CCNP: Switching Study Guide

CCNP: Switching Study Guide

by Todd Lammle, Eric Quinn

Hardcover(Study Guide)

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Product Details

ISBN-13: 9780782141535
Publisher: Sybex, Incorporated
Publication date: 10/10/2002
Edition description: Study Guide
Pages: 592
Product dimensions: 7.68(w) x 9.28(h) x 1.50(d)

About the Author

Todd Lammle is a CCNP, MCT, MCSE, CNI, and MCNE. He is president of Globalnet Training Solutions, Inc. (, and chief scientist of RouterSim, LLC ( He is the author of several Cisco and Microsoft study guides from Sybexr. Todd has more than 18 years of experience designing, installing, and troubleshooting LANs and WANS. Kevin Hales is a senior network engineer for the Utah Education Network, where he specializes in BGP and ATM. Using his five years of networking experience, Kevin manages a statewide WAN.

Read an Excerpt

Chapter 1: The Campus Network

A campus network is a building or group of buildings that connects to one network, called an enterprise network. Typically, one company owns the entire network, including the wiring between buildings. This local area network (LAN) typically uses Ethernet, Token Ring, Fiber Distributed Data Interface (FDDI), or Asynchronous Transfer Mode (ATM) technologies.

The main challenge for network administrators is to make the campus network run efficiently and effectively. To do this, they must understand current campus networks as well as the new emerging campus networks. Therefore, in this chapter, you will learn about current and future requirements of campus internetworks. We'll explain the limitations of traditional campus networks as well as the benefits of the emerging campus designs. You will learn how to choose from among the new generation of Cisco switches to maximize the performance of your networks. Understanding how to design for the emerging campus networks is not only critical to your success on the Switching exam, it's also critical for implementing production networks.

As part of the instruction in network design, we'll discuss the specifics of technologies, including how to implement Ethernet and the differences between layer 2, layer 3, and layer 4 switching technologies. In particular, you will learn how to implement FastEthernet, Gigabit Ethernet, Fast EtherChannel, and Multi-Layer Switching (MLS) in the emerging campus designs. This will help you learn how to design, implement, and maintain an efficient and effective internetwork.

Finally, you will learn about the Cisco hierarchical model, which is covered in all the Cisco courses. In particular, you will learn which catalyst switches can-and should-be implemented at each layer of the Cisco model. And you will learn how to design networks based on switch and core blocks.

This chapter, then, will provide you with a thorough overview of campus network design (past, present, and future) and teach you how, as a network administrator, to choose the most appropriate technology for a particular network's needs. This will allow you to configure and design your network now, with the future in mind.

Campus Internetworks

It doesn't seem that terribly long ago that the mainframe ruled the world and the PC was just used to placate some users. However, in their arrogance, mainframe administrators never really took the PC seriously, and like rock 'n' roll naysayers, they said it would never last. Maybe they were right after all-at least in a way. In the last year or two, server farms have replaced distributed servers in the field.

In the last 15 years we have seen operators and managers of the mainframe either looking for other work or taking huge pay cuts. Their elitism exacerbated the slap in the face when people with no previous computer experience were suddenly making twice their salary after passing a few key certification exams.

Mainframes were not necessarily discarded, they just became huge storage areas for data and databases. The NetWare and NT server took over as a file/print server and soon started running most other programs and applications as well.

The last 20 years have witnessed the birth of the LAN and the growth of WANs and the Internet. So where are networks headed in the twenty-first century? Are we still going to see file and print servers at all branch locations? Are all workstations just going to connect to the Internet with ISPs to separate the data, voice, and other multimedia applications?

Looking Backwards at Traditional Campus Networks

In the 1990s, the traditional campus network started as one LAN and grew and grew until segmentation needed to take place just to keep the network up and running. In this era of rapid expansion, response time was secondary to just making sure the network was functioning.

And by looking at the technology, you can see why keeping the network running was such a challenge. Typical campus networks ran on 10BaseT or 10Base2 (thinnet). As a result, the network was one large collision domainnot to mention even one large broadcast domain. Despite these limitations, Ethernet was used because it was scalable, effective, and somewhat inexpensive compared to other options. ARCnet was used in some networks, but Ethernet and ARCnet are not compatible, and the networks became two separate entities. ARCnet soon became history.

Because a campus network can easily span many buildings, bridges were used to connect the buildings together; this broke up the collision domains, but the network was still one large broadcast domain. More and more users were attached to the hubs used in the network, and soon the performance of the network was considered extremely slow.

Performance Problems and Solutions

Availability and performance are the major problems with traditional campus networks. Bandwidth helps compound these problems. The three performance problems in traditional campus networks included collisions, broadcasts and multicasts, and bandwidth.


A campus network typically started as one large collision domain, so all devices could see and also collide with each other. If a host had to broadcast, then all other devices had to listen, even though they themselves were trying to transmit. And if a device were to jabber (malfunction), it could almost bring the entire network down.

Because routers didn't really become cost effective until the late 1980s, bridges were used to break up collision domains, but the network was still one large broadcast domain and the broadcast problems still existed. However, bridges did break up the collision domain, and that was an improvement. Bridges also solved distance-limitation problems because they usually had repeater functions built into the electronics and/or they could break up the physical segment.


The bandwidth of a segment is measured by the amount of data that can be transmitted at any given time. Think of bandwidth as a water hose; the amount of water that can go through the hose depends on different elements:

  • Pressure
  • Distance

    The pressure is the current and the bandwidth is the size of the hose. If you have a hose that is only 1/4 inch in diameter, you won't get much water through it regardless of the current or the size of the pump on the transmitting end.

    Another issue is distance. The longer the hose, the more the water pressure drops. You can put a repeater in the middle of the hose and reamplify the pressure of the line, which would help, but you need to understand that all lines (and hoses) have degradation of the signal, which means that the pressure drops off the farther the signal goes down the line. For the remote end to understand digital signaling, the pressure must stay at a minimum value. If it drops below this minimum value, the remote end will not be able to receive the data. In other words, the far end of the hose would just drip water instead of flow. You can't water your crops with drips of water; you need a constant water flow.

    The solution to bandwidth issues is maintaining your distance limitations and designing your network with proper segmentation of switches and routers. Congestion on a segment happens when too many devices are trying to use the same bandwidth. By properly segmenting the network, you can eliminate some of the bandwidth issues. You never will have enough bandwidth for your users; you'll just have to accept that fact. However, you can always make it better...

  • Table of Contents

    Assessment Test

    Chapter 1: The Campus Network
    Chapter 2: Connecting the Switch Block
    Chapter 3: VLANs
    Chapter 4: Layer 2 Switching and the Spanning Tree Protocol (STP)
    Chapter 5: Using Spanning Tree with VLANs
    Chapter 6: Inter-VLAN Routing
    Chapter 7: Multi-Layer Switching (MLS)
    Chapter 8: Multicast
    Chapter 9: Configuring Multicast
    Appendix A: Commands Used in This Book
    Appendix B: Internet Multicast Addresses


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