by Jeff Carrell, Electronic Communications Chairman
Computers "talk" together using a set of languages called protocols. Network protocols are as different as spoken languages around the world. Unfortunately, there is not a single protocol standard that all computers use, but there are a few common ones that most computers can use.
TCP/IP
The primary protocol used on the Internet and on UNIX based networks is TCP/IP. The actual address component is IP. There has been one protocol version in use for the last 18 years, called IPv4. The maximum limit of addresses available on any one network is over 16 million, but only 127 of these network numbers exist. In 1991 the IETF formed a committee to design a new numbering system that would allow for many more numbers, while still being backward compatible to IPv4. This new IP numbering scheme is called IPv6 and is in the final stages of testing and should become a standard soon.
Any network requiring connection to the Internet needs a valid assigned IP address. The actual controlling body that assigns the addresses is called the InterNIC. Although it looks like a lot of addresses could be used, the actual limit of assigned addresses is about to be reached. Factors contributing to the shortage: many companies with assigned numbers are not directly connected to the Internet and recently, the InterNIC started assigning contiguous blocks of addresses to Internet Service Providers (ISPs), which in turn assigns addresses to its subscribers.
Class | First Octet | Max Networks | Max Hosts per network | Format | Subnet Mask (default | Address Example |
|---|---|---|---|---|---|---|
| A | 1-127 | 127 | 16777214 | net.host.host.host | 255.0.0.0 | 45.1.87.62 |
| B | 128-191 | 16384 | 65534 | net.net.host.host | 255.255.0.0 | 154.165.12.48 |
| C | 192-223 | 2097152 | 254 | net.net.net.host | 255.255.255.0 | 205.168.25.49 |
IPv4
IPv4 uses a 32 bit number, represented by four 8-bit bytes (or octets) in dotted decimal notation. The address is broken down into two parts: the first is called the "network" address and the second is called the "host" address. There are also certain "class" numbers used and denoted in the first octet. The class designation defines how many actual host addresses are available in that specific network number. Network address 127 and all Class D addresses are reserved for specific use. The chart below indicates the numbering layout.
Intranets use an additional addressing scheme, subnetting, in order to have more host addresses than might normally be available with the IP address assigned.
With subnets, the host portion of an IP address is partitioned into a subnet number and a 'real' host number. The IP address is now defined as net.subnet.host. Routers outside of the Intranet do not interpret separately the subnets and host partitions of the overall IP address. Routers inside the Intranet and connected to the subnets use a 32 bit subnet mask that identifies the extension bits. The network administrator allocates bits within a subnet address and assigns values to the subnet and host addresses. The chart below indicates some subnet mask numbering schemes.
| # Bits | Subnet Mask | # Subnets | # Hosts |
|---|---|---|---|
| Cls B | |||
| 1 | 255.255.128.0 | 2 | 32766 |
| 2 | 255.255.192.0 | 4 | 16382 |
| 3 | 255.255.224.0 | 8 | 8190 |
| 4 | 255.255.240.0 | 16 | 4094 |
| 5 | 255.255.248.0 | 32 | 2046 |
| 6 | 255.255.252.0 | 64 | 1022 |
| 7 | 255.255.254.0 | 128 | 510 |
| 8 | 255.255.255.0 | 256 | 254 |
| 9 | 255.255.255.128 | 512 | 126 |
| 10 | 255.255.255.192 | 1024 | 62 |
| 11 | 255.255.255.224 | 2048 | 30 |
| 12 | 255.255.255.240 | 4096 | 14 |
| 13 | 255.255.255.248 | 8192 | 6 |
| 14 | 255.255.255.252 | 16384 | 2 |
| Cls C | |||
| 1 | 255.255.255.128 | 2 | 126 |
| 2 | 255.255.255.192 | 4 | 62 |
| 3 | 255.255.255.224 | 8 | 30 |
| 4 | 255.255.255.240 | 16 | 14 |
| 5 | 255.255.255.248 | 32 | 6 |
| 6 | 255.255.255.252 | 64 | 2 |
IPv6
IPv6 (formerly IPng) uses a 128 bit number, represented by eight 16-bit sections. An example might be: 5F03:2500:CFB5:D700:0000: 0260:8C6C:9A9C. With leading zero's truncated, you would have: 5F03:2500:CFB5: D700::260:8C6C:9A9C.
