A few rudimentary physical components are common to most small-to-midsized business (SMB) networks. From physical cables to intelligent Ethernet switches and routers, these pieces help you move the data that keeps your company in business. Although installation and configuration of some of this equipment requires specialized knowledge, you can easily implement most of these components if you're savvy enough to connect a VCR. Even if you rely on outsourced help for the installation of your SMB network, knowing the components and understanding their functionality can help you troubleshoot and repair common network problems.

LANs and WANs
A plethora of technologies are available for enabling communications between computers. This article discusses the technologies and hardware that you would use in a LAN. A LAN is a computer network that spans a relatively confined area, such as a single building or a group of buildings that are in close proximity to one another. A WAN, on the other hand, is designed to bridge the communication gap between remote sites. Although you'll find differences in the topologies, protocols, and media that LANs and WANs use, the general building blocks remain the same. Client systems and servers utilize a NIC to access the network media, which is typically twisted-pair copper cabling. Switches and hubs connect to the media to allow multiple devices to communicate with each other, and routers connect discrete networks, sometimes in the form of a WAN.

Cable Plant and Facility Considerations
Regardless of the size of your business, adhering to accepted standards regarding cable layout within the building will help you interface with other entities, such as ISPs, and will also let you grow your network more readily, when necessary. One such widely accepted standard, TIA/EIA-568, is jointly developed and maintained by the Telecommunications Industry Association and Electronic Industries Alliance. This standard has much more detail than is useful to typical SMB IT personnel, but the basic framework of the standard applies to every network, at least in part.

In general, TIA/EIA-568 spells out how to implement a standardized telecommunication-wiring infrastructure that can support just about any network configuration you throw at it. The specification splits a wiring system into six categories: work-area wiring, horizontal wiring, telecommunication closets, equipment rooms, backbone wiring, and entrance facilities. As an SMB, you probably won't need to address all six categories, but you should be aware of the concept and function of each part so that you can either know you don't need it or employ a hybrid implementation.

Work-area wiring. Work-area wiring consists of cables, connectors, wall boxes, and wall plates that allow for communications equipment such as PCs and printers to connect to the network. The standard specifies that at least one voice circuit and one data circuit should be present at each wall plate.

Horizontal wiring. Horizontal wiring refers to the cables that run from the work-area wiring to a telecommunications closet. The standard specifies the type of cable you should use in this application. As the standard has evolved, it has called for higher grades of cabling. You should use at least Category 5e (Cat5e), if not Cat6 cable, both of which I discuss later.

Telecommunications closet. A telecommunications closet can house connection equipment for local-vicinity work areas. This equipment might include a switch or hub, as well as a cross-connect to the equipment room. Depending on the size of your facility, you can use as many telecommunications closets as you require.

Equipment room. An equipment room is a centralized space where backbone cabling from telecommunications closets terminates. Also, as the name states, equipment serving the tenants of a building resides here. SMBs might want to combine the functionality of a telecommunications closet with that of an equipment room, but be sure to acknowledge the physical security requirements of the equipment in the room as you consider who will need to access the room.

Backbone wiring. Backbone wiring interconnects telecommunications closets, entrance facilities, and equipment rooms. Typically fiber-optic or coaxial cable, backbone wiring can run across a single floor, through the floors of a building, or across a campus.

Entrance facility. An entrance facility refers to the location at which your telecommunications service enters your building. The entrance facility also houses a demarcation point (or demarc), which is simply the point at which an external telecommunications provider's equipment ends and your internal equipment takes over.

Those considerations might seem like a lot to digest, and if you're in the position of creating your support infrastructure from scratch, you're right. However, before you become overwhelmed by the details of the TIA/EIA-568 specification, take a look at your facility. Chances are that some, if not all, of what you need is already present. To uncover a wealth of information about cabling specifics, right down to the pin-outs of individual connectors, perform an Internet search on the term "TIA/EIA-568."

On the subject of pin-outs (which describe where each wire belongs within a specific cable), you'll find two standards (T568A and T568B) for wiring RJ-45 jacks and plugs, as Figure 1 shows. T568A is generally reserved for voice circuits, and T568B for data. Although either standard will work for both voice and data, best practice is to apply just one of the standards consistently for your data-network cabling infrastructure.

