Cisco 7965G Administration Guide - Page 30

Understanding Security Features for Cisco Unified IP Phones Chapter 1 An Overview of the Cisco Unified IP Phone 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 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. 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 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 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, make sure that you have properly configured the other components before enabling it on the phone. See the "802.1X Authentication and Status" section on page 4-34for more information. • Configure PC Port-The 802.1X standard does not take into account the use of VLANs and thus recommends that only a single device be authenticated to a specific switch port. However, some switches (including Cisco Catalyst switches) support multi-domain authentication. The switch configuration determines whether you can connect a PC to the phone PC port. - Enabled-If you are using a switch that supports multi-domain authentication, you can enable the PC port and connect a PC to it. In this case, Cisco Unified IP Phones support proxy EAPOL-Logoff to monitor the authentication exchanges between the switch and the attached PC. For more information about IEEE 802.1X support on the Cisco Catalyst switches, refer to the Cisco Catalyst switch configuration guides at: http://www.cisco.com/en/US/products/hw/switches/ps708/tsd_products_support_series_home. html 1-16 Cisco Unified IP Phone 7965G and 7945G Administration Guide for Cisco Unified Communications Manager 6.1 OL-14641-01