Monday, September 22, 2008

IPexpert Volume 1 Section 21 - IPv6, RIPng

This is not an extremely difficult lab but it did bring up some good troubleshooting. In it we have two RIPng processes running over each other, cisco12 and cisco275 are their names.

Here is the basic topology:


R2 and R5 have two connections, one via frame-relay, and another over an ipv6ip tunnel. RIPng process cisco275 runs from R7 to R5, and R5 to R2 over frame link. RIPng process cisco12 runs over the tunnel and R1 to R2.

After redistributing between the two processes on R5, R7 still cannot ping R1 even though it has a route. Both routes below belong to R1's loopbacks.

R7#show ipv6 route rip

R 2000:1:1:1100::/64 [120/5]
via FE80::21B:D5FF:FE0F:F358, FastEthernet0/0
R 2000:1:1:1111::/64 [120/5]
via FE80::21B:D5FF:FE0F:F358, FastEthernet0/0

When we ping from R7 here is the debug on R1:

R1#debug ipv6 packet
IPv6 unicast packet debugging is on
*Sep 23 01:22:44.255: IPV6: source 2000:1:1:75::7 (FastEthernet0/0)
*Sep 23 01:22:44.255: dest 2000:1:1:1111::1
*Sep 23 01:22:44.259: traffic class 0, flow 0x0, len 100+14, prot 58, hops 62, forward to ulp
*Sep 23 01:22:44.259: IPV6: source 2000:1:1:1111::1 (local)
*Sep 23 01:22:44.259: dest 2000:1:1:75::7
*Sep 23 01:22:44.259: traffic class 0, flow 0x0, len 100+14, prot 58, hops 64, Route not found

Whats the ulp!? don't know right now...Let's check R2 since it is upstream from R1:

R2#show ipv6 route 2000:1:1:75::

R 2000:1:1:75::/64 [120/2]
via FE80::5, Serial0/1/0.1

R2 is learning the route but why isn't it sending it to R1? If we debug ipv6 rip on R2 we will see why:

*Oct 4 20:18:45.243: RIPng: response received from FE80::9664:1905 on Tunnel0 for cisco12
*Oct 4 20:18:45.243: src=FE80::9664:1905 (Tunnel0)
*Oct 4 20:18:45.243: dst=FF02::9
*Oct 4 20:18:45.243: sport=521, dport=521, length=132
*Oct 4 20:18:45.243: command=2, version=1, mbz=0, #rte=6
*Oct 4 20:18:45.243: tag=0, metric=4, prefix=FEC0:0:0:6419::/64
*Oct 4 20:18:45.243: tag=0, metric=4, prefix=2000:1:1:5500::/64
*Oct 4 20:18:45.243: tag=0, metric=4, prefix=2000:1:1:75::/64
*Oct 4 20:18:45.243: tag=0, metric=1, prefix=2000:1:1:25::/64
*Oct 4 20:18:45.243: tag=0, metric=4, prefix=2002:2:2:2::/64
*Oct 4 20:18:45.243: tag=0, metric=4, prefix=2000:1:1:7700::/64

*Oct 4 20:18:55.915: RIPng: response received from FE80::5 on Serial0/1/0.1 for cisco275
*Oct 4 20:18:55.915: src=FE80::5 (Serial0/1/0.1)
*Oct 4 20:18:55.915: dst=FF02::9
*Oct 4 20:18:55.915: sport=521, dport=521, length=192
*Oct 4 20:18:55.915: command=2, version=1, mbz=0, #rte=9
*Oct 4 20:18:55.915: tag=0, metric=1, prefix=FEC0:0:0:6419::/64
*Oct 4 20:18:55.915: tag=0, metric=1, prefix=2000:1:1:5500::/64
*Oct 4 20:18:55.915: tag=0, metric=1, prefix=2000:1:1:75::/64
*Oct 4 20:18:55.915: tag=0, metric=4, prefix=2000:1:1:25::/64
*Oct 4 20:18:55.919: tag=0, metric=2, prefix=2000:1:1:7700::/64
*Oct 4 20:18:55.919: tag=0, metric=4, prefix=2000:1:1:2222::/64
*Oct 4 20:18:55.919: tag=0, metric=4, prefix=2000:1:1:2200::/64
*Oct 4 20:18:55.919: tag=0, metric=4, prefix=2000:1:1:1100::/64

R2 is hearing two advertisements for 2000:1:1:75::/64, one is coming through the tunnel process cisco12 and the other is coming through the frame-relay cloud process cisco275.

R2 is installing the one from cisco275 because it has a lower metric and thus not advertising it to R1 because that's where process cisco12 is running.

We resolve this by redistributing between cisco12 and cisco275 on R2.

R2(config)#ipv6 router rip cisco12
R2(config-rtr)#redistribute rip cisco275 include-connected metric 3
R2(config-rtr)#ipv6 router rip cisco275
R2(config-rtr)#redistribute rip cisco12 include-connected metric 3

Now we have reachability:

R7#ping 2000:1:1:1111::1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2000:1:1:1111::1, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/20/20 ms

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