What About Cables?
By far, the most common media used in SMB networking is unshielded twisted pair (UTP) cabling. This cable consists of eight individual wires, twisted into pairs to cancel signal degradation that radio frequencies or electromagnetic interference might cause. Each end of a UTP networking cable is usually terminated with an RJ-45 connector, which is commonly used for NIC and switch connections. You'll find many grades, or categories, of UTP cabling. Higher grades are capable of transmitting data at speeds as fast as 1000Mbps (1Gbps). Generally speaking, you shouldn't use anything less than Cat5 cable for today's networking environments. Cat5e can carry a 1Gbps load, but if you're installing a new cabling infrastructure, Cat6 is your safest bet. (To easily determine which category of cabling you're working with, read the text imprinted on the cable's outer jacket. Every foot or so, you'll see a reference to Catx.)

Cat5e, Cat6, and Cat7 all support today's fastest network standard—1Gbps. So, why should you invest in anything above Cat5e? The answer is in future-proofing your infrastructure. Cat6 and Cat7 will support emerging standards, such as IEEE 802.3an, which purports 10Gbps transmission over copper using Cat7 cable. If you wire with Cat6 or Cat7 today, you'll be able to use that cabling for a long time.

UTP is the fastest copper-based networking medium and carries the lowest price tag on a per-node basis, but its primary limitation is distance. The TIA/EIA standard specifies a theoretical 100-meter maximum distance. For distances greater than 100 meters, you'll need to either use specialized hardware to boost the signal or use an alternative medium such as coaxial or fiber-optic cable. Fiber-optic cable is a much better choice for covering long hauls and is supported by most business-class equipment vendors for inter-switch links and connections to systems such as servers. Coaxial cable, which has a theoretical maximum run length of 500 meters, has few practical applications these days. Fiber-optic cables can reach much farther, and the cost of fiber-optic installation and maintenance isn't as prohibitive as it once was.

Regardless of the medium you choose to carry your data, careful installation and termination of the cabling infrastructure is of the utmost importance. A kink in a UTP cable or a poorly attached RJ-45 connector can cause intermittent network problems that can drive you batty. Additionally, be aware of any regulations that might stipulate the installation of only certain types of cable in your building's plenum spaces. If you aren't confident in your ability to run and properly terminate your network-cabling infrastructure, hire a professional who is familiar with the best practices and specifications of business-network installations. (Be sure to check with your local building-code enforcement agency to check on any regulations regarding low-voltage computer-cable installations. Generally speaking, because network cabling is considered low voltage, you don't need a licensed electrician to do the job.) Once the cabling is in place, use a network tester to certify each run so that you ferret out any potential problems before they spell downtime for your users.

Tools and Other Equipment
If I haven't scared you off, and you're ready to build some or all of your network infrastructure, you'll still need a few items to achieve success. You'll need raw materials: cable, connectors, patch panel(s), patch cables, and wall plates. You'll also need some basic tools: crimpers, diagonal cutters, strippers, and a cable tester. The good news is that many suppliers can fulfill an order for one or all of these items.

An Internet search—using search terms such as "Cat5 wiring tools"—will dig up the goods for you. Bulk Cat5 cable usually comes in 1000' lengths in a ready-to-dispense box. If you can use the length, buy several boxes; doing so will let you pull multiple cable runs to a given location in your building simultaneously, resulting in significant time savings.

Before you rush off to place your order, you should conduct one last gut-check. Take a look at the overall size of your project, and realistically gauge your ability to complete all the steps necessary to build an infrastructure that not only works but provides a solid foundation for your business data. Also, be realistic about the amount of time the project with take, and determine whether hiring a cabling contractor to do the "dirty" work might be a good idea. Of course, you could order the equipment and change your mind halfway through, but taking this route might actually end up costing you more than hiring a contractor at the start.

A Basic Network Wiring Trace
To illustrate the overall layout of a basic Cat5 network in a small office, Figure 2 provides a simplistic look at the physical path of a data packet traveling through a LAN. Let's walk through it step by step, so that you can clearly understand the layout.

  1. From a PC in a work area, the packet travels out of the NIC through a patch cable to the RJ-45 jack in a wall plate.
  2. From the wall plate, the packet travels over the wall plate–connected cable (i.e., horizontal wiring) to a telecommunications closet that terminates at a jack in a patch panel.
  3. The packet then goes through a patch cable that cross-connects the horizontal wiring to the backbone wiring.
  4. The packet then heads to the equipment room, where it connects to another patch panel.
  5. A final patch cable connects the equipment room's patch panel to a network switch.
  6. The switch then sends the packet to its destination, which could be a server on the LAN or a router interface to another LAN or the Internet.

