bird2 doesn't negotiate with gobgp over ipv6

[Maria Matejka]

Not at my computer, just a wild guess – would you try please, instead of ::/0, narrowing the range, e.g. like 2000::/3? I haven't seen the code recently but this may help.

Maria

On 4 May 2024 17:16:21 CEST, Vladimir Pouzanov <farcaller at gmail.com> wrote:
>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?

-- 
Maria Matejka (she/her) | BIRD Team Leader | CZ.NIC, z.s.p.o.
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