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Technology Stocks : LAST MILE TECHNOLOGIES - Let's Discuss Them Here -- Ignore unavailable to you. Want to Upgrade?

To: MikeM54321 who wrote (5272)	9/17/1999 11:48:00 AM
From: elmatador	Read Replies (1) \| Respond to of 12823

Perhaps this helps, Mike: Will Statistical Multiplexing Kill ADSL? (Part of an article Malaga, Northpoint CEO) An ISP wants to offer customers what ADSL can deliver -1.5Mbit/s/s downstream signal with an upstream signal of 64Kbit/s or higher - must consider the impact on the backbone network. But the ISP that pays to upgrade that backbone so it can guarantee 1.5 mbits throughput, to its customers is going to want to charge more for the ADSL offering to cover its costs, Malaga says. " The first place where expectations may not be met is in regard to pricing" he says. "UUnet charges $2000 for a T1 link to the high speed backbone. An ISP isn't going to turn around and sell 1.5 Mbit/s service for $80 and guarantee that throughput." More typically, smaller ISPs buy a connection to high-speed networks and oversell that link, counting on technical methods such as statistical multiplexing to get customers' traffic through--and hoping that not everyone is trying to get very high-speed access exactly the same moment. At the same time, however, the company providing the ADSL transport - a telephone company or competitive carrier-- also has to oversell the backbone network, Malaga Says. Say, DS-3s (45Mbit/s) go for about $2.000. If I guarantee that bandwidth, I can only put 24 to 28 customers on that DS-3, and that's not economic," he says. So the telephone company also uses statistical multiplexing, which combines packet stream onto a backbone network, and oversell the DS-3. If the oversubscription is too high, everyone's traffic is delayed, prompting error messages and latency that is too high for services such as voice-over-the-internet Protocol. "Thje customer thinks they are going to get 1.5Mbit/s to the internet and that's not going to happen," Malaga says. The ISP is oversubscribing and the local company is oversubscribing because they are managing their network as well. As more and more users start using this kind of network, the throughput for everyone drops. And ADSL gets a black eye.

To: MikeM54321 who wrote (5272)	9/17/1999 12:03:00 PM
From: D. Newberry	Read Replies (2) \| Respond to of 12823

Hi Mike, In regards to your questions on US WEST new "On Demand" DSL. Your assumptions on the DSLAM are correct. When you make a connection to the internet, you are assigned a modem in the DSLAM in the central office. After a period of inactivity, you are disconnected so someone else may use it. The impact to the user is minimal, but you do run the risk that a modem may not be available to you during high usage times, like early evening. The service is targeted to the casual residential user who wants high speed access, but doesn't need 24x7 access. This reduces the costs to provide the service, since less hardware is required in the central office. Subsequently, the service is provided at a very attractive price. As for your voice calls, you have a 24x7 connection to the central office switch at all times, so your telephone operates the same whether you are connected to a modem or not. Regards,