Many new features and enhancements are designed into IPv6. Some of these are: enhanced addressing capabilities - from 32 bits (IPv4) to 128 bits; authentication and privacy capabili- ties and extensions to support these security features; and flow labeling capability - providing for special handling of data. There are many tests still in process on Ipv6 and many products will require extensive software rewrites in order to allow IPv6 to interoperate with IPv4. Router software, DNS applications, client protocol stacks, TCP/IP applications, will all be required to update to IPv6 and network administrators will need a general understanding of the IPv6 protocol addressing scheme.
There is a test network available on the Internet, called the 6bone, on which vendors and ISPs are currently conducting stress tests. It may be a year or two before most products are commercially available. Before a company tries to implement IPv6, it is highly recommended that they acquire the IPv6 products and connect to the 6bone and participate in the IPv6 tests to ensure proper operation before introducing the products in their Intranets.
Copyright © 1997 Jeffrey L. Carrell All Rights Reserved
The Section will be sponsoring two major technical events next year - Metrocon and Techcon, the technical conference and exhibit preceding the Region 5 meeting. We are looking for suggestions on topics and speakers for both events. Techcon's technical tracks:
Consult Section's Web page for
more information and a complete listing. Send suggestions to ftwsuggest@ieee.org.
See Chairman's Message.
Signals is now available via email to anyone requesting
it. Contact j.carrell@ieee.org or
j.eason@ieee.org to subscribe.
You will continue to receive the print copy (a couple of weeks
after the email) - however, in the future you can help us save
some trees (and money).
IEEE-USA SPONSORS MAJOR ENGINEERING EXHIBIT - In concert with National Engineers Week 1998, scheduled for Feb. 22-28, the National Building Museum in Washington will present a major new exhibit entitled, "Breaking Through: The Creative Engineer." IEEE-USA is sponsoring the exhibit together with more than 50 other organizations. Robert Friedel, former director of the IEEE Center for the History of Electrical Engineering and curator of the new exhibit, is inviting engineers to submit by Sept. 30 candid photographs of themselves or others in representative work environments. The submissions should include the subject's quotable thoughts on creativity in engineering. For more information, contact Chris Currie at 202-785-0017 or c.currie@ieee.org.
EMPLOYMENT ASSISTANCE SCORES BIG - IEEE-USA's Employment Assistance Committee achieved several milestones recently:
Contact Bill Anderson, 202-785-0017 or w.anderson@ieee.org for more information.
CALL FOR PAPERS - IEEE-USA is seeking success stories from engineers and their organizations for its 1998 Careers Conference, "Engineering Careers into the 21st Century: Maximizing Individual and Organizational Growth." The only national conference devoted entirely to engineering careers will be held April 30-May 1, in Phoenix. Prospective presenters with current research, experience or expert opinion on ways to promote greater capacities for engineers to manage their careers are invited to submit proposals and 500-word abstracts for consideration by Oct. 1. For further information, contact Scott Grayson at 202-785-0017 or s.grayson@ieee.org.
IEEE-USA DEBATES HIGH-TECH IMMIGRATION ON CNBC - On Monday, August 11, Career Policy Council Chair Paul Kostek discussed high-tech immigration with New York immigration lawyer Allen Kaye on the noontime edition of CNBC Business News and in an MSNBC forum. Kostek presented IEEE-USA's response to recent reports of high-tech worker shortages and calls for lifting current limits on H-1B temporary visas. He argued that the current tight labor market is caused by rapidly changing technologies, not a shortage of people. The CNBC News segment and the MSNBC forum were being run in conjunction with the August 18th special edition of Business Week magazine. Additional information available at www.businessweek.com and www.msnbc.com/news/92513.asp.
FEDERAL BUDGET DEAL LEAVES GLASS HALF-FULL - The Taxpayer Relief Act of 1997 (H.R. 2014), which President Clinton signed in August, offers a mixed bag for engineers looking for tax relief. On the plus side, tax-deductible IRA eligibility increases and new "IRA Plus Accounts" will offer tax-free distributions. Also, self-employed persons will enjoy a gradual increase to full deductibility for health-insurance expenses and a broadening of the home-office deduction. However, House provisions which would have created a safe harbor for independent contractors for Federal tax purposes were dropped from the final accord. And the tax exclusion for employer-provided educational assistance (Section 127) was extended for three years for undergraduate courses only - falling short of the IEEE-USA-supported Senate provision which would have extended it permanently and included graduate level courses.
