头部压缩技术在无线虚拟专用网中的应用研究

Application Research of Header Compression Technique in Wireless Virtual Private Network

无线虚拟专用网技术解决了移动办公员工希望通过移动终端随时随地访问公司局域网的问题。但是用来实现VPN技术的IPsec安全机制引起了数据包的增大,这是在无线网络中所不希望看到的。针对该问题,研究传统的头部压缩机制只压缩外部IP头的不足,并提出应用头部压缩技术对IPsec数据包内外部IP头进行压缩的机制。该机制在IP数据包未进行ESP封装之前先运用IPHC算法进行IP头部压缩处理,然后再进行ESP封装,最后再对ESP封装的数据包的外部IP头和ESP头运用ROHC算法进行压缩处理。分析结果表明:该机制有效地减小数据包大小,从而降低无线虚拟专用网中的丢包率和传输代价。

The problem that mobile employees access the corporate LAN with mobile terminal regardless of the time they wish and place where they are is solved by wireless virtual private network. But the IPsec security mechanism to implement VPN technology causes a problem of a considerable data size expansion which is undesirable in wireless network. For the problem, in this paper the shortage of traditional mechanism of header compression which compresses the outer IP header only is studied and a mechanism is present that apply header compression technology to compress inner and outer IP header of IPsec packet. The IP header is compressed by IPHC algorithm before ESP encapsulation, then ESP encapsulation is processed. Finally, the outer IP header and ESP header of packet encapsulated by ESP is compressed by ROHC algorithm. Analyses results show that the packet size is reduced by the mechanism and consequently the packet- loss rate and transmission costs are reduced.