On Tue, Aug 16, 2005 at 01:54:46AM -0700, J.C. Roberts wrote: > On Tue, 16 Aug 2005 08:20:33 +0100, Simon Farnsworth > <[EMAIL PROTECTED]> wrote: > > >On Tuesday 16 August 2005 06:34, J.C. Roberts wrote: > >> You seem to be confused on your terms. The term "PPPoA" means > >> Point-to-Point Protocol over ATM (Asyncronous Transfer Mode). I > >> seriously doubt you're running ADSL over ATM. ;-) > >> > >Given that G.992 DSL protocols are all ATM physical layers, it's quite likely > >that he's running PPPoA. The (slight) advantage of PPPoA over PPPoE for ADSL > >is twofold: firstly, the MTU is slightly larger. Secondly, there's one less > >encapsulation layer involved; PPPoE on ADSL is in fact PPP over Ethernet over > >ATM. > > > >If you don't believe that ADSL is an ATM physical layer, go read G.992.1 (the > >international ADSL standard), or a manufacturer's spec sheet (like > >http://www.draytek.co.uk/products/vigor2600plus.html), where it explicitly > >refers to "ATM Protocols". > > Great info Simon, thank you. All the DSL modems I've seen here in the > USA are ethernet based on the user side and as misfortune would have > it, many providers *require* using their particular modem, so the user > side of it is all that matters.
i wonder if that's s/require/only support/ eg, others will work, but don't expect to be able to call anyone and get a "yes that will work, here's what you need it to configure it as <blahblah>", but that doesn't preclude the modem from being able to function on the network just fine. i haven't shopped around, but i imagine that a DSL modem on the market for end-users to buy would probably not be very successful unless it supported the standard suite/combination of parameters that the DSLAM you're below is going to expect. modems i have PPPoA experience with (second-hand, as the portion of the network i'm on is not PPPoA): speedstream 5930, 5861, 5667, 5200, dlink 504, 3com 812. the 5667 was a trooper, but had limited ability to do inbound forwarding (eg, "rdr" in pf). the 5200s had a better firmware but weren't as reliable in poor line condition situations (just fine if line isn't marginal) and had no activity LED, and used "DSL" to indicate both sync with dslam (solid green), training/losing sync (slow blink), no sync (off) and activity (fast blink). kinda ambiguous. the 5861 is cute because it has a CLI and 4 ports, but the "services" it provides are probably of no value to someone running any unix/linux. the 5930 has IPsec crapola, but again, what value is that to someone who has isakmpd? (outside of being able to avoid NAT-T... woo) i'm willing to be wrong, but i would imagine that if you find a thingy that says it is an A) DSL Modem who B) supports PPPoA, and you get DSL from the ISP and they use PPPoA, it'll only be a matter of getting the right configuration. the hardest thing would be to know the PVC that you should program into the modem so that it matches the cross connect on your port on the DSLAM you're on. tech support *should* be able to answer that, i hope. eg: "hi, i'm going through the setup of my DSL modem, and i've got it all sorted out, except i forgot what VPI/VCI to put in here" there's at least some chance they won't ask you what modem you're using, etc; at that point you have a potential to be a 30 second call for them. that's pure gold. the thread has kinda gone this way already, but i believe the only way you can get true "i don't have NAT" on PPPoA, outside of getting a "business class" service plan (or anything else with static IP WAN and LAN allocations) is going to have to end up with you running PPP daemon/process on your machine. for it to leave your PC to the modem as ATM would be a rare hardware combination. outside of a niche market, it would probably be rare to find one that didn't take a phone cord coming in and an ethernet cord going out. it's possible i suppose there could be a It's all been consumer grade kit, even > though a lot of it is in business use, none the less, I have not seen > a DSL modem with ATM on the user side (probably because it would be > pointless to make it that way). > > Assuming you don't have a provider requirement of using their > specified DSL modem, it may be possible to use OpenBSD as a > *replacement* for the DSL modem itself. I know we've got some degree > of ATM support but I don't know how well (or if) all the other needed > stuff works. that would be > > > Kind Regards, > JCR - [ openbsd 3.7 GENERIC ( jul 12 ) // i386 ]
