This document specifies ROHC (Robust Header Compression) profiles that efficiently compress RTP/UDP/IP (Real-Time Transport Protocol@ User Datagram Protocol@ Internet Protocol)@ RTP/UDP-Lite/IP (User Datagram Protocol Lite)@ UDP/IP@ UDP-Lite/IP@ IP and ESP/IP (Encapsulating Security Payload) headers. This specification defines a second version of the profiles found in RFC 3095@ RFC 3843 and RFC 4019; it supersedes their definition@ but does not obsolete them. The ROHCv2 profiles introduce a number of simplifications to the rules and algorithms that govern the behavior of the compression endpoints. It also defines robustness mechanisms that may be used by a compressor implementation to increase the probability of decompression success when packets can be lost and/or reordered on the ROHC channel. Finally@ the ROHCv2 profiles define their own specific set of header formats@ using the ROHC formal notation.