The Last Word on ISDN--Maybe

If you've followed my plight over the past 3 months, you know I've been waiting for US West to install an ISDN line in my small office/home office (SOHO) lab to connect to the Windows NT Magazine enterprise Lab at reasonable speeds. I submitted this request more than 5 months ago. I hadn't planned to continue documenting my plight, but readers have written to me with interesting suggestions and observations that I want to share.

Several readers suggested I try Multilink Point-to-Point Protocol (MPPP) to obtain more speed. I was ahead of this suggestion because I already reconfigured the enterprise Lab and my SOHO lab to accommodate MPPP. MPPP lets you combine two (or more) modems into one high-speed link. The modems can be any variety: You can mix-and-match X2 and V.34 devices or ISDN and V.34 devices.

To implement MPPP, I had to make changes in both the enterprise Lab and my SOHO lab. In the enterprise Lab, I hooked the analog channel that comes out of the ISDN modem into a standard, no-name V.34 modem. I then used a serial cable to connect the V.34 modem to the same server that hosts the ISDN modem. I'd already configured the ISDN modem for Remote Access Service (RAS) operation, so I only had to configure the V.34 modem, enable it for RAS, and enable MPPP under RAS.

Back in my SOHO lab, I added a second modem to the workstation I was dialing in from. This workstation has both a 3Com/U.S. Robotics V.everything modem and a Zoom V.34 modem connected to it. I needed two separate phones lines, which was no problem because I'm waiting for US West to convert my free analog line to ISDN. Finally, I had to create Dial-Up Networking (DUN) that supported multiple lines and configure the two modem links. This process was simple. If you'd like more details about MPPP configuration under Windows NT, see Paula Sharick, "Tech Stories from the Trenches," December 1997.

With my modems and phone lines in place, I invoked the MPPP connection. The V.everything modem negotiated a connection rate of 44Kbps and the V.34 modem negotiated a rate of 28.8Kbps, giving me a combined data rate of 72.8Kbps. Although this connection is not as fast as ISDN speed (128Kbps), it was a big improvement over my X2 connection rate of 44Kbps.

One reader wrote to me with an interesting observation. He said that many people have an ISDN line installed but then use the analog channel for X2 or K56 connections to an Internet Service Provider (ISP). Why would anyone want to do that? Well, most ISPs apply extra charges to ISDN access but don't apply extra charges to X2 or K56 access. Because the analog channel is a digital link, you can connect an X2 or K56 modem to it and often obtain full 56Kbps speeds over the B2 link. Unfortunately, I was unable to test this idea because I'm still waiting for ISDN at my SOHO lab. Nonetheless, this solution seems viable and clever.

Finally, many readers wrote about how much better asymmetric digital subscriber line (ADSL) or consumer digital subscriber line (CDSL--a variation of ADSL) will be than ISDN. Currently, regional phone companies are testing both DSL technologies in different areas of the country. Of course, I'm not living in one of these areas, so these technologies don't do me any good.

DSL promises high-speed links that are much faster than ISDN. For example, a typical DSL link can run up to 8Mbps. The problem with DSL technology is it requires telephone companies to put new equipment at their switching sites because existing phone switches can't handle DSL. I'm always skeptical about how fast the telephone companies can deploy new equipment, so I'm in a wait-and-see mode on DSL.

My quest for ISDN access has led me down many paths and has given me the opportunity and motivation to experiment with alternative technologies (e.g., X2, K56, MPPP). But this quest has pushed my patience to its limit. Along the way, I've often had to remind myself of a simple saying, "The reward of patience is patience." I take comfort in this saying because I now know that the reward of patience is not ISDN.

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