Cisco Nexus 5000 to NetApp FlexPod FCoE Configuration - Flow Control

[mbroberson1]

I have an environment were we have a pair of Nexus 5K's connected (FCoE with VPC) to a NetApp FlexPod. The issue is it's believed that the Nexus 5K's  may be dropping traffic from the NetApp but I can't seem to find any evidence (me or Cisco TAC) to suggest this. I have been through the Cisco/NetApp FlexPod FCoE with VPC configuration guide (link below) and we seem to be spot on. One area I'm verifying is with the Flow Control setup on the 5K's. The configuration guide does not go to deep into the details of the Flow Control config and was looking for some suggestions from the field with anyone who may have had a similar experience or issue. 

http://www.cisco.com/c/en/us/support/docs/switches/nexus-5000-series-switches/118811-config-switch-00.html

Regards

[Drew Russell]

Apparently, I glanced over that question and focused in on Flow Control too much. Thanks for double checking me here Walter.

Anyway, I haven't run into issues in terms of FCoE on the NetApp / 5K. I also found an good article from Cisco that confirms there is no special configuration needed on the 5K side.

Per NetApp TR-4182 the best practice is to disable Flow Control throughout the environment.

'With that said, due to limitations with buffer designs on switches in the industry today, the best practice recommendation is to disable flow control throughout the network. This includes host ports, switch ports, and all ports on a NetApp node/controller; regardless of the make, model or speed (1Gb, 10Gb, doesn’t matter) of the interface. Allow the upper layer protocols to handle congestion control as needed. '

I would also recommend taking a look at the To flow or not to flow blog post by Justin Parisi who is a TME at NetApp. It does a great job and going into more detail around why the recommendation is to turn off flow control.

[Walter Dey]

Not sure, but this document refers to classical Ethernet (e.g. for NFS, iSCSI,....) not FCoE ?

FCoE requires lossless Ethernet which is not possible without flow control !