ICVPN: Misconfigured IPv6 BGP peers

[Sven Eckelmann]

Hi,

I've looked through my logs and noticed that a get a lot of messages related 
to "Received: Required capability missing: 0104000200014600" from bird6

 * aachen1 (ok, actually Leo Krueger saw that in his logs)
 * augsburg1 (not in my logs but from lg.ff3l.net)
 * franken_fff_icvpn
 * innsbruck_ffibk1

010400020001 is the multiprotocol extension which selects IPv6. This has to be 
set for IPv6 peers to IPv6. An example BGP packet which incorrectly sets it to IPv4
in his OPEN message can be seen here:

    Frame 4349: 139 bytes on wire (1112 bits), 139 bytes captured (1112 bits)
    Ethernet II, Src: 4a:2a:22:45:37:c9 (4a:2a:22:45:37:c9), Dst: e6:f8:0c:30:51:dc (e6:f8:0c:30:51:dc)
    Internet Protocol Version 6, Src: fec0::a:cf:0:43, Dst: fec0::a:cf:0:25
    Transmission Control Protocol, Src Port: 38956, Dst Port: 179, Seq: 1, Ack: 1, Len: 53
    Border Gateway Protocol - OPEN Message
        Marker: ffffffffffffffffffffffffffffffff
        Length: 53
        Type: OPEN Message (1)
        Version: 4
        My AS: 65052
        Hold Time: 180
        BGP Identifier: 10.207.0.67
        Optional Parameters Length: 24
        Optional Parameters
            Optional Parameter: Capability
                Parameter Type: Capability (2)
                Parameter Length: 6
                Capability: Multiprotocol extensions capability
                    Type: Multiprotocol extensions capability (1)
                    Length: 4
                    AFI: IPv4 (1)
                    Reserved: 00
                    SAFI: Unicast (1)
            Optional Parameter: Capability
                Parameter Type: Capability (2)
                Parameter Length: 2
                Capability: Route refresh capability (Cisco)
                    Type: Route refresh capability (Cisco) (128)
                    Length: 0
            Optional Parameter: Capability
                Parameter Type: Capability (2)
                Parameter Length: 2
                Capability: Route refresh capability
                    Type: Route refresh capability (2)
                    Length: 0
            Optional Parameter: Capability
                Parameter Type: Capability (2)
                Parameter Length: 6
                Capability: Support for 4-octet AS number capability
                    Type: Support for 4-octet AS number capability (65)
                    Length: 4
                    AS Number: 65052

Please check why you have added an IPv6 peer to your IPv4 BGP configuration. 
This currently breaks some of the BGP session for IPv6.

Kind regards,
	Sven
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