-------------------------------- Modem News, Friday 01 March 1996 -------------------------------- Late yesterday afternoon (Thursday, 29 Feb 1996) we brought up 48 additional lines on the 296-5500 modem pool, for a total of 112 modems on that number. This will ease the busy signal problem considerably. The new modems and the terminal servers that connect them to our network are housed in a unit called a "Cisco Access Server 5100". The three terminal server cards in the AS5100 are functionally identical to the Cisco 2511 terminal servers we are already using with our older modems, so they are familiar territory. The modem cards in the AS5100 are U.S. Robotics Digital Quad Modems, which are functionally equivalent to USR Courier modems. The chassis, power supplies, and interface cards in the AS5100 are made by U.S. Robotics. In fact, the whole unit is also sold by USR under a different name. The AS5100 has three major advantages from our point of view: 1. It takes up very little space compared to the MultiTech rack-mount modems and Cisco 2511 terminal servers we've been using. 2. The modems can be managed remotely. We can telnet into each one from a desktop computer (or from home) to tweak the configuration. Our older modems require a physical serial connection to each modem in order to reconfigure. 3. The telephone lines which connect to the new modems are two T1 lines, which are digital lines usable for a variety of purposes. For example, the connection between the BCPL network and UUNET (our pipeline to the rest of the Internet) is carried on a T1 line. In the case of the new modem lines, we are using the multi-channel capability of a T1 line to carry 24 incoming calls on each T1. This makes it possible to provide telephone service to all 48 modems with only two pieces of cable, not the one-cable-per-modem tangle we have with our older modems. The initial installation took place on Wednesday, and wasn't entirely smooth. A combination of incorrect factory configuration of the AS5100 and several dead T1 channels made many of the modems unavailable Wednesday night and caused many callers to get a "ring - no answer". On Thursday a Cisco technician spent the day working on the unit, and late in the afternoon two Bell Atlantic technicians got all 48 T1 channels working correctly. By about 5:30 Thursday evening all 48 new modems were working perfectly, so we now have 112 modems available on 296-5500. The Next Phase -------------- On March 11 Bell Atlantic will bring in 64 temporary POTS (plain old telephone service) lines to allow us to connect 64 more modems. These are more MultiTech modems (like our original 64) which we have had in storage waiting for Bell Atlantic to provide phone lines. If all goes well, these modems will be up and running by March 15. This will bring our total to 176 modems on 296-5500. Beyond That ----------- Some time in April, Bell Atlantic will install a 12-strand fiber optic cable from their Towson central office directly into our computer room. Within the computer room the fiber optic cable will be broken out into T1 lines. The cable will be capable of carrying the equivalent of 82 T1 lines, which gives us plenty of room for future expansion. We will probably switch our existing incoming lines from copper to the new fiber for greater reliability. Once the 64 old-style MultiTech modems mentioned above are in use, any future modem pool expansion will be in the form of additional Cisco AS5100s or similar equipment that can receive calls over T1 lines.