CDRouter includes a built-in RADIUS server that the DUT can use to authenticate clients when 802.1X is enabled on the WAN. By default CDRouter places the RADIUS server on the WAN remoteHost. CDRouter Multiport Add-On users can optionally move the RADIUS server from the WAN remoteHost to an unused interface on the LAN, as outlined in this Knowledge Base article.
This parameter is used in configurations where the RADIUS server is located on the LAN. In these configurations this paramter can be configured to match the testvar_group name of an additional LAN interface that uses a hostIp style configuration.
For general information on configuring 802.1X, EAPOL, and RADIUS on the LAN, please see the LAN Configuration section of the CDRouter User Guide.