Gigabit with Jumbo Frames - Does it work at all?

[Rooke]

The hardware:

Two PCs - System A and System B. Both running XP SP2. Latest drivers, all updates, as current as possible.

System A has two Marvell Yukon PCI-E onboard Gigabit adapters. Let's call them A1 and A2. A2 is connected to a Fast Ethernet Router which in turn is connected to a cable modem, and is using all of the speedguide tweaks and works fine.

System B has one Linksys EG1032 ver2.0 Gigabit adapter. Call it B1.

A1 and B1 are connected together with a Linksys 5-port Gigabit workgroup switch over Cat6 cable. The switch's indicators show the connection is 1000Mb on both sides.

When I have the MaxFrameSize on A1 and B1 set to 1514 and the TCP MTU for both adapters set to 1500, the TcpWindowSize(s) set to 513920, and Tcp1323Opts = 1, everything works fine.

Here's the problem:

I want to maximize my performance across the Gigabit using Jumbo Frames - 9014.

If I set the MaxFrameSize(s) to 9014, adapter MTUs to 9000, TcpWindowSize for the adapters to 501760, and Tcp1323Opts = 1, then things get screwy.

Printer and File Sharing only work if the data being sent/received is "small" - short directory lists or small text files to be printed. Anything larger than that and the initiator hangs up.

If I ping from System A or B to the other side, it works fine so long as the buffer size is 1476 or less. Any ping with a buffer size between 1477 and 8972 times out, and anything over 8972 gets "Packet needs to be fragmented..." - as it should.
Ex: Ping -f -l 1477 SystemA

I've been researching this for days now, and all that I can come up with is other 2K/XP users trying this seem to be having similar problems.

Am I missing something? Has anyone actually gotten Gigabit with Jumbo buffers to work on a simple Windows-to-Windows connection?

Any help with this would be greatly appreciated.

Thank you.

[Rooke]

I think I already found the answer to my problem. I found a document on Google that says most SOHO gigabit switches do NOT support jumbo frames.

That's gonna be (expletive deleted) if its true.

I'm going to contact Linksys and see if they can confirm this about their Gigabit switch.

[Sid]

Please let us know the outcome! I'm very interested cause I just switched over to a gb LAN.

[Rooke]

I fired an e-mail off to them last night. They haven't gotten back to me yet. In the mean time, I did some more googling and the info I got was that Linksys claims the EG005W supports jumbo frames, but real-world reports (not from Linksys supported offshore unsupport personel) indicate it just ain't so.

And I tend to agree with the real-world reports. Every ping buffer over 1476 stops dead at the originating port on the switch - everytime.

I also found that there are only 3-4 soho gigabit switches that do support jumbo frames. Google for "gigabit switch" + "jumbo frames" to find them.

I've seen benchmarks that claim when using jumbo frames -9000, up to 900Mb/sec can be achieved using TcpWindowSize's 2MB or greater, but the best that can be acheived using standard ethernet frames - 1500, is only between 500-700Mb/sec.

I can live with 500-700Mb/sec, but it would have been better if the jumbo frames were really supported.

My take is, if you *have* to have the fastest transfer speed possible, don't get a Linksys soho gigabit switch.

[Atreyu]

Check out the SMP switches. They all support Jumbo Frames, and I think at this point they are the only ones that do.

http://www.smc.com/index.cfm?event=view ... =7&scid=39

[magoood]

Regarding Jumbo Frames, i wanna know if this setting will have any performance boost in my case

I am having the Marvell Ykon Gigabit chipset too (that came with the Asus A7N8X-E deluxe board i use) and i am connected 2 the net via a LAN network where the router's location is at my neighbour's house.

I am interested 2 know if there will be any effect 4 me if i choosed Jumbo frames to be e.g. 4088 Bytes. In fact i have done that already but nothing different i noticed but this may be due 2 my ignorance with such advanced settings

Also, if i am not a burden, i am really very interested 2 know what other vague options do & how can i tweak 'em (if possible) e.g. Options like:
Flow Control
Max IRQ per sec
Interrupt Moderation
Number of Rcieve buffers
Number of Transmit buffers

THANKS IN ADVANCE

[Shinobi]

http://www.enterpriseitplanet.com/netwo ... hp/3497796

The above URL really helped me out with both Windows and Linux Gigabit Config's.. a lot of differnt factors to consider...

Hope it helps.

Shinobi

[magoood]

http://www.enterpriseitplanet.com/netwo ... hp/3497796

The above URL really helped me out with both Windows and Linux Gigabit Config's.. a lot of differnt factors to consider...

Hope it helps.

Shinobi

Unfortunately, the link u gave me points only 2 some tweaks in the TCP/IP parameters but i was talking about tweaks for the chip itself.

Anyway i fiddled with the "# of send/receive buffers" by increasing 'em from the default 50 to 200 and i found my connection speed became really better and faster somehow.