Setting system jumbomtu on 6500 (720-PFC3b)

[ryan.lambert]

Hi all,

Quick question I believe. It's been so long since I last had to and I don't have a test environment presently.

In setting the system jumbomtu on a 6506 switch with trunks/port-channels configured, is this briefly service impacting? I know there are some extra considerations on NX-OS, not sure about IOS (15.x) with sup720. 

I'll obviously choose to do this activity in a maintenance window regardless, just curious what to expect.

Thanks.

[Reza Sharifi · Accepted solution]

Hi,

According to this document system jumbomtu is 9216 by default.

You can verify that using

show system mtu

Switch# show system mtu
System MTU size is 1546 bytes
System Jumbo MTU size is 9000 bytes

When jumbo frames are enabled on the Catalyst 6500, an MTU range from 1500 bytes to 9216 bytes can be chosen. The system's default MTU is 9216 bytes, but this can be changed with the following command:

6K-LV2-CL3(config)# system jumbomtu ?

  <1500-9216>  Jumbo mtu size in Bytes, default is 9216

http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/prod_white_paper0900aecd805457cc.html

HTH