9.30 Automatic 6to4 Tunnels


Sub-task 2 needs us to create loopback interfaces with subnet number 0, however it is not configured like that in SG.  The correct loopback interface's IPv6 address would be:

2002:9601:0303:0::/64 or to be precise:2002:9601:0303::/64 

However in SG, the loopback interface is configured with subnet 1, and instead the tunnel interface is configured with subnet 0.

Please comment.




  • We have your issue noted and it's in the queue.  Well get to you as
    fast as we can.  We'll try to have a response by tomorrow evening.

    --The TechEdit Team


  • Hello INE ,


    I have the same qouestion .. Can we have it checked.


    Thanks ,

  • As we are aware with 6to4 and ISATAP, the IPV4 address is encoded in the IPV6 address - don't forget to covert your rack number (coded in the second octet of IPV4 addresses) to hex - which was my schoolboy error.

    My rack was 19 (decimal).

    Doing a debug ipv6 packet and ipv4 packet illustrated my error!!!


    Jan 25 01:29:46.377: IPv6: SAS picked source 2002:9619:303:FFFF::3 for 2002:9619:404::4 (Tunnel345)
    Jan 25 01:29:46.377: IPV6: source 2002:9619:303:FFFF::3 (local)
    Jan 25 01:29:46.381:       dest 2002:9619:404::4 (Tunnel345)
    Jan 25 01:29:46.381:       traffic class 0, flow 0x0, len 100+0, prot 58, hops 64, originating
    Jan 25 01:29:46.381: IPv6: Sending on Tunnel345

    Jan 25 01:29:46.391: IP: s= (local), d=, len 120, unroutable

    Obviously if your on rack 19 IP address does not exist!

    Guess what 0x19 = 25d!!!

    If you are alway using rack 1 or rack numbers less than 10 you will fall into trap!!!!


    Also I made the same mistake on the ISATAP task.

    The lesson for today is never forget to convert to hex any numbers you are transposing into an IPV6 address.

  • I think the question needs to be,
    ..every router with the subnet number "1" ...

    One more thing, no error but,

    interface Tunnel 345
     ipv6 address 2002:9601:404::5/64
    intention could be,
     ipv6 address 2002:9601:404::4/64

    Is this thing still in the TechEdit Team's queue since 2008?

  • welshydragon, good catch.  That's exactly what was giving me a hard time.

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