09-04-2018 02:23 PM
I have some sysadmins trying to add Dell storage to a Cisco 9k. They are seeing a lot of latency in storage operations. Dell insists that the problem lies in needing flow control enabled. My question is more general. If the client to the storage is say three hops away from the 9k with the SAN - is there any need to have flow control enabled at all three switches? e.g. [ESX]--Edge SW--Core SW-Cisco 9K-[Dell Storage].
Or would flow control only be relevant at the CIsco 9k to which the Dell storage is attached?
I think the answer is that if the Ethernet port on the Cisco 9k has FC enabled and it received a flow control frame from the Dell - it would pause the next transmission until a free buffer on the Dell. In this cause there would be no need to propagate flow control info to the other switches or the client/the ESX.
Thank you for clarifying.
09-13-2018 05:46 AM
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