomous <m/switch/</tag> + <tag><label id="radv-prefix-autonomous">autonomous <m/switch/</tag> This option specifies whether hosts may use the advertised prefix for stateless autoconfiguration. Default: yes - <tag>valid lifetime <m/expr/ [sensitive <m/switch/]</tag> + <tag><label id="radv-prefix-valid-lifetime">valid lifetime <m/expr/ [sensitive <m/switch/]</tag> This option specifies the time (in seconds) how long (after the receipt of RA) the prefix information is valid, i.e., autoconfigured IP addresses can be assigned and hosts with that IP addresses are considered directly reachable. 0 means the prefix is no longer - valid. For <cf/sensitive/ option, see <ref id="dsc-trigger" name="trigger">. + valid. For <cf/sensitive/ option, see <ref id="radv-trigger" name="trigger">. Default: 86400 (1 day), <cf/sensitive/ no. - <tag>preferred lifetime <m/expr/ [sensitive <m/switch/]</tag> + <tag><label id="radv-prefix-preferred-lifetime">preferred lifetime <m/expr/ [sensitive <m/switch/]</tag> This option specifies the time (in seconds) how long (after the receipt of RA) IP addresses generated from the prefix using stateless autoconfiguration remain preferred. For <cf/sensitive/ option, - see <ref id="dsc-trigger" name="trigger">. Default: 14400 (4 hours), + see <ref id="radv-trigger" name="trigger">. Default: 14400 (4 hours), <cf/sensitive/ no. </descrip> @@ -3377,12 +3429,12 @@ definitions, prefix definitions and DNS definitions: <p>RDNSS specific options: <descrip> - <tag>ns <m/address/</tag> + <tag><label id="radv-rdnss-ns">ns <m/address/</tag> This option specifies one recursive DNS server. Can be used multiple times for multiple servers. It is mandatory to have at least one <cf/ns/ option in <cf/rdnss/ definition. - <tag>lifetime [mult] <m/expr/</tag> + <tag><label id="radv-rdnss-lifetime">lifetime [mult] <m/expr/</tag> This option specifies the time how long the RDNSS information may be used by clients after the receipt of RA. It is expressed either in seconds or (when <cf/mult/ is used) in multiples of <cf/max ra @@ -3395,12 +3447,12 @@ definitions, prefix definitions and DNS definitions: <p>DNSSL specific options: <descrip> - <tag>domain <m/address/</tag> + <tag><label id="radv-dnssl-domain">domain <m/address/</tag> This option specifies one DNS search domain. Can be used multiple times for multiple domains. It is mandatory to have at least one <cf/domain/ option in <cf/dnssl/ definition. - <tag>lifetime [mult] <m/expr/</tag> + <tag><label id="radv-dnssl-lifetime">lifetime [mult] <m/expr/</tag> This option specifies the time how long the DNSSL information may be used by clients after the receipt of RA. Details are the same as for RDNSS <cf/lifetime/ option above. Default: 3 * <cf/max ra interval/. @@ -3408,6 +3460,7 @@ definitions, prefix definitions and DNS definitions: <sect1>Example +<label id="radv-exam"> <p><code> protocol radv { @@ -3447,8 +3500,10 @@ protocol radv { <sect>RIP +<label id="rip"> <sect1>Introduction +<label id="rip-intro"> <p>The RIP protocol (also sometimes called Rest In Pieces) is a simple protocol, where each router broadcasts (to all its neighbors) distances to all networks it @@ -3474,6 +3529,7 @@ convergence, big network load and inability to handle larger networks makes it pretty much obsolete. It is still usable on very small networks. <sect1>Configuration +<label id="rip-config"> <p>RIP configuration consists mainly of common protocol options and interface definitions, most RIP options are interface specific. @@ -3516,11 +3572,11 @@ protocol rip [<name>] { </code> <descrip> - <tag>infinity <M>number</M></tag> + <tag><label id="rip-infinity">infinity <M>number</M></tag> Selects the distance of infinity. Bigger values will make protocol convergence even slower. The default value is 16. - <tag>ecmp <M>switch</M> [limit <M>number</M>]</tag> + <tag><label id="rip-ecmp">ecmp <M>switch</M> [limit <M>number</M>]</tag> This option specifies whether RIP is allowed to generate ECMP (equal-cost multipath) routes. Such routes are used when there are several directions to the destination, each with the same (computed) @@ -3528,42 +3584,42 @@ protocol rip [<name>] { nexthops in one route. By default, ECMP is disabled. If enabled, default value of the limit is 16. - <tag>interface <m/pattern [, ...]