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| Link_Layer_of_the_Internet_Protocol |
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Tuesday, August 06, 2024 |
Link Layer of the Internet Protocol Suite
The Link Layer is the lowest level of the network stack that makes up the Internet Protocol Suite. It is concerned with the physical and logical connections between hosts on the same local network.
The physical and logical connections are known as Links.
Link Layer protocols goven communication between devices. Examples include:
- WiFi
- For wireless communication between devices using radio waves
- Ethernet
- Wired communication
MAC addresses
Each device on a link has a network address that uniquely identifies it. For most Link Layer Protocols this is a Media Access Control (MAC) address.
A device receives data addressed to its MAC address.
MAC addresses are limited to local networks. Remote networks cannot send data to a specific MAC address. This is off-limits from the outside.
Frames
Link Layer data is divided into small units called "frames". The anatomy of a frame is as follows:
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| header | data | footer |
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The header contains the source and destination MAC address plus a descriptor of the type of data it contains. The data is the payload. The footer is used to detect errors.