3Com 5108M-TP manual Redundant Links, Redundant Twisted Pair Configuration

While there is no fiber in this configuration, the fiber equivalent distance can be calculated as follows:

Total link distance: 150 m + 100 m + 100 m + 50 m + 20 m = 420 m

Total equivalent distance of 10BASE-T Modules:

4 * 420 m + 4 * 165 m = 2340 m

(signal externally enters four 10BASE-T Modules: 4 * 420 m)

(signal enters four 10BASE-T Modules from the backplane: 4 * 165 m)

Total equivalent distance: 420 m + 2340 m = 2760 m

Since the total equivalent distance (2760 m) is less than 4200 meters, this is a legitimate configuration.

Note that if shielded twisted pair cabling is used, each link in the network could run up to 300 meters using Low Squelch (refer to Dip Switch SW3 (Crossover Mode, Channel Select, Squelch) in Chapter 1 for information on Squelch levels and the Squelch dip switch setting). Low Squelch is acceptable for all shielded twisted pair applications since external noise is not a problem.

Redundant Links

You can implement twisted pair link redundancy between ONline System Concentrators using Network Management. Figure 2-3 below shows an example of a redundant configuration between concentrators using 10BASE-T Modules.

Figure 2-3. Redundant Twisted Pair Configuration

2 - 12 ONline Ethernet 10BASE-T Module User’s Guide