Jumbo Frames on Intel Interfaces

[aviegas]

Tossing the discussion around using Jumbo Frames to the side, I'm trying to set it up on TrueNAS Core 12U2 and I'm seeing some really weird results.

System (old system repurposed for testing) has 3 Intel Ethernet adapters (1 x 82579LM and 2 x 82574L) all capable of handling JF@9000B.

In theory 2 interfaces (any 2) will be part of a lagg, but this fact seems to be irrelevant. I've tried all possible combinations of interfaces, with and without the lagg, and I can only get it to work with one of the 82574L adapters:

- ifconfig shows MTU correctly set to 9000, for all cases/combinations
- I use the same network cable to test (moving it from one Ethernet port to another). This eliminates the switch or the destination test host as the problem.
- I can always ping with a payload up to 1954 with any of the adapters. Above that only one adapter works (isolated or as part of a lagg).
- On the TrueNAS side, I can "send" a ping of any size (up to 65507), but I know it's not real. If I come from the other side (tried Linux and VMWare) I can only get 8972.

Ignoring the lagg, what bugs me is that it works with one of the 3 adapters only and ifconfig shows that MTU 9000 is configured.

Any ideas?

 

[Spearfoot]

What kind of switch are you using? And is it configured to support jumbo packets?

I use a Brocade 6610 switch. To enable support for jumbo packets I have to include 'jumbo' in its startup configuration.

 

[aviegas]

What kind of switch are you using? And is it configured to support jumbo packets?

I use a Brocade 6610 switch. To enable support for jumbo packets I have to include 'jumbo' in its startup configuration.

Cisco and yes, it's properly handling jumbo frames. All other hosts in the network (VMWAre and NAS boxes) are using jumbo frames for quite some time. As I said, I'm using the same network port and even the same cable and it work on one port but not on the others. Even on a second instance of the same network card.