Because of the three-tier exchange of technology is not a standardized technique, three-tier exchange equipment from different manufacturers using different methods to achieve the same equipment, three listed below are several widely used to exchange technology. Fast IP 3Com, and this technology uses a decline in the subsequent exchange of strategies based on their technical resolution protocol next station on the source host and destination host needs to run Fast IP protocol, when the exchange source host must first initialize a standard IP communication process source host sends a Fast IP connection request, the request as normal data packets routed through the same network, if the destination host is also running Fast IP protocol, you return a response containing the MAC address of the NHRP, If there is a path between the two exchange swap otherwise continue the route. FIRE 3Com is called flexible intelligent routing engine FIRE, using ASIC to achieve the third layer of wire-speed routing and forwarding is an innovative interconnection architecture shadowless Chenghua, this technology offers a wide range of first the second floor and the third floor features and provides a flexible network control capabilities, including bandwidth optimization of network security and QoS traffic lock. Cisco's NetFlow this technique is forwarded to the decline of traditional techniques to improve its basic principle is still the first packet Layer 3 routing using the traditional way of forwarding, Layer 3 switches after forwarding the information is recorded on a data packet adjustment in NetFlow cache, subsequent data packet arrives after the first match to find if you use the Cache Cache Hit decline information directly forwarded otherwise the route in the Cache. Nanjing site design zczxweb.cn