The topology of Ethernet is "bus type". The topology used by Ethernet is basically a bus type. The bus topology uses a single cable trunk as a public transmission medium, and all computers in the network are directly connected to the shared bus through corresponding hardware interfaces and cables; the bus topology needs to ensure that when data is finally sent There is no conflict.
The topology used by Ethernet is basically "bus type".
Bus-type topology uses a single transmission as a common transmission medium, and all computers in the network are directly connected to this shared bus through corresponding hardware interfaces and cables. What needs to be solved when using a bus topology is to ensure that no conflicts occur when end users use the media to send data.
When configuring a point-to-point link, if the link operates in half-duplex, a simple mechanism can be used to ensure that two users work in turns. In point-to-multipoint mode, access to the line is determined by polling from the control end.
Ethernet topology advantages and disadvantages
Advantages:
1. Simple network structure and easy network expansion ;
2. Less equipment, low cost, easy to install and use;
3. High reliability. Because the failure of a single node will not affect the entire network.
Disadvantages:
1. The bus transmission distance is limited and the communication range is restricted;
2. Fault diagnosis and isolation are difficult. Fault isolation is difficult. When a node fails, it is more convenient to isolate it. Once the transmission medium fails, the entire bus needs to be cut off;
3. Data collisions are prone to occur, and line contention is serious;
4. Distributed protocols cannot guarantee the timely transmission of information and do not have real-time functions. The site must have a media access control function, which increases the hardware and software overhead of the site.
Ethernet communication protocol
The more common Ethernet communication protocol is the TCP/IP protocol. Compared with the open interconnection model ISO, the TCP/IP protocol adopts A more open approach, it has been recognized by the US Department of Defense and is widely used in practical engineering. The TCP/IP protocol can be used on a variety of channels and underlying protocols (such as T1, X.25, and RS-232 serial interfaces). To be precise, the TCP/IP protocol is a protocol group including TCP protocol, IP protocol, UDP (User Datagram Proto-c01) protocol, ICMP (Internet Control Message Protoc01) protocol and some other protocols.
The TCP/IP protocol does not fully comply with the OSI seven-layer reference model. The traditional open system interconnection reference model is a seven-layer abstract reference model of a communication protocol, in which each layer performs a specific task. The purpose of this model is to enable various hardware to communicate with each other on the same level. The TCP/IP communication protocol adopts a four-layer structure, and each layer calls the network provided by the next layer to complete its own needs. These four layers are:
(1) Application layer: the layer for communication between applications, such as Simple Email Transfer Protocol (SMTP), File Transfer Protocol (FTP), Network Remote Access Protocol (Telnet), etc. .
(2) Transport layer: In this layer, it provides data transmission services between nodes, such as Transmission Control Protocol (TCP), User Data Packet Protocol (UDP), etc. TCP and UDP provide data packets Add the transmission data and transfer it to the next layer, which is responsible for transmitting the data and ensuring that the data has been delivered and received.
(3) Network layer: Responsible for providing basic data packet transmission functions so that each data packet can reach the destination host (but does not check whether it is received correctly), such as Internet Protocol (IP).
(4) Interface layer: Management of actual network media, defining how to use actual networks (such as Ethernet, Serial Line, etc.) to transmit data.
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