Motorola 68338 User Guide - Page 41

RTP/UDP/IP Header Compression RTP/UDP/IP Header Compression Introduction The Vanguard router can provide RTP/UDP/IP header compression on a link-by-link basis. This section examines the options for RTP/UDP/IP header compression. What is a RTP/UDP/ User Datagram Protocol (UDP) is a transport layer protocol that provides best effort IP Header? packet delivery on top of IP. As it is best effort service, UDP does not guarantee reliable delivery. The Real Time Protocol (RTP) resides on top of UDP/IP and provides fast delivery of real time traffic such as voice. Motorola's implementation of VoIP uses UDP/IP or RTP/UDP/IP protocols to carry packetized voice. Why Is RTP/UDP/IP Packetized voice is encapsulated into IP packets before being transported over an IP Header network. In encapsulating the packetized voice, RTP, UDP and IP header Compression information is added to the packet to provide information on how the IP packet is to Needed? be the routed through the IP network. This RTP/UDP/IP header information is typically 40 bytes in size. This is a relatively large overhead considering that an average voice packet is approximately 64 bytes. Comparing the encapsulated data payload and voice payload shown in Figure 2-16, the 40 byte RTP/UDP/IP header is a significant overhead when it is applied to the voice packet. The motivation for compressing the RTP/UDP/IP header is to reduce overhead and bandwidth usage. 40 Bytes IP UDP RTP 2048 Bytes Data Packet 40 Bytes 64 Bytes IP UDP RTP Voice Packet Figure 2-16. Encapsulated Data Packet and Voice Packet Vanguard Routing Model T0100-01, Revision B 2-25 Release 5.4