Cisco Networking All-in-One For Dummies

Edward Tetz

• Publisher: For Dummies
• Year: 2011
• ISBN:
  9781118137857
• Edition: 1
• Topic: Computer Science
• Subtopic: Computer Networking
• Index: Computer Science

A helpful guide on all things Cisco

Do you wish that the complex topics of routers, switches, and networking could be presented in a simple, understandable presentation? With Cisco Networking All-in-One For Dummies, they are! This expansive reference is packed with all the information you need to learn to use Cisco routers and switches to develop and manage secure Cisco networks. This straightforward-by-fun guide offers expansive coverage of Cisco and breaks down intricate subjects such as networking, virtualization, and database technologies into easily digestible pieces.

• Drills down complex subjects concerning Cisco networking into easy-to-understand, straightforward coverage
• Shares best practices for utilizing Cisco switches and routers to implement, secure, and optimize Cisco networks
• Reviews Cisco networking solutions and products, securing Cisco networks, and optimizing Cisco networks
• Details how to design and implement Cisco networks

Whether you're new to Cisco networking products and services or an experienced professional looking to refresh your knowledge about Cisco, this For Dummies guide provides you with the coverage, solutions, and best practices you need.

Book IV

Routing

Chapter 1: Making the Wide Area Network (WAN) Wide

In This Chapter

Identifying the differences between WAN types

Introducing routing protocols

This minibook on routing logically begins with where you are likely to use routers. Although some people use routers on the interior of a well-connected network to separate a larger number of users or to aid in implementing a set of security features, most people use routers to connect remote offices that are linked through their telephone company’s network infrastructure.

This chapter looks at the key elements of technologies you can use to make the connections between all your routers. In addition to covering the infrastructure elements, I introduce you to different routing protocols you can implement for your wide area network (WAN).

Identifying Features of a WAN

First, I want to explain what makes up a WAN. Sometimes people want to identify a WAN by the size of the network or by the devices that compose the network, but I disagree with both methods of classification. For example, if your network has 5,000, or even 100,000, devices and you are not using WAN technologies to interconnect them, you do not necessarily have a WAN. If you have a large campus network using routers and dynamic routing protocols and the infrastructure that it runs over is all internal to your organization, you do not necessarily have a WAN.

So, in case you have not already guessed, a WAN, by definition, uses infrastructure that you do not own, but that is owned by a telephone company or another external provider. If your network uses a network infrastructure that is owned by your service provider, implementing WAN technologies, you have a WAN. This infrastructure can fall into many areas or technologies; the big criterion is that the infrastructure is not yours.

Sending data long distances

Although I said that long distances are not criteria for defining a WAN, commonly, WANs do span substantial distances. If your WAN spans only a single city, across town is a long way; nevertheless, your carrier may choose different technologies for that distance than they would if your network spanned a state, country, or continent. So, although distance is not a true criterion for determining whether your network is a WAN, most WANs do span a great distance, and the technologies used in the WAN depend a great deal on the distances involved.

Implementing routing protocols

Routing protocols are also not true criteria for a WAN definition. A WAN can either use manual routing or implement a routing protocol such as RIP or EIRGP, which are discussed in the section, “Choosing a routing protocol,” later in this chapter. Although larger, more complex networks like a national WAN may be easier to manage when implementing a routing protocol, their use does not dictate that you have a WAN. A large corporation could have a single (but large) building or a campus of several buildings that causes the network to have several routers. To make life easier on the routing front, you could choose to implement one of the many available routing protocols. So, although most WAN environments make use of routing protocols, not all networks that implement routing protocols are necessarily WANs.

Using carrier equipment

By carrier equipment, I mean the equipment from your telephone company that allows you to connect your network to the backbone of its network. These network connections can be digital subscriber line (DSL), frame relay, fiber optic, broadband cable, or another technology used by your telephone company or network provider. This component really turns a network into a WAN, allowing your traffic to trave...