Wireless i~; becoming a pop•ular way to connect mobile computers to the Internet and other networks.The bandwidth of wireless links will probably always be limited d1lf to properties of the physical medium and regulatory limits on the n~;e of frcqncncies for radio communication.Therefore.it is necessary for network protocols to utilize the available bandwidth efficiently.If enders of IP packc/s arc growing and the bandwidth required for transmitting headers is increasing.With the coming of I Pvfj the addre8.ssize in creases from 4 to 16 bytes and the basic IP head a increases from 20 to 4 0 bytes.Monovcr, most mobility schemes tunnel packets addressed to mobile hosts by adding an extra JP header o1• eJ:lm routing information, typically increasing the .size of TCP/IPv4 headers to 60 bytes and TCP/!Pvfi headers to 100 bytes.In this paper, we provide new header compres~;ion schemes for UDP/IP and TCP/IP protocols.IVc show how to reduce the size of UDP /IP headers by an order of magnitude, down to four to five bytes.Our method worl.'s Ol'el' simplex links, lossy links, multi-access links, and supporls multicast communication.IVe also shou.: how to generali.~ethe mo::;l commonly used method for header compres~;ion for 'J'CP/IP!•.{, dereloped by liau Jacobson, to !Pv6 and nwltiple JP headtrs.The resulting scheme nnfortun at ely reduces TCP throughput ova los~;y link$ due to unfavorable interaction with TCP's congestion control mechanisms.However, by addin_q two•This work was supported by grants from the c..,nt.re for Dist.anceSpanning Technology (COT).Lul<!t•, Sweden, and Ericsson Radio Systems AB.