IPv6 Configuration Issues

[taylor.gravis]

I preface this by saying, I am new to IPv6.  I am testing IPv6 configuration between two routers (Cisco 7204VXR), in one configuration I attempted to use the following configuration:

ipv6 unicast-routing

R1 - FE0/0 - ipv6 address 2001:aaaa:bbbb::1/64

R2 - FE0/0 - ipv6 address 2001:aaaa:bbbb::2/64

I was not able to ping across the Ethernet link, but I was able to ping the interface address on each router.  In other words, R1 could ping 2001:dead:beef:1/64 on its local interface and R2 could ping 2001:dead:beef::2/64 on its local interface, but they could not ping each other across the Ethernet link.

After that test, I used the EUI-64 address configuration below, which did work.  I was able to ping from R1 to R2 and R2 to R1.

R1 - FE0/0 ipv6 address 2001:aaaa:bbbb::/64 eui-64

R2 - FE0/0 ipv6 address 2001:aaaa:bbbb::/64 eui-64

Any input would be great, I know that I am missing something, but I don't know what it is (by the way IPv4 works just fine).

Thank you,

Taylor

[Marcin Latosiewicz]

Taylor,

Not sure what went wrong, I can tell you though what to check in future if you face a problem like this.

You need to first of all check interface information and nighbors (I know it might seem obvious).

What you're looking for is that ND was done correctly and that there were no DAD filures.

An example of working ping between two sides and how this affects neighbor table.

BB_964#show ipv6 neighbors
IPv6 Address                              Age Link-layer Addr State Interface
FE80::A8BB:CCFF:FE03:C700                   0 aabb.cc03.c700  STALE Et0/0

BB_964#sh ipv6 interface e0/0
Ethernet0/0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::A8BB:CCFF:FE03:C400
  No Virtual link-local address(es):
  Global unicast address(es):
    2001:DB8:DB1:3::1, subnet is 2001:DB8:DB1:3::/64
  Joined group address(es):
    FF02::1
    FF02::2
    FF02::5
    FF02::6
    FF02::1:FF00:1
    FF02::1:FF03:C400
(...omitted...)

BB_964#ping 2001:DB8:DB1:3::2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:DB1:3::2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/8/44 ms
BB_964#show ipv6 neighbors
IPv6 Address                              Age Link-layer Addr State Interface
2001:DB8:DB1:3::2                           0 aabb.cc03.c700  REACH Et0/0
FE80::A8BB:CCFF:FE03:C700                   3 aabb.cc03.c700  STALE Et0/0

It's the place to start, just remember to check this out on both sides 😉

Marcin