[SOLVED] sessions locking using jumbo frames

clcbluemont · 09-08-2010, 05:33 PM

With Mellanox 10G NICs and the MTUs set from 1600 to 9000 we have tcp sessions hanging. Executing ls during an sftp session just hangs. The same thing happens for an ssh session, if execute ls I might get few item in the directory but then the session hangs. Like wise for FTP. The Fujitsu switch is configured by default to handle jumbo frames. At 1500 MTU everything works fine.

We are running the 2.6.25.14 kernel with CentOS 5.2 and the Mellanox driver.

Why are these sessions dying?

grim76 · 09-08-2010, 09:11 PM

Have you setup your network gear to support the larger MTU?

clcbluemont · 09-09-2010, 02:27 PM

Thanks for your response. I am trying to break into the switch. The last administrator did no leave the access information.

clcbluemont · 09-09-2010, 03:17 PM

I was sure that fujitsu switch being a 10G switch would have jumbo On by default. I was wrong.
Executed "bridge jumbo-frame" and the connection worked, however now dmesg is showing:
SKB BUG Invalid true size (9208) len=16498 Sizeof (sk_buff)=208

I will start searching the web for answers to what this means.