This section of the Guide describes the basics of home networks primarily for computer equipment and its connection to the internet. The term "Home Network", coined by the computer industry in the late 1990's, has come to mean Ethernet based high-speed data networks in the home to support the interconnection of personal computers and peripheral equipment for data sharing and Internet access sharing. However, the popularity of these networks, and the very low cost of the technology (due to the wide commercial use) has expanded their use to audio/video applications and home automation. Ethernet based networks that tie the home directly to the Internet are commonly referred to as the next "utility" for the home.


Since Ethernet based networks primarily use the protocol of the Internet (TCP/IP), they allow an easy and seamless connection from in-home applications and subsystems to the Internet. More and more home automation systems, A/V equipment, and even appliances rely on a broadband, always-on connection to the Internet for everything from remote monitoring to content download.

Home networks have traditionally been driven by homeowners who have high-speed Internet connections, such as cable modems or DSL modems. Typically, these connections cost at least $30 a month or more. Rather than having to pay a separate connection fee for each computer, a properly installed home network will allow two or more computers to share the same high-speed connection.

Having a good working knowledge of home network technology, components, and installation techniques will continue to be a necessity for automating and interconnecting subsystems in the home.

This section will overview the basics of Ethernet based high-speed data networks, the components, and the basics of how to configure the networks for the most common applications. You can read through this section in the order it is presented (recommended for those new to this subsystem), or jump directly to the section that interests you.

Typical Home Networks
The network–referred to as the home LAN–connects several computers and peripheral devices (printers, storage devices) together through a hub device and through a router and gateway to the Internet. The network allows any networked device to communicate with any other device on the network, sending text, pictures, music, control information, and data files as well as providing any device access to the Internet.

The hub connects all the networked devices together at a central location, thus forming the "hub" of the network. The hub receives network packets transmitted from any attached device and relays them to all other attached devices including the router.

The router does the work of interfacing the network to the Internet. It examines the destination address of each packet on the network. If the address is on the home LAN, it ignores the packet. If the destination address is not on the LAN, it assumes the packet destination lies outside the LAN and sends the packet to the Internet via the gateway. Likewise, if the router receives a packet from the internet via the gateway, it examines the destination address. If the address is one assigned to a device on the home LAN, it forwards the packet to the hub. If it is not a home LAN address, the packet is discarded.

The gateway is an interface between two dissimilar networks. It performs protocol translation as well as the physical interface between the service providers network and the home network (typically a TP based Ethernet network). Typical gateways include cable and DSL modems that convert the WAN analog signals to a local network protocol. Figure 4.9.2 shows a representation of the network in a more schematic form.

Schematic representation of a typical Ethernet home network. This shows five networked deviced connected to a hub or switch via CAT5 TP cable. The hub connects to a router to provice shared internet access for all devices. The router is in turn connected to some type of Internet gateway such as a cable or DSL modem. The router and hub/switch are typically enclosed in the same box

LAN Network Types

There are basically three types of physical networks that can be installed in the home: wired networks, no-new-wires networks, and wireless networks. These network types can be combined in a typical home network installation

Wired networks rely on unshielded twisted pair cable, either installed in new construction or retrofit as part of a structured cabling system. Wired networks use either 10 Mbps or 100 Mbps (10Base-T or 100Base-T) Ethernet technology over CAT5 TP cable with 8-pin modular connectors as described in Section 2. Structured cabling systems, wired per the TIA-570A specification, using CAT5 TP cable or better will support data rates of 100 Mbps (100Base-T Ethernet). Wired networks are the most reliable since they are dedicated to carrying the network data and use digital baseband signaling.

No-new-wires technology is intended to be used in homes with little or no high quality TP cable by utilizing the existing older phone wiring or the power line wiring to carry the data. These networks use a modified Ethernet physical layer technology to "piggy-back" analog signals on the existing phone wiring or power line wiring in the home. The most popular technologies are currently HomePNA and HomePlug.

HomePNA is a technology that uses the existing phone wiring to send analog signals modulated by digital data up to about 10 Mbps. It places a high-frequency, broadband signal on the same wires used for phone service in the home. This lets the phone lines be used for regular voice service and data transmission service at the same time. HomePNA devices simply plug into existing phone jacks using regular phone cords. HomePNA is limited by the fact that typical older homes were only wired with a few telephone outlets.

