The other day one of my colleagues, Mugdha Kulkarni, brought an interoperability issue to my attention involving a Brocade 1010 / 1020 CNA (Windows Server 2008, Driver 18.104.22.168) and a Cisco Nexus 5596 (NX-OS 5.0(3)N1(1c)).
The problem was the Brocade CNA was unable to login to the Nexus 5596. Complicating matters was the fact that the problem would not reproduce on a Nexus 5548. This was of particular interest to me since based on what we’ve observed (and what we’ve been told by Cisco), the 5548 and 5596 should be identical from a protocol interoperability point of view.
With this in mind, I spent a bit of time in the lab yesterday trying to figure out if the problem was related to a specific Nexus platform or NX-OS revision. Based on the testing results and after looking at the traces, my working hypothesis is the problem is due to a DCBX version negotiation problem.
We are actively working on the problem but unfortunately as of 6/30/2011, there is no workaround.
UPDATE: As of 10/19/2011, there is still no workaround for this problem but we were able to confirm that the issue is being caused by both devices failing to agree on which version of DCBX to use. As with almost all interoperability issues, the problem is being caused by unique characteristics of both implementations. As a result, the "fix" for the problem is for either vendor to slightly alter their DCBX negotiation behavior. Also as is typical for these types of interop issues, both vendors are providing a "fix" so that the issue can be addressed in as many different environments as possible. With this in mind, I received confirmation from Brocade that this issue will be fixed with driver version 22.214.171.124 (scheduled to be released early in Q1-2012). I also received confirmation from Cisco that this issue will be fixed in their next major NX-OS version (also scheduled to be released early in Q1-2012).
Thanks for reading!