Ethernet (Data link layer) Learning notes

The development process of Ethernet:

1. Transfer media from coaxial cable to twisted pair cable and fiber
2. From the development of shared Ethernet to switched Ethernet
3. VLAN and layer three switching technologies appear
4. Development from low-speed Ethernet to high-speed Ethernet

Transfer media from coaxial cable to twisted pair cable and fiber

From the development of shared Ethernet to switched Ethernet bus-shaped Ethernet topology

In order to solve the problem of weak signal, we need to join the proper repeater.

Total Linear Ethernet Functional Requirements

To achieve data communication between the two terminals, you must resolve

• Send what? What do you charge?

  The data is received in frames.

• How to send? How to collect?

  Change the bits flow of the constituent frame into a signal, and then convert the received signal from the bus into a string
  Bits stream, extracting each frame correctly from the bits stream

• When did you send it? When do you collect it? Who's going to collect it?
  Due to the terminal competition bus, there is a mechanism to ensure that only one terminal can successfully send the data, and each end of the probability of the successful transmission of data is equal

Total Linear Ethernet Architecture

The architecture of TCP/IP based on Ethernet

Physical layer: frame-to-bounds, data and signal conversion, detection bus status
MAC layer: Addressing, fair competition bus, data encapsulation

Ps:
Baseband Transmission with Manchester code

Baseband transmission is the transmission of baseband signals. Manchester code, also called phase encoding, is a synchronous clock encoding technique used by the physical layer to encode a synchronous bit stream clock and data.

Mac

CSMA/CD algorithm

SMA/CD algorithm is an algorithm designed for terminal fair competition bus
"Carrier interception" is the detection of a carrier on the bus
"Multi-point access" means that multiple terminals can be connected to the bus
"Conflict detection" is to detect collisions on the bus

Work flow with fallback algorithm

Network Bridge and Conflict domain segmentation

Principle of Network Bridge segmentation conflict Domain

Divide the large Ethernet into a number of small collision domains, so that each
Reduce the number of endpoints in a conflict domain and shorten the distance. Then use a
Devices to connect these conflicting domains.

Forwarding post and Mac frame forward process
The forwarding of Mac frames with the help of forwarding statements

Network Bridge Workflow

VLAN and three-layer switching technology what is broadcast domain

A broadcast domain is a network range in which Mac frames are traversed when all bridges are broadcasting output MAC frames.

What are the dangers of broadcasting?

1) Waste network link bandwidth and Network Bridge, terminal processing capacity
2) easy to cause safety problems

Reasons for introducing VLANs

What is a VLAN

Dividing each broadcast domain generated by physical Ethernet is equivalent to a logically independent Ethernet, which is called a virtual local area network (Virtuallan,vlan) because these logically independent Ethernet exist in the same physical Ethernet.

To be blunt is to customize the broadcast domain.

The partitioning process of VLANs

Single Switch Partitioning
Can be partitioned directly in the switch configuration.
multi-Switch partitioning
You must explicitly set the shared port between the access port and the switch for each VLAN.

About the division of VLAN, here is not detailed, can self-Baidu.

Low to High speed

Ethernet based on the transmission media and transmission rate combination classification standards, transmission media are divided into twisted-pair cable, multimode fiber and single-mode fiber, transmission rate is divided into 10Mbps, 100Mbps, 1Gbps, and 10Gbps.

Ethernet (Data link layer) Learning notes