enable jumbo frames on a vDistributed switch

[iinfi]

Hello,

I am looking to enable Jumbo frames on my DVS. I have done it all my life on a Standard Switch and in that case we have to enable on a per vmkernel port level.

I read the documentation about DVS which says we can enable it at the DVS level. The documentation also says there is a way to do it at vmkernel port level (even if your switch is a DVS)

My confusion is, in case of a DVS do I have to enable Jumbo frames at Switch and VMkernal port level or does the switch level setting over-ride whats set at VMKernel port?

In my setup, what I see though I have set the Jumbo frames as 9000 in the DVS level, the VMkernel port MTU still shows as 1500. Any inputs appreciated.

Thank you

[npadmani]

My confusion is, in case of a DVS do I have to enable Jumbo frames at Switch and VMkernal port level or does the switch level setting over-ride whats set at VMKernel port?

the way it works is, if you want Jumbo frames to be enabled for all the ports and port groups in your DVS, just do this setup at DVS level. Let's say this is kind of switch wide setting.

alternatively you can set it up per VMKernel Port basis too if you wish. I would say, settings done at Switch Wide can be over-ridden at Port level.

Ref: https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=10388...

[iinfi]

settings done at Switch Wide can be over-ridden at Port level

This is exactly my concern now. The reason being, though I have set MTU = 9000 at the DVS level, the VMKernel ports still show 1500. I didnt touch the VMKernel port settings. So basically, if I want to make it 9000, I would have to do it at both switch and Port-level>

Is my understanding correct?

[npadmani · Accepted solution]

OK, now there's a small thing to remember which I forgot to mention in the earlier post.

when you are changing MTU setting at DVS level, if your VMkernel port are already on your DVS, that setting is not going to be affecting existing ports. But since MTU at DVS level is already set to let's say 9000 bytes, then any new port created on your DVS will pickup this new setting.

so, for existing ports, you still got to adjust the value separately.

[iinfi]

Awesome ....looks like that was the crux.
Let me try this in my setup. Dont think this part is mentioned anywhere.

[SebastianGrugel]

If this rule is related with VSphere 5.5 too?

[npadmani]

Yes, same is applicable for vSphere 5.5  version of DVS too.