dacs.doc electric

 

How to Network Your Home

By Rich Chernock

 

DISCLAIMER: My level of expertise in network installation is that I've done it once-successfully.

A recent (1998) estimate showed that approximately a third of U.S. households have at least one computer. Although I couldn't dig up any data, I'd guess that significant portions of these have more than one. The marketing model for computers today is obsolescence within a few years. Old computers have very little resale value and sometimes get pressed into some kind of secondary service. In many cases the kids get the new machine (to run their games), and the parents continue using the old one for work. Once there is more than one computer in the house, a home network then becomes an interesting proposition, with attractive possibilities for resource sharing (files and printers), multiplayer gaming, and even Internet connection sharing.

Difficulties

There are basically two major difficulties in installing a home network-connecting the computers and configuring them. Of the two, the actual connections are probably the most difficult and require the most time. In this article, I will discuss the former and punt the latter, since the details vary by operating system and there are numerous references on the Web. The biggest problem is that most of us are already living in the house that we want to network and don't have the luxury of being able to string cables through exposed studs (as would be the case for a house being built).

Available Technology

The conventional approach to networking involves physically running cable throughout the house, which often involves a considerable amount of work, the amount depending upon how handy the installer is and the WAF (wife acceptance factor: "Are exposed wires OK?"). The most common type of network, Ethernet, requires a cable connecting each computer and a central hub.

A number of technologies have been or are being developed to sidestep the problem of installing wiring in preexisting houses: wireless technology, sharing the phone line and sharing the power line. All of these avoid the work and frustration of running wiring but have some disadvantages. In each case, the technology is still maturing, and the products being sold have varying degrees of stability.

The usefulness of wireless (RF) networks often depends on the distances between the computers and what is in between (walls, wiring, people). Sharing the phone line depends on a phone jack already existing near where the connection is desired. Power-line sharing is at a very early stage. In all three cases, the bandwidth is limited-often one to four Mbps (Megabits per second)-compared to conventional Ethernet, which can easily and cheaply provide 100Mbps today.

Ethernet has evolved over an extended period of time, and the necessary components have become plentiful, stable, and cheap. A few years ago Ethernet was typically used at 10Mbps connection speeds. Today, 100Mbps is commonplace, with gigabit (1,000Mbps) appearing on the market. Numerous simple, two-computer networks kit for 100Mbps (cards, hub, and cables) are available for a street price around $100.

My Preferred Solution

I have quite a few computers in the house (Why I do is the subject of another article). Since I believe that there is no such thing as too much bandwidth, I selected the physical wiring approach to a home network, with 100Mbps Ethernet. I was lucky in the installation phase, since the layout of my house made running cable fairly easy. My house has closets that allow easy access to the attic and basement, as well as to each other. In addition, I could find a path between bedrooms that ran along the heating pipes. I chose to run Ethernet cable from a "wiring" closet to my den, each of the bedrooms, and the kitchen. Since most of the effort went to doing the wiring, I chose to run two Ethernet cables, as well as coax for video (no extra effort involved for future expansion).

Materials and Sources

100Mbps Ethernet must be run on Category 5 (Cat5) cabling, which is a cable consisting of four tightly twisted pairs of wire in a common sheath. There are two forms of Cat5 cable commonly available: ordinary and plenum. Plenum is recommended (possibly required by code) when the wiring runs through walls. Bulk Cat5 cable is available at Home Depot for approximately $58 for a 1000-foot box. Plenum cable is also available there for about twice the cost. I had no need to fish wires through the walls, so non-plenum would work fine.

In addition to the wire, you need termination hardware (jacks and boxes). Again, all items were available at Home Depot. Leviton makes a line of wiring jacks called "On Port," which includes the RJ45 jacks required for Ethernet connections. These jacks pop into wallplates, which are then mounted in your favorite termination box (either J-Box for in-wall, or surface-mount boxes). The plates come in a variety of configurations, holding up to eight jacks per single plate. The cost for each termination (box, plate and jack) should be less than $10.

To complete the network installation, an Ethernet hub must be used, as well as Ethernet cards (NICs) in each computer and patch cables to connect the computer to the termination jack. If only two computers are to be connected, a hub can be avoided through the use of a crossover cable. Hubs are available from the usual PC hardware sources. A four-port 10/100Mbps hub can be found for about $50. I used an eight-port, dual-speed hub (supporting both 10Mbps and 100Mbps simultaneously), which cost about $100.

