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| -rw-r--r-- | doc/bird.sgml | 82 |
1 files changed, 43 insertions, 39 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 0945b24d..7ddf82c7 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -98,42 +98,6 @@ be relatively easy due to its highly modular architecture. <p>This documentation can have 4 forms: sgml (this is master copy), html, ASCII text and dvi/postscript (generated from sgml using sgmltools). You should always edit master copy. -<sect>About routing tables - -<p>Bird has one or more routing tables, which may or may not be -synchronized with kernel and which may or may not be synchronized with -each other (see the Pipe protocol). Each routing table contains list of -known routes. Each route consists of: - -<itemize> - <item>network this route is for - <item>preference of this route (taken from preference of - protocol and possibly altered by filters) - <item>ip address of router who told us about this route - <item>ip address of router we should use for packets routing - using this route - <item>other attributes common to all routes - <item>dynamic attributes defined by protocols, which may or - may not be present (typically protocol metric) -</itemize> - -Routing table maintains more than -one entry for network, but at most one entry for one network and one -protocol. The entry with biggest preference is used for routing. If -there are more entries with same preference and they are from same -protocol, protocol decides (typically according to metrics). If not, -internal ordering is used to decide. You can -get list of route attributes in "Route attributes" section in -filters. - -<p>Protocols are connected to routing tables using filters. Routes -that come from network go to the protocol, it then passes them to -filters, if import filter accepts route, it gets to main routing -table. It is then broadcasted to all other protocols (filtered through -their export filters), which typically send it to the network. - -Filters can alter routes passed between routing tables and -protocols. <sect>Installing BIRD @@ -173,6 +137,43 @@ options. Most important (and not easily guessed) option is use given filename for socket for communications with bird client, default is <file/bird.ctl/. </descrip> +<chapt>About routing tables + +<p>Bird has one or more routing tables, which may or may not be +synchronized with kernel and which may or may not be synchronized with +each other (see the Pipe protocol). Each routing table contains list of +known routes. Each route consists of: + +<itemize> + <item>network this route is for + <item>preference of this route (taken from preference of + protocol and possibly altered by filters) + <item>ip address of router who told us about this route + <item>ip address of router we should use for packets routing + using this route + <item>other attributes common to all routes + <item>dynamic attributes defined by protocols, which may or + may not be present (typically protocol metric) +</itemize> + +Routing table maintains more than +one entry for network, but at most one entry for one network and one +protocol. The entry with biggest preference is used for routing. If +there are more entries with same preference and they are from same +protocol, protocol decides (typically according to metrics). If not, +internal ordering is used to decide. You can +get list of route attributes in "Route attributes" section in +filters. + +<p>Protocols are connected to routing tables using filters. Routes +that come from network go to the protocol, it then passes them to +filters, if import filter accepts route, it gets to main routing +table. It is then broadcasted to all other protocols (filtered through +their export filters), which typically send it to the network. + +Filters can alter routes passed between routing tables and +protocols. + <chapt>Configuration <sect>Introduction @@ -741,9 +742,12 @@ protocol bgp { multihop 20 via 62.168.0.13; # Which is connected indirectly export filter { # We use non-trivial export rules if source = RTS_STATIC then { # Export only static routes - bgp_community.add((65000,5678)); # Assign our community - if bgp_path ~ / 65000 / then # Artificially increase path length - bgp_path.prepend(65000); # by prepending local AS number twice + # Assign our community + bgp_community.add((65000,5678)); + # Artificially increase path length + # by prepending local AS number twice + if bgp_path ~ / 65000 / then + bgp_path.prepend(65000); accept; } reject; |