[c-nsp] Allow only PPPoE packets on specific vlans

[lists at Hojmark.ORG]

> mac access-list extended PPPoE
>   permit any any 0x8863 0x0
>   permit any any 0x8864 0x0
>   deny   any any

You're permitting only PPPoE... 

> First i applied it on 1 switch all was good. Then i started 
> to apply it to all others and when i configured the 5-th i
> lost ALL network.

I think it would be wise to also permit at least STP BPDUs, or
think very very closely about which VLANs it's turned on for,
and the topology of those VLANs.

-A