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Is it possible to deploy VSS configuration between Catalyst 4503-E and Catalyst 4507+RE ?

This is what I am trying to do, but at VSL establishment I get the following error messages :

*May 26 04:35:16.443: %C4K_REDUNDANCY-6-DUPLEX_MODE: The peer Supervisor has been detected
*May 26 04:35:35.770: %SW_LEVEL-6-RESULT: Operational redundancy mode is UNKNOWN, due to software license-level mismatch at ACTIVE and STANDBY. Software Level on     Active: entservices; on Standby: entservices.
*May 26 04:35:45.785: %ISSU-3-PEER_IMAGE_INCOMPATIBLE: Peer image (cat4500e-UNIVERSALK9-M), version (03.04.03.SG) on peer uid (11) is incompatible
*May 26 04:35:45.785: %ISSU-3-PEER_IMAGE_INCOMPATIBLE: Peer image (cat4500e-UNIVERSALK9-M), version (03.04.03.SG) on peer uid (11) is incompatible
*May 26 04:35:55.194: %C4K_REDUNDANCY-2-IOS_VERSION_CHECK_FAIL: IOS version mismatch. Active supervisor version is 15.1(2)SG3 (cat4500e-UNIVERSALK9-M). Standby supervisor version is 15.1(2)SG3 (cat4500e-UNIVERSALK9-M). Redundancy feature may not work as expected.
*May 26 04:35:55.198: %C4K_REDUNDANCY-6-MODE: ACTIVE supervisor initializing for rpr mode
*May 26 04:35:55.462: %C4K_REDUNDANCY-3-COMMUNICATION: Communication with the peer Supervisor has been established

After this error message, the redundancy mode on the VSS Standby goes to RPR instead of SSO and it reloads indefinitely because this redundancy mode is not accepted.

I checked my IOS versions on both chassis & they are the same :

ROM: 15.0(1r)SG10
System image file is "bootflash:cat4500e-universalk9.SPA.03.04.03.SG.151-2.SG3.bin

I am running license level entservices for both chassis

Module Name     Role           Current Level     Reboot Level
WS-X45-SUP7L-E  Active         entservices       entservices

My 2 chassis are also configured with redundancy SSO.

Is there a caveat I am not aware of ?

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up vote 1 down vote accepted

The two chassis must have the same number of slots.

Refer to: Cisco: Configuring VSS - Chassis and Modules

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Indeed Adam, I just found this also. But I think that with IOS XE 03.05.02 SG and ulterior, I can achieve with asymmetric chassis :… I am testing this and will update accordingly. – Jeremy G. May 26 '14 at 12:46

In fact I found out it is possible with IOS XE > 03.05.00 SG. This was not possible before, on IOS XE train 03.04.xx SG

I have tried myself with IOS XE 03.05.02 SG and did not encounter any issues with a 4503-E on one side and a 4507+RE on the other side, the two of them having Sup7-LE.

There is reference on this here

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