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

[Daniel Roesen]

On Wed, Jun 16, 2010 at 03:39:47AM +0200, Volker D. Pallas wrote:
> 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.

According to the OSPFv3 spec (RFC2740), JUNOS is correct in sending
MTU 0 on a tunnel interface:

Interface MTU
      The size in bytes of the largest IPv6 datagram that can be sent
      out the    associated interface, without fragmentation.  The MTUs
      of common Internet link  types can be found in Table 7-1    of
      [Ref12]. Interface MTU should be set to 0 in Database Description
      packets sent over virtual links.

> 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

I'd say Quagga is wrong to expect anything else than MTU 0 on a
tunnel type interface...

Best regards,
Daniel

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