What is the difference between a three-tier switch and a router?

Three-tier switches and routers have routing capabilities.

But the main function of the three-tier switch is still data exchange, its routing function is usually relatively simple, because it is mainly faced with a simple LAN connection, routing path is far from the router so complex, it used in the main use of the LAN or provide fast data exchange functions to meet the local area network data exchange frequent application characteristics.

The main function of the router is the routing function, its routing function is more embodied in the interconnection between the different types of networks, such as the connection between LAN and WAN, the connection between different protocols, etc., so the router is mainly used between different types of networks. Its main function is routing forwarding, solve a variety of complex routing network connection is its ultimate goal, so the router's routing function is usually very powerful, not only applicable to the same protocol LAN, more suitable for different protocols of the LAN and WAN. It has the advantage of choosing the best routing, load sharing, link backup and the exchange of routing information with other networks, and so on. In order to connect with various types of network, routers have very rich interface types, while the three-tier switch is generally only the same type of LAN interface, very simple.

Technically speaking, routers and three-tier switches have significant differences in packet switching operations. Routers typically perform packet switching by a microprocessor based software routing engine, while a three-tier switch performs packet switching through hardware. Three-tier switches after the first data flow is routed, it will generate a MAC address and IP address mapping table, when the same data flow through again, according to this table directly from the two layer through rather than again routing, thus eliminating the router routing and resulting in network delay, improve the efficiency of packet forwarding. At the same time, three-layer switch routing lookup is for the data stream, it uses the caching technology, it is easy to use ASIC technology to achieve, therefore, can greatly save costs, and realize fast forwarding. But the router's forwarding uses the longest matching way, realizes the complexity, usually uses the software to realize, the forwarding efficiency is low.

Because of this, in terms of overall performance comparisons, three-layer switch performance is much better than the router, very suitable for data exchange frequently in the LAN, while the router is very powerful, but its packet forwarding efficiency is much lower than the three-tier switch, more suitable for data exchange is not very frequent interconnection of different types of networks, such as LAN and the Internet interconnection. If the router, especially high-end routers for the local area network, then to a large extent, is a waste (in terms of its powerful routing function), but also can not well meet the requirements of LAN communication performance, affecting the normal communication between the subnet

To sum up, in the local area network for multiple subnet connections, preferably three-tier switches, especially in different subnet data exchange frequent environment. On the one hand, it can ensure the communication performance requirement between subnets, on the other hand, save the investment of switch. Of course, if the communication between the subnets is not very frequent, the use of routers is understandable, but also to achieve the subnet security isolation and communication purposes. Specific according to the actual needs to be determined.

The most important difference between three-tier switching and routing is that the route supports NAT conversion, while the three tier does not support it. In the actual project reflected in: the route directly connected to the Internet, and the fiber to the three-tier equipment is not on the Internet. Three-tier each port has a dedicated MAC address, there is a dedicated ASIC integrated circuit.

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