Home Networking - Overview

Disclaimer - These notes are neither comprehensive nor authoritative; they are intended to show the big picture of home networking as viewed by the author.

AT&T is staking its future on cable, including Internet access from home via cable modems.  Home networking expands the value of AT&T service.  We must research and promote home networking, we must overcome many challenges to providing service, and we must exploit new capabilities enabled by the convergence of computer, networking, and media technologies.


Some components and exaples of this convergence include: All of these point towards smart web-enabled devices in the home.  One solution is to load a web-connected PC with TV/FM/AM/MPEG tuner/encoder/decoder cards.  This is an obviously workable example that is happening and will continue to develop.  But this solution is complex, expensive, noisy, and typically not user friendly.


More mature design recognizes that special purpose tools outperform general purpose tools - a tool that does one thing well can be made to be easier to use than a general purpose tool.  However, space, cost, marketing, and other issues complicate design decisions.  What is the proper partitioning and packaging of various functions?  While many solutions can be marketed, we do want to focus on ease of use - we want to develop "network appliances."

Network Appliance Example

An example of a network appliance is the audio endpoint.  The audio endpoint is a box with an RJ45 10BT-ethernet jack and stereo RCA audio jacks.  It streams MPEG2-AAC audio from a web (HTTP) server and decodes it to analog on the RCA jacks.  The box uses DHCP to configure its IP address.

Controller Appliance Example

The audio enpoint is controlled a wireless hand-held PC.  The convenience of wireless is essential.  The jukebox application is easier to use than Netscape.

Browser Technology

Browser and HTML technology as exemplified by Netscape have enabled the web revolution.  They provides for hyper-text and image layout, and the browser can be used as a simple universal GUI.  However, current browsers are complex, cranky, bulky, and difficult to program at the plugin level.  There must be a solution that combines the flexibility of the browser with the ease of use.

Network Layers

Some technologies are dominant and ubiquitous, they must be exploited.  Following the OSI reference model, here are some of the given protocols and standards, forced into approximate layers:
Layer # Layer Name Given Others Comment
7 Application HTML XML ?
6 Presentation HTTP, MIME   ?
5 Session     ?
4 Transport TCP, UDP    
3 Network IP DHCP ?
2 Data link Ethernet    
1 Physical 10/100BT 802.11, Bluetooth  


Here's an categorization of the components of a home network:

Physical components

  1. WAN access - cable modem
  2. LAN - Ethernet switch or hub plus 10/100BT wiring
  3. network appliances - e.g., audio & video endpoints
  4. controllers - both wired and wireless
  5. other - computers, etc.

Software components

  1. embedded operating system
  2. protocol stacks
  3. endpoint applications
  4. controller applications - browser


There are major challenges in defining and integrating the piece parts.
  1. naming - MAC and IP addresses are user-hostile
  2. high-level (control) protocols - HTML is a document markup, a protocol for control is essential.
  3. browser software - implementing GUIs for each app is prohibitive, and current browser software is bloated and un-maintainable; a browser for embedded systems is essential.


How do you want to network your home? This depends on a variety of factors, including cost, the layout of your house, and your computer networking needs. There are many connection technologies that can be explored, and there are many solutions to wiring a home. The future solution is likely to be different from the short term solution.

While analog cables are an obvious first solution, what we really want for the future is a home network that interconnects rooms containing many smart devices, especially addressable speakers. When all is said and done, the de facto network of choice is Ethernet (ATM is the next candidate because it adds QOS, but there may be solutions for QOS over ethernet). Inexpensive 100BT/10BT switches are available in the $100 range, and one or two switches should suffice for wiring nearly all homes.

Unfortunately, no one manufactures ethernet connected DACs or speakers or simple to use ethernet telephones, so at present, home-network devices must be pieced together using existing computers, sound cards, amps, and/or AES/SPDIF/USB/powered speakers. Some PC/104 products provide the necessary integration in fairly small packages, but what we are really waiting for are chips that will provide the basis for network connectivity, intelligence, protocol processing, decoding, and cost reduction.

NoBell Home - gjm - last update 8/10/2001