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Network Topologies: How Your Home Network Comes Together

As you're learning, new home network technologies are making lives easier for people like you, me, and even dear old Grandma. Grandma, you ask? Certainly that nice little lady who knits me overly large sweaters and bakes the world's best apple pie (although her meatloaf might leave something to be desired) wouldn't want to set up a home network. Or would she?

Actually, don't be surprised if someday everyone has a home network. And chances are that when this happens, most people still won't know what the term network topology, or neuro-photonic asynchronous reassemblator, for that matter, means. This is because as home networking advances and becomes easier for everyone, traditional networking terms that were born out of the business-networking world will take on less meaning to the home user. The user won't have to put thought into such things as network topologies and other traditional networking considerations. Someday (within the next 10 years, but not quite yet), we'll just plug things in and they'll be networked. But because you are a curious sort, I'll briefly discuss network topologies with you, Mr. Pocket-Protector.

So, what is a network topology? In the simplest description in history of network topology descriptions (will someone alert the Guinness Book for me?), a network topology describes how network communication links or "roads" run from one PC to the other. In other words, it's the way the cables and networking equipment are arranged.

Why do we need to even think about this? Well, even in the case of a home network, it is important to think about how things are arranged or risk running into confusion and clutter down the "road." Network topology is important to consider when you look at how your network will evolve. To understand this, let's look at the different types of network topologies.

The Three Network Topologies

The three basic network topologies you need to consider for a home network are bus, ring, and star. Each of these looks and operates differently from the others.

Bus

Like its name, a bus topology is like a basic bus route going from point A to point B and point C. Our bus is very simple in that it is straight and simple as a direct connection between the PCs on the network. Of course, in real life, your bus network might not be as simple as shown in Figure 3.4. Not all PCs on a bus network sit next to each other in a straight line, but still the bus network has connections that are "direct and straight" from one PC to the next.

Figure 3.4 A "bus" topology.

The appeal of a bus connection is that it is simple to create. No network equipment other than a single cable and couple of NICs are needed. Some phoneline or powerline networks are not really called "bus" networks, but some can in essence be basic "bus" networks using the phone or power wiring in your home. The difference here is that you do not lay the cabling, but instead use your existing phone or powerline wiring.

The disadvantage of the bus network is that it relies on one cable, and if this cable were to become disconnected from one of the PCs or to break, the entire network would stop working. This would not be the case with a phoneline or powerline network.

Ring

A ring topology is much like it sounds: The different nodes or PCs on the network form a ring like that shown in Figure 3.5.

Ring topologies are probably the least likely to be used in a home environment. The type of technology used to make ring networks is called Token Ring, which is more expensive than other types of network technologies we will discuss in Part II.

Figure 3.5 A ring topology.

NOTE

Token Ring is a technology for networking in which PCs communicate by sending an information "packet" around a ring until the packet finds the PC it was intended for. This technology is very polite in that a packet will not be sent by another PC until the packet circulating at a given time finds its destination. Token Ring, while being a very stable technology, is not as popular for new network installments and is not a good choice for a home network.

Star

The star topology, also called spanning tree, is the most common topology used in business networks, and is also very popular with home networks. This is because the star topology is used with the networking technology called Ethernet, which is also very popular.

NOTE

What is Ethernet? Ethernet, like Token Ring, is a kind of communication protocol, except that Ethernet operates over cable networks using a star topology as opposed to the ring topology explained previously. We'll go more in depth into Ethernet in Part II, but it's important to remember that Ethernet is an extremely popular and reliable way to network.

Star networks using Ethernet look like—what else—a star, with a center and several "spokes" reaching out from the center to the different PCs on the network. As shown in Figure 3.6, the network hub is the center of the star, with the different PCs connected through the hub.

Figure 3.6 A star topology.

As to be expected, a network might in reality look a little different from the simplified picture in Figure 3.6, with the network hub sitting in one of the rooms of your house, and the cabling running throughout your walls to reach it.

Network Topologies with Wireless Home Networks

If you are one of those who are set on using a wireless network in your home (if you haven't decided, don't worry; we'll go over each way to network your home in Part II and help you reach a decision), you might be asking whether this discussion about how to set up the network cabling is even necessary.

Well, even if you are going to use a wireless network, this discussion about network topology is still useful in helping you to understand how a network communicates. With wireless LAN technology, there is usually a type of device that acts as a wireless "hub," taking and receiving the wireless signals from the different PCs equipped with wireless NICs and directing them to the other PC that the communication is directed to. This "wireless hub" is called an access point.

NOTE

An access point is a piece of equipment used in wireless LANs, both for home networks and for business LANs. The access point acts as a central transmitter and receiver (some technical types combine these to words to call the access point a "transceiver") for the radio signals that are going back and forth to the different PCs or those going out on the Internet.

You can think of a wireless LAN that uses an access point to communicate with the different end points on the network as acting like a star network. In fact, one of the wireless LAN technologies, called 802.11b, or Wi-Fi, refers to itself as "Wireless Ethernet." Remember, Ethernet is the most popular kind of star network.

But to make things more interesting (a polite word for confusing), not all wireless LANs use access points. Some are built to allow for the wireless NICs in each PC to communicate directly without going through a central access point or hub. These wireless LAN configurations are called "peer-to-peer." This term is familiar to you from our discussion at the beginning of this chapter regarding the different network types (peer-to-peer versus client/server). Although the term peer-to-peer is helpful in describing the direct nature of the communication within these types of wireless LANs, it should not be confused with the network type discussed earlier in the chapter.

You can learn all about wireless home networking in Chapter 7, "The Wonderful World of Wireless Networking."

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