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I have just set up my new gigabit network and when I was about to increase the MTU to use jumbo frames, I get this error:

root@rayquang-desktop:~# ifconfig eth1 mtu 9000 SIOCSIFMTU: Invalid argument

Could anyone help me to increase the MTU.

Details: NIC: NETGEAR GA311; Switch: NETGEAR GS105, running Ubuntu 10.10 and Debian Lenny on desktop, server respectively.

Help would be greatly appreciated, RayQuang

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6  
It seems that your NIC does not support jumbo frames! –  Khaled Dec 29 '10 at 12:26
    
khaled is right. try lower values, ~7000 works on my NICs –  Sirex Dec 29 '10 at 12:29
    
aparantly 1500 is the maximum that i can get :(. Is there no other choice but buying a better NIC? If i should buy a new one which one should it be? Thanks, RayQuang –  RayQuang Dec 29 '10 at 12:42
    
Remember that the switches also must have the ports configured to use jumbo frames or BTWH –  coredump Dec 29 '10 at 12:43
    
@coredump I checked the PDF datasheet for the switch, apparently that model does support JF. –  Tom O'Connor Dec 29 '10 at 12:56

2 Answers 2

up vote 8 down vote accepted

Yep. I just looked at the PDF datasheet for your NIC

No mention of Jumbo Frame support there, so I suspect you're out of luck.

Buy a new nic. Go for something Intel or Broadcom and you'll probably have more luck. Shouldn't set you back too much.

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Or just forget about jumbo frames; it's not like they make much difference with current CPU's @1Gb. –  janneb Dec 29 '10 at 13:32
    
~20% throughput improvement is not to be sniffed at, don't know if its worth spending cash though. –  Sirex Dec 29 '10 at 14:58
    
@Sirex: 20% under what circumstances? @work I just measured 940 Mb/s using iperf without jumbo frames, which is 94% of the theoretical maximum, so a 20% improvement is just impossible in that case. (CPU usage was 5% of one core on the sender and 1% on the receiver; not only CPU's but also NIC's and the network stack in OS'es are different from 10 years ago.) –  janneb Dec 30 '10 at 11:02

Why do you need jumbo frames in the first place?

It is not common on desktop PCs.

UPDATE: @Sirex I still think it is uncommon in home environment. He has netgear nic and switch. These are a SOHO stuff. People should not use some technology because it has a good name. They do because of real need.

I run high-end blade servers and I do not feel the need for jumbo frames.

UPDATE2: @RayQuang Then I think upgrading your switch and NIC can help much more than enabling jumbo frames. Others already suggested Broadcom and Intel as a NIC and I suggest Cisco (not the small business thingy) or HP as a switch.

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this sums it up overall, and imho it's not that uncommon on gigabit networks; 63.196.71.246/~phil/jumbo.html –  Sirex Dec 29 '10 at 14:11
    
@Sirex I still think it is uncommon in home environment. He has netgear nic and switch. These are a SOHO stuff. // I edited my answer to include this. // –  cstamas Dec 29 '10 at 14:33
    
Swings and roundabouts i guess. I only know of 3 home networks running at gigabit speeds. All use jumbo frames. (n.b: I didn't set those networks up, but mine also uses jumbo @ gigabit) –  Sirex Dec 29 '10 at 14:47
    
I'm sorry if I did not make it clear that this is is for a corporate network that just in this case happens to be in a home. I need the high throughput for large data transfers of OS images and for the link with database and other application servers. –  RayQuang Dec 31 '10 at 9:02

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