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Author: Tianle Yuan

Network Layer⚓︎

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Definition⚓︎

Demand?

Data need to be transferred from one location to another.

Why don't we use Data Link Layer?

If we need the data to be transferred from the western coast LAN to the eastern coast LAN across the US, we have the below plans:

  • Plan A: LAN is limited locally. So we should use other long-distance links such as using PPP/MPLS/ATM. Obviously, building specific p2p networking is costly and messy.
  • Plan B: The protocols used in the Layer2 network are not always the same. Compatibility is a problem.

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How?

To solve this problem, we need to import a new layer. Layer3 -- Network Layer is where Internetworking comes from.

We need to use IP protocol and IP packets.

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IP packets⚓︎

IP packets?

IP packets is the data unit used within the Internet Protocol. It is similar to frame in the Layer 2.

Datagram is an alternative term for "packet".

Structure

There are two types of IP packets for IPv4 (Internet Protocol version 4) and IPv6 (Internet Protocol version 6):

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References⚓︎

Networking Fundamentals: OSI 7 - Layer 3 - the network layer - Part 1

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