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| -rw-r--r-- | doc/bird.sgml | 33 |
1 files changed, 25 insertions, 8 deletions
diff --git a/doc/bird.sgml b/doc/bird.sgml index c69ab87f..e15e3dd1 100644 --- a/doc/bird.sgml +++ b/doc/bird.sgml @@ -671,14 +671,24 @@ agreement"). This is an optional description of the protocol. It is displayed as a part of the output of 'show protocols all' command. - <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. In BGP, this can be avoided by using + <ref id="bgp-strict-bind" name="strict bind"> option. <tag><label id="proto-channel"><m/channel name/ [{<m/channel config/}]</tag> Every channel must be explicitly stated. See the protocol-specific @@ -1896,12 +1906,11 @@ the BFD session went down). advanced features like the echo mode or authentication are not implemented), IP transport for BFD as defined in <rfc id="5881"> and <rfc id="5883"> and interaction with client protocols as defined in <rfc id="5882">. -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"> @@ -1918,6 +1927,14 @@ 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 |