Return traffic back to the initial PC would traverse the same equipment in reverse order.

Network Clients
Because the typical purpose of a network is to allow a client system to communicate with other systems, let's discuss the requirements of a networked client. Assuming the client's OS supports networking via a supported protocol (which is almost always TCP/IP), all that's necessary is a NIC and a path to another system. The simplest computer network consists of two systems, each with a NIC, and with a specially wired crossover cable between them. Although most business-class systems feature an integrated NIC, you should know that multiple varieties of NICs exist. Offerings from 3Com and Intel—by far the most popular—are good choices. Don't settle for a NIC that has less than full-duplex 100Mbps capabilities, which shouldn't be a problem; tier-one suppliers are including 1000Mbps (Gigabit) NICs onboard their systems.

Hubs and Switches
Although you can use minimal equipment to configure a two-system network, configuring three or more systems requires at least one additional piece of hardware: a switch or a hub. Switches and hubs both permit multisystem communication on a network, but for a few good reasons, switches are by far the favored choice of today's businesses. In simple terms, whereas a hub provides a shared connection to the network for all connected devices, a switch establishes a dedicated communication path for network conversations between two devices on the network. This functionality greatly reduces the chance of collisions (multiple conversations on the same network media conflicting with one another) and thus increases throughput. Also, devices connected to a hub share all the hub's available bandwidth, but devices connected to a switch receive a predefined allotment of bandwidth. Switches also offer improved security by preventing a host from seeing traffic not directed to it.

An excellent choice for SMBs today, 100Mbps switches are quite affordable. Those businesses that have a higher demand for bandwidth might need to implement 1Gbps switches.

Routers
It doesn't make sense for network traffic destined for your LAN to travel across expensive WAN or backbone connections. A router's job is to contain local network traffic while ensuring that traffic destined for another segment has a path, or route, to get there. An ideal location for a router is between your corporate network and the Internet. One of the first vendor names to come to mind when you think of routers is Cisco, but in the SMB space you have many fine choices that will provide what you need without breaking your budget. Cisco recognizes the need for some middle ground and targets its Linksys brand to SMBs.

Other SMB Networking Considerations
SMBs can no longer hide from the wireless-network push. As soon as an executive asks to use a wireless-enabled laptop in a meeting room, the proverbial genie is out of the bottle. To protect your network and effect a smooth transition to wireless, you can adhere to Wi-Fi standards such as 802.11g and purchase proven solutions by name-brand vendors. Watch for a later article in this series to walk you through the implementation of a wireless network. In the meantime, consider how a wireless network might help you build your network infrastructure in areas where physical wiring is prohibitively expensive or impossible to install.

Also, if you plan to connect your company's network to the Internet, you must take precautions to protect your internal resources from intrusion and attacks. Connecting your company's network to the Internet without a firewall is like leaving the doors to your headquarters unlocked 24 × 7. Just one unscrupulous visitor can wreak havoc on your company's assets. Firewalls inspect the network traffic between security zones and decide whether to permit or deny that traffic. Generally speaking, this inspection occurs at either the network layer or the application layer of the protocol stack. Network-layer inspection is considered faster than application-layer inspection, but it doesn't provide as detailed an inspection of the packets. This lack of a thorough inspection might make packets more susceptible to breach.

Whether you build your entire network internally or use outside resources, employing proven design and implementation techniques will ensure a solid foundation for your data movement in your company. Additionally, having the knowledge and documentation for how your network is put together will save many hours of troubleshooting when a problem does arise.

Project Snapshot: How to
PROBLEM: You need to set up the basic physical components of an SMB network to ensure a solid foundation for data movement throughout your company.
WHAT YOU NEED: A cable plant and facility; appropriate cabling; a hub or switch; a router; a knowledge of basic networking fundamentals
DIFFICULTY: 1.5 out of 5
PROJECT STEPS:
  1. Implement a standardized telecommunication-wiring infrastructure.
  2. Choose your cabling media.
  3. Implement a switch or hub.
  4. Install a router.
  5. Ensure successful communication.