Change MTU setting for VCSA

[JudgementDay]

Hi.

I would like to change the MTU setting for the VCSA.

I've tried the instructions in the thread - Re: Change MTU in VCSA 6.5

Which do not work - MTU is not changed from the default 1500.

Has anyone manged to change the VCSA MTU successfully? Is this documented from VMware anywhere ? - I can't find anything.

Thanks in advance...

[GayathriS]

Did you check this :

https://www.virtualizationhowto.com/2017/02/vmware-vsphere-6-5-change-vmkernel-mtu-size/

Also when you say it is not working , whats happening , are you getting any error ? if yes post the error

regards

Gayathri

[JudgementDay]

Thanks GayathriS,

The link you refer to is not for the VCSA.

In reply to your question: Once the instructions are followed to set the Service and VCSA is rebooted, I check the MTU setting using

ip ad | grep mtu

or

networkctl status eth0

This returns the current set MTU (which in my case is the old one and incorrect).

Thanks...

[daphnissov]

I'm just curious here, but for what purpose would you want to change the MTU of the vCSA?

[JudgementDay]

For example, If I wanted to enable jumbo frames, I would enable across my physical network, ESXi, vSwitches and VM guest OS's....correct?

[daphnissov]

Not necessarily. You only need to enable jumbo frames on devices and systems where that makes a difference, but keep in mind that just because you set jumbo frames on your networking infrastructure does *not* mean that devices cannot continue to send smaller packet sizes. They can and will. So you really don't gain anything by trying to increase the MTU on vCSA. It can continue to work just fine even on a jumbo frames network.

[JudgementDay]

Thanks daphnissov. Understand, but If you I wanted to decrease the MTU (which is common for a VPN) how is that achieved? 

[daphnissov]

Default MTU is 1500. Decreasing an MTU from there probably isn't the best idea as that is a very common transmission size. Again, however, from vCSA's perspective, you're not gaining anything by changing this value as it isn't likely to transmit enough larger packets to "do" anything.

[JudgementDay · Accepted solution]

The instructions in the thread Re: Change MTU in VCSA 6.5 were slighlty incorrect.

After correction (which I have posted on the thread) the method works ok.