Ccna routing and Switching Complete Study Guide

The Access Layer

The access layer controls user and workgroup access to internetwork resources. The access 

layer is sometimes referred to as the desktop layer. The network resources most users 

need will be available locally because the distribution layer handles any traffic for remote 

services.

 The following are some of the functions to be included at the access layer:

 

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Continued (from distribution layer) use of access control and policies

 

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Creation of separate collision domains (microsegmentation/switches)

 

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Workgroup connectivity into the distribution layer

 

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Device connectivity

 

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Resiliency and security services

 

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Advanced technology capabilities (voice/video, etc.)

Technologies like Gigabit or Fast Ethernet switching are frequently seen in the access layer.

I can’t stress this enough—just because there are three separate levels does not imply 

three separate devices! There could be fewer or there could be more. After all, this is a 

layered approach.

Summary

In this chapter, you learned the fundamentals of Ethernet networking, how hosts 

communicate on a network. You discovered how CSMA/CD works in an Ethernet 

half-duplex network.

I also talked about the differences between half- and full-duplex modes, and we 

discussed the collision detection mechanism called CSMA/CD.

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Exam Essentials 

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I described the common Ethernet cable types used in today’s networks in this chapter as 

well, and by the way, you’d be wise to study that section really well!

Important enough to not gloss over, this chapter provided an introduction to encapsula-

tion. Encapsulation is the process of encoding data as it goes down the OSI stack.

Last, I covered the Cisco three-layer hierarchical model. I described in detail the three 

layers and how each is used to help design and implement a Cisco internetwork.

Exam Essentials