For the Home Technology Enthusiast

Home Networking Basics



Home Networking

Not long ago, having one computer at home was in itself a proposition that only a select few could afford. And not that long ago even, having a connection to the World Wide Web (Internet) was a proposition that a select fewer could afford.  Thanks to continuously advancing technology and downward movement of cost of computers and Internet connections, this scenario is changing rapidly. Now, it is fairly common place for a home to have several computers for simultaneous use by family members, with a high-speed connection to the Internet such as DSL and Cablemodem.


Home Networking is a reference to the collection of hardware devices and software applications by which all computers and peripherals within a home are given the abiity to communicate with each other. Networking computers within a home offers several advantages, the prime ones being:

  • sharing of resources that otherwise need to be replicated - printers, scanners, etc.

  • sharing of a single Internet connection

  • protecting against data loss in one computer by backing it up on the other

  • availability of a computer at convenient locations as opposed to having a 'computer room'

What's the difference between Home Networking and say 'Enterprise' or 'Business' networking?

It's all in the scale and cost! Fundamentally, they achieve the same objective of interconnecting computers and peripherals for shared use and communication. And they are largely based on the same underlying hardware and software technologies. Home Networking may involve half a dozen computers and peripherals. Networking across an enterprise may involve thousands of computers and peripherals and also involve geographic spread. Another key difference is in the level of security that is implemented. Home networks have basic security mechanisms (e.g., firewalls, anti-virus software, etc.), while an enterprise will likely have multi-level security with intrusion detection  and prevention capabilities.


Establishing a home computer network can be a daunting proposition for the non-technical members of our society, given the myriad of technological solutions available and the constantly evolving nature of the beast that is technology. We attempt here to explain the key concepts and tips relating to the implementation of home networks. We do not attempt to explain in detail the theoretical concepts. Such details are available in books, in tech journals and on various websites.


The Interconnection

Two aspects need to be considered in the interconnection of computers within a home. The first aspect is the interconnection of computers themselves. And the second aspect is the interconnection of peripheral devices (printers, scanners, etc.).


The predominant technology for interconnecting computers is 'Ethernet'. Ethernet is a tried, tested and standardized technology that has its origins in the professional computing world. 'Standardized' means that its specifications are not proprietary to any one vendor and that it is supported by a great variety of manufacturers. A Ethernet network interface adapter card (NIC) can be picked up for under $20.00. Most new computers have this interface built-in. Ethernet is not a single or simple specification. The one that is commonly used in home networks is called 10BaseT or 10/100BaseT (shortened as 10BT or 10/100BT). 


Ethernet in its very simple form requires the use of data-grade cable (as opposed to telephone grade or power-grade cable) connecting the computers to be networked. Such a data-grade cable is called Category-5 cable or Cat-5 cable for short. Plugging a cross-over cat-5 cable to the connectors on NICs is all it takes to network two computers. While this simple form is still in use, a plethora of new technologies are available in the market that offer alternative interconnection methods other than a cat-5 cable. The more promising of these new technologies are:

  • Wireless (radio frequency)

  • Powerline Carrier (using the existing power cables within a home)

  • Phoneline Ethernet (using existing telephony wires within a home)

Important to note that these alternative technologies still are fundamentally Ethernet. Meaning, they are all in the business of emulating a cat-5 wired Ethernet connection.


Two terms are generally used when describing the entity that connects a computer to a network - modem and adapter. Modem is a term generally used for a device that supports a data connection on one end (e.g., 10BT), and an appropriate connection to the transmission medium on the other (e.g., power plug in the case of a Powerline modem). Adapter is a term that is generally used for a device that adapts a type of data interface (e.g., PCI) to a type of interconnection (e.g., wireless). For example, a PC Card wireless adapter is usually a device that has has a PCMCIA interface on one end and a wireless Ethernet interconnection interface on the other.


Of the new technologies, wireless is seen to be the most versatile one and is expected to be the most widely used in the future. Commonly called 'Wi-Fi', wireless Ethernet connection does eliminate the need to worry about running a physical cable between the entities to be connected. This by far is its greatest advantage over the other technologies, all of which require a physical interconnection cable. It also means that devices connected using Wi-Fi can be portable and even better, completely mobile. Conceivably therefore, a PDA or a cell phone can now become part of your home network. Tech-speak for Wi-Fi is 802.11 (pronounced eight-o-two-dot-eleven). 802.11 comes in three flavors (as of the date of this document) - 802.11b, 802.11a, 802.11g, and 802.11n - in the order of their market entry, last one being the latest.


But...wireless does come with some baggage such as the susceptibility to tapping - which is the unauthorized eavesdropping of your signal. And then there is the issue of bandwidth. As a general rule, a wired cat-5 ethernet connection offers more throughput (data carrying capacity) than a wireless connection. So, before going nuts over wireless Ethernet connection it is important to analyze one's needs and make a wise choice which in the end may be a mix of wireless and wired technologies.


Powerline and Phoneline Ethernet connection technologies spawned from the same desire that wireless did - and that is the avoidance of having to install new cat-5 cables around the home. Like wireless, they do come with baggage. Powerline technology is also susceptible to tapping since the signals that travel down the power cables within your home also travel down the power feeder cable to your neighbors' homes connected to the same feeder transformer. Further, the technology doesn't often work across different phases of power within your home. Meaning, if one Powerline modem is connected to one phase of your home and another to a different phase, then the two modems will not communicate with each other and therefore will not be able to provide a Ethernet connection between the devices connected to the modems.


