Running different versions in a VRRP/MLAG cluster?

[Chris1]

We're running 15.6.2.12-nopatch, and we've been getting some odd random reboots and ospf issues, so we're looking to move to a new version i guess latest recommended is 15.6.4.2-patchLatest

We run Sets of x670-G2 and x670's in MLAG clusters with VRRP between pairs of them with OSPF.

My question is will i run into any issues if i do the upgrade above on 1 unit, wait a few days make sure all is stable them do the other one? Will this give me a hitless upgrade?

[PeterK]

In XOS 15.5 I had a problem in the past, that mac learning were not correct working, when mlag peers run different 15.5 versions.
I personally would recommend to upgrade the g1 to last 15.7 or 16 and the g2 to XOS 21.

I don't like XOS Version 15.6 and prior. to much trouble. I know, it's recommended for a lot of systems. But I'm running at least XOS 15.7 on all my customers and have no problems.

Last year in july I set up a new core with 2 X670G2 as MLAG Peer with Vrrp on XOS 15.7 at a customer. Until March this year no problems. In March I upgrated to XOS21 with nearly no traffic interrupt.

In the near future I will configure vrrp fabric routing (activ/active).

[Chris1]

Peter thanks for your input ya i'm wondering if i shouldn't just jump to XOS21... i was worried since it was such a big version jump it would be buggy... but honestly 15.5 seems to be very buggy even though it was the recommended release at the time.

[Chris1]

was going to actually move to 15.6.4 latest instead of 15.6.2 ... i figured higher release = more bugfixes/security fixes ... Theres a lot of release notes between 15.6.2.12 and 15.6.4.2-latest 

[Chris1]

the path architecture between branches seems sooo crazy i mean you would think that any patch with a publish date later than the original patch that had a fix would include the fix from said problem. I think one of our problems with the 15.5 releases is we're hitting a xos bug that causes Unable to Add IPmc sender entry s,G,v=x.x.x.x,224.0.0.5,2022 IPMC 8 flags 4 unit 0, Entry exists which i believe, which might be whats affecting ospf... and then we have random reboots on both of our XOS boxes that are OSPF/VRRP routers.

The recommended software list is sorta funny considering it doesn't recommend latest branches, but on top of that it doesn't even recommend latest patch version of those releases.