DSL modem standard gets final approval from ITU

drama writes "The International Telecommunications Union today gave final approval to a long-awaited digital subscriber line standard that could hasten consumer use of high-speed Net connections." The article has some interesting information. Essentially, they've approved the G.lite standard, which is a lower-cost version, meaning that the consumer can buy the parts at the store, rather then the phone company needing to send people out - does that mean I can have DSL before 2020, please? *sigh*

Comments

G.Lite vs. ADSL: cheap vs. higher quality

[Cato]

G.Lite doesn't require a truck roll (i.e. a visit from an engineer), since it doesn't have a 'splitter' that separates the POTS (Plain Old Telephone System, i.e. phones, etc.) frequencies from the xDSL frequencies.

This means you can just buy a G.Lite modem from whoever, plug it in, and start working (in theory) - the modem ideally is an analogue modem for when xDSL breaks and also so it can automagically request xDSL service for you via the modem link when first installed.

You may also be able to get G.Lite service at some speed (maybe lower than ADSL) beyond 18,000 feet from the central office.

The price you pay for this is that any POTS equipment's hook-on/off activity can disrupt the G.Lite modem (yes, it really is a modem :) and require both ends to do a 'fast retrain' lasting 1.5 seconds. Also badly-behaved POTS equipment could disrupt things even more, and in-home wiring quality is a big factor.

My prediction, FWIW: people will get sufficiently annoyed with the G.Lite data getting disrupted that they'll convert their whole house to Voice over IP - either buying IP phones and using in-home networking over the existing phone wiring. Or they can keep their existing phones and wiring and just have a VoIP card in their Linux firewall that acts as a home PABX as well - park, hold, etc. Though hopefully with a nicer user interface... The end result is that there is no POTS voice whatsoever, everything is IP data or VoIP, all on top of G.Lite, hence no disruption...

ADSL seems to be positioned as a premium service - due to the splitter being installed, it will cost more but will also enable pretty much guaranteed bandwidth independent of home wiring and on-off hook activity.

There's a good article in IEEE Communications Magazine, May 1999, called 'Residential Broadband Architecture over ADSL and G.Lite: PPP over ATM' - talks a lot about how PPP sits on top of ATM, and how the xDSL provider only goes up to layer 2, with any layer 3 services (ISPs, video, other content) being supplied via ATM links direct to the provider. Since I work for an IP QoS company, I feel somehow this should be doable with IP, but that presumes an all-IP world which this architecture does not.

The real issue with DSL

[ciurana]

First a word of clarification: There is no such thing as a DSL modem, just like there isn't such thing as an ISDN modem. The correct name is ATU/R or Adaptive Transceiver Unit/Remote.

The G.lite DSL article misses the most critical point regarding DSL: Availability and quality of service within the subscriber's area. We've used Rythms Net Connections (mentioned in the article also) ADSL for roughly a year (very happily) and we found that the ATU/R was the least of our worries. The real problem was dealing with Pacific Bell, our local carrier.

When we first requested DSL we had to wait until Pacific Bell installed the physical line, by far the biggest hurdle. Essentially, the telco must add a pair of wires to the local MPOE (minimum point of entry) to access the physical network. That installation took about a month. Installation of the ATU/R by Rythms technicians, including configuration (physical, IP,etc.) of all my Linux and Winblows boxes (6) took about 1 hour at no additional cost. This including laying the wires.

Over the year we experienced a number of outtages thanks to PacBell's ineptitude. We've been able to trace line problems to them 99% of the time, the most recent one took us off-line for 36 hours because some Dumb Ass technician disconnected our DSL line "because he didn't hear a dial tone."

Other problems included PacBell's reluctance to support anything other than Winblows or Mac and their condescending attitude, and their insistence on providing the NIC, hub, and ATU/R even if you already have the equipment (I had to install PacBell's ADSL at one of my developer's home and Rythms et. al. didn't service his area [Belmont, CA]). I won't even go into how hard it was for them to understand that my developer uses a laptop, thus his NIC is actually a PCMCIA card...

Our advise when installing DSL: Get your service, if you can, from someone other than your local telco. Third party providers tend to be more expensive, but they provide 7x24 support, including hardware replacement, and at least 7 IP addresses per contract. We run a full development lab on 644 kbps ADSL without problems, and we're very happy.

As for the ATU/R itself: We have a Paradyne Hotwire model 5446. It survived a surge PacBell sent up our DSL line without trouble.