It's no longer good enough to just focus on amps and volts. If you want to succeed in today's world, you better be able to speak in bits and bytes, too.
The home technology integrator (HTI) must be knowledgeable about several diverse disciplines, one of which is computer networking. The computer network is a data communications system that allows several independent devices to communicate directly with each other. This second installment in EC&M's series on Cisco Learning Institute's HTI+ training program will cover how to design a computer network with the needs of the customer in mind, install the necessary equipment, and configure the network.
Network design. The infrastructure for a computer network in a new home should be installed during the electrical phase of construction. All rooms should be set up with the appropriate wall jacks and a central location selected for the router or switching equipment. Consider things like e-mail, Internet, video entertainment, and remote access needs when determining network requirements. Physical size and the layout of the home will also be a major consideration.
You should keep current with the latest technology so you can help homeowners make informed decisions. Consider the number of computers and the peripherals that will be included on the network and their applications. Telecommuting will also require high-speed Internet access. Plan for and design future functionality that will allow the family to place computers in the kitchen, den, and master bedroom. Computer outlets should be installed in every room of the home.
Before homeowners can choose an infrastructure, they need to have a clear understanding of what's available. The most common type of wired network for businesses is Ethernet, but other systems are available for using existing wiring in the home.
An Ethernet network is easy to set up in a home under construction. In an existing home it requires running the cable through the attic or along the baseboards.
Networks can also be established using existing wiring infrastructures. HomePNA systems take advantage of existing telephone wiring to carry network data. Using telephone wiring reduces the complexity of rewiring an existing home or wiring a new one. However, even the new HomePNA 2.0 operates slower than the typical Ethernet installation.
Networks can also be wired using a PLC system, which uses existing power line cabling. Power receptacles are positioned in multiple locations within each room in most homes. The PLC system works out well for many telecommunications requirements. However, it's the lowest-performing LAN because of the high tendency for interference between devices that obtain AC voltage from the power-line and devices that transmit data along the same line.
Like power lines and phone lines, coaxial cabling is already found in many homes and can be used for network infrastructure. The type of data-transmission that can simultaneously carry multiple signals is called broadband.
Wireless installations are also a possibility when building network infrastructure. In addition, there are a variety of radio frequency technologies that can be employed. Bluetooth is another industry group developing a specification for low-cost, short-range radio links between mobile computers, cameras, and other portable in-home devices.
Service and access.
A high-speed Internet access point links a home network to the outside world. There are several different types of high-speed services.
Digital service line (DSL) takes advantage of the frequencies that go unused on the telephone wire and move significant quantities of data without affecting the voice portion of the line.
A DSL circuit consists of two modems connected by a copper, twisted-pair telephone line. To maintain backward compatibility with the standard telephone system and to avoid disruption of service due to equipment failure, the voice part of the frequency spectrum is separated from the digital modem circuitry by means of a passive filter called a plain old telephone system (POTS) splitter. Under this configuration, users can simultaneously make voice calls and transmit Internet data over the same broadband DSL pipe.
The customer must be located fairly close to the telco central office because the DSL signal can't travel as far down the lines as typical voice data.
Cable modems are another form of broadband service. A standard cable modem will have two connections; one port is connected to the TV outlet on the wall and the other to the subscriber's PC. Cable modems can approach speeds of 30 Mbps depending on traffic levels and the overall network architecture.
Integrated services digital network (ISDN) is another type of high-speed Internet access over telephone lines. It provides a faster data transfer rate for computers obtained from modems by using a bearer channel (B channel) of 64 Kbps.
Although the connection is digital, ISDN still supports analog telephones and fax machines. When a telephone call comes in while a computer connection is in progress, the computer automatically scales back to allow 64 Kbps until the phone call is terminated.
Satellites can also provide broadband access. A new suite of services called the direct broadcast satellite (DBS) system has been developed to provide residential networking consumers with a range of high-speed Internet access options.
A DBS system consists of a mini dish that connects in-home networks to satellites with the ability to deliver multimedia data to a home network at speeds in excess of 45 Mbps. However, this speed can only be achieved when downloading content. To upload or send information to the Internet, the system uses a telephone connection.
Optical fiber cabling may prove to be the most popular medium for delivering high-speed Internet access for the home of the future. Fiber optic cable can transmit enormous bandwidth over very long distances. Fiber optic cabling systems are also immune to electromagnetic interference. These systems are also highly reliable, which tends to lower long-term cost of maintenance.
Computer network equipment.
You also need to be familiar with several pieces of computer equipment for designing and building a computer network.
Network interface card.
A network interface card (NIC) is a circuit card with a built-in MAC address that plugs into one of the expansion slots in the back of a personal computer. It interprets information between the computer and the network and feeds information in and out of the computer so that both the computer and the network can accept it. A second address, known as the Internet protocol (IP) address, is assigned and binds to the NIC.
