Jumbo Frames and Etherchannel (LACP) on 2960

[bill.morton]

Are Jumbo Frames supported on the 2960 switch for Etherchannel links? I can't find anything in the documentation. I have found that the 3750 states that the MTU must be the same for the links to come up. I had jumbo frames working just fine until I setup an etherchannel between my blade switch and 2960 switch, and I was wondering if it is a limitation of the 2960.

[Jon Marshall]

Bill

Yes the 2960 supports jumbo frames - see attached link.

http://www.cisco.com/en/US/products/hw/switches/ps700/products_configuration_example09186a008010edab.shtml#c4a

Jon

[bill.morton]

John,

Thanks for the quick response; however, I want to know if there is a specific limitation of Jumbo Frames in an LACP etherchannel. I know that the switch itself supports jumbo MTU as I have had this working until I changed the ports into an LACP link. If the switch is process switching the etherchannel packets (which I dont think it should be) that would limit the frames to the 1500 byte MTU limitation of the CPU which is the only thing I can think of.

[lamav]

Bill:

What do you have your Jumbo MTU size set for?

Im asking becuase the 2960 does not support CPU-bound packet sizes greater than 1998 bytes. CPU-bound traffic refers to control traffic, like SNMP, telnet, and I imagine PAgP protocol traffic.

HTH

Victor

[bill.morton]

System Jumbo MTU size is 9000 bytes

I would agree that the control traffic is limited, but I would think all the actual data-traffic is hardware switched.

More information: the etherchannel is between a HP GbE2c Ethernet Blade Switch, which according to their documentation supports Jumbo in etherchannel, so I am not quite sure where the problem is. The servers report they have Jumbo, so I think there must be something between the two switches.