802.1X Multiple Authentication Mode - Cisco Catalyst 2975 Software Configuration Manual

Chapter 10 Configuring IEEE 802.1x Port-Based Authentication
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For more information, see the

802.1x Multiple Authentication Mode

Multiple-authentication (multiauth) mode allows multiple authenticated clients on the data VLAN. Each
host is individually authenticated. If a voice VLAN is configured, this mode also allows one client on
the VLAN. (If the port detects any additional voice clients, they are discarded from the port, but no
violation errors occur.)
If a hub or access point is connected to an 802.1x-enabled port, each connected client must be
authenticated.
For non-802.1x devices, you can use MAC authentication bypass or web authentication as the per-host
authentication fallback method to authenticate different hosts with different methods on a single port.
There is no limit to the number of data hosts can authenticate on a multiauthport. However, only one
voice device is allowed if the voice VLAN is configured. Since there is no host limit defined violation
will not be trigger, if a second voice is seen we silently discard it but do not trigger violation.
OL-19720-02
The guest VLAN and restricted VLAN features only apply to the data devices on an MDA-enabled
port. The switch treats a voice device that fails authorization as a data device.
If more than one device attempts authorization on either the voice or the data domain of a port, it is
error disabled.
Until a device is authorized, the port drops its traffic. Non-Cisco IP phones or voice devices are
allowed into both the data and voice VLANs. The data VLAN allows the voice device to contact a
DHCP server to obtain an IP address and acquire the voice VLAN information. After the voice
device starts sending on the voice VLAN, its access to the data VLAN is blocked.
A voice device MAC address that is binding on the data VLAN is not counted towards the port
security MAC address limit.
MDA can use MAC authentication bypass as a fallback mechanism to allow the switch port to
connect to devices that do not support 802.1x authentication. For more information, see the
Authentication Bypass" section on page
When a data or a voice device is detected on a port, its MAC address is blocked until authorization
succeeds. If the authorization fails, the MAC address remains blocked for 5 minutes.
If more than five devices are detected on the data VLAN or more than one voice device is detected
on the voice VLAN while a port is unauthorized, the port is error disabled.
When a port host mode changes from single- or multihost to multidomain mode, an authorized data
device remains authorized on the port. However, a Cisco IP phone on the port voice VLAN is
automatically removed and must be reauthenticated on that port.
Active fallback mechanisms such as guest VLAN and restricted VLAN remain configured after a
port changes from single-host or multiple-host mode to multidomain mode.
Switching a port host mode from multidomain to single-host or multiple-hosts mode removes all
authorized devices from the port.
If a data domain is authorized first and placed in the guest VLAN, non-802.1x-capable voice devices
need their packets tagged on the voice VLAN to trigger authentication. The phone need not need to
send tagged traffic. (The same is true for an 802.1x-capable phone.)
We do not recommend per-user ACLs with an MDA-enabled port. An authorized device with a
per-user ACL policy might impact traffic on both the port voice and data VLANs. You can use only
one device on the port to enforce per-user ACLs.
10-36.
"Configuring the Host Mode" section on page
Catalyst 2975 Switch Software Configuration Guide
Understanding IEEE 802.1x Port-Based Authentication
10-43.
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