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Standard User thomaswarne01
(regular) Thu 01-Mar-12 22:45:01
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Efficient MTU


[link to this post]
 
Hi there,
I currently have my MTU setting at 1472 on PPPoE and i was wondering what is the most efficent mtu setting for PPPoE?
BT Business 8Mb unlimited
ADSL Link Downstream Upstream
Connection Speed 8128 kbps 448 kbps
Line Attenuation 24.0 db 15.0 db
Noise Margin 12.2 db 25.0 db

Administrator MrSaffron
(staff) Thu 01-Mar-12 23:13:28
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Re: Efficient MTU


[re: thomaswarne01] [link to this post]
 
Why are using PPPoE? What hardware was supplied with the service?

20CN ADSL generally is best with PPPoA on the router, and 1500 MTU

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User thomaswarne01
(regular) Thu 01-Mar-12 23:56:55
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Re: Efficient MTU


[re: MrSaffron] [link to this post]
 
I was using it as that was what the router detected, bt supplied a business hub but i dont like them as they crash all the time, so i use a netgear dgn2200 and i have reconfigured it to PPPoA with 1458 mtu and i think it is much better.

Is this efficient in terms of throughput?

Thanks.


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Standard User camieabz
(sensei) Fri 02-Mar-12 00:48:33
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Re: Efficient MTU


[re: thomaswarne01] [link to this post]
 
What operating system are you using?

~~~~~~~~~~


© Camieabz 2002-2012

All Connection Data ~ plusnet

Scottish Labour politician: “The SNP are on a very dangerous tack. What they are doing is trying to build up a situation in Scotland where the services are manifestly better than south of the border in a number of areas.”

Interviewer: ”Is that a bad thing?”

Scottish Labour politician: “No, but they are doing it deliberately.”
Standard User chris6273
(member) Fri 02-Mar-12 01:30:36
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Re: Efficient MTU


[re: thomaswarne01] [link to this post]
 
I used to be able to squeeze 859KB/s throughput out of my 8128Kbps connection by using 1430 as my MTU, with PPPoA (Compared to setting the MTU to 1458 where I had a maximum of 848KB/s).

I always found that the throughput was lower when using PPPoE.

-------------------------------------------------------------------
My Broadband Speed Test

Downstream Upstream
Connection Speed: 24000 kbps 1223 kbps
Line Attenuation: 16.5 db 6.4 db
Noise Margin: 0.6 db 6.4 db

Edited by chris6273 (Fri 02-Mar-12 01:35:44)

Standard User AbandonShip
(fountain of knowledge) Fri 02-Mar-12 16:05:15
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Re: Efficient MTU


[re: chris6273] [link to this post]
 
A packet size of 1478 should give the lowest overheads on PPPoA, due to it not having any ATM padding bytes. The next most efficient is 1430 (exactly one ATM cell's worth of data less, so again no padding bytes). I used to notice a small but consistent (and measurable) boost by using an MTU of either 1478 or 1430 rather than the default when I was on a fixed 1mbps connection, can't say I notice any difference now I'm on adsl2+ as my speeds vary too much anyway.

I don't recall the best MTU for PPPoE, but as it uses more protocol bytes per packet than PPPoA, the throughput would be lower.

Edited by AbandonShip (Fri 02-Mar-12 16:15:40)

Standard User XRaySpeX
(eat-sleep-adslguide) Fri 02-Mar-12 16:25:02
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Re: Efficient MTU


[re: thomaswarne01] [link to this post]
 
Measure it using instructions in http://www.kitz.co.uk/adsl/MTU2.htm . Set router to MTU = 1500 before doing so.

If using Win XP, have you changed its default MTU from 1500?

1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC
Standard User thomaswarne01
(regular) Fri 02-Mar-12 18:44:30
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Re: Efficient MTU


[re: camieabz] [link to this post]
 
Win7 64

Standard User camieabz
(sensei) Fri 02-Mar-12 18:51:30
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Re: Efficient MTU


[re: thomaswarne01] [link to this post]
 
Pop into a command line box:

netsh interface ipv4 show subinterfaces (or ipv6 if applicable)

That will show your MTU for the network devices. Forget fiddling with RWIN in Vista. Best to set MTU on the router to 1500, especially if the PC is set to that.

N.B. - I'm talking PPPoA though.

~~~~~~~~~~


© Camieabz 2002-2012

All Connection Data ~ plusnet

Scottish Labour politician: “The SNP are on a very dangerous tack. What they are doing is trying to build up a situation in Scotland where the services are manifestly better than south of the border in a number of areas.”

Interviewer: ”Is that a bad thing?”

Scottish Labour politician: “No, but they are doing it deliberately.”

Edited by camieabz (Fri 02-Mar-12 18:52:01)

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