Strange network issues using jumbo packets.

From: Brent Clements (
Date: Wed Mar 05 2003 - 14:04:18 EST

Here is our situation.

We are running hp zx6000's with the latest kernel release for the
ia64(2.4.20 w/febuary patches).

We have broadcom cards onboard. We have a foundry switch that is capable
of doing jumbo frames...and jumbo frames are turned on in the switch

Now my problem. Using mtu's of 1500 on two linux boxes connected through
the switch, we can nfs mount each other and read and write to each

We move both linux machines over to mtu's of 9000 and then remount the
directories, but the machine that we are writing from or reading to will
just its network port freezes.

At first glance it looks like the switch is the cause of issue, but
we've had the network technician from foundry verify that the jumbo
frames are configured correctly and he's saying it's linux.

I'm at wits end here.

Does anyone else have experience running linux boxes with jumbo frames
through a foundry switch?

What should I set my linux boxes too? What do you guys recommend in
general? Could this be an autonegotiation issue?

Brent Clements

To unsubscribe from this list: send the line "unsubscribe linux-net" in
the body of a message to
More majordomo info at

This archive was generated by hypermail 2b29 : Fri Mar 07 2003 - 22:00:01 EST