Unanswered Question
Mar 16th, 2009

Would it be possible to implement qos on srdf/s traffic? Presently we have 4 dedicated LES100 links which we use to replicate the srdf/s traffic from one site to another. I've been asked if the srdf traffic could moved over to our LES1000 link which we use to route all other traffic from site to site. We use 3750 switches to terminate the LES100 links and to connect to the EMC equipment. There is just one vlan on which spans across the LES100 links for the srdf/s traffic.I have no experience of the SAN but would imagine the srdf/s traffic would need an LLQ.



I have this problem too.
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Michael Brown Tue, 03/17/2009 - 03:22


I assume your FC traffic on the LES circuits is FCIP? If so, then the MDS can mark the IP packets with a specific DSCP value, and if the routing/switching gear in the LES is configured for OoS, and the load is sufficient to invoke QoS, you can prioritize the FC traffic.

With FCIP you can mark control and data traffic with the same, or different DSCP values. You can not distinguish between SRDF and other FC traffic. All FC data traffic is treated the same by the FCIP tunnel with regards to DSCP marking.

I have never seen any recommendations for SRDF/S to require an LLQ.

The recommendation for a FCIP synchronous traffic is to mark the Control traffic with DSCP 48, and Data with DSCP 26. Control traffic is Switch to Switch, and Data is RDF port to RDF port traffic. This should put the FC Control traffic in the same class as Routing protocol frames, and the Data slightly below voice and video, and above Network Management and best effort.

Your specific QoS schema might be different, so you should work with the network engineers managing the LES for specific values to use.

Here is a link to some Cisco information on DSCP marking.

Hope this helps,



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