ESXi - dvswitch, intel X540, Cisco switch - no jumbo frame

Rand__

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Mar 6, 2014
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I cobbled together a temporary esxi box where i want to run my primary VMs during a maintenance of my primary cluster/mlx switch.
I used some spare parts that were around, one is a X540-T2 NIC that is supposed to provide 10 gig upload (and dvswitch compatibility) for this box ( the other boxes use CX3 as dvswitch uplink, but i want to turn of the mlx too). DVswitch compatibility in the sense that I have a high speed nic I can add to it so the VMS do not need network reassignment.

My problem is now that for some reason something in the chain is blocking jumbo frames.
Chain is ESXi -X540T2- dvswitch_uplink- Cisco sg350x

On the esxi I am able to ping self with Jumbo, but not another esxi box.
-X540T2 should support jumbo but I have not found a way to verify on esxi
-the dvswitch is configured for Jumbo frames (its working fine on other esxi boxes with same jumbo settings)
-the switch is configured for Jumbo frames globally and it should work since other ports work fine with it

-I also moved the nic to a local vswitch with jumbo configured, same issue.

Will need to run some more tests tomorrow, but maybe somebody has another idea?

Thanks
 

Rand__

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Mar 6, 2014
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Actually for the stand alone vswitch I did not, good catch.
Unfortunately it does not help, and the dvswitch is o/c set up correctly (its been in use for a while)
 

kroy

New Member
May 17, 2019
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Actually for the stand alone vswitch I did not, good catch.
Unfortunately it does not help, and the dvswitch is o/c set up correctly (its been in use for a while)
Right, but on ESXi, there are two places you need it.

  • On the vSwitch/dvSwitch
  • On the VMKernel adaptor

So check to make sure your vmk0/1 whichever is attached to that portgroup/dvSwitch is marked a 9000 MTU.
 

Rand__

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Mar 6, 2014
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Yes I had set vswitch already, just not vmk for the standalone switch. the dvswitch is set up ok.

As of current testing it looks to be the Cisco switch...

vmnic5 (cx3->6036) ok
vmnic4 (cx3->sg350x via adapter) nok
vmnic2 (intel->6036 via adapter) High power transceiver is not supported. => switch to different port "SX6036 - use ports 1,3,33,35 only in Ethernet mode" -> OK
vmnic3 (intel->sg350x ) NOK

adapters used: QSFP->SFP+, SFP+->10GbE (S+RJ10, Rev 2.1)

Thats honestly quite shocking. O/C Jumbo support is turned on on it...

So new question - why does the SG350x not support Jumbo frames :eek:

Cross reference: SG350XMP jumbo frames not working - Cisco Community
 
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