Introduction 1 - 9
Backup Controller Module
The controller is vital to th e system because it performs important functions
including:
❑synchronizing all modules
❑monitoring concentrator condi tions (temperature, power supp ly
status, etc.)
❑recognizing failures
❑clocking and timing to the ONline Concentra tor backplane
By using two 3Com Fault-Tolera nt Con troller Modules (5000M-RCLS) in
your concentrator you can protec t these critical tasks if a controller fails.
Note: You cannot use the 5000M-RCTL or 5000M-CTL con trol ler
in a load-sharing concentrator (Mo del 5017C-LS or Model
5017C with load-sharing upgrade).
Redundant Cable Links
Cable breaks or failures are the most co m mon problem in any network.
Using the ONline Ethernet Fib er Module in your ONline S ystem
Concentrator enables you to implem ent full cable redundancy for your
network's backbone. Thereafter, if one port should fail, or if a cable is
disconnected or cut, the backup port w ill take over in 100 milliseconds. A
sample redundant network conn ection is shown in Figure 1-6.