ipv6 connectivity bugs


     I have a 7201 and an ASR1000 and they share a link and run ipv4 and bgp over it no problem.

     I am experimenting and have now added some static ipv6 configuration, and I can't seem to ping across the link. The issue looks like one side us advertising prefixes correctly and the other isn't. Here's my interface configs:


interface TenGigabitEthernet0/1/0.110025
   encapsulation dot1Q 25 second-dot1q 11
  ip address x.x.x.1
  ipv6 address xxxx:yyyy::1:1/126


interface GigabitEthernet0/0.110025
   encapsulation dot1Q 25 second-dot1q 11
  ip address x.x.x.2
  ipv6 address xxxx:yyyy::1:2/126

When I try pinging 7201 from the asr1000, no response. I do see a neighbor entry on the asr1000:

sh ipv6 neighbors
IPv6 Address Age Link-layer Addr State Interface
xxxx:yyyy::1:2 0 xxxx.yyyy.8e1b REACH Te0/1/0.110025
FE80::xxxx:yyyy:FE49:8E1B 0 xxxx.yyyy.8e1b REACH Te0/1/0.110025

On the 7201 however, there seems to only be the link local address neighbor entry for the asr1000:

sh ipv6 neighbors
IPv6 Address Age Link-layer Addr State Interface
FE80::xxxx:yyyy:FE2D:D190 0 xxxx.yyyy.d190 STALE Gi0/0.110025

Can anyone spot what I am doing wrong?


Do you have anything in the way of COPP on either box that may be
dropping packets? I would imagine the issue is likely to be on the
AS1k end.

Additionally I see you have different interface speeds at each side.
Is the thing in the middle at fault? ND is done using multicast.

One final thing is attempt to ping across the link local addresses.
Make you you set the source address correctly.


I am able to ping the link local address of the 'opposite end' from each side, so it looks so me like that is working. I also notice, when I try pinging the 7201 from the asr1000, during that time, the output of 'show ipv6 neighbors" shows me this:

sh ipv6 neighbors
IPv6 Address Age Link-layer Addr State Interface
FE80::xxxx:yyyy:FE2D:D190 6 xxxx.yyyy.d190 STALE Gi0/0.110025
xxxx:yyyy::1:1 0 - INCMP Gi0/0.110025

     It looks to me like enough is 'working' that the asr1000 -> c7201 path is working, but not the other way around. And no, far as I know, I have no copp or other filtering that would (to my knowledge) create a one way situation. As far as the middle, I have ip/mpls that is bridging my vlan25 across the network:

! ME3600x - Facing ASR1000
Interface TenGigabitEthernet0/1
switchport trunk allowed vlan none
  switchport mode trunk
  mtu 9216
  service instance 25 ethernet
   encapsulation dot1q 25
   rewrite ingress tag pop 1
   xconnect 2 encapsulation mpls
    mtu 9216

! ME3600 - facing c7201
interface Vlan25
  mtu 9216
  no ip address
  xconnect 2 encapsulation mpls

Do I need to make a special provision somewhere for multicast? This seems pretty basic setup to me.


Just a shot in the dark, are you able to run port-mode EoMPLS on the
ME3600X side as well?


Thats a good question. I would need to move some things around in my network in order to test it, not sure if I have the resources at the moment but I'll keep it in mind.

Well, the switch facing the 7201 is also an ME3600X. Meaning that you
can use EVC Xconnect on there like you did on the one facing the ASR9001.

EoMPLS on an EFP is the same as port-mode EoMPLS. So where you have the
BD for VLAN 25, consider running EoMPLS directly on that EFP instead of
on the SVI.


For the group, I finally discovered the problem. Under the switchport config connected to the 7201, I had "switchport block multicast" - which seems to block in only 1 direction (inbound). Removing that line and all of a sudden ipv6 starts to work.

Thanks for the suggestions all.