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[Chrysalis]

most likely their page is simply wrong (out of date).

1500 bytes on ipv4 will still work as mtu discovery wll fix it on the fly, but it will slow things down.

[loonylion]

1492 for FTTC
1500 for ADSL

1500 can be used for FTTC with some adjustments to jumbo frames, but if you dont know what thats about do 1492.

ADSL used 1492. I know because I spent months arguing with plusnet over it (the DSLAM was trying to use a 64kb mtu and screwing up my connection badly, PN and BT denied there was anything wrong, despite my repeatedly providing proof) I had to manually override it at my end, which improved things but still didn't fix the problem, which wasn't solved until I switched to LLU.

[JustAnother]

My understanding was PPPoA VS PPPoE - my ADSL line used the former throughout its life, meaning the standard ethernet max of 1500 was fine and I knew nothing about MTU - but with ppp over ethernet (VS ATM), you lose some capacity due to the extra ethernet frame involved.

Disclaimer: This is off the top of my head.

[loonylion]

My understanding was PPPoA VS PPPoE - my ADSL line used the former throughout its life, meaning the standard ethernet max of 1500 was fine and I knew nothing about MTU - but with ppp over ethernet (VS ATM), you lose some capacity due to the extra ethernet frame involved.

Disclaimer: This is off the top of my head.

PPPoA actually used 1492, but 1500 would work. 64kb worked but the throughput was atrocious.

[JustAnother]

I'm not saying it didn't in your case, but normally I don't think it has a special lower MTU - e.g. MTU is mentioned very early on in the PPPoA wiki article.

[Chrysalis]

"It also avoids the issues that PPPoE suffers from, related to having a MTU lower than that of standard Ethernet transmission protocols"

as I said 1500 bytes for pppoa

[NewtronStar]

Kitz has a nice tutorial on MTU http://www.kitz.co.uk/adsl/tweak2.htm

I just keep it at the default of 1500 on FTTC but play around with it and see http://www.linksys.com/us/support-article?articleNum=134914

[ejs]

I tried to answer Oldjim's question previously on the plusnet forums. I thought the 1492 MTU limit does not apply to combined VDSL2 modem/routers because there's no Ethernet link between the modem and the router.

If there's an Ethernet connection between a separate VDSL2 modem and router, without jumbo frames, that would limit the Ethernet payload to 1500, and to allow for the PPPoE layer overheads, that limits the IP packet size to 1492.

[Oldjim]

I thought I remembered raising it there but I couldn't remember 
Old age strikes again

[HighBeta]

In aa's clueless* there's  LCPFix for talktalk lines.

LCPFix
Re-negotiates PPP LCP after acquiring the connection from BT (who may provide a wrong high MTU of 1500 on a 1492 link)
More info: During the ppp connection when your router initially syncs up and logs in to us, the ppp connection is passed via BT. Sometimes BT can change the MTU. With this option we will accept the PPP connection from BT, but will then re-negotiate the PPP connection with your router allowing the MTU to be reduced. On TalkTalk connections the MTU is always negotiated as 1492, you need to select LCPFix and an MTU 1500 to fix this (otherwise the LNS will use 1492 when re-negotiating)

http://support.aa.net.uk/Other_Line_Options 

Chrysalis's useful  thread from a while back 
http://forum.kitz.co.uk/index.php?topic=12842.0


--------------------------------------------------------------------------------------
*Had no issues  using 1508 or 1526 setting with aa -

[kitz]

So does that mean that TalkTalk do that automatically or that they don't use PPPOe
http://help2.talktalk.co.uk/what-mtu

Please note: There is one exception to this rule with TalkTalk fibre routers. They normally have the MTU set to 1500 and you should not change this to 1432.

TT have always been weird.  Possibly down to the fact that they inherited a some of their backhaul from AOL.  Which historically has always been prone to MTU issues.

TT Fibre is the only one that uses IPoE, all the others use PPPoE.

[burakkucat]

Hmm . . . Perhaps all this MTU/MRU discussion should be split off into its own thread? 

I had to double check the subject line:  Billion Bipac 8800NL. 

[Chrysalis]

So does that mean that TalkTalk do that automatically or that they don't use PPPOe
http://help2.talktalk.co.uk/what-mtu

Please note: There is one exception to this rule with TalkTalk fibre routers. They normally have the MTU set to 1500 and you should not change this to 1432.

TT have always been weird.  Possibly down to the fact that they inherited a some of their backhaul from AOL.  Which historically has always been prone to MTU issues.

TT Fibre is the only one that uses IPoE, all the others use PPPoE.

ok sorry I wasnt aware they didnt use PPPOE.

[Colsey85]

Hi sorry to butt into the middle of this convo. I have got a billion 8800nl and im just wondering if my stats look normal to you guys? I am worried I have a lot of ES. I have come from a huawei hg523a which said I had 0 ES (over a 48hour period not sure if I believed it).

The hg523a also seemed slightly faster in speedtests, 5.8meg compared to 5.4meg on the billion.

DLM kept putting my snr up with the billion so I got talktalk to put me on the 9db profile and turn off dlm.

Anyway here are my stats from 5 days of use:

[NewtronStar]

Anyway here are my stats from 5 days of use:

Not to bad for a 3.4km line lets take your errored second total over 5 days 2841 we divide by 5 and that will give you 568 ES per day then we divide by 24 to get ES per hour = 23.6 it's ok

You can go a bit further and divide 23.6 by 60 to get errored seconds per minute = 0.39