A server is set up near the distribution panel with specialized software that allows it to serve as the repository for files and programs. All computers on the network can be connected to the server with a router or a switch that provides access to run programs and retrieve saved documents. A major concern in a home network is security on the Internet. A server provides access that can be secured with hardware firewalls and specialized firewall software.
Switches and hubs.
A switch connects network devices and filters and forwards data packets between LAN devices. A hub differs from a switch in that all devices on the network can see all packets at any time.
Residential gateways and routers.
The residential gateway (RG) is a pre-assembled and pre-configured package of a modem, switch or hub, and router or bridge devices to make the home network installation easy. Gateways, routers, switches, and hubs are usually installed on a distribution panel located in the telecommunications room.
Wireless access points.
Wireless networks consist of radio-transceivers and special-purpose NICs known as wireless distributors that send signals around the home. Wireless computer subsystems within the home networking space require a wireless backbone hub to be installed on a conventional Ethernet LAN to distribute the signals to the computers equipped with wireless Ethernet cards.
Connect, configure, and test the network.
One of the most important documentation activities is establishing a wire detail chart. It shows the devices, outlets, and types of wiring used as well as their location. The computer and telephone subsystems consist of a device symbol, a device description, and outlet prefix. Several types of documents may be included as part of the connectivity documentation:
A signal flow diagram shows the path that signals follow through the system.
A schematic block diagram and equipment layout shows the theoretical connection of the gateway, hardware, and components.
A floor plan incorporates the network into the original floor plan design.
A wire detail chart specifies the media type and connections for each icon on the floor plan.
Like computer operating systems, the networks also run on software called network operating systems. The version you acquire for the network and the way it's installed and configured will determine the network functionality, responsiveness, and availability.
An IP address is the means by which a device on a home network identifies and communicates with other devices within the network and on the Internet.
One static, or fixed, IP is usually sufficient, as long as all the home network access goes through the residential gateway. However, if the customer has a home control super-system requiring remote control, multiple IPs are desirable. A home super-system that needs to be remotely hit via the Internet is assigned a separate static IP outside of the residential gateway.
Dynamic host configuration protocol (DHCP) is a software utility that runs on a computer and is designed to assign IP addresses to clients — PCs and other networked devices known as a node — that log onto a TCP/IP network. This eliminates the need for manual IP address assignments.
NAT enables all devices on a home network to share one IP address provided by an ISP. The NAT program makes all the necessary address translations. Managing the number of addresses is an important function of the network. The use of address conservation techniques in designing the IP addressing scheme for a home network is an important skill required for the home integrator. One such method is the use of network address translation by which one or two public addresses can be used with a private IP address to access the Internet via NAT translation. Private addresses are known as request for comments (RFC) 1918 addresses.
Connecting the network devices properly is crucial for performance and stability. The network termination point is the weakest point of the cable. The functionality of any wires installed as part of the home networking wiring depends on proper terminations. Several network termination points are involved in any network installation. Terminations occur at the distribution panel and the wall outlets. Distribution panels vary according to application:
110-style termination blocks for voice and data cabling applications.
66-type termination blocks for voice (telephone) wire terminations.
A BIX uses a one-piece, pass-through unit that's reversed in its mount after termination.
A Krone LSA provides silver-plated contacts at a 45° angle.
The wiring infrastructure connects the distribution panel to the outlet terminations. Outlets vary according to application:
Phone outlets connect a phone using an RJ connector.
Cable outlets use a coaxial series 6 (RG-6) style connection.
Data outlets connect Cat. 5 wiring to Cat. 5 data jacks.
Power outlets connect the power line to the power connector.
Universal outlets are customizable to the types of jacks required at the outlet.
The final phase of connectivity is equipment installation and hardware testing. Just about all the equipment that you order comes with comprehensive installation manuals. Drivers and all necessary software are also normally included in the shipment or are available at manufacturer sites.
After installing the computer network, proceed with some basic tests to ensure the system is functional. The start page should appear on each PC when you open the Internet browser. You'll need to set up each computer independently for file sharing and printing.
Test connectivity by pinging every device on the network. First, ensure that the active equipment is working properly by checking on a known good circuit and other stress points in the system. Use the appropriate test equipment for accuracy. So-called stress points you need to test may include line and patch cords.
Do a test run at the end of the installation and have your customer watch it. This can be anything from more comprehensive tests to something simple like sending a document to a newly installed printer for test printing. Once your customer is satisfied that the system works and you're satisfied that they know how to use it, you're ready to enter the next phase of the relationship: customer support. Just because you've completed the system installation, that doesn't mean your job is done — keeping the customer happy is just as important.
Dusthimer is publisher of Cisco Learning Institute Press, York, Penn.