虚拟专用网 ( VPN)的网关使用加密算法保护网络信息 .但是加密算法占用大量的 CPU资源 ,降低了 VPN网关的吞吐量 .提出一种新的快速转发技术 ,利用网络分组在一段时间内存在极大相似性的原理 ,减少网关设备的冗余操作 ;讨论了网络流理论 ,并根据 IPSEC协议和 NAT协议 ,修正了网络分组的相似性定义 ;提出了 IPSEC和 NAT网络流快速交换的理论 ,并介绍了 VPN网关的快速转发功能的实现过程 .该技术可提高 VPN网关的吞吐率 ,降低分组的时延 . The gateway of Virtual Private Network (VPN) uses the encryption algorithm to protect the network information, but the encryption algorithm occupies a large amount of CPU resources and reduces the throughput of the VPN gateway.A new fast forwarding technology is proposed, which uses network packets to exist for a period of time The principle of large similarity reduces the redundant operation of gateway equipment. The theory of network flow is discussed. According to IPSEC protocol and NAT protocol, the definition of similarity of network packets is modified. The theory of fast exchange between IPSEC and NAT network flows is proposed. The implementation process of VPN gateway fast forwarding is introduced, which can improve the throughput of VPN gateway and reduce the packet delay.