Data Communications Networking Devices - 4th Ed.pdf

3.2 TECHNOLOGICAL CHARACTERISTICS ___________________________________________ 283designed to make under-carpet installation as unobtrusive as possible. AlthoughType 8 cable can be used in a manner similar to Type 1, it provides only half of themaximum transmission distance obtainable through the use of Type 1 cable.Type 9Type 9 cable is essentially a low-cost version of Type 1 cable. Like Type 1, Type 9cable consists of two twisted-pairs of data cable; however, 26 AWG conductors areused in place of the 22 AWG wire used in Type 1 cable. As a result of the use of asmaller diameter cable, transmission distances on Type 9 cable are approximatelytwo-thirds those obtainable through the use of Type 1 cable. The color coding onthe shield of Type 9 cable is the same as that used for Type 1 cable.Summary of cable typesAll seven types of cables de®ned by the IBM cabling system can be used toconstruct Token-Ring networks. However, the use of each type of cable has adifferent effect upon the ability to connect devices to the network, the number ofdevices that can be connected to a common network, the number of wiring closetsin which hubs can be installed to form a ring, and the ability of the cable to carryseparate voice conversations. The latter capability enables a common cable to berouted to a user's desk where a portion of the cable is connected to their telephonewhile another portion of the cable is connected to their computer's Token-Ringadapter card.Table 3.3 summarizes the performance characteristics of the cables de®ned bythe IBM cabling system. The drive distance entry indicates the relative relationshipbetween different types of cables with respect to the maximum cabling distancebetween a workstation and a hub as well as between hubs. Type 1 cable provides amaximum drive distance of 100 m between a workstation and hub and 300 mbetween hubs for a network operating at 4 Mbps. Other drive distance entries inTable 3.3 are relative to the drive distance obtainable when Type 1 cable is used.Table 3.3IBM cabling system cable performance characteristicsCable typePerformancecharacteristics1 2 3 5 6 8 9Drive distancerelative to type 1) 1.0 1.0 0.45 3.0 0.75 0.5 0.66Data rate Mbps) 16 16 4* 250 16 16 16Maximum devices 260 260 72 260 96 260 260per ringMaximum closets 12 12 2 12 12 12 12per ringVoice support no yes yes no no no no*Note: Although 16-Mbps operations are not directly supported by Type 3 cable, its use is quitecommon when drive distances are very short.