PPPoE and non-ethernet modems

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looking at
http://www.dlink.com.au/products/broadband/dsl200 /

it says
"The DSL-200 supports Static IP, Dynamic IP, as well as PPPoE/PPPoA and
Bridge connections terminating on the local PCs."

Firstly,  don't modems just convert digital to analogue and vice versa,
and dial numbers.   They would just provide the connection, withot
knowing about PPP's username, and passord. So 'd have thought that all
modems  'support ppp' as they should any computer protocol since it's
just a digital signal.

Secondly,how can you have PPPoE i.e. PPP over ethernet, on a
non-ethernet modem?



Re: PPPoE and non-ethernet modems
> Firstly,  don't modems just convert digital to analogue and vice versa,
> and dial numbers.   They would just provide the connection, withot
> knowing about PPP's username, and passord. So 'd have thought that all
> modems  'support ppp' as they should any computer protocol since it's
> just a digital signal.
>
> Secondly,how can you have PPPoE i.e. PPP over ethernet, on a
> non-ethernet modem?

DSL CPE devices aren't simple modems in the same sense as POTS devices.
They often have bridging and/or routing capabilities in them in addition to
the analog modulating capabilities.  A DSL modem providing the phone line to
ethernet connection most of the time acts as a bridge.  The DSL devices that
support PPPoE are also acting, in a fashion, as a router; making the PPPoE
connection and providing a bridge to it.

PPPoE is, more or less, a tunnelling protocol.  In the same fashion as PPP
over a serial link or dial-up.



Re: PPPoE and non-ethernet modems
jameshanley39@yahoo.co.uk writes:
>looking at
>http://www.dlink.com.au/products/broadband/dsl200 /
>it says
>"The DSL-200 supports Static IP, Dynamic IP, as well as PPPoE/PPPoA and
>Bridge connections terminating on the local PCs."

>Firstly,  don't modems just convert digital to analogue and vice versa,
>and dial numbers.   They would just provide the connection, withot
>knowing about PPP's username, and passord. So 'd have thought that all
>modems  'support ppp' as they should any computer protocol since it's
>just a digital signal.


Yes, its a router that has a DSL modem in it. But that would be lost
on 99.9% of the customer base they are looking for, who all refer to
it as a modem, so they lose the technical terms that would confuse the
end-user. Pretty much any DSL CPE is called a modem no matter what it
actually does or how much hardware is actually inside by the end-users.


>Secondly,how can you have PPPoE i.e. PPP over ethernet, on a
>non-ethernet modem?

Pretty easily, its just a protocol, the router just has to talk the
right bits for the other end to understand. Doesn't matter if its
physically not there, it is virtually in this device.





Re: PPPoE and non-ethernet modems

Doug McIntyre wrote:
> jameshanley39@yahoo.co.uk writes:
> >looking at
> >http://www.dlink.com.au/products/broadband/dsl200 /
> >it says
> >"The DSL-200 supports Static IP, Dynamic IP, as well as PPPoE/PPPoA
and
> >Bridge connections terminating on the local PCs."
>
> >Firstly,  don't modems just convert digital to analogue and vice
versa,
> >and dial numbers.   They would just provide the connection, withot
> >knowing about PPP's username, and passord. So 'd have thought that
all
> >modems  'support ppp' as they should any computer protocol since
it's
> >just a digital signal.
>
>
> Yes, its a router that has a DSL modem in it. But that would be lost
> on 99.9% of the customer base they are looking for, who all refer to
> it as a modem, so they lose the technical terms that would confuse
the
> end-user. Pretty much any DSL CPE is called a modem no matter what it
> actually does or how much hardware is actually inside by the
end-users.
>
>
> >Secondly,how can you have PPPoE i.e. PPP over ethernet, on a
> >non-ethernet modem?
>
> Pretty easily, its just a protocol, the router just has to talk the
> right bits for the other end to understand. Doesn't matter if its
> physically not there, it is virtually in this device.

my old 56k dial up modem must have 'supported PPP' in a similar way ,
done through the OS, you provide a user/pass, it's authenticated and
you get a dynamic IP. This router/modem by DLink also has PPP at the OS
level not at the hardware level.  However, if the feature of supporting
PPPoE is a factor that makes the DLink device more than just a modem,
then wouldn't the feature of supporting PPP make my old 56k modem more
than just a modem?



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