смотри PPP
(PPP) The protocol defined in RFC 1661, the Internet standard for transmitting network layer datagrams (e.g. IP packets) over serial point-to-point links. PPP has a number of advantages over SLIP; it is designed to operate both over asynchronous connections and bit-oriented synchronous systems, it can configure connections to a remote network dynamically, and test that the link is usable. PPP can be configured to encapsulate different network layer protocols (such as IP, IPX, or AppleTalk) by using the appropriate Network Control Protocol (NCP). RFC 1220 describes how PPP can be used with remote bridging.