diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/bird.sgml | 99 | ||||
| -rw-r--r-- | doc/reply_codes | 1 |
2 files changed, 78 insertions, 22 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index e9c61526..3ea90920 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -157,6 +157,9 @@ options. The most important ones are: <tag>-f</tag> run bird in foreground. + + <tag>-R</tag> + apply graceful restart recovery after start. </descrip> <p>BIRD writes messages about its work to log files or syslog (according to config). @@ -187,6 +190,7 @@ configuration, but it is generally easy -- BIRD needs just the standard library, privileges to read the config file and create the control socket and the CAP_NET_* capabilities. + <chapt>About routing tables <p>BIRD has one or more routing tables which may or may not be @@ -242,6 +246,20 @@ using comparison and ordering). Minor advantage is that routes are shown sorted in <cf/show route/, minor disadvantage is that it is slightly more computationally expensive. +<sect>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 +cases, because if the forwarding plane (i.e. kernel routing tables) remains +intact, then its synchronization with BIRD would temporarily disrupt packet +forwarding until protocols converge. Graceful restart is a mechanism that could +help with this issue. Generally, it works by starting protocols and letting them +repopulate routing tables while deferring route propagation until protocols +acknowledge their convergence. Note that graceful restart behavior have to be +configured for all relevant protocols and requires protocol-specific support +(currently implemented for Kernel and BGP protocols), it is activated for +particular boot by option <cf/-R/. + <chapt>Configuration @@ -371,6 +389,12 @@ protocol rip { would accept IPv6 routes only). Such behavior was default in older versions of BIRD. + <tag>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> This option allows to specify a format of date/time used by BIRD. The first argument specifies for which purpose such @@ -1493,6 +1517,8 @@ extended communities (RFC 4360<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4360.txt">), route reflectors (RFC 4456<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4456.txt">), +graceful restart +(RFC 4724<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4724.txt">), multiprotocol extensions (RFC 4760<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4760.txt">), 4B AS numbers @@ -1502,9 +1528,7 @@ and 4B AS numbers in extended communities For IPv6, it uses the standard multiprotocol extensions defined in -RFC 2283<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc2283.txt"> -including changes described in the -latest draft<htmlurl url="ftp://ftp.rfc-editor.org/internet-drafts/draft-ietf-idr-bgp4-multiprotocol-v2-05.txt"> +RFC 4760<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc4760.txt"> and applied to IPv6 according to RFC 2545<htmlurl url="ftp://ftp.rfc-editor.org/in-notes/rfc2545.txt">. @@ -1716,6 +1740,26 @@ for each neighbor using the following configuration parameters: capability and accepts such requests. Even when disabled, BIRD can send route refresh requests. Default: on. + <tag>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 + specifies an optional graceful restart mechanism to alleviate this + issue. This option controls the mechanism. It has three states: + Disabled, when no support is provided. Aware, when the graceful restart + support is announced and the support for restarting neighbors is + provided, but no local graceful restart is allowed (i.e. receiving-only + role). Enabled, when the full graceful restart support is provided + (i.e. both restarting and receiving role). Note that proper support for + local graceful restart requires also configuration of other protocols. + Default: aware. + + <tag>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> RFC 1997 demands that BGP speaker should process well-known communities like no-export (65535, 65281) or no-advertise (65535, 65282). For @@ -2063,25 +2107,36 @@ overcome using another routing table and the pipe protocol. <sect1>Configuration <p><descrip> - <tag>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> Time in seconds between two consecutive scans of the - kernel routing table. - <tag>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> 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> Select which kernel table should - this particular instance of the Kernel protocol work with. Available - only on systems supporting multiple routing tables. + <tag>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> + Time in seconds between two consecutive scans of the kernel routing + table. + + <tag>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> + 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> + Select which kernel table should this particular instance of the Kernel + protocol work with. Available only on systems supporting multiple + routing tables. + + <tag>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. </descrip> <sect1>Attributes diff --git a/doc/reply_codes b/doc/reply_codes index 45b42e00..cd5f2620 100644 --- a/doc/reply_codes +++ b/doc/reply_codes @@ -32,6 +32,7 @@ Reply codes of BIRD command-line interface 0021 Undo requested 0022 Undo scheduled 0023 Evaluation of expression +0024 Graceful restart status report 1000 BIRD version 1001 Interface list |