Local Aea Networking (LANs)

I have been involved in consultancy activities related to LAN technologies since 1984, when I started attending meetings of IEEE Project 802, the US-based standards body that develops the majority of the International standards for Local Area Networks. My involvement in IEEE 802 covers the following primary areas of LAN standardisation:

In March 2000, I was appointed as Chair of the IEEE 802.1 Working Group.

The IEEE 802.1 Working Group's website can be found at:


The IEEE 802 LAN/MAN Standards Committee website, with details of upcoming meetings and other working group activities, can be found at:


Recently, the IEEE has decided to make IEEE 802 LAN standards freely available in PDF format, 6 months after the date of publication. These standards can be accessed via the following web page:


LAN Management

During 1984, I started what has proved to be a lengthy and active involvement in Network Management standardisation. Initially, I attended meetings of IEEE Network Management Task Group in IEEE 802.1, which is responsible for the development of standards for Network Management in the context of Local Area Networks. In November 1985 I was appointed Chairman of the Network Management Task Group, chairing the group until its work was completed in 1993. The work of the task group resulted in the publication of IEEE/ANSI standard 802.1E (System Load Protocol) in March 1991, and IEEE/ANSI standard 802.1B (LAN/MAN Management) in August 1992. Two further LAN management standards, 802.1F and 802.1k, were published in 1993. I was also active in taking these IEEE standards through the ISO standardisation process, resulting in publication as ISO/IEC 15802-2 in 1995.

MAC Bridging and Virtual LAN (VLAN) technologies

In 1995, I was contracted to work on the development of further standards in IEEE 802.1, aimed at providing support for the needs of Multimedia traffic in LANs. I am currently the Editor for this work in the 802.1 Interworking Task Group; this development, under project P802.1p, completed during 1998. As part of this activity, a maintenance revision of the IEE MAC Bridge standard, 802.1D was undertaken, and the revised standard was published at the end of 1998 with the 802.1p extensions incorporated in the text. To confuse matters more, this standard was published in its ISO form, as ISO/IEC 15802-3 : 1998 (AKA IEEE Std 802.1D, 1998 edition).

Towards the end of 1995, the work in IEEE 802.1 was further extended to cover the development of a standard for Virtual LANs (VLANs). I was the coordinating Editor responsible for this activity. This work completed during 1998, under project P802.1Q. It has now been published as IEEE Std 802.1Q, 1998 Edition.

During 1999, a number of projects related to Bridging and VLANs were initiated, for which I was, or still am, the Editor. The most significant of these is P802.1w, Rapid reconfiguration.

Other Bridging-related projects currently under development in 802.1:

Link Aggregation

In early 1998, a development activity started in IEEE 802.3 to develop a standard for Link Aggregation (sometimes known as Trunking) - this is about bundling together LAN links of a given data rate to produce a single logical link with N times the data rate. I was involved in this activity since its inception, particularly in the development of the Link Aggregation Control Protocol (LACP) that underpins the mechanism. I was one of the two editors responsible for developing the standard. This project has now successfully completed its technical development and was published as an IEEE standard in July 2000.

The IEEE 802.3 website can be found at:


Port-based Network Access Control

LANs are increasingly being deployed in "public" areas of buildings, where it may be possible for unauthorized people to gain physical access to a LAN connection. For example, conference room facilities often provide LAN connections for use in presentations; it would be a simple matter for a visitor to the building to plug a laptop into the LAN socket and thereby gain access to corporate information. A second, and increasingly important, example is that wireless LAN technologies are being deployed in public areas, such as airport lounges, as a public service. In both cases, it is important to be able to restrict access to the LAN's services only to those systems (and users) that are authorized to connect. The IEEE 802.1X project has developed a means of providing access control in these kinds of situations. The project is in its final stages, and it is expected that the 802.1X work will gain IEEE Standard status in June 2001. Already, the existence of the 802.1X mechanisms is creating considerable interest in the LAN marketplace - particularly with wireless LAN technology, where the absence of comprehensive security provision has been a hinderance to its widespread adoption.

Rapid Spanning Tree Reconfiguration

MAC Bridges (often known as LAN Switches) rely on the Spanning Tree algorithm and protocol in order to detect, and prevent, loops in the physical topology of a LAN. In modern switched LANs, where extensive use is made of redundant paths in order to provide resilience in the face of component failure, Spanning Tree plays an important role in automatically reconfiguring the LAN connectivity as devices are added, links moved, and so on.

The Spanning Tree algorithm, originally developed in the early '80s, has remained unchanged until very recently, despite major advances in the LAN technologies that it is used with. One of the problems with the Spanning Tree algorithm is that, in a large LAN, it can take a considerable time for the lan topology to stabilize following a reconfiguration event - times of the order of 30 seconds being typical of the original form of the algorithm. Some of the applications of today's LANs are particularly sensitive to that kind of delay; an extreme example would be voice over IP (the "Internet Phone"), where a 30-second break in connectivity would simply blow away any calls in progress.

The 802.1w project has developed a new version of Spanning Tree, known as the Rapid Spanning Tree Algorithm and Protocol or RSTP, which addresses the issue of reconfiguration time in a dramatic fashion. Using RSTP, it is possible to reconfigure a LAN very rapidly indeed - in tens of milliseconds - meaning that instead of losing the connection, the users of an internet phone might simply hear a click on the line. This technology, coupled with the gigabit- and ten gigabit-Ethernet technologies now available, mean that it is realistic to use switched Ethernet technology as the basis for metropolitan area interconnection. So, nearly a decade after the world was told that ATM would provide a solution to both wide area and local area interconnection, it looks like switched Ethernet will actually deliver what ATM has failed to do.

It is expected that 802.1w will gain IEEE Standard status in June 2001.

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