Just to add to Joseph's post, as he is always adding to mine :-)
the supervisor engine is the "brains" of a modular switch such as the 4500 or 6500. Without the supervisor engine, no matter what other modules you had in the chassis, you just have a very expensive doorstop.
It is responsible for the control and data plane ie. how to get traffic from A -> B and how to treat that traffic (control plane) and the actual forwarding of the data.
Note that with the 6500 some of the functionality of the supervisor has been integrated into the actual module, think distributed forwarding, but you still need a supervisor for the switch to work.
Thanks for the quick reply .. what I am looking for is a scenario like type. I know it used for redundancy, but still need to understand the concept. if any one can explain by example I appreciate it
Not sure what you want. Is there perhaps a certain scenario you are thinking of.
You can have supervisor redundancy in certain chassis's but your question was what does the supervisor engine do. Redundancy is just a feature of having more than one supervisor.
Perhaps if you could elaborate on what you are thinking of ?
Hooooooooo boy. What type of redundancy?
The latest "fad" is the Sup720 VSS. Have a read of the data sheet and let us know if this is what you have in mind.
Cisco Catalyst 6500/Cisco 7600 Series
Supervisor Engine 720 Data Sheet
Hope this helps.
here is a scenario
we have 2 x 4510's one of them went down and I think the 2nd router witch is placed for redundancy did not fail over or something , I heard someone said to resolve this issue we need to get supervisor installed. I do not think I provided the hole details , but I can ask again and get back to you.. Thanks
The 4510Rs support dual supervisors in the same chassis. Of course, if only one is installed the chassis will fail if the supervisor does.
With regard to two 4510Rs, much depends on how they and your topology are configured to support redundancy. Just having two doesn't guarantee fail over support, but often can provide it.
here is what i found out. is that the CORE switch went down. they changed the SUP module and the router come up .// can SUP module take the router down ? or make it unstable ? ..
If it's a chassis switch, and there's only one sup module, if it goes down (for any reason, including swapping it), generally, so does the whole chassis goes down.