Info about eBGP/iBGP

[Ponikierski, Grzegorz]

According to my knowledge letter “i” in “[AS201701i]” means “IGP”. “e” is for “EGP” and “?” is for “INCOMPLETE”. This is for BGP origin code.

Other method to check eBGP vs iBGP is to check which protocol learned given route and then verify configuration of protocol or do `show protocol all` to figure out if it was eBGP or iBGP session. It works but it is indirect method which requires extra steps. It would be useful and timesaving that `show route` shows this information directly. Is it problem with proper “print” function for “show route” or Bird just don’t keep such info together with route due to performance issues or memory saving?

Regards,
Grzegorz

From: Bird-users <bird-users-bounces at network.cz> on behalf of Maximilian Wilhelm <max at rfc2324.org>
Date: Wednesday, 18 September 2024 at 21:01
To: "bird-users at network.cz" <bird-users at network.cz>
Subject: Re: Info about eBGP/iBGP

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Anno domini 2024 Ponikierski, Grzegorz via Bird-users scripsit:

Hi,

Am I blind (possible) or Bird doesn’t show if route is eBGP or iBGP? If it shows it, then can you please help me to see it?

I don't think there is an indication whether a route was learned
locally via iBGP or eBGP. Depending on your environment there may be
some clues though.

If you're using route reflectors, routes learned from one of the RRs
will have an originator ID and cluster list set.

Also a route has the originating AS shown in the last column of the output,
e.g.

0.0.0.0/0          via 100.64.0.234 on gre_ffrl_fra_a [ffrl_fra_a 2024-08-06] * (200) [AS201701i]

A route learned via iBGP AND originating from the internal AS shows as
just '[i]' (for origin internal):

10.132.251.53/32   via 10.132.252.5 on vlan1012 [infra_upb_in_ffho_net 2024-07-26 from 10.132.255.34] * (100/100) [i]

Note that this only works as distinction if a route was originated
internally; it will not work for a route learned from an external peer
and further originated internally.

Best,
Max

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