Core Switch MTU setting for VMware

[manly009]

Hi there, 

Currently, we have been moving a big file server from old cluster to new cluster. We have failed twice when migrating, it gave us Timedout error on Vm. 

VMware suggested increase MTU jumbo frame size. So, my question is: 

We have default MTU 1500 for all of switches. If I increase Jumbo Frame on our L3 core switch (it does ip routing for vlans)to 9000 for example, would I need to increase for all of our access switches and even for router? Needless to say I might need to do for VM hosts MTU settings as well, to keep consistence. 

Thanks

Manly009

[balaji.bandi]

Not sure what device you are using here in your environment.

check the is your device can able to support jumbo frames, if the vendor suggests increasing the MTU as per the requirement, you can increase that MTU size suggested to the particular connected interface (depends and device you using).

other devices not required to change.

[manly009]

I got a stuck of C3KX and 7 - 8 Access Switches. I can see now we got: system mtu routing and Jumbo Frame: 1500 in our core switch. Can I still change Jumbo MTU Frame default 1500 bytes to 9000 bytes to different ports that connecting VMware hosts without affecting something else?

Thanks
Mang

[balaji.bandi]

Depends on the version of code, if you like to change whole switch MTU you can change or per interface MTU

#show system mtu  - will give you information.

As per the requirement, you can only change connected interface to VMware.

here is the reference guide to set MTU

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-6000-series-switches/24048-148.html