Anyone used or know anything about jumbo frames?

[Cliotoby]

As title.

Got a 3760 stack with 9100 MTU configured across the switches. (Not me that did it)

Getting loads of drops. And I mean loads. That's not just a possible bug in the stack either - I read that there is a bug. If I am to transfer via ftp from one server to another on the same subnet then I lose a lot of packets, though it would appear the data arrives ok anyway - maybe it is resent and gets clogged up as I can see a 2GB file get half way through then slow down. Using wireshark I can see approx 11% is dropped. We have a 10G link across two sites (Dont ask) and I think the guys thought that it would perform better. We made the buffers bigger too. 40 to 4096.

Im wondering if anyone has come across problems before with jumbo frames.

 

[gbwarrior]

For jumbo frames to work don't you need all devices taking part to support jumbo frames and have it enabled, including the 2 servers or workstations. Are the servers or workstation and server both enabled for jumbo frames. To be honest I would steer clear of jumbo frames unless you are using them on a dedicated iSCSI network.

I saw stupidly low throughput once where traffic was going through a 10gig link but that was using HP kit, that was resolved by using flow control.

 

[gbwarrior]

Also is the problem with some specific servers or is it more widespread? Might be worth updating NIC drivers and NIC firmware.

 

[bmh.01]

They're more hassle than they are worth and aren't worth a lot with modern equipment. As said unless everything that is connected is set to support jumbo frames the oversized (to other gear) ones will be getting dropped left/right/center/etc.