Repeater (RP repeater) is connected network line of a device that is often used in two nodes physical signal bidirectional forwarding work. Repeater is the most simple network interconnection equipment, mainly completes the function of the physical layer, is responsible for two nodes according to the physical a transfer information, complete signal reproduction, adjustment and amplification function, so as to extend the length of the network. In the presence of loss, online road transmission signal power will gradually decay, attenuation to certain degree will cause signal distortion, so can lead to receive error. Repeater is to solve the problem and design. It complete physical line connection, the attenuation of signal amplification, and keep the same with original data. Usually, repeater at both ends of the connection is the same media, but some repeater can also complete different media adapter work. Theoretically Repeaters use is infinite, network and therefore can extend unlimited. In fact this is not possible, because the network standard in all the signal delay range made specific provision, repeater can only in the regulations within the effective work, otherwise it will cause network fault.

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The role of Repeaters

 

Repeater (Repeater) work in the OSI physical layer, LAN is the center of all nodes and its role is to enlarge signal, compensation signal attenuation, support remote communication.

OSI

Rendering function

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The working principle of Repeaters

 

 

Repeater is a small invention, it is designed to give your network signal to promote, in order to make them transmission farther.

Due to the influence of transmission line noise, carrying information digital signal or analog signal transmit only limited distance, repeater function is of received signal regeneration and send, thus increasing the distance of signal transmission. It is the most simple network interconnection equipment, the same network connection of two or more network segment. Such as Ethernet often use repeater expansion bus cable length, the standard fine cable Ethernet every length maximum 185 meters, most can have five section, so increasing the repeater, the largest network cable length can be increased to 925 meters. Generally speaking, the repeater both ends of the network part is the network segment, not subnet.

Repeater can connect two LAN cable, retime and regeneration of cable digital signals, then send out coaxial cable, these functions is the first layer of the OSI model, the typical physical function. Repeater role is to increase local area network coverage area, for example, Ethernet standard gauge order period of signal transmission cable maximum length for 500 meters, but use repeater connection four period of cable, Ethernet in signal transmission cable the longest can amount to 2000 meters. Some brands of repeater can connect different physical medium cable section, such as fine coaxial cable and optical fiber cable.

Repeater will only any cable segment data sent to another section cable, and no matter whether there is error in the data data or is not suitable for the data segment.

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The advantages of Repeaters

 

(1) expanded the communication distance, but the price is to increase some store and forward delay.

(2) increased the maximum number of nodes.

(3) each network segment can use different communication rate.

(4) improve the reliability. When the network failure occurs, usually affect individual segment.

(5) the performance improved.

Of course, the use of repeater also to have certain shortcomings, for example:

(1) with Repeaters to received the attenuation of the signal regeneration (restoration) to send state, and forward out, increased the time delay.

(2) the CAN bus MAC sublayer and no flow control function. When the network load are very heavy, may for repeater in buffer storage space is not enough and produce overflow, so that produce frame loss phenomenon.

(3) repeater if malfunction, the adjacent two subnet work will impact.