The difference between a repeater, a hub, a bridge, a switch, a router, and a gateway

First, repeater

Repeaters (Repeater) work in the first layer of the OSI (physical layer), the repeater is the simplest network interconnection device, connected to the same network of two or more network segments, mainly to complete the physical layer function, responsible for the two network nodes on the physical layer to transmit information on a bit, to complete the signal replication, adjustment and amplification functions, This increases the distance of the signal transmission, extends the length of the network and covers the area, and supports long-distance communication.

In general, the network part of the repeater is a network segment, not a subnet. Repeaters only send data on any cable segment to another cable, regardless of whether the data has incorrect data or is not suitable for the network segment. The most common contact is the network repeater, in the communication also has the microwave repeater, the laser repeater, the infrared repeater and so on, the mechanism is similar, comprehend by analogy.

Second, the Hub

Hubs, also called hubs, work on the first layer of physical layer of the OSI seven-layer structure, which is a shared device that receives data broadcast and is typically a star-connected topology within the LAN, each connected to a hub. Because the bandwidth sharing feature of the hub leads to a very low efficiency of network utilization, it is generally not used in large and medium-sized networks. Now the hub is basically full-duplex mode, the most common hub transmission rate in the market is generally 100Mbps.

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Third, Network Bridge

Bridges, like switches, work in the second layer of the OSI model (the Data Link layer) and can be seen as a two-tier router (the real router is working at the network layer, packet forwarding based on the IP address). The bridge can effectively connect two local area networks (LAN), according to the MAC address (physical address) to forward the frame , so that local traffic limit in this network segment, and forwarding the corresponding signal to another network segment, the bridge is usually used to join a few, the same type of network segment.

Four, switch

The switch, as its name implies, works on the second layer of the OSI (data Link layer) and data forwarding based on the MAC address . Each port of the switch belongs to a conflict domain, and all ports of the hub belong to a conflict domain. The switch analyzes the header information of the Ethernet packet (which contains the source MAC address, destination MAC address, information length, etc.), after obtaining the target MAC address, find the Address table stored in the switch (the port corresponding to the MAC address), and verify which port the NIC with this MAC address is connected to. The envelope is then sent to the corresponding port, effectively suppressing the IP broadcast storm. And the packet is in the parallel state, the efficiency is high.

Switch forwarding delay is very small, mainly due to its hardware design mechanism is very efficient, in order to support the maximum data transfer rate of each port, the switch internal forwarding envelope of the backplane bandwidth must be much larger than the port bandwidth, with a strong overall throughput rate, to provide each workstation with higher bandwidth and higher network utilization, It can meet the requirements of large-scale network environment for data parallel processing.

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V. Routers

Unlike hubs and switches, routers are working on the third layer of the OSI (Network layer) and forwarding packets based on IP addressing . A router is a network device that can connect to multiple networks or network segments, which can transform the data information between different networks or segments (such as a local area network-a large network) and allocate the most appropriate path for packet transmission, so that data can be transferred between them, thus constituting a larger network.

The router has the main two functions, namely the data channel function and the control function. Data channel functions include forwarding decision, backplane forwarding and output link scheduling, which is usually done by specific hardware, and the control function is usually implemented by software, including information exchange between neighboring routers, system configuration, system management, etc.

Vi. Gateways

Gateway is also called the Protocol Converter, the concept of the gateway is actually not a problem with the above device type, but for the convenience of reference or put here together.

Gateway is a complex network connection device, which can support the conversion between different protocols, and realize the interconnection between different protocol networks. Gateways have the ability to convert incompatible high-level protocols, and in order to communicate between heterogeneous devices, gateways need to translate and transform different link layers, dedicated session tiers, presentation tiers, and application layer protocols. So the gateway has the characteristics of routers, bridges, repeaters .

To connect two disparate networks (heterogeneous networks), typically using gateways, the two networks in the Internet also need to be interconnected via a computer called a gateway. This computer can decide whether to send the user's information out to the local network according to the IP address of the target computer, and it will send the information from the outside to the local network computer, it is a channel connected with another network. In order for the TCP/IP protocol to be addressable, the channel is given an IP address, which is called the gateway address.

Therefore, the function of the gateway is to connect two network segments using different protocols together, the two network segments of the data using different transport protocols to translate each other. In interconnected devices, due to the complexity of protocol conversions, a one-to-one conversion is generally possible, or a small number of specific application protocol conversions.

Reference Documentation:

http://blog.csdn.net/liuaibing/article/details/8591019

The difference between a repeater, a hub, a bridge, a switch, a router, and a gateway