Repeater is a physical layer device, which regenerates and amplifies the received weak signal and forwards it to another network segment. Can be used to extend the cable connection length.
What is a bridge? What is its function?
A bridge is a device at the data link layer. He selectively transmits messages with address signals from one network segment to another to connect similar or different LANs.
What is a router? What is its function?
A router is a network interconnection device that works at the network layer. It is mainly used to realize routing and protocol conversion (heterogeneous network interconnection), and can also be used to form a firewall.
What is a gateway? What is its function?
Gateway realizes network connection at high level. Gateway is mainly used to complete protocol conversion, grouping and recombination.
There are those internet devices. Which floor of equipment do they belong to? What is its format for processing information?
There are repeaters (hubs), bridges, routers and gateways.
Repeater belongs to physical layer equipment, and its information format is bits.
Bridges are data link layer devices, and the information format is frames.
Routers are network layer devices, and the information format is packets (data packets).
The gateway realizes the interconnection of networks above the transport layer, and the processing information format is message.
What are the functions of bridges, repeaters and routers, and what floor do they work on?
A bridge is a device that connects two LANs and forwards real messages according to MAC addresses, and works at the data link layer.
Repeater is a device that simply increases the transmission distance of LAN. As a signal amplifier, the actual network can span a larger distance. Work at the physical layer
Routers are devices connecting different networks, which are mainly used to realize protocol conversion, path selection and network mutual training. Work in the network layer. end
What is the connection and difference between a bridge and a router?
Bridges are devices that work at the data link layer, while routers are network layer devices.
Although the bridge segments the network through its own routing table, it cannot isolate the network storm generated in the network; Routers can segment the network according to their own default routes or through routing information protocols, and at the same time, they can also block the network storm generated in the network.
What are the advantages of routers? What kind of technology is used?
The networks in Togo can be connected together.
Effectively isolate data traffic and improve network performance.
Routers connect two subnets to form two logical network segments, which can prevent broadcast storms.
Provide firewall technology to enhance security
Routing adopts static routing and dynamic routing technology]
List six common network devices in the network and briefly describe their various characteristics?
Hub: it only plays the role of signal amplification and forwarding in the network, with the purpose of expanding the transmission range of the network, and does not have the directional transmission ability of signals.
Bridge: A trunking system used to connect two LANs using similar LAN protocols.
Switch: It is a multi-port bridge, and each port has soybean oil bridging function, so it can forward frames between any pair of ports.
Router: Connect multiple independent networks or subnets to achieve the best path between the Internet.
MOdem: mainly realizes the conversion between digital signal and analog signal, so as to realize the transmission on telephone line.
Repeater: Regenerates the signal passing through him.
What is routing?
Refers to the path that should be taken from the local to all parts of the network, and the router forwards the data frame to different paths according to the destination address.
What is a Layer 3 switch?
The three-layer switch under the three-layer switching technology is actually a variety of routing devices at the third layer of the OSI reference model. However, because the speed of Layer 3 switch is equivalent to that of layer 2 switches, people still call it a switch, but the name is Layer 3 switch or routing switch.
Layer 3 switch is an organic combination of router and switch with routing function, rather than simply superimposing the hardware and software of routing equipment on the switch. In a three-layer switch, the routing is still completed by the router, but the routing result is saved in the routing buffer (routing table) by the switch. In this way, only the first packet needs to go through the router, and all subsequent packets can be forwarded directly by the switch after consulting the routing table without going through the router.
Compare the differences between common hubs and network switches?
1. From the perspective of OSI architecture, hubs belong to the first-layer physical layer devices of OSI, while switches belong to the second-layer data link layer devices of OSI. Hub only plays the role of synchronization, amplification and shaping in data transmission, and can't effectively deal with short frames and fragments in data transmission, and can't guarantee the integrity and correctness of data transmission. On the contrary, switches can not only synchronize, amplify and shape data transmission, but also filter short frames and fragments.
2. From the working mode, the hub is a broadcast mode, that is to say, when one port of the hub works, all other ports can receive information, which is prone to broadcast storm, and only one port sends data at a time. In addition, the security is poor, all network cards can receive the sent data, but the non-destination network card discards the data packet. When the switch works, only the request port and the destination port respond to each other without affecting other ports, so the switch can isolate the collision domain and effectively suppress the broadcast storm.
3. In terms of bandwidth, no matter how many ports there are in the hub, all ports share a bandwidth, only two ports can transmit data at the same time, other ports can only wait, and the hub can only work in half-duplex mode; For the switch, each port has its own bandwidth, and when two ports work, it will not affect the work of other ports. At the same time, the switch can work not only in half-duplex mode, but also in full-duplex mode.