Which of the following headers can be reduces by making use of RTP header compression? (Choose all that apply.)

A.
IP

B.
TCP

C.
UDP

D.
RTP

E.
PPP

Explanation:

All compression methods are based on eliminating redundancy when sending the same or similar data over a transmission medium. One piece of data, which is often repeated, is the protocol header. In a flow, the header information of packets in the same flow does not change much over the lifetime of that flow. Therefore, most of header information could be sent only at the beginning of the session, stored in a dictionary, and then referenced in later packets by a short dictionary index.
Two methods were standardized by the IETF (Internet Engineering Task Force) for use with IP protocols:
TCP header compression (also known as the Van Jacobson or VJ header compression) is used to compress the packet TCP headers over slow links, thus considerably improving the interactive application performance. RTP header compression is used to compress UDP and RTP headers, thus lowering the delay for transporting real-time data, such as voice and video over slower links.
Source: Cisco IP QoS Link Efficiency Mechanisms, Page 6-21