IPV6 far end address

August 31, 2006 @ 9:59 pm · Filed under CCIE Study

Hi Charles,
ipv6 has functionality built in to actually sense what other devices are connected to a segment.
If you run “show ipv6 routers”, then you should see addresses and details pertaining to directly connected ipv6 capable routers. ipv6-enabled interfaces run ICMP neighbour discovery by default (to disable this capability, you suppress the neighbour discovery messages using “ipv6 nd suppress-ra” on the particular interface). You can fine-tune the neighbour discovery interval so that messages are sent more quickly (”(config-if)# ipv6 nd ra-interval [3-1800]”). The general idea behind ICMP neighbour discovery is to allow configuration of ipv6 hosts on a network segment.
Run a debug for these neighbour discovery messages to verify.
R6#debug ipv6 nd ICMP Neighbor Discovery events debugging is on *Sep 1 01:49:10.107: ICMPv6-ND: Received RA from FE80::1 on GigabitEthernet0/0.136 *Sep 1 01:50:37.279: ICMPv6-ND: MTU = 1500 *Sep 1 01:50:37.279: ICMPv6-ND: prefix = 2001:CC1E:136::/64 onlink autoconfig *Sep 1 01:50:37.279: ICMPv6-ND: 2592000/604800 (valid/preferred) *Sep 1 01:50:37.279: IPV6: source FE80::6 (local) *Sep 1 01:50:37.279: dest FF02::1 (GigabitEthernet0/0.136) *Sep 1 01:50:37.279: traffic class 224, flow 0×0, len 104+1396, prot 58, hops 255, originating *Sep 1 01:50:37.279: IPv6: Sending on GigabitEthernet0/0.1361 Output Interface:
The nice thing is that you don’t need to have generated any IPv6 traffic for the “show ipv6 routers” command to work correctly:
R6#sh ipv6 routers Router FE80::1 on GigabitEthernet0/0.136, last update 0 min Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0, MTU=1500 HomeAgentFlag=0, Preference=Medium Reachable time 0 msec, Retransmit time 0 msec Prefix 2001:CC1E:136::/64 onlink autoconfig Valid lifetime 2592000, preferred lifetime 604800 Router FE80::213:80FF:FEF0:A4A0 on GigabitEthernet0/0.136, last update 0 min Hops 64, Lifetime 1800 sec, AddrFlag=0, OtherFlag=0, MTU=1500 HomeAgentFlag=0, Preference=Medium Reachable time 0 msec, Retransmit time 0 msec Prefix 2001:CC1E:136::/64 onlink autoconfig Valid lifetime 2592000, preferred lifetime 604800
Running “show ipv6 neighbors” after executing the ping to the all-hosts address (as advised by Brian in an alternate response to this thread) or generating any other sort of broadcast traffic (such as RIP suggested by Sabrina) should also yield the addresses of any directly connected neighbours (media non-specific):
R1#ping FF02::1 Output Interface: gigabitEthernet0/0.136 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to FF02::1, timeout is 2 seconds: Packet sent with a source address of FE80::1
Reply to request 0 received from FE80::6, 4 ms Reply to request 0 received from FE80::213:80FF:FEF0:A4A0, 4 ms Reply to request 1 received from FE80::6, 0 ms Reply to request 1 received from FE80::213:80FF:FEF0:A4A0, 0 ms Reply to request 2 received from FE80::6, 0 ms Reply to request 2 received from FE80::213:80FF:FEF0:A4A0, 0 ms Reply to request 3 received from FE80::6, 0 ms Reply to request 3 received from FE80::213:80FF:FEF0:A4A0, 0 ms Reply to request 4 received from FE80::6, 0 ms Reply to request 4 received from FE80::213:80FF:FEF0:A4A0, 0 ms Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/4 ms 10 multicast replies and 0 errors.
R1#sh ipv6 neighbors IPv6 Address Age Link-layer Addr State Interface FE80::213:80FF:FEF0:A4A0 0 0013.80f0.a4a0 REACH Gi0/0.136 FE80::6 0 0013.c37c.7610 REACH Gi0/0.136
Lots of useful commands to achieve what you need here.
Regards,
Alex
—–Original Message—– From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of CharlesB Sent: Friday, 1 September 2006 8:25 AM To: ccielab@groupstudy.com Subject: IPV6 far end address
Group,
How can we obtain far end IPV6 address? If the media is Ethernet and Frame relay. For example for frame relay, if the task does not give us the link local address for the far end? For Ethernet, I am just trying to figure out how we can use the IPV6 tools.