Configuring Port-Based Access Control (802.1X)

802.1X Open VLAN Mode

Condition

Rule

 

 

Effect of Authorized-Client VLAN session on untagged port VLAN membership.

•When a client becomes authenticated on a port that is already configured with a static, untagged VLAN, the switch temporarily moves the port to the Authorized-Client VLAN (also untagged). While the Authorized-Client VLAN is in use, the port does not have access to the statically configured, untagged VLAN.

•When the authenticated client disconnects, the switch removes the port from the Authorized-Client VLAN and moves it back to the untagged membership in the statically configured VLAN. (After client authentication, the port resumes any tagged VLAN memberships for which it is already configured. For details, refer to the Note on page 8-22.)

Multiple Authenticator Ports Using

You can use the same static VLAN as the Unauthorized-Client VLAN

the Same Unauthorized-Client and

for all 802.1X authenticator ports configured on the switch. Similarly,

Authorized-Client VLANs

you can use the same static VLAN as the Authorized-Client VLAN for

 

all 802.1X authenticator ports configured on the switch.

 

Caution: Do not use the same static VLAN for both the unauthorized

 

and the Authorized-Client VLAN. Using one VLAN for both creates a

 

security risk by defeating the isolation of unauthenticated clients.

Effect of Failed Client Authentication Attempt

When there is an Unauthorized-Client VLAN configured on an 802.1X authenticator port, an unauthorized client connected to the port has access only to the network resources belonging to the Unauthorized- Client VLAN. This access continues until the client disconnects from the port. (If there is no Unauthorized-Client VLAN configured on the authenticator port, the port simply blocks access for any unauthorized client that cannot be authenticated.)

IP Addressing for a Client Connected

A client can either acquire an IP address from a DHCP server or have

to a Port Configured for 802.x Open

a preconfigured, manual IP address before connecting to the switch.

VLAN Mode

 

 

802.1X Supplicant Software for a

A friendly client, without 802.1X supplicant software, connecting to an

Client Connected to a Port Configured

authenticator port must be able to download this software from the

for 802.1X Open VLAN Mode

Unauthorized-Client VLAN before authentication can begin.

 

 

 

 

 

Note:

If you use the same VLAN as the Unauthorized-Client VLAN for all authenti-

 

cator ports, unauthenticated clients on different ports can communicate with

each other. However, in this case, you can improve security between authenticator ports by using the switch’s Source-Port filter feature. For example, if you are using ports B1 and B2 as authenticator ports on the same Unauthorized -Client VLAN, you can configure a Source-Port filter on B1 to drop all packets from B2 and the reverse.

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