3Com 4210 9-Port - Configuring a Guest VLAN

1-4
Operation Description Related section
Configuring quiet MAC function
on a port
Optional
Section “Configuring the Quiet MAC
Function on a Port
”
Configuring a Guest VLAN
Different from Guest VLANs described in the 802.1x and System-Guard manual, Guest VLANs
mentioned in this section refer to Guests VLANs dedicated to MAC address authentication.
After completing configuration tasks in
Configuring Basic MAC Authentication Functions for a switch,
this switch can authenticate access users according to their MAC addresses or according to fixed user
names and passwords. The switch will not learn MAC addresses of the clients failing in the
authentication into its local MAC address table, thus prevent illegal users from accessing the network.
In some cases, if the clients failing in the authentication are required to access some restricted
resources in the network (such as the virus library update server), you can use the Guest VLAN.
You can configure a Guest VLAN for each port of the switch. When a client connected to a port fails in
MAC address authentication, this port will be added into the Guest VLAN automatically. The MAC
address of this client will also be learned into the MAC address table of the Guest VLAN, and thus the
user can access the network resources of the Guest VLAN.
After a port is added to a Guest VLAN, the switch will re-authenticate the first access user of this port
(namely, the first user whose unicast MAC address is learned by the switch) periodically. If this user
passes the re-authentication, this port will exit the Guest VLAN, and thus the user can access the
network normally.
z Guest VLANs are implemented in the mode of adding a port to a VLAN. For example, when
multiple users are connected to a port, if the first user fails in the authentication, the other users can
access only the contents of the Guest VLAN. The switch will re-authenticate only the first user
accessing this port, and the other users cannot be authenticated again. Thus, if more than one
client is connected to a port, you cannot configure a Guest VLAN for this port.
z After users that are connected to an existing port failed to pass authentication, the switch adds the
port to the Guest VLAN. Therefore, the Guest VLAN can separate unauthenticated users on an
access port. When it comes to a trunk port or a hybrid port, if a packet itself has a VLAN tag and be
in the VLAN that the port allows to pass, the packet will be forwarded perfectly without the influence
of the Guest VLAN. That is, packets can be forwarded to the VLANs other than the Guest VLAN
through the trunk port and the hybrid port, even users fail to pass authentication.