Occasionally, the NAC acts as if it is a different switch type, and does not use the ctAlias MIB to query. This is often because the switch was modeled before nodealias command was enabled.
To clear this, webview must be entered in each NAChttps://<ipofNAC>:8443
These credentials may not be default - if so, check the following article.Where are the Admin Web Page Credentials for Extreme Control (NAC)
From Webview Diagnostic mode, we want to go to
Status->Switches and Routers
Scroll to Switch Dynamic Information
For the switch that is having issues with this, click on clear button This should not interrupt authentication process, and has been performed previously in critical environments at critical times.
The output there for the switch may or may not change. It is then best to use debug to ensure it uses ctAlias, like in below screenshot.
2018-01-09 15:14:59,403 INFO [CtAliasMacAddressIpResolutionSnmpWorker] ESDMAC:68-1D-C1 Starting CtAliasMacAddressTable IP resolution for: XX-XX-4F-68-1D-C1 on switch: 10.X.X.254 and ifIndex: 4031
2018-01-09 15:14:59,403 DEBUG [CtAliasMacAddressIpResolutionSnmpWorker] ESDMAC:68-1D-C1 Starting to read from: 220.127.116.11.18.104.22.168.22.214.171.124.126.96.36.199.0.xx.xx.104.29.193