[j-nsp] ospfv3 - JUNOS sends zero mtu in dbd -> stuck in ExStart

[Volker D. Pallas]

Hi,

I'm having an issue with an OSPFv3 neighborship between Linux/quagga (0.99.16) and JUNOS (10.1R2.8 on SRX-100) via a standard "ip"-tunnel:
the dbd info sent by JUNOS always contains "mtu 0", which quagga does not like at all. This keeps my neighborship in ExStart.

I set an ipv6 mtu on all kinds of underlying interfaces but the transmitted mtu does not ever change.

there is actually an mtu on the interface:
# run show interfaces ip-0/0/0.2 | match mtu
     Protocol inet6, MTU: 1472
# run show ospf3 interface ip-0/0/0.2 extensive
Interface           State   Area            DR ID           BDR ID          Nbrs
ip-0/0/0.2          PtToPt  0.0.0.1         0.0.0.0         0.0.0.0            1
   Address fe80::b2c6:9aff:fe39:b200, Prefix-length 64
   OSPF3-Intf-index 3, Type P2P, MTU 1472, Cost 1
   Adj count: 0, Router LSA ID: -
   Hello 5, Dead 10, ReXmit 5, Not Stub
   Protection type: None

still JUNOS sends 0 (excerpt from trace on JUNOS):
Jun 16 02:57:14.012463 OSPF sent DbD fe80::b2c6:9aff:fe39:b200 -> ff02::5 (ip-0/0/0.2 IFL 86 area 0.0.0.1)
Jun 16 02:57:14.012576   Version 3, length 28, ID 172.23.5.1, area 0.0.0.1
Jun 16 02:57:14.012669   checksum 0x0, instance-id 0
Jun 16 02:57:14.012763   options 0x13, i 1, m 1, ms 1, seq 0xac14361c, mtu 0

tcpdump on the linux side:
03:00:05.532800 IP6 fe80::b2c6:9aff:fe39:b200 > ff02::5: OSPFv3-dd 28: rtrid 172.23.5.1 area 0.0.0.1 V6/E/R I/M/MS mtu 0 S AC14361C

quagga log:
2010/06/16 03:01:19 OSPF6: DbDesc received on gre-nc
2010/06/16 03:01:19 OSPF6:     src: fe80::b2c6:9aff:fe39:b200
2010/06/16 03:01:19 OSPF6:     dst: ff02::5
2010/06/16 03:01:19 OSPF6:     OSPFv3 Type:2 Len:28 Router-ID:172.23.5.1
2010/06/16 03:01:19 OSPF6:     Area-ID:0.0.0.1 Cksum:6d7e Instance-ID:0
2010/06/16 03:01:19 OSPF6:     MBZ: 0 Option: --|R|-|--|E|V6 IfMTU: 0
2010/06/16 03:01:19 OSPF6:     MBZ: 0 Bits: IMm SeqNum: 0xac14361c
2010/06/16 03:01:19 OSPF6: I/F MTU mismatch

Unfortunately quagga does not support mtu-ignore, so how can I influence what JUNOS sends as mtu?

Thanks,
Volker