Tuesday, February 22, 2011

Basic IPv6 point-to-point interface setup on a Cisco router.

We have been slowly rolling out IPv6 throughout this past year. Here is a basic configuration to get IPv6 P2P links between 2 routers. This was mocked up in GNS3 for OSX.


ipv6 unicast-routing
interface GigabitEthernet1/0
 ip address
 negotiation auto
 ipv6 address FE80::9 link-local
 ipv6 address 2604:3E00:1:1::1/64
 ipv6 enable


ipv6 unicast-routing
interface GigabitEthernet1/0
 ip address
 negotiation auto
 ipv6 address FE80::11 link-local
 ipv6 address 2604:3E00:1:1::2/64
 ipv6 enable

Ping test from Router1 to Router2:

ping ipv6 2604:3E00:1:1::2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2604:3E00:1:1::2, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/7/16 ms

We statically set our link-local address so a easily understandable next hope can be determined when we view the routing table. What we do is setup all link-local addresses exactly the same on each router. For example all LL addresses on router1 are: FE80::9, all LL addresses on router2 are: FE80::11, etc... In the example below you can see how this makes it easier for a human to get the next hop.

Router1> show ipv6 route
IPv6 Routing Table - default - 11 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
       B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP
       I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
       D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery
       O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
OE2 ::/0 [110/1], tag 2552
     via FE80::11, GigabitEthernet1/0
OE2 2000:2000:666::/64 [110/1]
     via FE80::11, GigabitEthernet1/0
OE2 2000:2000:1000::/64 [110/1]
     via FE80::11, GigabitEthernet1/0
OE2 2000:2000:2000::/64 [110/1]
     via FE80::11, GigabitEthernet1/0
OE2 2000:2000:3000::/64 [110/1]

Need to see the IP's associated with the interface, run:

Router1> show ipv6 interface gi 1/0
GigabitEthernet1/0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::9 
  No Virtual link-local address(es):
  Global unicast address(es):
    2604:3E00:1:1::1, subnet is 2604:3E00:1:1::/64 

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