Peer switch port IP address in HA pair.

[Muhammed Adnan]

Hello Experts, 

In the latest code, we see the optional configuration of "Service Port Peer IP (IP address of the service port of the peer controller.)"

What is this configuration really needed for?

From my understanding, the Active standby pair will be communicating through:

1) Back to back connected redundancy ports.

2) Management and redundancy management IP addresses over the network. 

What is the significance of configuring "service port peer IP"?

[Leo Laohoo]

Service Port is for out-of-band-management. It is highly recommended to use a totally different subnet to do this. For example, if your main management IP address is 10.1.2.0/24 the the Service Port can be 192.168.19.0/24.

[Muhammed Adnan]

Thank Leo for the prompt response. 

Yep. Service port are just for OOB management and we generally consider the service port connectivity to dedicated OOB switches in dedicated OOB network. 

I am just trying to understand in config guide, why is there a mention of "Peer service port IP". From my understanding the Controller in HA pair don't talk on service ports IPs, then why the need for "Peer service port IP" configuration?

[Leo Laohoo]

When you have an HA peer you have two Service Port: The active unit's Service Port and the secondary unit's Service Port (aka PEER).

[Muhammed Adnan]

I can see the option for "Service port peer IP" only when the SSO is set to enabled in either primary / secondary unit. Just trying to understand the purpose it would serve. 

[Scott Fella]

Like Leo mentioned, it’s used for OOB. We use this all the time to be honest when we need onsite smart hands to connect to the unit for remote troubleshooting.  It was also best practice back in the days to make sure that the service port had an IP address assigned and not left at 0.0.0.0.  We use the same IP address for all service ports because it’s easy to remember and since it’s not connected to the network it’s okay. 

Remember if you don’t set the standby service port, if you have a failover, the standby that is active will have 0.0.0.0 as the service port. This doesn’t sync so that is why it’s there.