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Jumbo Frames and QoS for iSCSI (on Nexus 5548UP)


We have a FlexPod environment with only iSCSI. We also boot from iSCSI. We want to configure Jumbo Frames (MTU 9000/9216) on our Cisco Nexus 5548UP switces as part of the FlexPod. I have found many white papers, but they don't describe exactly wat we need.

First of all I am looking for a good white paper dat describes how to configure the Nexus 5548UP switces with Jumbo Frames for iSCSI. Also with platnum, gold, silver (for iSCSI) and bronze. I also have two other questions:

- Can you only enable Jumbo Frame switch wide on a Nexus 5548UP?

- Do you need to use QoS?

I hope somebody can advice me on this.


Everyone's tags (5)

Re: Jumbo Frames and QoS for iSCSI (on Nexus 5548UP)

After posting my question. I finally found a lot of information and took the change to configure QoS on our Nexus swithces. Although it get QoS working in the right policy-maps for type queuing I can't get Jumbo Frames to work properly. :-(

Re: Jumbo Frames and QoS for iSCSI (on Nexus 5548UP)

We have just succesfully implemented Jumbo Frames (MTU 9000) in our envornment on UCS, Nexus and NetApp. So far we have tested, it shows a big performance improvement.

I must add we had to open a case with Cisco TAC Support because we kept having issues with QoS on the Nexus switches. Although we had configured everything correctly, we finally found there was a very surprising reason for it related to NetApp. Apparently when you configure a trunk port with VLAN tagging on a NetApp filer, all traffic coming from the NetApp is tagged with a CoS value of 4. And it cannot be changed! It took us days to discover this. So be awar of this if you run in simular issues.

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