Techniques

Running the Cat5 cabling is similar to running other types of wiring within the house, with a few notable exceptions. The noise immunity and high bandwidth of the cabling depends on the tight twisting of the pairs, which requires some special handling. You have to be careful not to kink the wire, bend it too tightly or pull too hard on it, all of which have a tendency to untwist the pairs. Doing this step usually involves convincing the wire that it wants to go where you want it to. Simple aids such as a straightened coat hanger and electrical tape help a lot. If you have experience fishing wires, then this step will be quite familiar. One tip: Make sure you identify each end of each wire before pulling. If you forget to do this, you'll be faced with a multitude of wires coming out of a ceiling, with no clue to where the other end goes. It is possible to figure it out afterward, but it will take much longer than the few seconds required to first write a simple ID on each wire.

Once the wires are run, then termination needs to be done. The junction box is installed using conventional methods. After threading the Cat5 cable through the junction box, the RJ45 connector needs to be attached. The Leviton jacks come with color-coded IDs for each jack position. Simply match the wire color to the ID. The wires are attached with a punch-down tool, typically a simple plastic version is supplied with the jack. I used a single termination box in each room, with a more complex one in the closet, having one jack for each of the rooms to be connected.

The next step is to get the computers ready for networking by installing the NICs and connecting them to the jacks using patch cables. I will not discuss here the details of successfully installing network support, which depend heavily on the computer operating system. When setting up the network, some attention should be paid to the IP addresses assigned to each computer. There are a few ranges of addresses set aside for private use-I used the 192.168.0.xxx group. In the closet, attach each of the in-use jacks to the hub, again with patch cables. If you've done these steps correctly, a simple ping test of each computer should show positive results.

Connection Sharing

One major use of home networks is sharing a network connection, especially when broadband access is available (either cable modem or xDSL technology). There are a number of options available, the choice depending on the computer architecture within the house. The most typical is to designate one computer as the main gateway and to connect the broadband access to it.

The gateway computer needs two NICs (one for the broadband connection and the other for the internal network). In the Win world, the connection can be shared using Windows 98's ICS (Internet Connection Sharing) or with a third-party product such as Wingate or Sygate. This computer can be used for its normal purposes and shouldn't see much degradation in performance by the gateway activities.

Another possibility is to set up a dedicated machine for the gateway, essentially a home server. This is the route I chose, taking an old Pentium 166 machine and installing Linux on it. Linux has built-in capabilities for sharing a connection using IP Masquerading (the ipchains command). Some of the reasons I chose this path were the availability of this computer for other server tasks (file sharing and Web serving), which will allow me to do a number of interesting things (the subject of another article). In addition, I chose Linux because of its robustness and reliability-I expect the machine to run 7x24 until either a hardware failure or a power outage occurs.

Security

[Although this is the subject of an upcoming article, I think it's important to discuss the issue of security. As a result of the installation defaults built into Windows, many people who have cable modems discover that when they open their Network Neighborhood, they have become peeping Toms: Magically, they have acquired access to all their neighbors' computers. This is partly due to enabling Netbeui (the network protocol used for file and printer sharing) over the cable modem, as well as to using the default workgroup name in Windows. I strongly recommend only running TCP/IP over the modem--and choosing a new workgroup name.]

Although this is the subject of an upcoming article, the issue of security needs to be discussed. As a result of the installation defaults built into Windows, many people who have cable modems discover that when they open their Network Neighborhood, they have become peeping Toms: Magically, they have acquired access to all their neighbors' computers. This is partly due to enabling Netbeui (the network protocol used for file and printer sharing) over the cable modem, as well as to using the default workgroup name in Windows. A definite recommendation is to only run TCP/IP over the modem-and to choose a new workgroup name.

I opted for a stronger approach: The same command that allows Linux to share broadband connections also provides firewalling capabilities. I have set up firewall policies that allow virtually nothing originating from outside of my network to successfully connect, while allowing everything originating inside the house to occur normally. I strongly recommend that anyone installing a broadband connection take security seriously.

Results

The system works admirably. All of the computers in my house can talk to each other for gaming and file sharing. In addition, the Internet is available all of the time to every computer that is turned on, and I now have cable TV in each room and a spare Cat5 cable for future expansion. The results were definitely worth the effort.


RICH CHERNOCK is a senior engineer at IBM research working in the area of advanced digital television and data broadcast. You can e-mail Rich at mpeg2@earthlink.net.

BackHomeNext