HomePlug is a technology that uses the existing electrical power line wiring in the home for data transmission up to 10 Mbps. The technology is similar to DSL in that it uses many different analog channels in the 2 - 30 MHz spectrum to send the data over the power line wiring. Actual data rates will depend on the noise and attenuation on a individual home's power line but data rates of 5 Mbps are typical.

Both HomePNA and HomePlug send normal Ethernet data using an analog broadband technology. While some computers and network components have HomePNA and HomePlug interfaces built-in, most devices will need to use attached bridge products that convert 10Base-T Ethernet into phone line or power line signals.

Ethernet to HomePlug adapter on left and USB to HomePNA adapter on right.


Wireless networks for the home almost exclusively use the IEEE 802.11b wireless Ethernet standard. IEEE802.11b devices transmits digital data in the 2.4 GHz (2.4 - 2.483 MHz) unlicensed radio band at up to 11 Mbps at ranges up to 150 feet.

802.11b devices can typically expect a range of 100 feet from an access point (a bridge or router) to the portable device but the range varies greatly depending on the construction and layout of the home.

While some home computer and networking devices such as web tablets and routers have 802.11b interfaces built-in, most devices such as laptops can be made wireless by the installation of an 802.11b interface card such as a PCMCIA card.

Connecting wireless to wired networks is done with a wireless to wire bridge or connection point. An 802.11b bridge will typically have a 10Base-T jack on one side and a wireless antenna on the other side (see section 4.9.3). Wireless bridges can be plugged in anywhere there is a 10Base-T jack and more than one can be used to achieve complete coverage of a home.

All of the network types can and typically are combined in a home. HomePNA or HomePlug can be used to reach areas of a home where new network wiring is not installed and wireless technology can be used with either wired or no-new-wires networks for remote and portable devices such as laptop computers and web tablets

Integrating a wireless network with a wired network. The figure shows four wireless devices "connected"
to the network by a wireless bridge or by a wireless access point built into the router (a popular combination).

Networking Subsystems
Ethernet networks are quickly becoming a central data "backbone" in the home not only for sending files, music, and surfing the internet, but for home automation and control applications by interfacing to other subsystem. Several companies such as Lantronix produce Ethernet "bridges" that provide an IP addressable interface to a control network of some type such as RS232, RS485, IR, or even X-10 (in development?).

Ethernet bridges to other control networks and technologies are available to allow control
information to be sent to and from subsystems in the home such as HVAC, A/V, and security systems.

Home Network Components
Implementing home networks requires the use of several types of network devices. These devices form the "glue" that connects the network together, allows different types of networks to operate together, and make non-networked device networkable.

Network Interface Cards (NIC)
NIC's are used to allow a PC to connect directly to a network. The most popular NIC's are the 10Base-T and 100Base-T Ethernet cards with the 8-pin modular jack. These cards are typically used to upgrade older computers since almost all new computers come equipped with built-in Ethernet ports. Cards are also available for HomePNA and wireless 802.11b.

PC NIC card for 10/100Base-T (left) and 802.11 (right)

PCMCIA NIC plug-in "cards" are typically used on laptop computers and serve the same function as regular NIC's. However, many non-computer devices are being equipped to accept PCMCIA cards (especially 802.11b cards) such as cameras, appliances, even speakers!

Typical NIC PCMCIA card (this one wireless)


A "hub" is a device that connects physical wired branch cable runs of a network together. A hub gets its name from the analogy to the hub of a spoked wheel that connects the spokes together. Hubs typically have from 4 to 8 "ports" (RJ-45 jacks to allow connection of network cable runs) and are intended for relatively small networks such as a home LAN. A packet that arrives on any port is retransmitted on all other ports. Most hubs also have one port assigned as a "link" or "uplink" port to allow connection of additional hubs when more ports are needed.

Typical 6-port hub. One of the ports (on right) can be set to link to another hub to increase the number of ports.


A switch is similar to a hub but is selective in which port an arriving packet is retransmitted to. A switch looks at the destination local Ethernet address of an arriving packet and only retransmits the packet to the port that has the device with the destination address. This greatly reduces the packet traffic on the network and isolates the packet traffic between two devices at a time.

Switches are typically used in larger commercial networks and have from 8 to 24 ports. However, since the cost of switches has fallen to only slightly more than the cost of a hub (with the same number of ports), switches are becoming more popular in home networks.

