Mtu?

[markX]

Wot's with MTU setting? No ISP has asked me to do this before.


I'm connecting friends up to adsl24 in a day or two and obviously want their interweb to work straight off (it's taken me 3 years to convince them to have it!).
Further research says I should set this "MTU" on the router and all computers connected to it... Well, there's no way to do this on a Westell 2400, it involves fiddling with the registry in XP and I haven't even begun to try and figure it in Ubuntu Linux.

What's the chances of connection hassle if I just don't bother?

[the-bruce]

I left mine on default and it was fine m8

Brucey

PS.

Default on mine is 1500

[tonys]

http://www.kitz.co.uk/adsl/tweak2.htm

[Dae]

Having had a quick look through the 2400's manual there is certainly no web-interface method of changing the MTU value.
It might be possible to alter the setting by Telnet-ing in to the router and using the CLI in someway,
but you'd have to ask Westell about this.

In any case as long as when viewing 'Troubleshooting' > 'Ethernet Port Stats' on the Westell the MTU is set to 1500
I wouldn't worry about it too much :)

It is however still worth setting the MTU (& more importantly RWIN) of the OS to match what is set on the router.

And I tend to use TCPOptimizer (http://www.speedguide.net/downloads.php) from speedguide.net to set the MTU (and RWIN) settings in Windows XP.

But you have to use the following command(s) to set MTU in Windows Vista:

netsh interface ipv4 show subinterfaces [To show you the current settings]

netsh interface ipv4 set subinterface "Local Area Connection" mtu=1478 store=persistent [To set the MTU value]

(Where "Local Area Connection" is the name of the relevant connection)

I am not sure if the RWIN settings can be easily altered in Vista as they are dynamically assigned by the TCP/IP stack.
(Unless someone can correct me on this? still don't use Vista much)

The following link may be useful on the Broadband & Linux (http://www.santa-li.com/linuxonbb.html) front.

[markX]

Thanks everyone for help so far.
I did connect the friends up today up today and found that the Westell wouldn't even log them in but the Draytek router would. They are 2kms from the exchange so the max speed is claimed to be up to 3meg. Their att and snr are pretty abysmal presently, about 5 snr and 50+ att, but this was at dusk, with an asteroid allegedly upsetting the magnetics of the atmos and a long tel extension cable .
Wondering what will happen after 10 days for the tel exchange to set something.
It looks like I will have to do my best to tweak things, move the router next to the BT socket and use a longer ethernet cable instead. Checked the BT socket and it's 2 wire.
I can apparently telnet the Draytek (checked their FAQ) to set the MTU, and fiddle with XP as people suggested. Not sussed how to do it in Linux yet (I have vowed never to use Vi$ta but to migrate to Linux instead).

[James]

I wouldn't bother messing with the MTU unless you have browsing issues. Leaving it at default should be fine more most.

[markX]

I'll see how it's going after the alleged 10 day "tuning" period. Cheers