Supporting 802.1X Authentication On Cisco Unified Ip Phones; Overview; Required Network Components; Best Practices-Requirements And Recommendations - Cisco 7931G Administration Manual

Understanding Security Features for Cisco Unified IP Phones

Supporting 802.1X Authentication on Cisco Unified IP Phones

These sections provide information about 802.1X support on the Cisco Unified IP Phone:
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Overview

Cisco Unified IP phones and Cisco Catalyst switches have used CDP traditionally to identify each other
and determine parameters such as VLAN allocation and inline power requirements. However, because
CDP is not used to identify any locally attached PCs, Cisco Unified IP Phones provide an EAPOL
pass-through mechanism, whereby a PC locally attached to the IP phone may pass through EAPOL
messages to the 802.1X authenticator in the LAN switch. This capability prevents the IP phone from
having to act as the authenticator, yet it allows the LAN switch to authenticate a data end point before
accessing the network.
In conjunction with the EAPOL pass-through mechanism, Cisco Unified IP Phones provide a proxy
EAPOL-Logoff mechanism. If 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 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 current release of the phone 802.1X supplicant uses the EAP-FAST,
EAP-TLS, and EAP-MD5 options for network authentication.

Required Network Components

Support for 802.1X authentication on Cisco Unified IP Phones requires several components, including:
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Best Practices—Requirements and Recommendations
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Cisco Unified IP Phone 7931G Administration Guide for Cisco Unified Communications Manager 8.0 (SCCP and SIP)
1-18
Overview, page 1-18
Required Network Components, page 1-18
Best Practices—Requirements and Recommendations, page 1-18
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 grants or denies the phone access to the network.
Enable 802.1X Authentication—If you want to use the 802.1X standard to authenticate
Cisco Unified IP Phones, make sure that you have properly configured the other components before
enabling it on the phone. For more information, see
Chapter 1 An Overview of the Cisco Unified IP Phone
802.1X Authentication and Status, page 4-40.
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