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Cisco Unified IP Phone Administration Guide for Cisco Unified CallManager 5.1 (SIP), Cisco Unified IP Phones
OL-11524-01
Chapter1 An Overview of the Cisco Unified IP Phone
Understanding Security Features for Cisco Unified IP Phones
the LAN switch. This prevents the IP phone from having to act as the
authenticator, yet allows the LAN switch to authenticate a data end point prior to
accessing the network.
In conjunction with the EAPOL pass-through mechanism, Cisco Unified IP
Phones provide a proxy EAPOL-Logoff mechanism. In the event that the locally
attached PC is disconnected from the IP phone, the LAN switch would not see the
physical link fail, because the link between the LAN switch and the IP phone is
maintained. To avoid compromising network integrity, the IP phone sends an
EAPOL-Logoff message to the switch, on behalf of the downstream PC, which
triggers the LAN switch to clear the authentication entry for the downstream PC.
The Cisco Unified IP phones also contain an 802.1X supplicant, in addition to the
EAPOL pass-through mechanism. This supplicant allows network administrators
to control the connectivity of IP phones to the LAN switch ports. The initial
release of the IP phone 802.1X supplicant implements the EAP-MD5 option for
802.1X authentication.
Required Network Components
Support for 802.1X authentication on Cisco Unified IP Phones requires several
components, including:
•Cisco Unified IP Phone—The phone acts as the 802.1X supplicant, which
initiates the request to access the network.
•Cisco Secure Access Control Server (ACS) (or other third-party
authentication server)—The authentication server and the phone must both be
configured with a shared secret that is used to authenticate the phone.
•Cisco Catalyst Switch (or other third-party switch)—The switch must support
802.1X so it can act as the authenticator and pass the messages between the
phone and the authentication server. When the exchange is completed, the
switch then grants or denies the phone access to the network.
Best Practices—Requirements and Recommendations
•Enable 802.1X Authentication—If you want to use the 802.1X standard to
authenticate Cisco Unified IP Phones, be sure that you have properly
configured the other components before enabling it on the phone. See the
“802.1X Authentication and Status” section on page4-42 for more
information.