Auth success in ISE02. but session connects in ISE01

[JustTakeTheFirstStep]

We are using Meraki, and we use ISE01,ISE02 as RADIUS SERVER.

Auth success in ISE02. but session connects in ISE01

Why is ISE02 trying to authenticate?

[ammahend]

auth is at 9:32 session at 9:52, the session doesn't look like its for the same auth, Can you disable suppression for successful authentication and test again. 

[Arne Bier · Accepted solution]

With the endpoint data hidden, it's hard to see whether this is the same endpoint. But I assume it is. In that case, the blue icon indicates that this is Accounting (Session) data sent by the network device. Authentication was sent to ISE1, but the RADIUS Accounting was sent to ISE2 - the RADIUS server (ISE) doesn't make that decision - it's the network device that is sending it to a specified RADIUS server. Check whether you have the IP addresses of the ISE servers swapped around for Authentication and Accounting

[JustTakeTheFirstStep]

Why did I authenticate on ISE2 and connect the session to ISE1?
ISE IP has never changed.
Some devices authenticate with ISE1 and ISE2 alternately.
Devices all tried to connect with one SSID.

[Arne Bier]

Maybe the Meraki is configured for load balancing. ?

[thomas · Accepted solution]

RADIUS is a request/response protocol so your network devices are the ones requesting an authentication of an endpoint by ISE.

ISE has no control over which RADIUS server instance the network device (Meraki in this case) is going to send the request to. If you list both of your ISE instances in Meraki, it is free to choose either one. Every network device may implement a different algorithm for which server it uses. If you see alternate authentication requests by the same network device, that is probably a sign of a simple round-robin algorithm.

And you did not mention if there was a load balancer in which case you need to look at your load balancer for why it is doing what it is doing.

Learn about load balancing algorithms from our recent ISE Webinar :

▷ Cloud Load Balancing with ISE 2023/06/15

02:15 What is a proxy server?
03:10 What is a reverse proxy server?
03:49 Load Balancing to many ISE PSNs and Groups
04:44 Load Balancing Methods: Round Robin, Weighted RR, Hash, Least Connections, Least Time to Connect (first byte, last byte), Random