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Diffstat (limited to 'doc/bird.sgml')
| -rw-r--r-- | doc/bird.sgml | 40 |
1 files changed, 25 insertions, 15 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 8dc872e7..c76873cd 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -2220,9 +2220,9 @@ using the following configuration parameters: the number of hops is 2. Default: enabled for iBGP. <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. + Define local address we should use as a source address for the BGP + session. Default: the address of the local end of the interface our + neighbor is connected to. <tag><label id="bgp-strict-bind">strict bind <m/switch/</tag> Specify whether BGP listening socket should be bound to a specific local @@ -2565,19 +2565,29 @@ be used in explicit configuration. <p>BGP channels have additional config options (together with the common ones): <descrip> - <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><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><label id="bgp-next-hop-keep">next hop keep <m/switch/|ibgp|ebgp</tag> + Do not modify the Next Hop attribute and advertise the current one + unchanged even in cases where our own local address should be used + instead. This is necessary when the BGP speaker does not forward network + traffic (route servers and some route reflectors) and also can be useful + in some other cases (e.g. multihop EBGP sessions). Can be enabled for + all routes, or just for routes received from IBGP / EBGP neighbors. + Default: disabled for regular BGP, enabled for route servers, + <cf/ibgp/ for route reflectors. + + <tag><label id="bgp-next-hop-self">next hop self <m/switch/|ibgp|ebgp</tag> + Always advertise our own local address as a next hop, even in cases + where the current Next Hop attribute should be used unchanged. This is + sometimes used for routes propagated from EBGP to IBGP when IGP routing + does not cover inter-AS links, therefore IP addreses of EBGP neighbors + are not resolvable through IGP. Can be enabled for all routes, or just + for routes received from IBGP / EBGP neighbors. Default: disabled. <tag><label id="bgp-next-hop-address">next hop address <m/ip/</tag> - Avoid calculation of the Next Hop attribute and always advertise this address - as a next hop. + Specify which address to use when our own local address should be + announced in the Next Hop attribute. Default: the source address of the + BGP session (if acceptable), or the preferred address of an associated + interface. <tag><label id="bgp-missing-lladdr">missing lladdr self|drop|ignore</tag> Next Hop attribute in BGP-IPv6 sometimes contains just the global IPv6 @@ -2618,7 +2628,7 @@ be used in explicit configuration. the channel is connected to (if eligible). <tag><label id="bgp-import-table">import table <m/switch/</tag> - A BGP import table contain all received routes from given BGP neighbor, + A BGP import table contains all received routes from given BGP neighbor, before application of import filters. It is also called <em/Adj-RIB-In/ in BGP terminology. BIRD BGP by default operates without import tables, in which case received routes are just processed by import filters, |