On 20. Apr 2020, at 05:05, Ondrej Zajicek <santiago@crfreenet.org> wrote: On Mon, Apr 20, 2020 at 12:46:17AM +0200, Sebastian Hahn wrote:
In a bird 2.0.7 setup, I was unable to import routes from one of my peers. It is the only one using frr (version 6.02-2 on debian), most other peers use bird1 or bird2. I noticed immediately after adding the peering that I received "Invalid NEXT_HOP attribute" errors in the log. Unfortunately, no more information than that was provided in the log, so I went on a little hunt. Since the exact error is raised from many places, I added some logs to identify the GW_DIRECT case in bgp_apply_next_hop() as the culprit. Here I realized that both gw and ll are set, which means a neighbor is tried to be found which doesn't involve the ll case. I then noticed that in bgp_decode_next_hop_ip(), this can only happen if len == 32. This is where I am absolutely clueless what it means for the nh len to be 32, and thus I don't know if the patch I came up with is correct, even though it works for my testing. Only this one peer using frr causes nh len to be set to 32, so I suppose it might be a ! rare configuration.
What is your BIRD config? It seems that most likely BIRD cannot resolve the global next hop IP address (the on in gw). Because it is GW_DIRECT, it is resolved only in local addresses.
Hi, and thanks for the responses. Here is the config: protocol bgp v6_frr_peer { local as <myas>; direct; neighbor fe80::1 as <theiras>; interface "frr_peer"; ipv6 { import keep filtered; import filter import_filter; export filter export_filter; }; } I use fe80::42, the peer uses fe80::1 on this link. Please let me know if I can provide more information in any way. Thanks Sebastian