pppoa connection

[Bruce M. Simpson]

Nikos Vassiliadis wrote:
> flakey fingers...
>
> On Friday 26 October 2007 10:06:30 Kim Shrier wrote:
>   
>> Other people successfully use this modem to connect to their ISP
>> when the ISP accepts pppoe connections and the modem is configured
>> as a bridge.  Unfortunately, my ISP doesn't support pppoe, only
>> pppoa.
>>     
>
> The only way to do PPPoA is to have a device that does the DSL and
> ATM layers and handles the rest to FreeBSD. 

Nope - there are devices out there such as the D-link single port 
DSL-5xxx modems which are able to bridge ethernet to PPPoA, which allows 
you to *not* use NAT on the device.

They do this by running a DHCP client on the outward face, a DHCP server 
on the inward 'face and allocating itself YourIP+1/24 on that face. Your 
machine inside then gets assigned YourIP.

This is a hybrid form of router/bridging which relies on the IP 
addressing trick. Obviously the subnet mask is wrong - I haven't figured 
out if this can be changed in the firmware - which means trouble if you 
have to route to folk in the same net block.

Most consumer DSL 'access devices' force you to use NAT because they 
don't know how to bridge in this way.

However, if you really need to do native PPPoA in BSD, you need an ngATM 
supported device - /usr/sbin/ppp knows about pppoa devices and should 
suffice for running it over a single VC. This support was originally 
added for the Alcatel Speedtouch.

Of course if you have an ngatm supported ATM card, and an ATM25-to-ADSL 
modem (such beasts exist) you can do it that way too - this is how you 
plug an old Cisco 4xxx into consumer ADSL, by the way.

[I'm not sure if MPD groks PPPoA too, but that would let you channel 
bond with multiple physical circuits.]

I should point out that the use of ATM over xDSL is actually part of the 
G.DMT-lite specs... inquiring individuals can make their own minds up 
about this and why that happened

regards,
BMS