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| -rw-r--r-- | doc/bird.sgml | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index 2419768b..3dbb40b8 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -599,14 +599,23 @@ agreement"). <tag><label id="proto-table">table <m/name/</tag> Connect this protocol to a non-default routing table. - <tag><label id="proto-vrf">vrf "<m/text/"</tag> + <tag><label id="proto-vrf">vrf "<m/text/"|default</tag> Associate the protocol with specific VRF. The protocol will be restricted to interfaces assigned to the VRF and will use sockets bound - to the VRF. Appropriate VRF interface must exist on OS level. For kernel - protocol, an appropriate table still must be explicitly selected by - <cf/table/ option. Note that for proper VRF support it is necessary to - use Linux kernel version at least 4.14, older versions have limited - VRF implementation. + to the VRF. A corresponding VRF interface must exist on OS level. For + kernel protocol, an appropriate table still must be explicitly selected + by <cf/table/ option. + + By selecting <cf/default/, the protocol is associated with the default + VRF; i.e., it will be restricted to interfaces not assigned to any + regular VRF. That is different from not specifying <cf/vrf/ at all, in + which case the protocol may use any interface regardless of its VRF + status. + + Note that for proper VRF support it is necessary to use Linux kernel + version at least 4.14, older versions have limited VRF implementation. + Before Linux kernel 5.0, a socket bound to a port in default VRF collide + with others in regular VRFs. </descrip> <p>There are several options that give sense only with certain protocols: @@ -1624,7 +1633,7 @@ in the future. Also note that we currently support at most one protocol instance <p>BFD packets are sent with a dynamic source port number. Linux systems use by default a bit different dynamic port range than the IANA approved one (49152-65535). If you experience problems with compatibility, please adjust -<cf>/proc/sys/net/ipv4/ip_local_port_range</cf> +<cf>/proc/sys/net/ipv4/ip_local_port_range</cf>. <sect1>Configuration <label id="bfd-config"> @@ -1641,6 +1650,14 @@ configuration is often sufficient. <p>Note that to use BFD for other protocols like OSPF or BGP, these protocols also have to be configured to request BFD sessions, usually by <cf/bfd/ option. +<p>A BFD instance not associated with any VRF handles session requests from all +other protocols, even ones associated with a VRF. Such setup would work for +single-hop BFD sessions if <cf/net.ipv4.udp_l3mdev_accept/ sysctl is enabled, +but does not currently work for multihop sessions. Another approach is to +configure multiple BFD instances, one for each VRF (including the default VRF). +Each BFD instance associated with a VRF (regular or default) only handles +session requests from protocols in the same VRF. + <p>Some of BFD session options require <m/time/ value, which has to be specified with the appropriate unit: <m/num/ <cf/s/|<cf/ms/|<cf/us/. Although microseconds are allowed as units, practical minimum values are usually in order of tens of |