Ethernet

1. Ethernet frame: the data link layer

"Ethernet" is not a specific network, it is a technical standard; Already contains the content of the data link layer, also contains some of the physical content.

For example: rules on the network topology, access control mode, transmission rate, etc.;

For example in the Ethernet cable must use twisted pair;
Transmission rate has a 10 m, 100 m, 1000 m, etc.;
Ethernet is currently the most widely used LAN technology; Coordinate and token ring, Ethernet and wireless LAN, such as Ethernet in the same time only allow a person to network communication.

Common topology:

• the star topology
• ring topology
• the total linear topology
• the tree topology
• a mesh topology
• hybrid topology

LAN contention issues
Collision domain: Since Ethernet allows only one person to communicate with the network at the same moment, the whole LAN can be considered as a collision domain.

https://blog.csdn.net/qq_45313714/article/details/119054395

Solving LAN contention problems-switches

Operating Principle:
The switch operates at layer 2 of the OSI reference model, the data link layer. The CPU inside the switch will form a MAC table by corresponding MAC addresses to ports as each port is successfully connected. In future communications, packets destined for that MAC address will be sent only to its corresponding port, not to all ports. Therefore, the switch can be used to classify data link layer broadcasts, i.e., conflict domains; however, it cannot classify network layer broadcasts, i.e., broadcast domains.
Effects:

1. Divide the collision domain to reduce the probability of collision
   For example, if hosts A and D want to communicate, the four hosts on the right, B, C, E and F, have a collision in the collision domain, which will not affect the communication of A and D.
2. Forwarding data frames