RObust Header Compression (ROHC): Framework and four profiles: RTP, UDP, ESP, and uncompressed

Abstract

This document specifies a highly robust and efficient header compression scheme for RTP/UDP/IP (Real-Time Transport Protocol, User Datagram Protocol, Internet Protocol), UDP/IP, and ESP/IP (Encapsulating Security Payload) headers.Existing header compression schemes do not work well when used over links with significant error rates and long round-trip times. For many bandwidth limited links where header compression is essential, such characteristics are common.

Error-resilient packet header compression

“…Perhaps the most effective header compression standard to date is known as RObust Header Compression (ROHC) RFC 3095 [12]. The fundamentals of ROHC are similar to previous header compression algorithms, but ROHC, through attention to detail, achieves superior compression.…”

“…Since ROHC is widely considered to be the state of the art, we briefly describe some of its key aspects. Due to space constraints the concepts are presented in a simplified form; the interested reader is invited to consult [12] for a more detailed treatment. The reader who is familiar with ROHC may safely bypass the remainder of this section.…”

“…To summarize, there is one small-scale FSM (Finite State Machine) describing the operation of the compression algorithm, while there is (another) large-scale FSM driving the movement between different modes. The interested reader is referred to [12], [13] for a more detailed treatment of these subjects.…”

Template-Based Signaling Compression for Push-To-Talk over Cellular (PoC)

“…Header compression such as Robust Header Compression (ROHC) [2] is used for the compression of protocol headers; Transport Layer Security (TLS) [3] and File Transfer Protocol (FTP) [8] have a compressed transmission mode and IP compression (IPComp) [11] is used to compress IP datagrams. All of these compression protocols, however, are not suitable for compression of application layer messages and while they can complement a compression mechanism at the application layer, they cannot replace it.…”

A Transport Independent Bandwidth Modifier for the Session Description Protocol (SDP)

“…For compressing packets with IP/UDP/RTP headers, CRTP [11] was created at the same time. More recently, the Robust Header Compression (ROHC) working group has been developing a framework and profiles [12] [8]. SDP -Session Description Protocol, see [1].…”