A question about jumbo frame.

[mekand]

Hi.

I'm looking for infos about jumbo frame and fragmentation when these move within the same vlan.

Two hosts must comunicate each other using jumbo frame but a switch does not support jumbo.

Is there a way to fragment?

Thanks.

Regards.

Andrea

[16again]

afaik, fragmentation is only possible at layer3 , not at layer 2.

The extra processing won't speed up transfers, if devices in the chain have max MTU=1500, just send end points MTU accordingly

[Vince-Whirlwind]

There are two types of Jumbo frames:

1. Actual jumbo frames, 6x bigger than normal. The idea is that instead of sending 6 frames, by sending 1 frame, you save on 5 headers. Depending on whether they are dot1q frames or not, this is a total saving of 90-110bytes (out of 9000). On the downside, a bigger frame means a CRC error causes a bigger re-transmit. 

2. Little Jumbo frames, where some kind of additional overhead (eg, VMWare VLAN-tunneling, or encryption) has bumped the frame size a bit higher than the usual maximum.

Either way, if your switch doesn't support Jumbo frames, you can't use them.