3Com 510M-FBP, 5102M-FBP, 5104M-FB1 Implementing Total Backbone Fault Tolerance

If the primary link experiences a local or remote fault (except Low Light):

❑The backup link activates within 10 milliseconds

❑The primary ports disconnect (that is, they do not pass data to and from the concentrator)

However, primary port diagnostics continue to operate. When the fault clears, the primary port is enabled automatically. Once a switchover occurs, the redundancy status indicators blink.

Each redundancy status LED (located beneath the Activity LEDs):

❑Is off - If you disable redundancy

❑Is on - If you enable redundancy and both ports are operational

❑Blinks - If a switchover occurs due to a link failure

Implementing Total Backbone Fault Tolerance

You can add a backup ONline System Concentrator to provide total backbone tolerance and link redundancy for your backbone network. As shown in Figure 2-11, if the primary concentrator or any primary links fail, the backup concentrator takes over. In this configuration:

❑One port on the 10BASE-FB Module connects to the primary concentrator

❑The other port connects to the backup concentrator

You must also have a direct connection between the two concentrators.

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