HP ProCurve Switch 6120G/XG Manual page 87

Web and MAC Authentication
How Web and MAC Authentication Operate
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The assigned port VLAN remains in place until the session ends. Clients may
be forced to reauthenticate after a fixed period of time (reauth-period) or at
any time during a session (reauthenticate). An implicit logoff period can be set
if there is no activity from the client after a given amount of time (logoff-period).
In addition, a session ends if the link on the port is lost, requiring reauthenti-
cation of all clients. Also, if a client moves from one port to another and client
moves have not been enabled (addr-moves) on the ports, the session ends and
the client must reauthenticate for network access. At the end of the session
the port returns to its pre-authentication state. Any changes to the port's VLAN
memberships made while it is an authenticated port take affect at the end of
the session.
A client may not be authenticated due to invalid credentials or a RADIUS
server timeout. The server-timeout parameter sets how long the switch waits
to receive a response from the RADIUS server before timing out. The max-
requests parameter specifies how many authentication attempts may result in
a RADIUS server timeout before authentication fails. The switch waits a
specified amount of time (quiet-period) before processing any new authenti-
cation requests from the client.
Network administrators may assign unauthenticated clients to a specific
static, untagged VLAN (unauth-vid), to provide access to specific (guest)
network resources. If no VLAN is assigned to unauthenticated clients the port
remains in its original VLAN configuration. Should another client successfully
authenticate through that port any unauthenticated clients are dropped from
the port.