Merge pull request #7709 from donaldsharp/vrf_doc

zebra: Slightly touch on the vrf route lookup semantics
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Mark Stapp 2021-02-04 13:53:07 -05:00 committed by GitHub
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@ -407,6 +407,14 @@ If no option is chosen, then the *Linux VRF* implementation as references in
https://www.kernel.org/doc/Documentation/networking/vrf.txt will be mapped over
the *Zebra* VRF. The routing table associated to that VRF is a Linux table
identifier located in the same *Linux network namespace* where *Zebra* started.
Please note when using the *Linux VRF* routing table it is expected that a
default Kernel route will be installed that has a metric as outlined in the
www.kernel.org doc above. The Linux Kernel does table lookup via a combination
of rule application of the rule table and then route lookup of the specified
table. If no route match is found then the next applicable rule is applied
to find the next route table to use to look for a route match. As such if
your VRF table does not have a default blackhole route with a high metric
VRF route lookup will leave the table specified by the VRF, which is undesirable.
If the :option:`-n` option is chosen, then the *Linux network namespace* will
be mapped over the *Zebra* VRF. That implies that *Zebra* is able to configure