Layer 1/2/3 Devices and their Function

Layer 1 - Devices and Their Functions
Layer 1 defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems. Some common examples are Ethernet segments and serial links like Frame Relay and T1.
Repeaters that provide signal amplification are also considered Layer 1 devices.
The physical interface on the NIC can also be considered part of Layer 1.

Layer 2 Devices and Their Functions
Layer 2 defines how data is formatted for transmission and how access to the physical media is controlled. These devices also provide an interface between the Layer 2 device and the physical media. Some common examples are a NIC installed in a host, bridge, or switch.

Layer 3 Devices and Their Functions
The network layer provides connectivity and path selection between two host systems that might be located on geographically separated networks. In the case of a host, this is the path between the data link layer and the upper layers of the NOS. In the case of a router, it is the actual path across the network.


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  2. simple and useful information

  3. This is one of my interview question,thank you!

  4. Thanks for given a clear idea about the layers.

  5. Perfect! Thank you!

  6. I can deal with TCP/IP layers, but OSI layers are a little different. Thank you for this good post.


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