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

1. The main functions are different. Although three-layer switches and routers have routing capabilities, but we can not equate them, just as many network devices now have a variety of traditional network equipment functions, as many broadband routers now have not only the routing function, but also provides the switch port, the hardware firewall function, But you can't equate it with a switch or a firewall. Because the main function of these routers is also the routing function, the other functions are only its additional functions, the purpose is to make the device suitable for a wider range, make it more practical. The three-layer switch here is also the same, it is still the switch product, but it is a few basic routing functions of the switch, its main function is still data exchange. In other words, it has two functions of data exchange and routing, but its main function is data exchange, and routers only have the main function of routing and forwarding.

2. The main application environment is different. The routing capability of layer three switches is usually simpler because it is primarily a simple LAN connection. Because of this, the routing capabilities of layer three switches are usually simpler, and routing paths are far less complex than routers. It is used in the main use of LAN or to provide fast data exchange function, to meet the frequent application characteristics of local area network data exchange. While routers are different, it is designed to meet different types of network connection, although also applicable to the connection between the LAN, but its routing function more reflected in the interconnection between different types of networks, such as the connection between the LAN and the WAN, the connection between different protocols, etc. So routers are primarily used between different types of networks. Its main function is routing and forwarding, to solve the various complex routing path network connection is its ultimate goal, so the router's routing function is usually very powerful, not only for the same protocol LAN, more suitable for different protocols of LAN and WAN. It has the advantage of choosing the best routing, load sharing, link backup and other network routing information exchange and so on routers have the function. In order to connect with various types of network, the router interface type is very rich, and the layer three switch is generally only the same type of LAN interface, very simple.

3. Performance does not reflect the same. Technically speaking, routers and layer three switches have significant differences in packet switching operations. Routers typically perform packet exchanges by a microprocessor-based software routing engine, while layer three switches perform packet exchange through hardware. Layer three switch after routing the first data stream, it will produce a MAC address and IP address mapping table, when the same data flow through again, will be based on this table directly from the two layer through rather than re-route, thus eliminating the router to make Routing and network delay, improve the efficiency of packet forwarding. At the same time, the three-layer switch routing lookup is for the data flow, it uses the caching technology, it is easy to use ASIC technology to achieve, therefore, can greatly reduce costs and achieve rapid forwarding. And the router's forwarding takes the longest matching way, realizes the complexity, usually uses the software to realize, the forwarding efficiency is low.

Because of this, the performance of the three-layer switch is much better than the router in terms of overall performance, which is very suitable for local area networks where data exchange is frequent; While routers are very powerful, the packet forwarding efficiency is much lower than the three-layer switch, which is more suitable for the interconnection of different types of networks where data exchange is not very frequent. such as the interconnection of LAN and Internet. If the router, especially the high-end routers for the local area network, is a considerable amount of 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 subnets.

Three layer switch does not support NAT does not support WIC does not support sub-interfaces

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