the cisco catalyst 4500 series redundancy scheme uses removable redundancy modules (also called mux-buffers), on the passive backplane to switch traffic to the active supervisor engine. there is one redundancy module per switching module. redundancy modules and a redundant clock ship standard with every cisco catalyst 4507r and 4510r chassis. spare redundancy modules (c4k-mux=) and a clock module (c4k-clock=) are available for serviceability.

    the following conditions indicate that you may need to replace the redundancy modules and clock module:

    1 the switch powers down and stays down for a few minutes to a few days for no clear reason.

    2 the output-fail led on the power supplies are red and no power is delivered to the chassis. the other leds on the power supply are green.

    3 the status leds on the switching modules and the supervisor engine are flashing green.

    4 cpu utilization leds are flashing green or off.

    if you observe these conditions, contact the cisco tac for assistance in ordering replacement redundancy modules and a clock.