CertiGuide to A+ (A+ 4 Real)  9  Chapter 13: Basic Networking Terminology       9  OSI Reference Model and Networking Protocols and Technologies            9  Layer 2 - Data Link Layer

GigaWare 1 Layer 3 - Network Layer

Some years ago, leading manufacturers of telecommunication equipment began to develop technology that would allow transferring the data in an inhabited building on existing telephone lines. Quality of telephone cables is not always high, but for a normal telephony, it is quite enough. The configuration of this wire has an arbitrary character and constantly changes. The connection by the tenant of the parallel telephone adds a new "branch" in available structure and the simple removal of the telephone receiver changes the electrical parameters, etc. In 1998, the Home Phoneline Networking Alliance (HPNA) was formed. Member of this alliance are a number of conducting manufacturers of telecommunication equipment such as, 3Com, Agere Systems, AMD, AT&T Wireless Services, Broadcom, Compaq, Conexant, Hewlett-Packard Co., Intel, Motorola and Tut Systems, which provide the transfer of technology data on telephone lines. The first version of this technology became known as HPNA 1.0 and it regulated the transfer of the data with a speed of 1Mbps. By the end of 1999, the new version of this technology was announced, HPNA 2.0. As compared to the first version, it provided an opportunity to work with speeds up to 10Mbps at range of more than 350m.¹⁹⁷

The technology HPNA uses a method of medium transmission access described in the standard IEEE 802.3. The pass band of a signal is located within limits of 5,5MHz to 9.5MHz allowing the application of this technology simultaneously with the xDSL equipment and normal telephones.

In HPNA, the repeated coding of a single bit pulse is applied which raises the stability of the transmitted information to noise. Inside each network interface circuit of the receiver, there are adaptations for various layers of noise that arise in a line. In addition to this, the transmitting circuit can vary the layer of the signal by accepting and transmitting circuits through which there are constantly supervised conditions of the signal passage and arrangements of the parameters under these conditions. Just this adaptability and noise proof coding has allowed essentially lowering the requirements for the data medium. Actually, the technology HPNA is megabit Ethernet working on telephone wires.

The majority of existing user's telephone lines allows achieving a speed of transfer of data up to 100 Mbps, with use of the frequency range 2 to 30MHz. The use of spectral-effective technology modulation in HPNA 2.0 guarantees a provided speed of data transfer of 10Mbps. Thus, not only the compatibility of the equipment with HPNA 1.0 is executed, there is an opportunity of an increased transfer speed up to 100Mbps for the future too. The technology thus dynamically allows an adapted data transfer speed and provides immediate tuning of parameters of a network depending on the change of the electrical characteristics in the communication channel.

Here are the advantages of HPNA:

• Simplicity of equipment installation and network configuration.
  
  
• Low cost.
  
  
• Presence of common standard supported by many manufacturers.
  
  
• High reliability.
  
  
• Does not require additional active network equipment
  
  
• Network topology concerns are rather rare. Supports up to 25 units in a network.
  
  
• Distance between units up to 350m (at 10Mbps), ~ the area 1000 m².
  
  
• Rather high speed of transfer suitable for a simple video and voice.
  
  
• Is compatible to other network technologies.

And a couple of disadvantages:

• Necessity of the socket availability for connection of the network adapter.
  
  
• Speed of transfer (10Mbps) is not high enough for advanced demands

GigaWare 1 Layer 3 - Network Layer