anandgopinath
Contributor
Contributor

Can a Dvswitch with MTU of 9000  host portgroups which use Jumbo frames and some which not use it ?

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Dear Community 

We  have a Dvswitch with  multiple Portgroups  ( vlans ) .

Can a Dvswitch with MTU of 9000  host portgroups which use Jumbo frames and portgroups which does not use jumbo frames  ? 

If we setup the Dvswitch with MTU of 9000,  will this MTU setting impact portgroups which may not use Jumbo frames  in any way ? 

Is there any way you can  force an MTU Setting at portgroup level  ? 

 

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a_p_
Leadership
Leadership

I'm not aware of any restrictions, or performance issues with using different MTU sizes for different connections on a single vSwitch. The important part is that the MTU size used for a given end-to-end connection is supported by all involved devices (virtual, and physical).

André

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lukaslang
Enthusiast
Enthusiast

The MTU setting on vDS level only allows Jumbo Frames to pass (like on any physical switch). As long as your VMs do not send jumbo frames, vSphere won't do it either (for VM traffic). Like written above, you cannot set different MTU values on portgroups, this will only work on vmkernel ports.

So in conclusion: if you want to use jumbo frames you have to do the following things:

- Check (and enable) your physical switch to allow jumbo frames

- Modify the MTU on vDS

- Modify your VM (on OS Level) to send jumbo frames

 

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a_p_
Leadership
Leadership

MTU is configured on the vSwitch, and the portgroup level. Note that the MTU on the port group must not be larger, then the one configured on the vSwitch.

André

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anandgopinath
Contributor
Contributor

Hello Andre  

Thank you for the quick help  🙂

 

how to set MTU on the Distributed port group  ?  Via web client GUI or CLI  ?  I dont see any MTU Setting against any existing Distributed port group via the  web client  😞

 

 

 

 

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a_p_
Leadership
Leadership

You can configure the MTU size only for VMkernel port groups, which means that you have to do this from the ESXi host level, i.e. select a host in the inventory, and edit its VMkernel adapter settings from the Configure tab.

André

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anandgopinath
Contributor
Contributor

Hello Andre ,

 

My query was around NON VMkernel  Distributed  Port groups   .

 

If we create a DVSWITCH with MTU9000 ,  should all the portgroups in that dvswitch  use MTU 9000 for traffic mandatorily ?  What if  a portgroup has traffic which does not use Jumbo frames  ?  Will there by any performance impact , supportability issues etc  ? 

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a_p_
Leadership
Leadership

I'm not aware of any restrictions, or performance issues with using different MTU sizes for different connections on a single vSwitch. The important part is that the MTU size used for a given end-to-end connection is supported by all involved devices (virtual, and physical).

André

View solution in original post

lukaslang
Enthusiast
Enthusiast

The MTU setting on vDS level only allows Jumbo Frames to pass (like on any physical switch). As long as your VMs do not send jumbo frames, vSphere won't do it either (for VM traffic). Like written above, you cannot set different MTU values on portgroups, this will only work on vmkernel ports.

So in conclusion: if you want to use jumbo frames you have to do the following things:

- Check (and enable) your physical switch to allow jumbo frames

- Modify the MTU on vDS

- Modify your VM (on OS Level) to send jumbo frames

 

View solution in original post