Mixed Feature Sets In 3750 Stack - Fully Supported?

[Jason Nash]

Hi All,

I have seen a few threads around this and I have asked a few questions of our partners and it seems to be a bit of a grey area. What is supported in terms of running a mixed feature set in a Cisco 3750 switch stack.

We are looking at setting up a stack consisting of 5 x 3750V2 and 2 x 3750G. Due to a requirement for full EIGRP we need the IP Services feature set. Is it a supported configuration to run with 2 or 3 switches running the IP Services feature set as stack masters and the others running IP Base?

I understand that if stack master priorities were set these switches with the higher feature set could manage the stack and offer IP Services accross the stack. If we were to lose all of the switches running IP Services the stack would drop back to IP Base.

I am looking for guidance as to if this is a supported configuration and not in breach of licensing? Is this likely to cause any problem other than above now and for future IOS releases?

Jason

[lgijssel]

Sorry to disappoint you: 

The Cisco StackWise technology requires that all units in the stack run the same release of Cisco IOS Software. When the stack is first built, it is recommended that all of the stack members have the same software feature set - either all IP Base or all IP Services. This is because later upgrades of Cisco IOS Software mandate that all the switches to be upgraded to the same version as the master.

http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps5023/prod_white_paper09186a00801b096a.html

regards,

Leo

[Joseph W. Doherty · Accepted solution]

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Posting

This is something I investigated several years ago for the original 3750 series.

As far as I could tell then, assuming licensing hasn't changed, you're legal if you only have installed on any individual stack member the IOS feature set to which you had a license (for that device).

It was legal to run the whole stack on a higher feature set as long as one member of the stack was licensed for it.  NB: stack election will 1st select higher feature set images.

If you wanted feature set redundancy, you would need to have at least two stack members with the licensed/installed higher feature set.

You do want IOS versions to be the same.

When you upgrade a stack with mixed feature sets, you need to update some or all individual member images instead just flashing the whole stack (which I've done - and it's a pain).