Like Poweline technology, Phoneline Ethernet technology was designed to use the existing telephony wires in a home. The constraint this technology places is that no other devices (e.g., telephones) can be connected to the same pair of wires that connect the Phoneline modems. The technology is also impaired by the physical condition of the telephony wires and the way they snake and mesh around the home.


Bottom line: Powerline and Phoneline Ethernet technologies by themselves do not offer complete solutions for a home network. But they do offer an alternative to installing new cat-5 cables and therefore may be a part of the overall home network.


It is important not to confuse the Phoneline modem mentioned above with the familiar analog modem that connects users to the Internet over a phone line. Phoneline modem in the context of home network is a device that emulates a cat-5 Ethernet connection using existing telephone wires within a home. The analog modem's job is to transfer data between your computer and the outside world over the same telephone cable that carries your regular telephone signals.


Peripherals Interconnection

In the early days, each peripheral connected to the computer in its own way. Printers used a parallel or centronics port, modems used a serial or RS-232 port, keyboards used a AT port, scanners used a SCSI port and so on. The result was a rats' nest of cables of varying dimensions and colors. Adding insult to injury was the need to load up different software drivers for each of the peripherals again each in a unique way. With a view to simplifying the interconnection of peripherals, the computer industry moved to standardize peripheral interconnection. Result - come the USB (for Universal Serial Bus) and Firewire standards. Tech-speak for Firewire is IEEE 1394.


Once the teething problems were ironed out, USB has come to be a very popular way to connect various peripherals to a computer. To the extent that it is hard to find new peripherals with any other type of interface. 

Firewire was initially designed as a higher-speed connection technology when compared to USB. Special peripherals (such as the ones with video processing capabilities, high-capacity storage devices, etc.) supported Firewire interface. 


With the introduction of a higher-speed USB specification (USB2.0), the difference in performance between USB and Firewire as far as an average home user is concerned has diminished greatly. Therefore, the choice is to be made based on the set of peripherals one desires. USB is closer to the ideal 'Plug and Play' interface than any other, and continues to be supported by a greater variety of peripherals as of the date of this document. 

Despite the wide adoption of USB2.0, Firewire continues to prosper. Most computers support both types of interfaces.


Hubs, Routers and Wireless Access Points

These three elements are increasingly becoming essential to a home network solution. As mentioned earlier, at least for the near term, a home network is likely to use both wired and wireless technology devices. Hubs, routers and wireless access points (WAPs for short) offer a very flexible, expandable and maintainable way of putting together such home networks.


A hub is a 'dumb' device in the sense that it does not add any functionality to the Ethernet network. It merely enables the physical interconnection of more than two computers in a network (recall that a simple cross-over cat-5 cable is all it takes to interconnect two computers).


A router is an intelligent device and adds functionality to your network.  Often a router has a hub built-in thus making it a very versatile home network device. By functionality we mean things such as:

  • enabling the sharing of a single high-speed Internet connection by all the computers in a home

  • preventing malicious attempts from the Internet side to access data on your computer or to download virus and other destructive programs into your computer

  • blocking access to the Internet from any of your home computers (e.g., young children's computer)

  • preventing un-intended transmittal of sensitive information from your computer to the Internet side

  • selective access to one or more of the home computers from the Internet side (e.g., access to a web server running on one of the computers)

  • ...and more

Routers were until recently fairly sophisticated devices requiring technical expertise to setup, operate and maintain. With increasing adoption of routers at home, manufacturers have simplified the setup and operational procedures.

Wireless Access Points (WAPs) need special mention because of their pivotal role in the wireless part of a home network. Their role is effectively that of a traffic cop for all the data that flows between the various wireless devices and the wired part of the network. An important feature to look for in a WAP is its support of encryption. Recall that wireless technology is inherently more susceptible to tapping. Encryption is a mechanism employed in wireless technology that at worst makes tapping difficult and at best defeats tapping all together.


Figure 1 below shows a sample home network using a mix of wired and wireless technologies interconnecting two computers, a router and a DSL modem.


Figure 1. Sample Home Network


A word on Protocols

We have discussed a bit on the interconnection aspects of a home network. Unfortunately, that's only part of the story. For computers and devices to communicate with each other and do something, we need software. And software is not a single entity but a set of inter-dependent entities that together perform the function we need from them. It is convenient and common in the industry to view software as a layered set of individual modules.


Application software is the highest layer of software that interacts with the user. Below that are a set of software modules that enable the communication between computers, between computers and peripherals, etc. The communication layer is an important element of any network and consists of instructions and data that allow computers and other entities to talk to each other - much like we humans use language to communicate with each other. And just as we have some rules or protocols to communicate with each other, computers also need protocols to communicate in an orderly and effective manner.


TCP/IP and UDP/IP are two such protocols in the computer network and Internet world. While there are other protocols that are also used in the industry, TCP/IP and UDP/IP have come to dominate because of their historical link to the Internet and the world-wide proliferation of Internet. TCP/IP and UDP/IP along with Ethernet has thus become the mainstay of home networks.


In implementing a home network, once the physical interconnection is completed it is important to ensure that all software modules relating to the communication layer are installed correctly. Fortunately for the average home user, this issue is becoming less and less of one to contend with since computers have built-in smarts to install and activate the necessary modules when they detect presence of a network.