Network+™: Study Guide, Fourth Edition

2.3. The OSI Model's Middle Layers

As you move up the OSI model, the protocols at each successive layer get more complex and have more responsibilities. At the middle are the Network and Transport layers, which perform the bulk of the work for a protocol stack. You'll see why in the sections to follow.

2.3.1. The Network Layer

The Network layer of the OSI model defines protocols that ensure that the data arrives at the correct destination. This is probably the most commonly discussed layer of the OSI model.

2.3.1.1. Network Layer Concepts

The following concepts are the most important Network layer concepts:

• Logical network addressing

• Routing

2.3.1.1.1. Logical Network Addressing

Earlier, you learned that every communicating LAN interface has ...