With Symantec Network Access Control (SNAC), a full (Basic Mode) LAN Enforcer configuration relies on communication between a client-side supplicant, an 802.1x enabled switch, the Symantec LAN Enforcer appliance, the Symantec Endpoint Protection Manager (SEPM) and a RADIUS server (such as Microsoft IAS).
This document provides links to articles with further information on how to deal with a non-response or network link being down between the various components.
No connection from the Enforcer to the Radius server:
TECH153860 - Handling a Radius server non-response in a LAN Enforcer environment; the no-radius-rsp option
No connection from the switch to the Enforcer:
TECH166196 - LAN Enforcer and Cisco switch - how to redirect to a particular vlan in case the Enforcer is unavailable
No connection from the Enforcer to the SEPM:
TECH91229 - What happens if an Enforcer appliance cannot communicate with the Symantec Endpoint Protection Manager?
No response from the client (or handling machines without a local supplicant):
TECH91230 - How does Symantec Network Access Control enforcement manage computers without the client installed?