Specifications

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Cisco Unified Wireless IP Phone 7921G Administration Guide for Cisco Unified CallManager Release 4.1, 4.2, 5.0
OL-10802-02
Chapter 2 An Overview of the Voice Over IP Wireless Network
Components of the VoIP Wireless Network
Encryption Methods
To ensure that voice traffic is secure, the Cisco Unified Wireless IP Phone 7921G
supports Wired Equivalent Privacy (WEP), Temporal Key Integrity Protocol
(TKIP), and Advanced Encryption Standards (AES) for encryption. When using
either of these mechanisms for encryption, both the signaling (SCCP) packets and
voice (RTP) packets are encrypted between the access point and the unified
IP
phone.
• WEP—When using WEP in the wireless network, authentication happens at
the access point by using open or shared-key authentication. The WEP key
that is setup on the phone must match the WEP key that is configured at the
access point for successful connections. The Cisco
Unified Wireless
IP
Phone 7921G supports WEP keys that use 40-bit encryption or a 128-bit
encryption and remain static on the phone and access point.
EAP and CCKM authentication can use WEP keys for encryption. The
RADIUS server manages the WEP key and passes a unique key to the access
point after authentication for encrypting all voice packets; consequently,
these WEP keys can change with each authentication.
• TKIP—WPA and CCKM use TKIP encryption that has several improvements
over WEP. TKIP provides per-packet key ciphering and longer initialization
vectors (IVs) that strengthen encryption. In addition, a message integrity
check (MIC) ensures that encrypted packets are not being altered. TKIP
removes the predictability of WEP that helps intruders decipher the WEP key.
• AES—An encryption method used for WPA2 authentication. This national
standard for encryption uses a symmetrical algorithm that has the same key
for encryption and decryption. AES uses Cipher Blocking Chain (CBC)
encryption of 128 bits in size, supporting key sizes of 128, 192 and 256 bits,
as a minimum.
Note The Cisco Unified Wireless IP Phone 7921G does not support Cisco Key
Integrity Protocol (CKIP) with CMIC.
Choosing Authentication and Encryption Methods
Authentication and encryption schemes are setup within the wireless LAN.
VLANS are configured in the network and on the access points and specify
different combinations of authentication and encryption. An SSID is associated