Var Jacobson压缩算法，在PPP或者SLIP这些串行线路协议中，不同于以太网中无法确定下一跳的位置，它们的通讯两端是固定的。很多TCP连接中的数据包都是一些交互数据，数据量非常小，而TCP/IP头占据了很大的比例。如果能够减少TCP/IP头的大小，则非常有效的减少网络负载。(Var Jacobson compression algorithm, in PPP or SLIP serial line protocol, is different from Ethernet. It cannot determine the location of the next hop, and their communication ends are fixed. Many of the data packets in TCP connections are interactive data, and the amount of data is very small, and the TCP/IP head occupies a large proportion. If you can reduce the size of the TCP/IP header, it is very effective to reduce the network load.)