Hi,
What is loopback and what is its purpose?
A loopback interface is a logical interface.
This means that it is not related to any hardware "feature" (cable connections, speed, duplex, etc.).
It can be configured with an IP address like a normal physical interface. It is always up.
Purpose: As I've said, it is not related to any hardware feature or problem, so it is always reachable since there is at least one physical interface up and running on the device (and obviously a route to it).
So, if you are having high utilization in that port, then there may be 2 scenarios as below:
Scenario 1:
As per scenario 1, you are pointing out all AAA service traffic in authenticator devices (switches, routers, and WLC) to the loopback interface, as well as device management traffic (SSH access to ISE) using this loopback interface. This may be the cause of the high volume of traffic. If it is true, then you can load-share the traffic by pointing the AAA traffic to the interface IP rather than the loopback IP.
You can use Network Interface Card (NIC) bonding or NIC teaming on the interface IP for high availability. Then redirect that traffic to that NIC teaming interface. This makes only management traffic in the loopback interface. So it will reduce the volume of traffic in the loopback interface.
Scenario 2:
If you are not using the loopback IP interface in AAA service and only management traffic is handled by the loopback interface,
Please check how much traffic is showing in SolarWinds and check the in/out the traffic of the ISE interface using CLI mode. And at what time is it showing high utilization?
Based on the above checking, we may find that the high traffic issue in ISE or SolarWinds monitoring tools is showing incorrect traffic utilization.
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