Router says I am using PPoE on 20CN connection

[davej99]

For reasons unknown to me, my Netgear DGN2200 is telling me I am using PPoE encapsulation on my plain old 20CN connection. I know not how long this has been the case but it seems to be working fine fine. I recollect the router on first use detecting the wrong encapsulation and I recollect changing it from oE to oA at the time. Now it may be the router is lying to me, because as I understand it PPoE is not the correct setting.  So I wonder if that is indeed the case and my router is telling me one thing and doing another. Or may be it has detected wrongly after a firmware update a few months ago.

{Edit} The other curiosity is that the router limits MTU to 1458 maximum. Does that make sense? {Edit}

Thanks, Dave

[Rik]

I've seen this, and it's worked regardless of the setting. Try forcing a manual change and see what happens.

A router change to 1458 would normally have to be made manually. Was the router supplied by IDNet.

[davej99]

I've seen this, and it's worked regardless of the setting. Try forcing a manual change and see what happens.

A router change to 1458 would normally have to be made manually. Was the router supplied by IDNet.

Thanks, Rik.

Does that mean connection will work on PPoE and PPoA. The router is my own DGN2200 and about a year old and trouble free. All IDNET settings. The router is working fine on manual PPoA settings, but it will not let me set MTU higher than 1458. Curious since my old DG834G would accept up to 1500 or 1492 as I used to use.

[Rik]

I've had connections work with the router reporting PPoE. Whether it was telling the truth I never did establish. Similarly, it worked whilst in bridge rather than routed mode - I sometimes think they do what's right and tell us what they want.

Do you have an MTU of 1458 set in Windows anywhere?

[Lance]

Interestingly my 2200 won't let me change the MTU any higher either. It does show pppoa though!

[Rik]

That is interesting, Lance. A Netgear foible, perchance?

[Lance]

Probably. In the "help" to the right of the screen it mentions 1500 along with a couple of othe values but when you try entering the higher value it pops up a message saying 1458 is the maximum.

[davej99]

It maybe the dgn2200 is cleverer than we think. Found the following note over at ADSL Nation, which I think is applicable just to 20CN, which I am using:

As the BT ADSL-line uses PPPoA with L2TP encapsulation the maximum value is 1458. 'Normal' Ethernet MTU is 1500 bytes, but after encapsulating in PPPoA you have only 1458 bytes left. The encapsulation itself effectively steals 42 bytes from your frames.

[Lance]

I was wondering if it could be that last night, I decided it wasn't because tht isn't how any other router I've come across works.