Question about Jumbo frames

[eyeball]

Hi everyone,

just wondering if anyone has any experience with jumbo frames and if they can answer this question:

If i have 2 switches, 1 that supports jumbo frames and 1 that does not what will happen to the data that passes between them? (more specifically Jumbo to non-jumbo) will the data be fragmented? or will it just not work?

Thanks for your time

[CoffeeFiend]

If i have 2 switches, 1 that supports jumbo frames and 1 that does not

Then you can't use jumbo frames.

the data that passes between them? (more specifically Jumbo to non-jumbo) will the data be fragmented? or will it just not work?

It doesn't pass then. If a switch doesn't support jumbo frames, it'll just "drop" them i.e. not work. Sounds like you're in the market for a new switch.

[eyeball]

Hi,

Yeah i have 2 switches at home. The Layout is as follows:

1GBswitch----------1GBSwitch------------100MBps(ROUTER)

I am looking at replacing the 2 switches with Jumbo Frame switches. I assume i would need a router capable of supporting jumbo frames then too?

Thanks for the help

[rendrag]

if the nodes you are sending information between exist on the 2 switches and you are wiring them exactly as shown, then you do not need a router that supports jumbo frames.

[eyeball]

Excellent!

Thanks for the help

[CoffeeFiend]

I am looking at replacing the 2 switches with Jumbo Frame switches.

Beware though. Lots of switches claim to support jumbo frames, but don't actually support them in a meaningful way. Some have a max packet size in the 1500's still (and often with small buffers), and not like 9000+ bytes like you'd expect.

[eyeball]

Yeah i noticed that, the ones im looking at (a 3com 8 port) support Jumbo frames of 9k which as you say is what you would expect.

[CoffeeFiend]

If you ever get that 3com, please report back I just ordered a Netgear GS608 (dirt cheap, 8 ports for $50! Minus a $25 main in rebate afterwards!) that's supposed to support 9000 bytes. It has a small 128KB buffer though, but you can only expect so much outta $50 (their JGS524 has 2MB, but it's also 5x the price). It gets OK reviews on newegg. I was looking at a very nice HP managed switch before, but it wasn't exactly in the same price range. This one's so cheap I figured I'd just try it. If/when it dies, or if it sucks too bad, then I'll get something else. SMB2 + IPv6 + jumbo frames should work nice Hopefully one day we'll see jumbograms support and 10 GigE too.

[eyeball]

I havent bought it yet, I sent a question to one retailer about another Switch (and compatability with Jumbo frames) and never got an answer. Im not sure what buffers these ones have, I will have a look.

Thing is I dont *need* jumbo frames, I just want them

D.amn my stupid obsession with all things ICT lol

I cant believe a 2mb buffer is 5X the price, thats just crazy.

Edited April 3, 2009 by eyeball

[CoffeeFiend]

Thing is I dont *need* jumbo frames, I just want them

Well, yeah. I didn't need them either, but it's highly desirable for sure. Faster speeds overall (roughly 1/3 faster or so), less CPU usage (about half) due to less headers to process (only like 1/6 as many packets), etc.

I think it's quickly becoming something close to a necessity for a lot of us with file servers and lots of large files (HD video, PVR'ed content, movie servers, VM disk image libs, ISOs, large archives, etc -- and possibly even thinking of things like a basic iSCSI SAN sooner or later). It's highly desirable for sure. I'll likely post back when I get around to test it.