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

Mack McBride mack.mcbride at viawest.com
Fri Jul 8 14:59:11 EDT 2016

You may want to hit up the Ciena mailing list, most people here are cisco oriented.
If storm control or multicast filtering is turned on/misconfigured, you could see that behavior.
It could be on any of the devices in the path, yours or theirs.
No clue how to tell on their side but on the cisco side the interface configs should be pretty obvious.

Mack McBride | Senior Network Architect | ViaWest, Inc.
O: 720.891.2502 | C: 303.720.2711 | mack.mcbride at viawest.com | www.viawest.com

-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Mike
Sent: Friday, July 08, 2016 12:03 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] ATT ASE Madness - one way ethernet


     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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