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Diffstat (limited to 'doc/bird.sgml')
| -rw-r--r-- | doc/bird.sgml | 58 |
1 files changed, 31 insertions, 27 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 421be713..52520a7e 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -1536,33 +1536,37 @@ 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> 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 to get consistent behavior.) - Optional <cf/ip/ argument specifies a source address, - equivalent to the <cf/source address/ option (see below). + <tag>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 to get consistent + behavior.) Optional <cf/ip/ argument specifies a source address, + equivalent to the <cf/source address/ option (see below). This + parameter is mandatory. + + <tag>neighbor <m/ip/ as <m/number/</tag> Define neighboring router this + instance will be talking to and what AS it's located in. In case the + neighbor is in the same AS as we are, we automatically switch to iBGP. This parameter is mandatory. - <tag>neighbor <m/ip/ as <m/number/</tag> Define neighboring router - this instance will be talking to and what AS it's located in. Unless - you use the <cf/multihop/ clause, it must be directly connected to one - of your router's interfaces. In case the neighbor is in the same AS - as we are, we automatically switch to iBGP. This parameter is mandatory. - - <tag>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 IP address have to be reachable through system - routing table. For multihop BGP it is recommended to - explicitly configure <cf/source address/ to have it - stable. Optional <cf/number/ argument can be used to specify - the number of hops (used for TTL). Note that the number of - networks (edges) in a path is counted, i.e. if two BGP - speakers are separated by one router, the number of hops is - 2. Default: switched off. + <tag>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> 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 IP address have to be reachable through + system routing table. The alternative is the <cf/direct/ option. For + multihop BGP it is recommended to explicitly configure the source + address to have it stable. Optional <cf/number/ argument can be used to + specify the number of hops (used for TTL). Note that the number of + networks (edges) in a 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> Define local address we should use for next hop calculation and as a source address @@ -1609,8 +1613,8 @@ for each neighbor using the following configuration parameters: 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: <cf/direct/ for singlehop eBGP, - <cf/recursive/ otherwise. + tables">. Default: <cf/direct/ for direct sessions, + <cf/recursive/ for multihop sessions. <tag>igp table <m/name/</tag> Specifies a table that is used as an IGP routing table. Default: the same as the table BGP is |