3Com 5104M-FB1, 5102M-FBP, 510M-FBP Fiber Network With 3 Concentrators

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Figure 2-12. Fiber Network With 3 Concentrators

In Figure 2-12, the fiber equivalent distance between transceivers attached to Concentrators C and D is:

3 * 190 m + 1000 m + 1000 m + 500 m + 1000 m = 4070 m

Because this is less than 4200 meters, the configuration is legal.

In Figure 2-12, if the main link from Concentrator A to Concentrator C faults, the signal path (enabled through redundancy) includes Concentrator

B.By adding Concentrator B, the fiber equivalent distance has become too great and the network cannot work because the path between Concentrators C and D is C-B-A-D:

4 * 190 + 1000 m + 2000 m + 500 m + 500 m + 1000 m = 5760 m

Because the sum is greater than 4200 meters, this configuration is not legal. When designing a redundant network, be sure to consider the backup route distance.

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