DSM-G600, DNS-3xx and NSA-220 Hack Forum

Diddycoon · 2007-08-28 20:00:33

Does the Marvell 88E1111 NIC on the DNS-323 support MTU jumbo frames?

Last edited by sala (2007-08-30 15:09:11)

dickeywang · 2007-08-28 23:46:45

Same question here. Has anyone tried to set the MTU via ifconfig?

Edit: Just found out that the Marvell 88E1111 is also used in the Linkstation pro, which supports 4k and 8k jumbo frames.

Last edited by dickeywang (2007-08-28 23:49:22)

Diddycoon · 2007-08-29 12:16:58

So does that mean it will automatically adjust to the MTU value I set on the gigabit NIC in my PC?
(I'm using a cat6 STP crossover cable to connect directly to the DNS-323).

dickeywang · 2007-08-29 18:10:50

I think the NIC is capable of using jumbo frames, but obviously the DNS is using MTU=1500 by default (if you have telnet access to the DNS, just assign the command "ifconfig" and it will tell you the MTU value).
I don't know if it is limited by the firmware, or other hardwares in the DNS. That's why I am asking if anyone has tried to use "ifconfig egiga0 mtu 8000" to change the frame size manually. I don't know if there is any risk to do so either.

Update: I just used ifconfig to set the MTU=8000 manually, and it now shows the following

egiga0 Link encap:Ethernet HWaddr --:--:--:--:--:--
inet addr:192.168.1.50 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:8004 Metric:1

Does it mean we now have jumbo frame?
PS: I am in my office and I did the ifconfig stuff remotely (the DNS is at home), so I will test if it helps to increase the transfer rate when I get home tonight.

Last edited by dickeywang (2007-08-29 18:31:18)

Diddycoon · 2007-08-30 14:35:40

Smaller frames usually mean more CPU interrupts and more processing overhead for a given data transfer size.

Will be interest to see if the transfer speed does slightly increase or decrease with different MTU values.
In that many people have said the bottleneck is the processing power of the DNS-323 chipset (like in many other NAS devices).

I eagerly await your benchmark results.

Emacs · 2007-08-30 15:34:38

Assuming I increase the MTU size on the DNS and my PC to let's say 4000 or 8000 to increase transferspeed between both - would that affect a third device in my network (media client) connecting to the DNS, where I cannot change the MTU size?

In other words, if the DNS is on jumbo frames, but my media client is still configured with 1500 MTU size, what'll happen?
I guess, the big frames will get fragmented down to the MTU size of the media client, wouldn't they?

Cheers,

Emacs

dickeywang · 2007-08-30 17:53:31

Diddycoon wrote:
Smaller frames usually mean more CPU interrupts and more processing overhead for a given data transfer size.
Will be interest to see if the transfer speed does slightly increase or decrease with different MTU values.
In that many people have said the bottleneck is the processing power of the DNS-323 chipset (like in many other NAS devices).

I eagerly await your benchmark results.

Yes, it does increase the transfer rate. Read speed is increased by 30% and write by about 15% (with MTU=4500). See my post:
http://dns323.kood.org/forum/t921-Jumbo … peed-.html

You need a switch that supports jumbo frame, you need enable jumbo frame on the desktop, then for the DNS you just need to assign the following command:

ifconfig egiga0 mtu 4500

cheers!

Diddycoon · 2007-08-30 22:54:29

Thanks I got it working and it does seem a little faster.

[img]http://pictureposter.allbrand.nu/pictures/[ D a Z l i N k ]/telnet.jpg[/img]

But after a reboot it still defaults back to a MTU of 1500 again.

Last edited by Diddycoon (2007-08-30 22:55:20)

dickeywang · 2007-08-30 23:45:08

Diddycoon wrote:
Thanks I got it working and it does seem a little faster.

[url]http://pictureposter.allbrand.nu/pictures/[ D a Z l i N k ]/telnet.jpg[/url]

But after a reboot it still defaults back to a MTU of 1500 again.

I guess you can add an entry into fun_plug if you want to, but personally I would test it for a while before I do so. Many people are saying that using jumbo frame can cause various problems.

PS: I know little about jumbo frame, but it seems when I type in "ifconfig egiga0 mtu 4500", the MTU is set to 4500, but when I type in "ifconfig egiga0 mtu 8000", the MTU is set to 8004. Where does the extra 4 bytes (8004-8000) come from?

Last edited by dickeywang (2007-08-30 23:47:02)

Focher · 2007-08-31 07:21:27

I recall seeing the jumbo frame option on the web configuration pages in one of the firmwares (I think 1.02) but it is definitely not there anymore. Of course, setting the MTU at the command line / in your fun_plug script is easy enough.

Skyweir · 2007-12-11 06:23:30

Well, I have tested it and it works very well for me. Can someone drop a hint as to where the entry would be entered in fun_plug and what it would look like?

DSM-G600, DNS-3xx and NSA-220 Hack Forum

Announcement

#1 2007-08-28 20:00:33

Quick question about MTU jumbo frames

#2 2007-08-28 23:46:45

Re: Quick question about MTU jumbo frames

#3 2007-08-29 12:16:58

Re: Quick question about MTU jumbo frames

#4 2007-08-29 18:10:50

Re: Quick question about MTU jumbo frames

#5 2007-08-30 14:35:40

Re: Quick question about MTU jumbo frames

#6 2007-08-30 15:34:38

Re: Quick question about MTU jumbo frames

#7 2007-08-30 17:53:31

Re: Quick question about MTU jumbo frames

Diddycoon wrote:

#8 2007-08-30 22:54:29

Re: Quick question about MTU jumbo frames

#9 2007-08-30 23:45:08

Re: Quick question about MTU jumbo frames

Diddycoon wrote:

#10 2007-08-31 07:21:27

Re: Quick question about MTU jumbo frames

#11 2007-12-11 06:23:30

Re: Quick question about MTU jumbo frames

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