ISL between code 3.2.3 and 4.1.1b

I haven't done that before, but the release notes of 4.1.1b clearly mentions that it's possible:
http://www.cisco.com/en/US/docs/switches/datacenter/mds9000/sw/4_1/release/notes/17675_02.html says:
Formerly known as Cisco SAN-OS, Cisco MDS 9000 NX Software is fully interoperable with earlier Cisco SAN-OS versions and enhances hardware platform and module support.

I didn't find a specific config example though.....

don't have a lab to test it so will upgrade one fabric ..if hosts are still able to see disk down that path will do the other fabric, otherwise roll-back. I am doing the upgrade on Saturday so will either come back with good results or will post my resume on Monster

1 Fabric at a time is a good plan anyway !

Tonight I will upgrade 1 of the 2 Brocade fabrics from FOS 6.2.0g to 6.2.1b. The current version has some SMI monitoring issues that we don't want to run in to. Two weeks after today we will upgrade the other fabric.

all working great.

Thanks for letting us know. This is good info, since we have customers with mixed SAN-OS / NX-OS as well with the need to use ISL's

Hmm..., IHAC who want to ISL MDS 9120, Firmware 3.1(3a) & MDS 9124, Firmware 4.1(1b). Based on the eLab I have to downgrade 9124. Looks like there is not general rule. Here are some examples:


17 Cisco MDS 9120 3.0.2a, 3.1.2 Cisco Fabric Manager 1, 2
Cisco MDS 9124 3.1.2 245
5 16 See1, 2, 3, 4
FC-SW
18 Cisco MDS 9120 3.0.2a, 3.1.2, 3.1.3a Cisco Fabric Manager 1, 2
Cisco MDS 9120, Cisco MDS 9140 3.0.2a, 3.1.2, 3.1.3a 24 5 4 See1, 2, 3, 4
FC-SW5

19 Cisco MDS 9120 3.0.2a, 3.1.2, 3.1.3a Cisco Fabric Manager 1, 2
Cisco MDS 9124 3.1.2, 3.1.3a 24 5 4 See1, 2, 3, 4
FC-SW5

20 Cisco MDS 9120 3.0.2a, 3.1.2, 3.1.3a Cisco Fabric Manager 1, 2
Cisco MDS 9140 3.0.2a, 3.1.2, 3.1.3a 24 5 8 See1, 2, 3, 4
FC-SW5

21 Cisco MDS 9120 3.0.2a, 3.1.2, 3.1.3a, 3.2.1a, 3.3.1c, 3.3.2, 3.3.3 Cisco Fabric Manager 1, 2, 13
Hewlett Packard Cisco MDS9124e SAN Switch for HP c-Class BladeSystem 3.1.2a, 3.2.1a, 3.3.1c, 3.3.2, 3.3.3, 4.1.1b, 4.1.3a 245
5 8 See1, 2, 3, 4
FC-SW

9120 does not support NX 4.x platform

http://www.cisco.com/en/US/docs/switches/datacenter/mds9000/sw/4_1/release/notes/17675_02.html#wp549970