802.1X Authentication With Voice Vlan Ports; 802.1X Authentication With Port Security - Cisco IE-3000-8TC Software Configuration Manual
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Understanding IEEE 802.1x Port-Based Authentication
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802.1x Authentication with Voice VLAN Ports
A voice VLAN port is a special access port associated with two VLAN identifiers:
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The IP phone uses the VVID for its voice traffic, regardless of the authorization state of the port. This
allows the phone to work independently of 802.1x authentication.
In single-host mode, only the IP phone is allowed on the voice VLAN. In multiple-hosts mode,
additional clients can send traffic on the voice VLAN after a supplicant is authenticated on the PVID.
When multiple-hosts mode is enabled, the supplicant authentication affects both the PVID and the
VVID.
A voice VLAN port becomes active when there is a link, and the device MAC address appears after the
first CDP message from the IP phone. Cisco IP phones do not relay CDP messages from other devices.
As a result, if several IP phones are connected in series, the switch recognizes only the one directly
connected to it. When 802.1x authentication is enabled on a voice VLAN port, the switch drops packets
from unrecognized IP phones more than one hop away.
When 802.1x authentication is enabled on a port, you cannot configure a port VLAN that is equal to a
voice VLAN.
If you enable 802.1x authentication on an access port on which a voice VLAN is configured and to which
Note
a Cisco IP Phone is connected, the Cisco IP phone loses connectivity to the switch for up to 30 seconds.
For more information about voice VLANs, see
802.1x Authentication with Port Security
You can configure an 802.1x port with port security in either single-host or multiple-hosts mode. (You
also must configure port security on the port by using the switchport port-security interface
configuration command.) When you enable port security and 802.1x authentication on a port, 802.1x
authentication authenticates the port, and port security manages network access for all MAC addresses,
including that of the client. You can then limit the number or group of clients that can access the network
through an 802.1x port.
These are some examples of the interaction between 802.1x authentication and port security on the
switch:
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Cisco IE 3000 Switch Software Configuration Guide
12-20
Voice VLAN—Inaccessible authentication bypass is compatible with voice VLAN, but the
RADIUS-configured or user-specified access VLAN and the voice VLAN must be different.
Remote Switched Port Analyzer (RSPAN)—Do not configure an RSPAN VLAN as the
RADIUS-configured or user-specified access VLAN for inaccessible authentication bypass.
VVID to carry voice traffic to and from the IP phone. The VVID is used to configure the IP phone
connected to the port.
PVID to carry the data traffic to and from the workstation connected to the switch through the IP
phone. The PVID is the native VLAN of the port.
When a client is authenticated, and the port security table is not full, the client MAC address is added
to the port security list of secure hosts. The port then proceeds to come up normally.
When a client is authenticated and manually configured for port security, it is guaranteed an entry
in the secure host table (unless port security static aging has been enabled).
Chapter 12
Configuring IEEE 802.1x Port-Based Authentication
Chapter 15, "Configuring VLANs."
OL-13018-03
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