RETIREMENT SECURITY REMAINS A PRIORITY - The
IRA provisions passed in the budget bill were only the beginning
of Congress' efforts to provide more American workers with a shot
at a secure retirement. At least five bipartisan bills have
been introduced in both House and Senate to expand IRAs to give
more workers the chance to have access to private pension plans
and to increase the portability of provisions of new and existing
pension plans. IEEE-USA has lobbied for the introduction and enactment
of portability improvement legislation in each of the last three
Congresses. Contact Vin O'neill, 202-785-0017, v.oneill@ieee.org.
IEEE OFFERS STANDARDS ASSOCIATION MEMBERSHIPS - For a $10 fee for 1998 membership, IEEE members can join the new IEEE Standards Association (IEEE-SA), a newly founded umbrella organization under which all IEEE standards programs will be carried out. IEEE members who join in 1997 receive free a CD-ROM version of the "IEEE Standards Reference Infobase: An Enhanced Version of the IEEE Standard Dictionary of Electrical and Electronics Terms." Contact ieee-sa@ieee.org.
WOMEN IN ENGINEERING COMMITTEE FORMALIZED BY BOD - In June, the IEEE Board of Directors approved changes to Bylaws and Policies & Procedures to make the ad hoc Women in Engineering Committee a standing committee of the Board. The WIE Ad Hoc Committee was established in 1994 and became active in 1995. Contact women@ieee.org.
NEW SELF-STUDY COURSES FROM EDUCATIONAL ACTIVITIES - IEEE Educational Activities group is introducing two new self-study courses: Electromagnetic Compatibility/Electromagnetic Interference (EMC/EMI) and analyzing and designing object oriented systems. The EMC/EMI course, authored by Dr. V. Prasad Kodali, teaches the approaches to model and understand the sources of EMI; techniques of measuring EMI; procedures for measuring immunity to pulsed interferences; and useful engineering practices and technology tools to minimize EMI and improve EMC. The object oriented systems course, authored by Dr. Eric J. Braude of Boston University, provides a practical roadmap for designing object-oriented applications. It will guide the users through the analysis, system design and object design phases of system building. For more information, contact Tatiana Garnys, 732-562-6526, t.garnys@ieee.org.
Y2K DATE PROBLEM: GET IN ON THE ACTION - As everyone knows, a significant percentage of the world's computer software and data is in jeopardy of failing or operating in an unpredictable manner on or around 1 January 2000. While the central element of this danger is the two-digit representation of the calendar year, there are numerous interrelated causes that contribute to the magnitude of this problem and the difficulty of solving it. A draft Technical Information Statement (TIS) on the Y2K date problem is being prepared by a joint TAB/SAB committee for review by all interested IEEE technical entities. Volunteers interested in contributing to the drafting of the TIS can contact Mark Haselkorn, m.haselkorn@ieee.org. The draft TIS, in progress, can be viewed at www.mindspring.com/ ~pci-inc/Year2000/y2ktech.htm.
The Section has two BIG events planned for the coming year: Metrocon taking place during E-Week in February, and the Region 5 Conference in April. Planning for even greater success this year, the Metrocon committee is looking for ideas. What do you, the members, want from Metrocon?
In the past we have had a diverse program covering topics from 'Building you own LAN' to to 'How to get your PE license.' There are over 1700 IEEE members in the Fort Worth Section and that means that there are 2000 opinions about what topics Metrocon should cover. Let us hear from you!
The Section has set up a special email address to make it easy for you to submit ideas: ftwsuggest@ieee.org. The Metrocon committee is eagerly waiting for your suggestions - but don't think your suggestions need only apply to Metrocon. The Executive Committee also wants and needs your input on how we can better serve the membership. Please send us any ideas, comments, complaints, or questions. I will personally read and respond to each message. We will be starting a contest for the best suggestion submitted each month, (rules and prizes will be detailed next month).
I will talk more about the Region 5 Conference in the coming months. This is a great chance to show the rest of the Region how we do things in Fort Worth.
-- Bob Geisel
Recognizing our Section members for their long-time commitment to the profession on the anniversary of their joining IEEE.
25 yrs
20 yrs
A box contains one ball. We don't know whether the ball is black or white, so the probability of either is1/2. An engineer drops in a black ball then reaches in and removes a ball, also black. "Aha," he says, "Now the probability that the other ball is black is 2/3." Is he right, or is the probability still1/2?
Answer to last month's Brainbuster:
Jean Eason, Editor