Data Link Layer

First, Introduction

The data link layer is the lower level in the computer network (the second layer in the OSI model), which can be simply understood as a data channel. The primary function is to provide an unreliable transport service for the upper (network layer) with error detection (which is later mentioned).

Second, solve the problem

1) package into frame: the data from the upper layers (network layer) is added to the header and the tail separately, encapsulated into frames.

2) Transparent transmission: No matter what data, link layer must be able to pass.

3) Error detection: Ensure that all frames are passed to the target machine and maintained in the correct order.

4) Flow control: When the sender sends the frame faster than the receiver receives the frame speed, the sender should handle it.

Iii. Type of communication

1) Point-to-point channel

http://zhaoyuqiang.blog.51cto.com/6328846/1570684

2) Broadcast channel

http://zhaoyuqiang.blog.51cto.com/6328846/1570775

Reference: http://zhaoyuqiang.blog.51cto.com/6328846/1575329

Data Link Layer