what is a role of supervisor module

[knaik99]

we use supervisor module in 4500,6500 switch and 9400 & 9500 switch so what is its role?

why do we have primary and secondary supervisor Module ?

is it CPU?

command to check its status or performance

[Giuseppe Larosa]

Hello @knaik99 ,

>> we use supervisor module in 4500,6500 switch and 9400 & 9500 switch so what is its role?

In modular distributed platforms the supervisor manages the chassis buillds and mantain L2 topology , L3 topology and routing protocols neighborships. By using this information it builds all the CEF related tables FIB, adjacency table that are downloaded to each linecard ( in a true distributed platform).

The supervisor provides the control plane and the management plane and programs the data plane forwarding on the linecards.

>> why do we have primary and secondary supervisor Module ?

For redundancy purposes if the primary sup fails the secondary can take over. For using SSO Stateful Switch Over redundancy strategy the two supervisors must be same model and loaded with the same image.  In SSO the complete state ( for example STP and OSPF neighbors and OSPF LSA database ) is passed internally from primary sup to secondary sup so that in case of a switchover the new primary SUP does not need to start from zero it can use info. With graceful restart the forwarding plane can keep forwarding user data packets duriing swithover.

Finally you can start using

show proc cpu sorted

Additional commands are needed on IOS XE platforms.

Hope to help

Giuseppe

[Joseph W. Doherty]

Overlapping with @Giuseppe Larosa's fine reply . . .

"we use supervisor module in 4500,6500 switch and 9400 & 9500 switch so what is its role?"

It's the primary "brain" of the chassis.

"is it CPU?"

Usually the supervisor card does have a CPU, but often has many other hardware components on it to handle some switch functions that would be too slow on the CPU alone.

(You might think of the supervisor card is like the main motherboard card found on many PCs or servers.  Also, although such motherboards usually host the CPU, they too might host other hardware chips, like "integrated" graphic processors on the same board rather than on an expansion card.)

"why do we have primary and secondary supervisor Module ?"

Usually, as also noted by Giuseppe, to provide redundancy, i.e. in case the operational supervisor fails, the whole chassis doesn't fail with it.  In some cases, a secondary supervisor might be also used to lend it's hardware to off-load some supervisor work load from the active/primary supervisor; thereby increasing overall chassis capacity.