Functions and comparison of repeaters, hubs, bridges, switches and routers

Repeater 、 A hub 、 bridge 、 Switch 、 Router function and comparison

• Repeater （RP repeater）：
  Due to the loss of data transmission on the line , The power of the signal transmitted on the line will gradually decrease , Attenuation to a certain extent will cause signal distortion , As a result, receiving errors may occur . Repeaters usually have only two ports , The received signal can be regenerated, shaped and amplified , To expand the transmission distance of the network .
• A hub （Hub）：
  Hubs are usually controlled by 4 to 20 Ports or more , The received signal can also be regenerated, shaped and amplified , To expand the transmission distance of the network . The hub transmits information by broadcasting .
• bridge （Bridge）：
  A bridge is also called a bridge , It's a storage that connects two LANs / Forwarding device , It can turn a big LAN Split into multiple segments , Or more than two LAN Interconnection is a logic LAN, send LAN All users on can access the server . The most common way to expand a LAN is to use a bridge . The simplest bridge has two ports , More complex bridges can have more ports . Each port of the bridge is connected to a network segment . The two ports of the bridge have an independent switching channel , Not sharing a backplane bus , Can isolate conflict areas . Bridges perform better than hubs , All ports on the hub share the same backplane bus . later , The bridge has more ports 、 At the same time, it can also be replaced by switches that isolate the conflict domain .
• Switch （Switch）：
  The most common switch is the Ethernet switch . Other common ones are telephone voice switches 、 Optical switch, etc . The switch has multiple ports , Each port has bridging function , It can be connected to a LAN or a high-performance server or workstation . Switches are sometimes called multi port bridges .
  The switch works on OSI Reference the second layer of the model , Data link layer . Inside the switch CPU When each port is successfully connected , By way of MAC The address corresponds to the port , Form a picture of MAC surface . In future communications , Send it to MAC The address packet will only be sent to its corresponding port , Not all the ports . therefore , Switches can be used to divide data link layer broadcasting , The conflict domain ; But it can't divide network layer broadcasting , The broadcast domain .
  The switch has a high bandwidth back bus and internal switch matrix . All ports of the switch are connected to this back bus , When the control circuit receives the packet , The processing port looks up the address comparison table in memory to determine the purpose MAC（ Hardware address of network card ） Of NIC（ network card ） Which port to hook up on , Through the internal exchange matrix, the packets are transmitted to the destination port quickly , Purpose MAC If it does not exist , Broadcast to all ports , Exchange opportunities after receiving port response “ Study ” new MAC Address , And add it inside MAC In the address table . Using a switch can also turn the network “ piecewise ”, By contrast IP Address table , The switch allows only the necessary network traffic through the switch . Filtering and forwarding through the switch , It can effectively reduce the conflict domain .
• Router （Router）：
  Two or more devices are connected to a network , Act as a gateway between networks , It's a dedicated intelligent network device that reads the address in each packet and decides how to transmit it . It can understand different agreements , For example, the Ethernet protocol used in a LAN , Used by the Internet TCP/IP agreement . such , The router can analyze the destination address of packets from different types of networks , Turn the non TCP/IP The address of the network is translated into TCP/IP Address , Or vice versa ; Then according to the selected routing algorithm, each packet is transmitted to the designated location according to the best route . So the router can put the non TCP/IP The Internet is connected to the Internet .

- Configuration mode of switch ：

1、 adopt “Console” The port is directly connected to the computer .
2、 Connect through ordinary port . At this time, the switch cannot be configured locally , It needs to pass Telnet perhaps Web Implement switch configuration by browser . The specific configuration method is as follows ：

• • ①Telnet
    Telnet Protocol is a remote access protocol , It can be used to log in to the switch for configuration .
    Suppose the switch IP by ：192.168.0.1, adopt Telnet It only takes two steps to configure the switch ：
    The first 1 Step , click start , function , Input “Telnet 192.168.0.1”
    The first 2 Step , After the input of , single click “ determine ” Button , Or click enter , Establish connection with remote switch . then , The switch can be configured and managed according to the actual needs .
• • ②Web
    adopt Web Interface , Switches can be set , The method is as follows ：
    The first 1 Step , function Web browser , Enter the switch in the address bar IP, enter , The following dialog box will pop up .
    The first 2 Step , Enter the correct user name and password .
    The first 3 Step , Connection is established , You can enter the switch configuration system .
    The first 4 Step , Set the switch and modify the parameters according to the prompts .