RFC2543中文文档，学习SIP编程的基础东东，把这个搞懂，SIP就学会了~-RFC2543 Chinese document, the basis of programmed learning Dongdong SIP, they get to know this, SIP learned ~

基于低速链路的IP/UDP/RTP报头压缩协议。-This document describes a method for compressing the headers of IP/UDP/RTP datagrams to reduce overhead on low-speed serial links.

在以太网上传输PPP的方法（PPPoE）,本文档描述的PPPoE是RedBack Networks, RouterWare, UUNET 及其它厂商所采用的在以太网上封装PPP的方法。-In the PPP method of transmission over Ethernet (PPPoE), this document describes the PPPoE is RedBack Networks, RouterWare, UUN