Hi Siddesh,
Supervisor engine is the heart of Chassis type switches like Cisco 4500,6500 switch. by default on chassis type switches, it doesn't have any supervisor engine fixed on to it, according to our requirement, we can choose the appropriate supervisor engine. assume that you have a Supervisor engine 1, which you have purchased few years before doesn't suppot 10Gbps Ethernet, since that you don't require 10Gbps Ethernet & now u have a requriment of 10Gbps Ethernet, what you need to do is juz replacing the supervisor engine 1 to Supervisor engine 720, here you are replacing the Supervisor engine & not the entire Switch Chassis on 6500 series switch,also sup. engine 2 which as max. back plane capacity of 256 Gbps, Sup. eng. 720 has got the backplane capacity of 720 Gbps, in this case u can alone change the sup. engine rather than changing the entire switch which will become huge investment once again, where as if a switch say eg. 3750 which is not a chassis type, in this case u need to change the entire switch as there is no detachable of replacing the sup. engine bcoz there is no concept of sup. engine in this switches.
hope it helps.
rate this post if it helps.