/ { <m/options/ }</tag> + <tag><label id="rip-iface">interface <m/pattern [, ...]/ { <m/options/ }</tag> Interface definitions specify a set of interfaces on which the protocol is activated and contain interface specific options. - See <ref id="dsc-iface" name="interface"> common options for + See <ref id="proto-iface" name="interface"> common options for detailed description. </descrip> <p>Interface specific options: <descrip> - <tag>metric <m/num/</tag> + <tag><label id="rip-iface-metric">metric <m/num/</tag> This option specifies the metric of the interface. When a route is received from the interface, its metric is increased by this value before further processing. Valid values are 1-255, but values higher than infinity has no further meaning. Default: 1. - <tag>mode multicast|broadcast</tag> + <tag><label id="rip-iface-mode">mode multicast|broadcast</tag> This option selects the mode for RIP to use on the interface. The default is multicast mode for RIPv2 and broadcast mode for RIPv1. RIPng always uses the multicast mode. - <tag>passive <m/switch/</tag> + <tag><label id="rip-iface-passive">passive <m/switch/</tag> Passive interfaces receive routing updates but do not transmit any messages. Default: no. - <tag>address <m/ip/</tag> + <tag><label id="rip-iface-address">address <m/ip/</tag> This option specifies a destination address used for multicast or broadcast messages, the default is the official RIP (224.0.0.9) or RIPng (ff02::9) multicast address, or an appropriate broadcast address in the broadcast mode. - <tag>port <m/number/</tag> + <tag><label id="rip-iface-port">port <m/number/</tag> This option selects an UDP port to operate on, the default is the official RIP (520) or RIPng (521) port. - <tag>version 1|2</tag> + <tag><label id="rip-iface-version">version 1|2</tag> This option selects the version of RIP used on the interface. For RIPv1, automatic subnet aggregation is not implemented, only classful network routes and host routes are propagated. Note that BIRD allows RIPv1 to be @@ -3572,12 +3628,12 @@ protocol rip [<name>] { RIP, the option is not supported for RIPng, as no further versions are defined. - <tag>version only <m/switch/</tag> + <tag><label id="rip-iface-version-only">version only <m/switch/</tag> Regardless of RIP version configured for the interface, BIRD accepts incoming packets of any RIP version. This option restrict accepted packets to the configured version. Default: no. - <tag>split horizon <m/switch/</tag> + <tag><label id="rip-iface-split-horizon">split horizon <m/switch/</tag> Split horizon is a scheme for preventing routing loops. When split horizon is active, routes are not regularly propagated back to the interface from which they were received. They are either not propagated @@ -3586,40 +3642,40 @@ protocol rip [<name>] { on the interface will not consider the router as a part of an independent path to the destination of the route. Default: yes. - <tag>poison reverse <m/switch/</tag> + <tag><label id="rip-iface-poison-reverse">poison reverse <m/switch/</tag> When split horizon is active, this option specifies whether the poisoned reverse variant (propagating routes back with an infinity metric) is used. The poisoned reverse has some advantages in faster convergence, but uses more network traffic. Default: yes. - <tag>check zero <m/switch/</tag> + <tag><label id="rip-iface-check-zero">check zero <m/switch/</tag> Received RIPv1 packets with non-zero values in reserved fields should be discarded. This option specifies whether the check is performed or such packets are just processed as usual. Default: yes. - <tag>update time <m/number/</tag> + <tag><label id="rip-iface-update-time">update time <m/number/</tag> Specifies the number of seconds between periodic updates. A lower number will mean faster convergence but bigger network load. Default: 30. - <tag>timeout time <m/number/</tag> + <tag><label id="rip-iface-timeout-time">timeout time <m/number/</tag> Specifies the time interval (in seconds) between the last received route announcement and the route expiration. After that, the network is considered unreachable, but still is propagated