Configuring Port-Based and Client-Based Access Control (802.1X)

How RADIUS/802.1X Authentication Affects VLAN Operation

This entry shows that port A2 is temporarily untagged on VLAN 22 for an 802.1X session. This is to accommodate an 802.1X client’s access, authenticated by a RADIUS server, where the server included an instruction to put the client’s access on VLAN 22.

Note: With the current VLAN configuration (figure 8-10),the only time port A2 appears in this show vlan 22 listing is during an 802.1X session with an attached client.

Otherwise, port A2 is not listed.

Figure 8-11. The Active Configuration for VLAN 22 Temporarily Changes for the 802.1X Session

With the preceding in mind, since (static) VLAN 33 is configured as untagged on port A2 (see figure 8-10),and since a port can be untagged on only one VLAN, port A2 loses access to VLAN 33 for the duration of the 802.1X session involving VLAN 22. You can verify the temporary loss of access to VLAN 33 with the show vlan 33 command.

Even though port A2 is configured as Untagged on (static) VLAN 33 (see figure 8-10),it does not appear in the VLAN 33 listing while the 802.1X session is using VLAN 22 in the Untagged status. However, after the 802.1X session with VLAN 22 ends, the active configuration returns port A2 to VLAN 33.

Figure 8-12. The Active Configuration for VLAN 33 Temporarily Drops Port 22 for the 802.1X Session

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