[c-nsp] MLD snooping breaks IPv6 neighbor discovery

[Bernhard Schmidt]

Bernhard Schmidt <berni at birkenwald.de> wrote:

> It looks like this problem is caused by IPv6 MLD snooping (default
> enabled) on the switch. It has an entry for the ND multicast group for
> *:??02:0001 pointing towards the second switch:
>
> # sh ipv6 mld snooping explicit-tracking vlan 6 | i FF02::1:FF02:1
>::/FF02::1:FF02:1               Te2/2:Vl6 FE80::207:E9FF:FE24:997E  EX
>::/FF02::1:FF02:1               Te2/2:Vl6 FE80::204:23FF:FEBC:C20E  EX

Another output:

# sh mac-address-table multicast vlan 6 | i 3333.ff02.0001
   6  3333.ff02.0001    static  Yes          -   Te2/2,Router

I tried some searches in Bug Toolkit but found nothing related. I would
be fine with disabling MLD snooping anyway, but apparently sending RA is
something pretty hard for a Sup720. We have another box that just does
not send RA packets on one particular SVI, although no setting on this
SVI is different from other boxes or other interfaces on this router.

Regards,
Bernhard