with infinity distance. Default: 180. - <tag>garbage time <m/number/</tag> + <tag><label id="rip-iface-garbage-time">garbage time <m/number/</tag> Specifies the time interval (in seconds) between the route expiration and the removal of the unreachable network entry. The garbage interval, when a route with infinity metric is propagated, is used for both internal (after expiration) and external (after withdrawal) routes. Default: 120. - <tag>ecmp weight <m/number/</tag> + <tag><label id="rip-iface-ecmp-weight">ecmp weight <m/number/</tag> When ECMP (multipath) routes are allowed, this value specifies a relative weight used for nexthops going through the iface. Valid values are 1-256. Default value is 1. - <tag>authentication none|plaintext|cryptographic</tag> + <tag><label id="rip-iface-auth">authentication none|plaintext|cryptographic</tag> Selects authentication method to be used. <cf/none/ means that packets are not authenticated at all, <cf/plaintext/ means that a plaintext password is embedded into each packet, and <cf/cryptographic/ means that @@ -3627,11 +3683,11 @@ protocol rip [<name>] { authentication to not-none, it is a good idea to add <cf>password</cf> section. Default: none. - <tag>password "<m/text/"</tag> - Specifies a password used for authentication. See <ref id="dsc-pass" + <tag><label id="rip-iface-pass">password "<m/text/"</tag> + Specifies a password used for authentication. See <ref id="proto-pass" name="password"> common option for detailed description. - <tag>ttl security [<m/switch/ | tx only]</tag> + <tag><label id="rip-iface-ttl-security">ttl security [<m/switch/ | tx only]</tag> TTL security is a feature that protects routing protocols from remote spoofed packets by using TTL 255 instead of TTL 1 for protocol packets destined to neighbors. Because TTL is decremented when packets are @@ -3648,22 +3704,22 @@ protocol rip [<name>] { For RIPng, TTL security is a standard behavior (required by RFC 2080) and therefore default value is yes. For IPv4 RIP, default value is no. - <tag>tx class|dscp|priority <m/number/</tag> + <tag><label id="rip-iface-tx-class">tx class|dscp|priority <m/number/</tag> These options specify the ToS/DiffServ/Traffic class/Priority of the - outgoing RIP packets. See <ref id="dsc-prio" name="tx class"> common + outgoing RIP packets. See <ref id="proto-tx-class" name="tx class"> common option for detailed description. - <tag>rx buffer <m/number/</tag> + <tag><label id="rip-iface-rx-buffer">rx buffer <m/number/</tag> This option specifies the size of buffers used for packet processing. The buffer size should be bigger than maximal size of received packets. The default value is 532 for IPv4 RIP and interface MTU value for RIPng. - <tag>tx length <m/number/</tag> + <tag><label id="rip-iface-tx-length">tx length <m/number/</tag> This option specifies the maximum length of generated RIP packets. To avoid IP fragmentation, it should not exceed the interface MTU value. The default value is 532 for IPv4 RIP and interface MTU value for RIPng. - <tag>check link <m/switch/</tag> + <tag><label id="rip-iface-check-link">check link <m/switch/</tag> If set, the hardware link state (as reported by OS) is taken into consideration. When the link disappears (e.g. an ethernet cable is unplugged), neighbors are immediately considered unreachable and all @@ -3673,17 +3729,18 @@ protocol rip [<name>] { </descrip> <sect1>Attributes +<label id="rip-attr"> <p>RIP defines two route attributes: <descrip> - <tag>int <cf/rip_metric/</tag> + <tag><label id="rta-rip-metric">int rip_metric/</tag> RIP metric of the route (ranging from 0 to <cf/infinity/). When routes from different RIP instances are available and all of them have the same preference, BIRD prefers the route with lowest <cf/rip_metric/. When a non-RIP route is exported to RIP, the default metric is 1. - <tag>int <cf/rip_tag/</tag> + <tag><label id="rta-rip-tag">int rip_tag/</tag> RIP route tag: a 16-bit number which can be used to carry additional information with the route (for example, an originating AS number in case of external routes). When a non-RIP route is exported to RIP, the @@ -3691,6 +3748,7 @@ protocol rip [<name>] { </descrip> <sect1>Example +<label