IEEE 802.3 and IEEE 802.11

To increase compatibility, international standards for Local and Metropolitan Area Networks were released by the IEEE Computer Society. These are updated on an ongoing basis.

IEEE 802.3 ~ CSMA/CD
IEEE 802.3 is the IEEE international standards for Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical layer specifications. IEEE 802.3 is the standard of the Ethernet network.

This standard is one part of a family of standards governing local and metropolitan area networks. IEEE 802.3 is part 3 and provides conformance test information to meet requirements for implementations of 10BASE-T. It was originally based on the Ethernet standard version 1.0 specification. The first draft of this standard was released in 1983, with the first official release following in 1985. Since 1985 numerous supplements have been released that have either added to, redefined or retired sections within the standard as technology has moved forward.

Under IEEE 802.3 there are currently 4 data rates defined governing operation of twisted-pair and optical fibre cables.

• 10 Mbps - 10Base-T Ethernet (IEEE 802.3)
• 100 Mbps - Fast Ethernet (IEEE 802.3u)
• 1000 Mbps - Gigabit Ethernet (IEEE 802.3z)
• 10-Gigabit - 10 Gbps Ethernet (IEEE 802.3ae)

The IEEE 802.3 standard defines requirements of layer 1, the Physical layer, and layer 2, the Data Link layer of the OSI.

IEEE 802.11 ~ Wireless LANs
IEEE 802.11 is the IEEE international standards for Wireless LANs, Medium Access Control (MAC) and Physical Layer specifications. IEEE 802.11 is the standard of Wi-Fi.

It denotes a set of standards that incorporate all Wireless LAN/WLANs and was first implemented in 1997. Similar to IEEE 802.3, it specifies the requirements of CSMA/CD though for data communications via the “air”, radio or infrared. Medium Access Control supports access point control and connection between independent stations. Included in the protocol is authentication, association and re-association services. There is also optional procedures for encryption and decryption as well as power management reducing power consumption in mobile devices.

IEEE 802.11 defines requirements of layer 1, the Physical layer, and layer 2, the Data Link layer of the OSI.

The Client Network

A Client-Server network connects a group of devices to a DHCP server, forming a LAN. The DHCP server controls the network and resolves all addressing requirements. It allocates a range of IP Addresses, so that each device connected to the network has a unique IP Address for that network.


Alongside a DHCP server, there may be another server providing internet connection sharing (ICS) functionality allowing each of the LAN devices to connect to the wide area network (WAN). Depending on requirements of the network, these two different servers may co-exist on the same hardware server.

A big advantage of the client-server network is the fact that the configuration of the network is centralised.

A limitation of the client-server network is the availability of servers that control the network. If for some reason a DHCP server is taken off-line, then the network it controls is effectively also out of action.

Why were networking standards needed?

Early development of LANs, MANs, and WANs was chaotic in many ways. The early 1980s saw tremendous expansion in networking. As companies realized how much money could be saved and how much they could gain in productivity by using network technology, they began adding networks and expanding existing networks almost as rapidly as new network technologies and products were introduced. By the mid-1980s, growing pains from this expansion were being felt.

Because many of the emerging network technologies were built using different hardware and software implementations, one problem that soon surfaced was that many of the new network technologies were incompatible. Increasingly, it became difficult for networks using different specifications to communicate with each other.

Why and how did networking start?

Applications written for business helped create the PC industry. Early computers were standalone devices. In other words, each computer operated on its own, independently from other computers. It soon became apparent that this was not an efficient or cost effective way for businesses to operate. A solution was needed that would successfully address three problems: duplication of equipment and resources, inability to communicate efficiently, and the lack of network management.

One early solution to these problems was the creation of local area networks, or LANs.

Because they connected workstations, peripherals, terminals, and other devices in a single building, LANs made it possible for businesses using computer technology to efficiently share such things as files and printers.

As the use of computers by businesses grew, however, it soon became apparent that even LANs were not sufficient. In a LAN system, each department or business was an electronic island.

