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hkleinsorge
Contributor
Contributor

Problem changing MTU on vSwitch

We're running 3 ESXi 5.0.0 on HP Hardware. I wanted to change the MTU Size for all of them from 1500 to 9000, but, two of them throw a message and deny the change.

The only for me recognizable difference between these three servers is the NIC. The successful server is equipped with a Broadcom NetXtreme II BCM5709, the two others with a Broadcom NetXtreme II BCM5708.

This is the (german) error message:

Ein angegebener Parameter war nicht korrekt.

Vim.Host.VirtualSwitch.LinkDiscoveryProtocoConfig

Fehlerstapel:

Aufruf von "HostNetworkSystem.UpdateVirtualSwitch" für Objekt "networkSystem-663" auf vCenter Server "OurServer" ist fehlgeschlagen.

Any suggestions?

Thanks a lot!

Heiko

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marcelo_soares
Champion
Champion

On the KB http://kb.vmware.com/kb/1007654 you have some limitations:

  • Ensure that your NIC or LOM supports Jumbo Frames.
  • For ESX/ESXi 4.x and ESXi 5.0, contact your NIC hardware vendor regarding support for Jumbo Frames.
    You  cannot use Jumbo Frames on a Broadcom card that is configured as a  hardware initiator performing iSCSI offload functions. You can either  use Jumbo Frames or iSCSI Offload and you cannot use both together with  the Broadcom adapters.

Aren't you on this case? Can you check if the firmware you are using on the nic supports jumbo frames?

Marcelo Soares
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hkleinsorge
Contributor
Contributor

Checked your hints:

  • the NICs support Jumbo Frames (9 KB)
  • they aren't configured as a hardware initiator performing iSCSI offload functions

And found out two more details:

  • one affected server runs ESXi 5.0.0, 515841, the other ESXi 5.0.0, 623860
  • the error message occures even after not changing values, just by closing the window by clicking OK.
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kjb007
Immortal
Immortal

Message state error with Link Discovery.  Do you have CDP or LLDP configured under dvSwitch properties tab under Advanced?

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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hkleinsorge
Contributor
Contributor

No; we don't run Distributed Switches, only Standard Switches.

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kjb007
Immortal
Immortal

Strange error.  Can you open a console to ESXi, and run 'esxcfg-vswitch -B both vSwitch#' where '#' is the vSwitch number.  That should reset the CDP settings to both Listen and Send.

Also, run 'esxcfg-vswitch -l' and make sure what you see in the output matches what you have in the client.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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hkleinsorge
Contributor
Contributor

I run both commands, but, the problem is yet unsolved.

Here's console's output:

This system has been migrated to ESXi 5.0.0.
~ # esxcfg-vswitch -l
Switch Name      Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch0         32          4           32                1500    vmnic0

  PortGroup Name        VLAN ID  Used Ports  Uplinks
  Management Network    0        1           vmnic0
  VMkernel              0        1           vmnic0

Switch Name      Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch1         128         11          128               1500    vmnic1

  PortGroup Name        VLAN ID  Used Ports  Uplinks
  VM Network            0        9           vmnic1

~ #

~ # esxcfg-vswitch -B both vSwitch0
~ # esxcfg-vswitch -B both vSwitch1

~ #
~ # esxcfg-vswitch -l
Switch Name      Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch0         32          4           32                1500    vmnic0

  PortGroup Name        VLAN ID  Used Ports  Uplinks
  Management Network    0        1           vmnic0
  VMkernel              0        1           vmnic0

Switch Name      Num Ports   Used Ports  Configured Ports  MTU     Uplinks
vSwitch1         128         11          128               1500    vmnic1

  PortGroup Name        VLAN ID  Used Ports  Uplinks
  VM Network            0        9           vmnic1

~ #

Might I eventually try esxcfg-vswitch -m 9000 vSwitch#?

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kjb007
Immortal
Immortal

Certainly try it.  That previous error seems associated with the GUI for some reason.

Use -m to set mtu at the vSwitch level, then you'll have to go back and set the MTU at the vmkernel portgroup also, so that means going back to the GUI, but the portgroup settings are typically another wizard, so that may work out ok.

Otherwise, if you have to resort to cmdline for that also, you'll have to use esxcfg-vmknic to recreate the vmkernel port.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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hkleinsorge
Contributor
Contributor

Kanuj, it's resolved now :slightly_smiling_face:

Thanks for helping out.

I tell you some "funny" behaviour of our GUI: Now, after configuring the MTU manually, I can switch to the GUI, change parameters as I want, and CAN save them. Same behaviour at both of the vSpheres.

Thanks for your quick in-time-support,

- Heiko

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kjb007
Immortal
Immortal

Yeah, usually happens when things are out of sync.  So, force an update, and everything is back to normal.

Glad it worked it out for you.

-KjB

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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cfizz34
Contributor
Contributor

Is it possible to change the MTU once a host is attached to a cisco nexus and using distributed switching? How can I change this to MTU 9000 for vmnic01 and vmnic1?

DVS Name         Num Ports   Used Ports  Configured Ports  MTU     Uplinks
s-grnvsm-02      256         46          256               1500    vmnic1,vmnic0

  DVPort ID           In Use      Client
  5440                1           vmnic0
  5441                1           vmnic1
  5442                0

I have sucessfully changed the vmkernels but would also like to change the vswitch MTU size as well.  BTW..I am using ESXi 4.1 U1.

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cfizz34
Contributor
Contributor

one more quesiton, is it possible to change the MTU for multiple vmkernels at the same time?

esxcfg-vmknic -m 9000 -s s-vsm-02 -v 265  <this works for one at a time but I have hundreds of dvports that I need updated.

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