Jumbo Frame - how do I implement it?

[wasc]

Hi all,

Some questions about JumboFrame.

1) I know I set the jumbo frame size in the properties for my NIC, but is that all I need to change, or do I also need to change the MTU in my windows registry???

2) If a device on my network doesn't support jumbo frames, will I lose connectivity to that device?

 

[wasc]

have a free bump.
I am interested to hear an answer too

Thanks

Well, I did a lot of reading and in the end decided to just give it a go

I have 3 machines (all of which support jumbo frames) so I enabled jumbo frames on the nic's of all 3 machines and then ran a network speed test - was no different. In addition, I tried to connect to another machine which didn't have jumbo frames on and that still worked as well, so basically enabling it did nothing.

Therefore I used a program called "Dr TCP" to change the MTU size in windows (on all 3 machines) to 4088 as this is supposed to be a good value according to a number of websites. I also enabled the MTU size discovery option in DR TCP and tested again. This time transfering files between the machines was quicker, so performance is now up. Also connecting to machines without Jumbo frame support still worked

**BUT** I lost connectivity to the computer in my DMZ. Therefore I put a rule on my firewall which was "Allow ICMP Code 3 Type 4 from ANY to ANY"

This restored my connectivity to my machine in my DMZ so obviously firewall was blocking this data. So far no other side effects but will update if I find one. Still in the early days of testing so far. Oh, very important - your switch MUST support jumbo frames (my netgear switch did).