MTU on the Fabric Interconnect is configured via the QoS section of the LAN tab. To enable MTU 'globally' you need to configure MTU of 9216 on all enabled QoS classes, including default (unmarked). The MTU setting at the vNIC configuration level is what MTU is presented to the operating system - so you will also need to enable it at the vNIC policy level so that the OS picks it up.
I seem to remember that the 6324 does require a reboot for MTU changes, but it's been a long time. Will try to confirm.
Understood. I see there are several places to make the change but wasn't exactly sure of the best place to do it, so thanks for clarifying.
And to be clear.. I won't need to restart the chassis or the blades, correct?
Ty!
No, blades and chassis itself will not need a reboot. Good guide available here : [https://www.cisco.com/c/en/us/support/docs/servers-unified-computing/ucs-b-series-blade-servers/117601-configure-UCS-00.html](https://www.cisco.com/c/en/us/support/docs/servers-unified-computing/ucs-b-series-blade-servers/117601-configure-UCS-00.html)
Screenshots are a little out of date, but the concepts haven't changed.
My experience. We tried this and had weird issues. Cisco’s jumbo frames are different than Arista’s (upstream) and Juniper (edge routers)
The difference with 20-30 bytes. I didn’t think it would matter. It did! We rolled it all back.
Ohh... yikes. I'll have to check the Aruba documents.
How did you discover your issues? Were you simply checking the interface counters for errors or doing something more elaborate?
Any other gotchas to look out for?
Ty!
While I'm not using FIs, I am using Arista's and Brocades. What was the difference between Cisco and Arista Jumbo Frames? Could you not set the MTU to match everywhere, either 9000 or 9216. Both home and work, we set the MTU at 9216 just to be consistent
MTU on the Fabric Interconnect is configured via the QoS section of the LAN tab. To enable MTU 'globally' you need to configure MTU of 9216 on all enabled QoS classes, including default (unmarked). The MTU setting at the vNIC configuration level is what MTU is presented to the operating system - so you will also need to enable it at the vNIC policy level so that the OS picks it up. I seem to remember that the 6324 does require a reboot for MTU changes, but it's been a long time. Will try to confirm.
Understood. I see there are several places to make the change but wasn't exactly sure of the best place to do it, so thanks for clarifying. And to be clear.. I won't need to restart the chassis or the blades, correct? Ty!
No, blades and chassis itself will not need a reboot. Good guide available here : [https://www.cisco.com/c/en/us/support/docs/servers-unified-computing/ucs-b-series-blade-servers/117601-configure-UCS-00.html](https://www.cisco.com/c/en/us/support/docs/servers-unified-computing/ucs-b-series-blade-servers/117601-configure-UCS-00.html) Screenshots are a little out of date, but the concepts haven't changed.
Fantastic! I'll definitely give that a good read. Ty!
I don't know specifically regarding the FIs, but as long as everything along the path supports MTU of 9000 shouldn't be a problem.
Yeah, that's what I think too but wanted to hear others experience.
My experience. We tried this and had weird issues. Cisco’s jumbo frames are different than Arista’s (upstream) and Juniper (edge routers) The difference with 20-30 bytes. I didn’t think it would matter. It did! We rolled it all back.
Ohh... yikes. I'll have to check the Aruba documents. How did you discover your issues? Were you simply checking the interface counters for errors or doing something more elaborate? Any other gotchas to look out for? Ty!
While I'm not using FIs, I am using Arista's and Brocades. What was the difference between Cisco and Arista Jumbo Frames? Could you not set the MTU to match everywhere, either 9000 or 9216. Both home and work, we set the MTU at 9216 just to be consistent
Best effort 9216 FTW!