I have ISE 2.6 and 3.1, but some specific networks in this segment should send to ISE3.1 Pool member

💎Solution :

Using i-RULE or Policies to solve the above issue

Step 1:

For ISE 2.6 and ISE 3.1, pool members should already be defined.

Local Traffic -> Pools ->

Step 2:

Under Data group, an IP source segment must be added.

Step 3:

i_RULE is below

Parameter for each single VS should call a different i-RULE. In my case, the ISE traffic for Radius, TACACS, Guest, and Profile was prepared independently and followed exactly.

i-RULE for Profiler:
--------------------

when CLIENT_ACCEPTED {
  log local0. "Client: [IP::client_addr]"
  if { [class match [IP::client_addr] equals DG_ISE3.1_10.X.X.X_25] } {
    log local0. "Pool Member Partition/Name: [LB::server pool]"
    pool PROD-Profiler-VXX_ISE3.1
  } else {
      pool PROD-Profiler-VXX
  }
}

i-RULE for Radius:
--------------------

when CLIENT_ACCEPTED {
  log local0. "Client: [IP::client_addr]"
  if { [class match [IP::client_addr] equals DG_ISE3.1_10.X.X.X_25] } {
    log local0. "Pool Member Partition/Name: [LB::server pool]"
    pool PROD-RADIUS-VXX_ISE3.1
  } else {
      pool PROD-RADIUS-VXX
  }
}

i-RULE for TACACS:
--------------------

when CLIENT_ACCEPTED {
  log local0. "Client: [IP::client_addr]"
  if { [class match [IP::client_addr] equals DG_ISE3.1_10.X.X.X_25] } {
    log local0. "Pool Member Partition/Name: [LB::server pool]"
    pool PROD-TACACS-VXX_ISE3.1
  } else {
      pool PROD-TACACS-VXX
  }
}

i-RULE for Guest:
--------------------

when CLIENT_ACCEPTED {
  log local0. "Client: [IP::client_addr]" --> Logging the client IP address
  if { [class match [IP::client_addr] equals DG_ISE3.1_10.X.X.X_25] } {
    log local0. "Pool Member Partition/Name: [LB::server pool]"
    pool PROD-Guest-VXX_ISE3.1
  } else {
      pool PROD-Guest-VXX
  }
}

Step 4:

Connect the i-RULE to the VS in F5, then set the default Pool's load balancing to none.

Note : For steps, see the screenshot in the attachment