Typical 24-port switch
Typical 24-port switch. Status lights show port activity, collission status, speed of attached device.

A router connects two networks together. The name router comes from the fact that the routers job is to "route" data between the two networks in an intelligent way. In the case of home networks, It joins the home network and the Internet, passing information from one to the other. It also protects the networks from one another, preventing the traffic on one from unnecessarily spilling over to the other. Regardless of how many networks are attached, the basic operation and function of the router remains the same. Since the Internet is one huge network made up of tens of thousands of smaller networks, routers are an absolute necessity.

Routers have two or more physical ports. One port is typically assigned to the home LAN and the other port to the WAN (Internet). When the LAN port receives a packet, a software routine called a routing process looks inside the TCP/IP address fields for the destination address. It then compares this address against an internal database called a routing table to determine if the address is in the home (the LAN), or outside the home (the Internet). The routing table has detailed information about the ports to which packets with various IP addresses should be sent. Based on what if finds in the routing table, the router either forwards the packet to the WAN or discards it. It does the inverse when it receives a packet from the Internet WAN side.

Typical router with built-in wireless access point and built-in 5-port hub. Most consumer routers have a
built-in hub or switch. Routers will always have a WAN port connection to attach to the Internet.


Every device on a TCP/IP network need to have an IP address (it's source address). IP addresses are dynamic and are assigned to a product when it is attached to the network (unlike Ethernet physical addresses which are hard-wired into a product when it is manufactured).

When a PC is turned on and connected to the network, it needs to have an IP address to connect to the Internet. Normally, when a PC is connected directly to a cable modem or DSL modem (i.e. no network), the IP address is given to the computer by the ISP that operates the cable modem or DSL service.

In a home network, each device needs an IP address. The addresses are assigned by the router. The router uses the single IP address assigned by the ISP (it takes the place of the attached PC in the above example).

The router and each attached device uses an address assignment protocol called DHCP (Dynamic Host Control Protocol). The router assigns addresses–such as —from its internal IP address table that is used only inside the home network. When a second networked device in the home is turned on, it does the same thing the first PC does: It contacts the router using DHCP and gets an internal IP address. This internal IP address will be different from the first — for example, it might be Other devices on the home network can get internal IP addresses and access to the Internet in the same way using the home router.

One of the most valuable feature that the router implements is Internet access sharing. The router uses a procedure known as Network Address Translation (NAT) to translate all in-home IP address to the common IP address assigned to the home account by the ISP. To the outside world every device in the home appears to use the same IP address or the same ISP account.

Configuration Tasks
The following steps assume a typical home network consisting of several PC's, a shared printer, a few networked client devices (cameras, internet radios, etc.), connected to a router, and a gateway modem.

1. Configure each PC

2. Configure the router

3. Use a configured PC web browser to configure any non-computer networked device

It will be helpful to have a known working laptop PC available that you can take to the customer site to help configure the network and test whether the customers PC's are working properly.

Computer Configuration
In general, each computer attached to the network will need to be configured for connection to the network. Two categories of software will need to be configured: the OS components that deal with network protocol, and client software such as email programs that connect to the Internet via the network.

There are too many versions of operating systems for PC's and Macintosh computers to cover in this Guide. The particular OS documentation must be consulted. In general, the OS must be configured for:

> The network protocol being used
> The port used for network attachment
> Various security and naming parameters
> Various IP addresses used by the ISP
> Use of networked peripherals such as printers

Router Configuration
The WAN side and LAN "side" of the router will need to be configured. Most routers are configured by the use of a web server in the router accessible by any configured PC web browser attached to the network. Routers typically use a default IP address of This address is typed directly into the web browser. The WAN side will need you to configure the IP address assigned to the customer account and any other addresses assigned by the ISP.

On the LAN side you will need to configure various firewall settings, address types to assign, and a host of optional parameters such as whether any of the attached devices should be "visible" from the Internet (no filtering or firewall protection from the router). This is useful when the customer would like to access an in-home security camera from work.

Network Client Device Configuration
Once the PC's and the router are configured, the remaining devices on the network can be configured by attaching them to the network (the router will provide them with an IP address), and using a web browser. The web server in most networked devices is fairly self-explanatory and many have help pages (even the manual) built-in.

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