RFC - design of more extensive babel protocol support

[tim-seoss]

Hello,

Thanks for merging the basic babel support!

I'd like to write a babel protocol parser/exporter (along the same lines as the OSPF functionality). I've got a basic proof of concept working, but I've got a few questions about how it should work...

• What are your thoughts about only supporting bird v2+ vs. also including v1 support? I haven't looked v1 (I don't have a bird v1.x installation), but I suspect that because babel supports dual-stack operation, that there will be a few differences if bird 1 is also to be supported.
• There isn't any overall summary information available via birdc for babel (i.e. no equivalent of birdc show ospf), so I think one viable way of supporting babel may be to parse the output of birdc show babel entries, and simply export the Prefix, Router ID, Sequence Number, Route, and Source counts (guages).

Here's some sample output from an isolated bird2 instance (no babel neighbours active):

bird> show babel entries
clusternet:
Prefix                   Router ID               Metric Seqno  Routes Sources
0.0.0.0/0                00:00:00:00:ac:12:fe:64      0     1       0       0
169.254.0.0/16           00:00:00:00:ac:12:fe:64      0     1       0       0
fec0:aaaa::8888/128      00:00:00:00:ac:12:fe:64      0     1       0       0

bird> show babel interfaces 
clusternet:
Interface  State  RX cost   Nbrs   Timer Next hop (v4)   Next hop (v6)
brint      Up          96      0   0.122 172.29.148.148  fe80::c491:7abf:a933:db5f

Any thoughts?

[tim-seoss]

n.b. rough draft here: https://github.com/seoss/bird_exporter/tree/babel_parser
This is unfinished, and has only been tested against bird 2.0.7 on Debian 11.