[ILUG] Linux Router + DSL

[Paul Jakma]

On Mon, 18 Oct 2004, Thomas Bridge wrote:

> On Fri, Oct 15, 2004 at 12:34:08AM +0100, Paul Jakma wrote:

>> 1. NB: Would it kill the ADSL providers to bump up the MTUs on their
>> link with Eircom (for eircom wholesale provision) or the ATM VC with
>> the customer by 8 bytes so the encapsulared PPP link doesnt have to
>> suffer 1492 MTU?
>
> Well yes.
>
> You see we use PPP over Ethernet - Ethernet has an MTU of 1500, but

s/has/once had/

> the PPP bit takes 8 bytes, hence 1492.

Really? ;)

How much of this goes over actual ethernet links though? The ATM VC 
to eircom - doesnt care about ethernet MTU... the circuit between 
Eircom and you, surely can be adjusted.. That leaves the internals of 
Eircom's router^W"BAS" - unless they terminate the VC on a different 
machine to where they encapsulate it into L2TP, that leaves only the 
link between the BAS and the router handling the link to the ISP.

So I can see why that'd be difficult.

However, in my case, the ATM VC terminates directly with you, doesnt 
it? And /you/ can just bump up the MTU on your router, no need for 
eircom to be involved.

(unless you do the PPPoE on a different router to that where the ATM 
VC terminates, /and/ you have an ancient, non-jumbogramme capable 
network between them, like Eircom do presumably..)

> T.

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
The reason computer chips are so small is computers don't eat much.