The difference between the hottest switch and rout

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Differences between switches and routers

traditional switches are developed from bridges and belong to the second layer of OSI, that is, data link layer devices. According to MAC address addressing, it selects routes through the station table, and the establishment and maintenance of the station table are automatically carried out by the switch. The router belongs to the third layer of OSI, that is, the network layer device. It is addressed according to the IP address and generated by the routing protocol through the routing table. The biggest advantage of the switch is that it is fast. Because the switch only needs to identify the MAC address in the frame, it directly generates and selects the forwarding port according to the MAC address. The algorithm is simple and easy for ASIC to implement, so the forwarding speed is very high. But the working mechanism of the switch also brings some problems

1. Loop: according to the switch address learning and station table establishment algorithm, no loop is allowed between switches. Once there is a loop, the spanning tree algorithm must be started to block the port that generates the loop. The router routing protocol does not have this problem. There can be multiple paths between routers to balance the load and improve the reliability

2. Load concentration: there can only be one path between switches, so that the information is concentrated on one communication link and cannot be dynamically distributed to balance the load. The router routing protocol algorithm can avoid this. These values of OSPF routing protocol can include: uncertainty of measurement results, detection limit, method selectivity, linearity, repeatability limit, reproducibility limit, robustness against external influences and interaction sensitivity against matrix interference from samples. The proposed algorithm can not only generate multiple routes, but also select different best routes for different network applications

3. Broadcast control: the switch can only narrow the conflict domain, not the broadcast domain. The whole switched network is a large broadcast domain, and broadcast messages are scattered to the whole switched network. If the router can be isolated, it is best to choose to leave the broadcast domain, and the broadcast packets cannot continue to be broadcast through the router

4. Sub division: the switch can only recognize the MAC address. The MAC address is a physical address and adopts a flat address structure. Therefore, the numerator cannot be divided according to the MAC address. The router recognizes the IP address. The IP address is assigned by the network administrator. It is a logical address and has a hierarchical structure. It is divided into network number and host number, which can be easily used to divide molecules. The main function of the router is to connect different networks

5. Confidentiality: Although the switch can filter the frame according to the source MAC address, destination MAC address and other contents of the frame, the router can filter the message according to the source IP address, destination IP address, TCP port address and other contents of the message, which is more intuitive and convenient

6. Media related: as a bridge device, the switch can also complete the conversion between different link layers and physical layers, but this conversion process is complex and not suitable for ASIC implementation, which will inevitably reduce the forwarding speed of the switch. Therefore, at present, switches mainly complete the network interconnection of the same or similar physical media and link protocols, and will not be used to interconnect the networks with very different physical media and link layer protocols. The router is different. It is mainly used for interconnection between different networks, so it can connect networks with different physical media, link layer protocols and network layer protocols. Although routers have advantages in function, they are expensive and have low packet forwarding speed. In recent years, many improvements have been made to improve the performance of switches, the most prominent of which are virtual network and layer 3 switching

dividers can narrow the broadcast domain and reduce the impact of broadcast storms on the network. Each interface of the router is connected to a sub, and the broadcast message cannot be broadcast through the router. The connection is at least 10 times stronger than that of ABS. The main functions of the router are different: the sub used for metal Charpy impact test belongs to different sub, and the sub range is physically divided by the router. For a switch, each port corresponds to a segment. Since the sub segment is composed of several segments, through the combination of switch ports, it can be logically divided into segments. The broadcast message can only be broadcast within a sub, and cannot be spread to other sub. The purpose of controlling the broadcast can be achieved by reasonably dividing the logical sub. Because the logical subunits are arbitrarily combined by switch ports and have no physical correlation, they are called virtual subunits, or virtual subunits. Virtual technology solves the isolation problem of broadcast packets without routers, and the virtual inner segment is independent of its physical location, that is, adjacent segments can belong to different virtual, while two segments far apart may belong to different virtual, and two segments far apart may belong to the same virtual. The terminals in different virtual machines can not communicate with each other, which enhances the access control of data in the network

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