Hi! I'm running bird 2.15.1 and I'm trying to make it talk to cilium that uses gobgp under the hood. I can negotiate the session over ipv4 with no issues, but due to a bug in the cilium implementation, the ipv6 routes aren't advertised properly. The suggestion from cilium was to negotiate the session over ipv6, but this creates issues for bird.
I have a config that looks somewhat like this: protocol bgp { local port 179 as 65100; neighbor range 0::/0 port 179 as 65100 internal; dynamic name "GW6_"; direct; passive; ipv4 { import all; }; ipv6 { import all; }; } protocol bgp { local port 179 as 65100; neighbor range 10.0.0.0/8 port 179 as 65100 internal; dynamic name "GW4_"; direct; passive; ipv4 { import all; }; ipv6 { import all; }; } When I connect to bird over ipv4, gobgp sends a packet like this: Frame 4: 154 bytes on wire (1232 bits), 154 bytes captured (1232 bits) on interface vmbrdev, id 0 Ethernet II, Src: 22:fc:7f:47:6b:f4 (22:fc:7f:47:6b:f4), Dst: 6e:82:6c:1b:e9:95 (6e:82:6c:1b:e9:95) Internet Protocol Version 4, Src: 10.224.129.15, Dst: 10.224.129.1 Transmission Control Protocol, Src Port: 39201, Dst Port: 179, Seq: 1, Ack: 1, Len: 88 Border Gateway Protocol - OPEN Message Marker: ffffffffffffffffffffffffffffffff Length: 88 Type: OPEN Message (1) Version: 4 My AS: 65100 Hold Time: 90 BGP Identifier: 10.224.129.15 Optional Parameters Length: 59 Optional Parameters Optional Parameter: Capability Parameter Type: Capability (2) Parameter Length: 57 Capability: Route refresh capability Type: Route refresh capability (2) Length: 0 Capability: FQDN Capability Type: FQDN Capability (73) Length: 12 Hostname Length: 10 Hostname: dev-master Domain Name Length: 0 Domain Name: Capability: Unknown capability 75 Type: Unknown (75) Length: 13 Unknown: 0c476f4247502f332e32332e30 Capability: Multiprotocol extensions capability Type: Multiprotocol extensions capability (1) Length: 4 AFI: IPv4 (1) Reserved: 00 SAFI: Unicast (1) Capability: Multiprotocol extensions capability Type: Multiprotocol extensions capability (1) Length: 4 AFI: IPv6 (2) Reserved: 00 SAFI: Unicast (1) Capability: Support for 4-octet AS number capability Type: Support for 4-octet AS number capability (65) Length: 4 AS Number: 65100 Capability: Extended Next Hop Encoding Type: Extended Next Hop Encoding (5) Length: 6 AFI: IPv4 (1) SAFI: Unicast (1) Next hop AFI: IPv6 (2) Which is followed up by OPEN from bird2 and they establish the session. The logs say: May 04 14:47:02 ammy bird[7755]: bgp2: Incoming connection from 10.224.129.15 (port 39201) accepted May 04 14:47:02 ammy bird[7755]: GW4_1: Initializing May 04 14:47:02 ammy bird[7755]: GW4_1: Starting May 04 14:47:02 ammy bird[7755]: GW4_1: State changed to start May 04 14:47:02 ammy bird[7755]: GW4_1: Started May 04 14:47:02 ammy bird[7755]: GW4_1: Got OPEN(as=65100,hold=90,id=10.224.129.15) May 04 14:47:02 ammy bird[7755]: GW4_1: Sending OPEN(ver=4,as=65100,hold=240,id=0ae08101) May 04 14:47:02 ammy bird[7755]: GW4_1: Sending KEEPALIVE May 04 14:47:02 ammy bird[7755]: GW4_1: Got KEEPALIVE May 04 14:47:02 ammy bird[7755]: GW4_1: BGP session established When I try to establish the connection over ipv6, gobgp sends an OPEN that's exactly the same sans being transferred over ipv6: Frame 15: 174 bytes on wire (1392 bits), 174 bytes captured (1392 bits) on interface vmbrdev, id 0 Ethernet II, Src: 22:fc:7f:47:6b:f4 (22:fc:7f:47:6b:f4), Dst: 6e:82:6c:1b:e9:95 (6e:82:6c:1b:e9:95) Internet Protocol Version 6, Src: 2a01:xxx:xxx:xxx:xxx:xxx:xxx:d930, Dst: fd00::53 Transmission Control Protocol, Src Port: 58663, Dst Port: 179, Seq: 1, Ack: 1, Len: 88 and then bird just stalls the connection. The logs say: May 04 14:49:17 ammy bird[7755]: bgp1: Incoming connection from 2a01:4f8:173:fe11:6f81:e7cd:2787:fb71 (port 35581) accepted May 04 14:49:17 ammy bird[7755]: GW6_1: Initializing May 04 14:49:17 ammy bird[7755]: GW6_1: Starting May 04 14:49:17 ammy bird[7755]: GW6_1: State changed to start May 04 14:49:17 ammy bird[7755]: GW6_1: Waiting for 2a01:xxx:xxx:xxx:xxx:xxx:xxx:d930 to become my neighbor I suspect it's either a bug or a misconfiguration on the bird side, because gobgp behaves the same in both scenarios. How do I investigate/debug this further?