Date: Thu, 23 Jan 1997 21:20:06 -0700 From: Doug Russell <drussell@internode.net> To: Allen Hyer <allenh@wtrt.net>, Brett_Glass@infoworld.com, gurney_j@resnet.uoregon.edu, lenc@earth.infinetconsulting.com Cc: spork@super-g.com, batie@agora.rdrop.com, freebsd-isp@freebsd.org, freebsd-hardware@freebsd.org, michael@memra.com Subject: Re: 56K vs X2? Message-ID: <1.5.4.32.19970124042006.00752f68@internode.net>
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Here's some of the answers that should clear things up. Yes, the server side has to be digital...... So for, say a connection to your home from the office, you need (as a minimum) an ISDN at the office, with an I-Modem, and an X2 modem at home on the analog line. I suppose if you wanted the fast channel to go outward from your home (a household web server? :-) ) you could have the ISDN end at your house and an analog at the other end. At least it would cost less. (Here anyway, the residential ISDN rates are lower than the business rates. Still pretty hefty though. Telus, the local phone company here in Calgary quoted me $85 per month for ISDN into my house. 1, 3, and 5 year contract plans drop the rate, (around 79, 75, and 69 dollars per month respectively if I remember right. The paper is on my desk at the office.) At least it's only a $60 installation fee. Although, I still have to pay the $200 to trench in more copper from the front yard... They only ran 2 pairs of copper into the houses in my area (an area new enough that they should have known better, BTW), and these temporary pair splitting devices to give me my current 4 phone lines don't work so hot... :-) ) >From USR's web site, URL http://x2.usr.com/solutions/corporate.html...... --- CUT --- x2 support on both ends: x2 must be supported on both ends of the connection, by the remote users' modem as well as by the remote access server or modem pool at the host end. The host-end device must implement x2 server functionality, and the remote user's modem must implement x2 client functionality. Typically, the remote user will be using a U.S. Robotics Courier, Sportster, or Megahertz modem (x2 client functionality) dialing into an MP I-modem, NETServer I-modem, Courier I-modem, or Total Control Enterprise Network Hub (x2 server functionality). Digital at one end: In typical remote access configurations, many remote users dial in to a concentration point where traffic from multiple remote users is aggregated. At this concentration point the connection to the phone network must be digital, meaning either a channelized T1, ISDN PRI, or ISDN BRI. The line must also be "trunk-side" and not "line-side." ISDN PRI and BRI lines are automatically trunk-side. Channelized T1s are typically trunk-side but may, in some circumstances, be line-side. Note that x2 speeds of 56,000 bits per second occur in the direction from the digital end of the connection to the analog end. One Analog-to-Digital conversion: There can only be one Analog-to-Digital (A/D) conversion in the phone network along the path of the call from the remote user to the call termination point (remote access server). Having a remote access server on the end of a trunk-side digital connection, with the remote user connected to an analog line, typically ensures this requirement will be met. Note that this means users connecting through a PBX (e.g. at a hotel) may not achieve x2 speeds, because there typically is an extra analog-to-digital conversion for data calls through a PBX. Quality of Line: As with V.34 technology, x2 speeds are somewhat dependent on line quality. However, because x2 is designed to take advantage of the digital nature of the phone network, it will typically be less susceptible to speed degradation than V.34. In fact, the maximum theoretical connect speeds of x2 exceed 60 Kbps. U.S. Robotics' initial testing has indicated that the vast majority of home users will be able to obtain x2 speeds. In situations where x2 is not obtainable, U.S. Robotics products will fall back to V.34 (with no user intervention required). --- CUT --- Later...... <Doug>
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