Information Technology Reference
In-Depth Information
TABLE 2.1
Typical Token-Ring Planning Calculation in 16 Mbps Networks
MTD, m (ft)
Number of telecommunications rooms
Number of
2
3
4
5
6
MSAUs
1 130 (430)
2 130 (420) 125 (410)
3 125 (410) 120 (400) 120 (390)
4 120 (400) 120 (390) 115 (380) 115 (380)
5 120 (390) 115 (380) 110 (370) 110 (360) 110 (360)
6 115 (380) 110 (370) 110 (360) 105 (340) 105 (340)
7 110 (360) 110 (360) 105 (350) 105 (340) 105 (340)
8 105 (350) 105 (350) 105 (340) 100 (330) 100 (340)
(NOTE: The maximum lobe distances are calculated from the adjusted ring length and the maximum transmission
distance, which varies with the numbers of MSAUs and TRs). (SOURCE: Andrew Corporation)
closets, and problems that occur when an insufficient number of active workstations
are on a large ring. Extended distance MSAUs or repeaters may be required to solve
these problems. In addition, the normal problems of bad or intermittent connectors,
cables, and jacks may affect the network. Token-Ring does exhibit a delay if an
improperly wired workstation/cable tries to insert itself into the ring. After a period
of time, the offending workstation adapter should deactivate, thus restoring the
ring. Some nonpowered MSAUs may get a relay stuck in the open position when no
cable is connected. The only way to cure this is to connect a cable from an active
station or use a battery-powered test plug to reset the relay.
FIGURE 2.10
A typical Token-Ring media filter.
