The difference between switch and router |
| Author： Date：2016/9/8 11:30:48 |
The traditional switch from the bridge to the development, belongs to the OSI second data link layer device. According to MAC address addressing, through the station to select the route, the establishment and maintenance of the station table by the switch automatically. The router belongs to the OSI third layer, the network layer device, which is based on the IP address, which is generated by the routing table routing protocol. The biggest advantage of the switch is fast, because the switch can only identify the MAC address in the frame, the MAC address directly based on the selection of the forwarding port algorithm is simple, easy to achieve ASIC, so the transmission speed is high. But the working mechanism of the switch also brings some problems.
1 circuit: according to the switch address learning and station table set up algorithm, there is no circuit between the switch. Once there is a loop, the spanning tree algorithm must be started to block the port of the resulting loop. The router routing protocol does not have this problem, the router can have a number of paths to balance the load, improve reliability. 2 load concentration: the switch can only have one path, the information is concentrated on a communication link, can not be dynamic allocation, in order to balance the load. The routing protocol algorithm can avoid this point, OSPF routing protocol algorithm can not only generate a number of routes, but also for different network applications to choose their different optimal routing. 3 broadcast control: switch can only narrow the conflict domain, but can not narrow the broadcast domain. The whole exchange network is a large broadcast domain, and the broadcast message is dispersed to the whole exchange network. The router can isolate the broadcast domain, and the broadcast message can not be broadcast through the router. 4 sub network division: switch can only identify the MAC address. MAC address is the physical address, and the use of a flat address structure, and therefore can not be based on the MAC address to divide the sub network. The router IP address, IP address assigned by the network administrator, is the logical address and the IP address is divided into hierarchical structure, network number and host number, can be used to partition the network conveniently, the main function of the router is used to connect the different network. 5 confidentiality issues: Although the switch may also according to the contents of the source MAC address, destination MAC address frame and other frames in the implementation of filtering on the frame, but the router based on the message source IP address, destination IP address and TCP address port to implement the content of message filtering, more intuitive and convenient. |