What was needed was a way to move information efficiently and quickly from one business to another. The solution was the creation of metropolitan area networks, or MANs, and wide area networks, or WANs. Because WANs connected networks that served users across a large geographic area, they made it possible for businesses to communicate with each other even though they were geographically distant from each other.

Local-area network (LAN) - High-speed, low-error data network covering a relatively small geographic area. LANs connect workstations, peripherals, terminals, and other devices in a single building or other geographically limited area. LAN standards specify cabling and signaling at the physical and data link layers of the OSI model. Ethernet, FDDI, and Token Ring are widely used LAN technologies. Compare with MAN and WAN.

Metropolitan-area network (MAN) - Network that spans a metropolitan area. Generally, a MAN spans a larger geographic area than a LAN, but a smaller geographic area than a WAN. Compare with LAN and WAN.

Wide-area network (WAN) - Data communications network that serves users across a broad geographic area and often uses transmission devices provided by common carriers. Frame Relay, SMDS, and X.25 are examples of WANs. Compare with LAN and MAN.

A Brief History of the Internet

The Internet can be traced back to the ARPANET (Advanced Research Projects Agency Network) formed in 1969 by the networking of computers at University College Los Angeles (UCLA), University College Santa Barbara, Stanford Research Institute and Utah University.

By 1972 23 nodes(computers) were connected and it had become international with University College, London and the Royal Radar Establishment Norway.

With many of the computers on the network using different protocols (sets of rules) to transfer information it became more and more difficult to manage the ARPANET. In January 1983 the TCP/IP protocol became the only official protocol on the ARPANET.

In 1985 a network of 5 supercomputers were formed by the National Science Foundation, USA called the NSFNET.

It had grown as shown by 1988.

In 1988 the NSFNET and the ARPANET were joined and the growth of the network became exponential.
Regional networks were linked to the network in Canada, Europe and the Pacific.

It was in the mid 1980's that the collection of networks that had been formed became viewed as an internet and eventually the Internet.

In 1992 the millionth host was attached and by 1995 hundreds of regional networks (MAN's, Metropolitan Area Networks) were linked, thousands of LANs (Local Area Networks) and millions of computers.

Much of the growth was due to existing networks being joined to the Internet.

In 1998 there were 16 million hosts attached.

The 'glue' that holds all of this vast network together is the TCP/IP protocol stack.

Most of this course will involve a detailed study of TCP/IP and how it works.

For a computer to be 'on the Internet' then the machine must:

1. be running the TCP/IP protocol stack
2. have an IP address
3. have the ability to send IP packets to other machines on the Internet.

The ability to just receive e-mails is not enough.

PCs using the internet are allocated temporary IP addresses by their Internet Service Provider (ISP) and so they have a temporary Internet presence as long as they are connected via the ISPs router.

The Internet traditionally provides four main applications:

1. e-mail
2. News: Newsgroups are subject groups that can hare information and ideas among like minded people.
3. Remote Login: Telnet, Rlogin allow remote access to a computer
4. File Transfer: FTP copies files from one machine to another.

In 1991 Gopher was released which was a program that allowed the fetching and searching of files on the Internet.

In 1991 Tim Berners Lee working at CERN in Switzerland proposed a method of sharing information on an internet by using documents that contained Hypertext links (Hypertext Markup Language (HTML)). This application became known as the World Wide Web or WWW for short.

Until the advent of the WWW, the Internet was mainly used by academics and researchers but when public access became available in 1992 then use of the Internet rocketed.

In 1993 the Mosaic Web Browser was launched which allowed searches over the WWW.

1994 saw the launch of Netscape Navigator its designers Marc Andreesen and Jim Clark immediately became multi-millionaires. This year also saw the release of the search engine Yahoo.

HTML documents are essentially static documents but the advent of JAVA in 1995 (Sun) saw the inclusion of video, animation and sound into WWW documents.

In 1995 Microsoft 'discovered' the Internet and launched Internet Explorer.