Cisco Cisco IOS Software Release 12.0(33)S

IP Header compression is a mechanism that compresses the protocol headers in a packet before the 
packet is transmitted. Header compression reduces network overhead and speeds up the transmission of 
both RTP and TCP packets. 

The IP Header Compression (IPHC) Over Frame Relay feature enables efficient transmission of real 
time traffic such as voice and video by compressing and decompressing the packet header. IPHC Over 
Frame Relay is supported on Cisco 12000 Series Engine 5 based SPA Interface Processor 
(SIP)-401/501/601 line cards on FR interfaces. For FR, Cisco encapsulation type is the only 
encapsulation type on which this feature is supported. This feature is already supported on PPP/MLPPP 
interfaces. 

Your software release may not support all the features documented in this module. For the latest feature 
information and caveats, see the release notes for your platform and software release. To find information 
about the features documented in this module, and to see a list of the releases in which each feature is 
supported, see the 

.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS, Catalyst OS, 
and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to 

. An account on Cisco.com is not required. 

Cisco IOS Release 
12.0(33)S2

This feature was introduced in Release 12.0(33)S2 for SIP-401/501/601 
line card on Frame Relay (FR) interfaces having Cisco as the 
encapsulation type for Cisco 12000 series routers.