[c-nsp] ATT ASE Madness - one way ethernet

Mike mike-cisconsplist at tiedyenetworks.com
Fri Jul 8 14:02:50 EDT 2016


     I have a new ATT ASE circuit and they have been troubleshooting now 
for two weeks. The symptom simply is that I appear to have one-way 
connectivity; Packets go from 'site a' to 'site b', but 
Broadcast/Multicast does not go back from 'site b' to 'site a'. For 
example, I can put static arp entries in both peices of my gear at 
either end, and have ping connectivity. But if I remove these, then arp 
doesn't complete and thus ping does not work. Stranger still, the 'site 
b' can see the CDP neighbor announcements from 'site a', but that site 
doesn't see the announcements from 'site b'.

     Naturally ATT thinks it's me and wants me to replace / test / etc, 
but I think it's misconfiguration on their end since its clearly 
broadcast/multicast not being forwarded. On ATT end they have a Ciena 
3960 if that helps anyone. On my side, 'site a' is a ME3600x while 'site 
b' is an ASR920, if that helps. Does anyone have a better idea as to 
what to look at here?


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