I'm getting ready to deploy a QoS strategy for a couple newly deployed Nexus 5020 switches, and I have a design/classification scenario that I'm not quite sure what would be the best practice? Anyway, our current 802.1p cos classification is setup as follows:
cos 6-7 - reserved data/control plane
cos 5 - VoIP traffic
cos 4 - interactive (video) traffic
cos 3 - mission critical (contains several apps, but most importantly, it includes SQL & Citrix traffic)
cos 2 - network ctrl (SNMP, RADIUS, telnet, ssh, etc)
cos 1 - scavenger/greyNet traffic
cos 0 - good 'ol best effort
Anyway, we are introducing SAN over IP, particularly iSCSI traffic, into this mix, and I want to make sure this is placed in a lossless (no-drop) queue. Given that the default setup of the Nexus 50X0 switches place all traffic marked with cos 3 in a fcoe class configured as lossless, it make sense (at least in my mind) that I should also mark iSCSi traffic cos 3 and place into this class (or a class setup just like class-fcoe). However, since I already have my mission critical traffic marked this way, would it be appropriate to place iSCSi, SQL, Citrix, and the rest of my mission critical traffic all in the same class? If not, what would be the recommended way to deploy this in this situation?
N5K is a bit special since it supports FCOE and configured it as COS3 by default. I don't think you should mix data and iSCSI in the same class. At lease I will not do it.
You need to ask yourself a question, do you have VoIP and Interactive video running through the N5Ks? I would think the N5K is a DC switch and such traffic is minimum.
I would considering marking it to COS4 or so and then remarking it when it leaves the N5Ks to your standard marking.