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Benefit using the full 1500 MTU yet?

Community Veteran
Posts: 3,181
Thanks: 19
Fixes: 2
Registered: 31-07-2007

Benefit using the full 1500 MTU yet?

Going to test it over the next few days, seeing as BT are doing the work to fix the problem. Just wondering if anyone has already changed and have noticed any change/improvement at peak times?
Unvalued customer since 2001 funding cheap internet for others / DSL/Fibre house move 24 month regrade from 8th May 2017
10 REPLIES
N/A

Benefit using the full 1500 MTU yet?

How do you get your RWIN of 64240 with an MTU of 1500?
Community Veteran
Posts: 3,181
Thanks: 19
Fixes: 2
Registered: 31-07-2007

Benefit using the full 1500 MTU yet?

Cause im pushing it to find faults, thats the maximum I can use. I will be trying other settings later if that gives packetloss

To find the other figures you can use with This link

ed: forgot to say only works in IE not Opera that link
Unvalued customer since 2001 funding cheap internet for others / DSL/Fibre house move 24 month regrade from 8th May 2017
N/A

Benefit using the full 1500 MTU yet?

From my understanding, the work to enable this is still ongoing.

BT are performing a service program at this time, visiting each exchange to make further required changes to enable this.

At the same time, PPPoE is being rolled out where possible, which is either part of the required changes, or is being enabled for customer choice (unsure).

Users will see very little improvment with this inclreased MTU value.

This setting will simply mean that default values will not cause slowdowns and data bottlnecks.

This roughtly means, for every 30 - 40 packets sent with a MTU of 1500, you will have sent 31 - 41 on the lower value.

This does not mean you have gained an extra packet of data. You will transmit the same amount, with the exceptio of sending one less header.

The changes BT are making will not affect those that have applied the tweak, nor is it designed to give you better speed. It is being implimented, to reduce the load on the BT systems, that have are having to deal with splitting the data when you have the default settings applied.
Community Veteran
Posts: 3,181
Thanks: 19
Fixes: 2
Registered: 31-07-2007

Benefit using the full 1500 MTU yet?

Well I know that my connection was affected because of packet loss before when using 1500. So if it's changed then all the better. If not then back to 1430.
Unvalued customer since 2001 funding cheap internet for others / DSL/Fibre house move 24 month regrade from 8th May 2017
N/A

Benefit using the full 1500 MTU yet?

Just tried it.
Noticed a big improvement in speed overall, but still slightly
slower (approx 2% )than using MTU of 1430. (tried 3 tests on each setting).
N/A

Benefit using the full 1500 MTU yet?

Heres my latest speed test with an MTU of 1500 & RWIN of 31775

http://www.btjones.plus.com/images/Speed%20test.jpg
Community Veteran
Posts: 3,181
Thanks: 19
Fixes: 2
Registered: 31-07-2007

Benefit using the full 1500 MTU yet?

Speed isn't the issue, more of packet loss. I will find out this evening if it appears from 6pm onwards, then the tweaking starts.

Plus the fact never found that speed tester to be accurate, better using a ftp download so no rouge readings from a possible cached image/file
Unvalued customer since 2001 funding cheap internet for others / DSL/Fibre house move 24 month regrade from 8th May 2017
N/A

Benefit using the full 1500 MTU yet?

The packet loss at MTU 1500 is caused by the routers @ BT.

The whole MTU issue suround the BT routers having to fragment packets.

Under heavy loads, aka, last year when nobody was using the tweaks, this puts major strain on the BT routers, which in some cases, drop your data.

The whole idea of the MTU fix BT are putting in place, is to prevent the fragmentation, saving any changes at all to be performed.
Community Veteran
Posts: 3,181
Thanks: 19
Fixes: 2
Registered: 31-07-2007

Benefit using the full 1500 MTU yet?

Well forgot all about this but in the week of using the higher MTU and Rwin, I've not noticed any increase in packetloss, which was a problem before. So guess my area has been fixed. But saying that, Sod's Law will start tomorrow :lol:
Unvalued customer since 2001 funding cheap internet for others / DSL/Fibre house move 24 month regrade from 8th May 2017
N/A

Benefit using the full 1500 MTU yet?

I used it and the setting has made a huge difference. In fact most of the web sites used to timeout before I changed the setting.

But intrestingly the plus.net web site was quite fast to load !

Cheers
S