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Community Member

sup engine redundancy


6500 series having a single sup2/msfc2 with pure IOS


I've understood that if we hot insert another sup2/msfc2 with pure IOS even with different version, the IOS in the active sup engine, along with the configuration will be automatically downloaded to the new (standby) supervisor engine.

My quetion now is, what will happen if the hot inserted sup engine is having a hybrid OS.


Re: sup engine redundancy

The IOS image will not get synchronised with Native IOS, the config will unless you manually disabled RPR(+). You will need to manually copy the IOS image onto the new Supervisor2/MSFC2 and set the boot parameters - its quite easy.

With CatOS (Hybrid) the Code is synchronised between the 2 Supervisors (unless High-Availability Redundancy and Versioning are enabled). The second supervisor must be able to boot initially though as the version is checked once the supervisor is booted.


Community Member

Re: sup engine redundancy

why iam saying that is because of the following paragraph ive read from chapter 22 (configuring redundancy) and i quote;

"If you hot insert a second supervisor engine, the second module communicates with the active supervisor

engine after completing its initial module-level diagnostics. Because the active supervisor engine is

already switching traffic on the backplane, no switching-bus diagnostics are run for the second

supervisor engine because running diagnostics can disrupt normal traffic. The second supervisor engine

immediately enters standby mode. The active supervisor engine downloads the software image and

configuration to the standby supervisor engine, if necessary."


Community Member

Re: sup engine redundancy

For redundancy betwen the sup engines both must be running either CAT OS or NATIV IOS.

Also they must be same version.

Otherewise Which ever boots first will becom active, and second sup will go in reset/standby mode.

regarding syncronisation

Only boot variables, configuration gets replicated.

Pls refer to

Community Member

Re: sup engine redundancy

i know that they should be the same..both hardware and software...what iam asking is what if you hot insert a second sup engine having a CAT OS.

Note that the active is already running pure IOS.

Community Member

Re: sup engine redundancy

Nothing will happen,

Primary will continue to be active.

Second Sup will boot and go in standby mode, both sup will not sync.

Gibic ports on second Sup will not be active.(You can not use)

If primary fails, then switch will get reboot, then second will boot from CAT OS and become active.

Community Member

Re: sup engine redundancy

ive replied and quoted something from cisco documentation to andy (above conversation)..if you can please go thru it i will appreciate it a lot..


Re: sup engine redundancy

As I said before, with Hybrid code (CatOS running on the Supervisor and IOS running on the MSFC) CatOS code will be synchronised if a new supervisor is inserted and sucessfully boots a version of CatOS. The logic works by the Active Supervisor checking what is running on the standby supervisor when it comes onlinel; if the versions are different then the Active Supervisor will initiate a copy of its running code to the Standby Supervisor, then set the Standbys boot variables and then finally reload it. The MSFCs will NOT synchronise their code you MUST do this manually.

With Native IOS (single IOS image controlling both the Supervisor and the MSFC) the IOS image is NOT automatically synchronised; the configuration is synchronised, so, the 'boot system flash:xxxxxxx' environmental variable will be synchronised but the code MUST BE MANUALLY COPIED. You can do this from the Active Supervisor as you have access to the flash of the Standby supervisor once it has booted.

I hope this makes more sense.

There are some notes here:


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