Normally an incoming connection uses RADIUS to obtain details of the IP addresses to use. It is also possible for RADIUS to provide relay tunnel endpoint details to pass the connection on to another LNS.

In addition to RADIUS based authentication it is also possible to pre-set local authentication details based on circuit ID and/or username and password. This bypasses RADIUS, and can be used to handle individual lines or patterns of login - e.g. use of a @realm to steer to another LNS for a wholesale customer.

In an ISP scenario this is typically used for special cases, test lines, etc. The main use of this feature is for a corporate LNS handling direct point to point tunnels, e.g. from other offices or roaming users.