id="rip-exam"> <p><code> protocol rip { @@ -3708,6 +3766,7 @@ protocol rip { <sect>Static +<label id="static"> <p>The Static protocol doesn't communicate with other routers in the network, but instead it allows you to define routes manually. This is often used for @@ -3736,14 +3795,14 @@ definition of the protocol contains mainly a list of static routes. <p>Global options: <descrip> - <tag>check link <m/switch/</tag> + <tag><label id="static-check-link">check link <m/switch/</tag> If set, hardware link states of network interfaces are taken into consideration. When link disappears (e.g. ethernet cable is unplugged), static routes directing to that interface are removed. It is possible that some hardware drivers or platforms do not implement this feature. Default: off. - <tag>igp table <m/name/</tag> + <tag><label id="static-igp-table">igp table <m/name/</tag> Specifies a table that is used for route table lookups of recursive routes. Default: the same table as the protocol is connected to. </descrip> @@ -3751,24 +3810,24 @@ definition of the protocol contains mainly a list of static routes. <p>Route definitions (each may also contain a block of per-route options): <descrip> - <tag>route <m/prefix/ via <m/ip/</tag> + <tag><label id="static-route-via-ip">route <m/prefix/ via <m/ip/</tag> Static route through a neighboring router. For link-local next hops, interface can be specified as a part of the address (e.g., <cf/via fe80::1234%eth0/). - <tag>route <m/prefix/ multipath via <m/ip/ [weight <m/num/] [bfd <m/switch/] [via ...]</tag> + <tag><label id="static-route-via-mpath">route <m/prefix/ multipath via <m/ip/ [weight <m/num/] [bfd <m/switch/] [via ...]</tag> Static multipath route. Contains several nexthops (gateways), possibly with their weights. - <tag>route <m/prefix/ via <m/"interface"/</tag> + <tag><label id="static-route-via-iface">route <m/prefix/ via <m/"interface"/</tag> Static device route through an interface to hosts on a directly connected network. - <tag>route <m/prefix/ recursive <m/ip/</tag> + <tag><label id="static-route-recursive">route <m/prefix/ recursive <m/ip/</tag> Static recursive route, its nexthop depends on a route table lookup for given IP address. - <tag>route <m/prefix/ blackhole|unreachable|prohibit</tag> + <tag><label id="static-route-drop">route <m/prefix/ blackhole|unreachable|prohibit</tag> Special routes specifying to silently drop the packet, return it as unreachable or return it as administratively prohibited. First two targets are also known as <cf/drop/ and <cf/reject/. @@ -3777,7 +3836,7 @@ definition of the protocol contains mainly a list of static routes. <p>Per-route options: <descrip> - <tag>bfd <m/switch/</tag> + <tag><label id="static-route-bfd">bfd <m/switch/</tag> The Static protocol could use BFD protocol for next hop liveness detection. If enabled, a BFD session to the route next hop is created and the static route is BFD-controlled -- the static route is announced @@ -3790,9 +3849,9 @@ definition of the protocol contains mainly a list of static routes. This option can be used for static routes with a direct next hop, or also for for individual next hops in a static multipath route (see above). Note that BFD protocol also has to be configured, see - <ref id="sect-bfd" name="BFD"> section for details. Default value is no. + <ref id="bfd" name="BFD"> section for details. Default value is no. - <tag><m/filter expression/</tag> + <tag><label id="static-route-filter"><m/filter expression/</tag> This is a special option that allows filter expressions to be configured on per-route basis. Can be used multiple times. These expressions are evaluated when the route is originated, similarly to the import filter @@ -3829,8 +3888,10 @@ protocol static { <chapt>Conclusions +<label id="conclusion"> <sect>Future work +<label id="future-work"> <p>Although BIRD supports all the commonly used routing protocols, there are still some features which would surely deserve to be implemented in future @@ -3846,6 +3907,7 @@ versions of BIRD: <sect>Getting more help +<label id="help"> <p>If you use BIRD, you're welcome to join the bird-users mailing list (<HTMLURL URL="mailto:bird-users@network.cz" name="bird-users@network.cz">) |