Establishing vPC with different NX-OS Version

[EJ Talamayan]

Hi,

Good Day!

Is it possible forming a vPC connection between two  Nk5 with different NX-OS version?

Network Device    NX-OS Version

N5K-C5596UP =    5.2(1)N1(6

N5K-C5596UP =    7.3(5)N1(1)

Both appliances are not yet connected.

Thank you!

[Remi Astruc]

Hello Ejah,

The question is, what can be your requirement to have such similar switches (same HW, want to merge in VPC to act as a logical switch) having such different OS version...

I suggest you upgrade them into the same OS version, and avoid uncertain behavior with such inconsistency.

Remi Astruc

[EJ Talamayan]

Hi Remi,

Here is the situation the Primary Nexus with NX-OS version of 5.2(1)N1(6) needs an upgrade because "mac address-table loop detect port-down" configuration is not supported by it. In order to do that we will migrate all the configuration from Primary Nexus to Backup Nexus with NX-OS version of 7.3(5)N1(1) but cannot afford a downtime. So we are planning to establish a vPC between the primary and backup nexus for redundancy.

[Remi Astruc]

Hello,

That may not be a solution.

By itself, enabling VPC feature and configuring it on 2 switches will not impact existing traffic.

But if I understand that your 2 switches are already interconnected in traditional STP design with some Vlans, moving this interco into VPC Peer-Link with the production Vlans into it will impact these Vlans while you perform the change (and again, not confident about such OS version difference within a VPC).

Also, if you are not yet in VPC, it means your attached devices don't have Port-channel to the pair yet. To leverage VPC feature, you will need to reconfigure these devices from individual ports into Port-channel, which will have impact as well.

To summarize, moving into VPC will not avoid impact on your infra, and you can instead just move your active links towards the secondary Nexus with pretty similar impact.

Remi Astruc

[EJ Talamayan]

Hi Remi,

Here is the current setup

And this is the propsed setup

[Remi Astruc · Accepted solution]

Hello,

Ok, so currently the second N5K is more a "spare" than a "backup"...

It is surprizing that you cannot afford an impact in your migration while your design currently includes a Single Point of Failure with only 1 N5K without resiliency mechanism.

The good news is then that you can establish VPC without impact, and you'll need to follow upgrade version path from 5.2(1)N1(6) to 7.3(5)N1(1).

- Downgrade "Backup" to 7.0(8)N1(1)

- Establish VPC peering

- Connect secondary links of surrounding devices onto Backup

- Upgrade Primary to 7.0(8)N1(1), then to 7.1(4)N1(1)

- Upgrade Backup to 7.1(4)N1(1), then to 7.3(5)N1(1)

- Upgrade Primary to 7.3(5)N1(1)

During failovers you still may encounter small cuts.

Remi Astruc

[EJ Talamayan]

Thank you Remi,

I guess i will try your method, will inform you the outcome after the activity.