Bad Peer AS with 4B AS issue

[Łukasz Jarosz]

Hello,
I have an issue with connectivity towards provider's router (out of my control).
I setup BGP session as usual:

protocol bgp [redacted] {
local [redacted] as [redacted];
neighbor [redacted] as [redacted];

ipv4 {
table bgp;
next hop self;

import filter bgp_in;
export filter bgp_out;
};
}

I think worth mentioning is that I have 4B AS whilst my peer has 2B AS.
All I get is this error:

BGP state: Idle
Neighbor address: [redacted]
Neighbor AS: [redacted]
Error wait: 48.720/60
Last error: Received: Bad peer AS

I checked pcap dumps and they seem reasonable. BIRD open is followed by peer OPEN with piggybacked NOTIFICATION message.

Based on MAC address my peer is Juniper, but that is just my guess.
I am running BIRD 2.0.2 (unfortunately straightforward upgrade is not exactly possible).

Anyone bumped into similiar issue or can give me any pointers?
Best regards,
Łukasz Jarosz
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://trubka.network.cz/pipermail/bird-users/attachments/20230614/540c1831/attachment.htm>