Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Active and Standby problem with SUP IV engines in 4507

I have a 4507R wtih two SUP IV engines,when there is a cold restart,the engine in slot 2 always be the active ,i have exchange the two engines in slot 1 and 2,but engine in slot 2 still to be active after a cold restart,eager for your help!

  • Other Network Infrastructure Subjects
Cisco Employee

Re: Active and Standby problem with SUP IV engines in 4507

This is normal behavior due to the algorithm used to elect the active supervisor.

"When the switch is powered on, the two supervisor engines determine which will serve

as the primary and which will be the standby. Usually, the supervisor engine that boots first,

either in slot 1 or 2, becomes the active supervisor engine."

The following algorithm is used to decide which Supervisor is active:

1. If only one Supervisor in slot 1 is installed, then it's active.

2. If Supervisor-slot 2 has declared itself active after switchover, then the Supervisor in slot 1

becomes standby until the next reload or until Supervisor in slot 2 is reset or power is cycled.

3. If Supervisor-slot 2 hasn't declared itself active, then the Supervisor-1 is active after passing

POST diagnostics test.