"Dennis Ferguson" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> On 2007-02-07, Ken Wheatley <(E-Mail Removed)> wrote:
>> On Tue, 06 Feb 2007 12:10:28 -0600, Dennis Ferguson
>><(E-Mail Removed)> wrote:
>>
>>
>>>Routers for ADSL use in the UK have ADSL modems built in since this is
>>>required by the use of PPPoA signaling. In countries where PPPoE is
>>>used instead, people may be used to the router and modem being
>>>separate boxes connected by an Ethernet cable.
>>>
>> I don't understand this. I have a separate DSL modem connected to a
>> router by Ethernet. Are you saying this shouldn't work for PPPoA?
>
> I don't see how it can, though I'm prepared to be educated. The BRAS
> box at the far end of the connection is expecting PPP over ATM
> encapsulated frames, but the router connected to the Ethernet has
> no way to send them. The modem would need to be doing some pretty
> fancy translation to splice these together; I guess this might be
> possible, but I've not yet seen a modem which could actually do this.
>
> I've not been in the UK long but the only two arrangements I've seen
> used with ADSL here (a USB-connected modem or a router with the DSL
> modem built in) are consistent with the constraints of PPPoA as I
> understand them.
>
> What model of modem are you using? I'd like to understand how it works.
It is possible to obtain stand-alone ADSL modems. For example
http://www.dlink.com/products/?sec=0&pid=554
I haven't read the manual but the key point in the sales blurb is that to
use it with more than one computer one must connect it to a router. I
presume that the modem does not perform NAT so the single computer must have
the IP address issued by the ISP.
Many of the router suppliers offer both ADSL routers and ethernet routers -
but they generally don't offer ethernet-ADSL modems - presumably because the
usual need for an ethernet router is where there is already a cable modem.
--
Graham J