Cabletron Systems switches - Manual (Page 20)

Review of Networking
2-8 Token Ring
• Number of Stations Per 4 Mbps Token Ring: In the same fashion as the limits
imposed on cable lengths due to the operating speed of the network and type
of cabling used, there are limitations on the number of stations that may be
connected to a single ring using active circuitry. If these numbers are exceeded,
a bridge, switch, or other segmentation device must be used to break the ring
into two or more smaller rings as detailed in the list below:
- IBM Types 1, 2 STP: 250 stations
- IBM Types 6, 9 STP: 250 stations
- Category 5 UTP: 150 stations
- Categories 3, 4 UTP: 150 stations
- Multimode Fiber Optics: 250 stations
- Single Mode Fiber Optics: 250 stations
• Number of Stations Per 16 Mbps Token Ring: The limitation on the number of
stations in the Token Ring also applies to 16 Mbps networks. In one case, the
number of stations supported by these faster Token Ring networks is
significantly lower than the number supported by the 4 Mbps rings.
- IBM Types 1, 2 STP: 250 stations
- IBM Types 6, 9 STP: 136 stations
- Category 5 UTP: 150 stations
- Categories 3, 4 UTP: 150 stations
- Multimode Fiber Optics: 250 stations
- Single Mode Fiber Optics: 250 stations
The Token Ring limitations that are described above are summarized for your
ease of reference in Table 2-1. This table is also repeated in Appendix A, Charts
and Tables
.
a. IBM Type 6 cable is recommended for use as jumper cabling only and should not be used for
facility cabling installations.
Table 2-1. Token Ring Maximums
Media
Cable
Type
Max # of Stations
Max Lobe Cable
Length
4 Mbps 16 Mbps 4 Mbps 16 Mbps
STP IBM Types 1, 2 250 250 300 m 150 m
IBM Types 6, 9
a
250 136 200 m 100 m
UTP Category 5 150 150 250 m 120 m
Categories 3, 4 150 150 200 m 100 m
Fiber Optics Multimode 250 250 2000 m 2000 m
Single Mode 250 250 2000 m 2000 m