Madge Perspective

Madge
Perspective
Blueprint for Token Ring in the 21st
Century
Madge Networks

Madge Perspective
4 Copyright © 1998 Madge Networks
Executive Summary
From its inception in the mid-1980s, Token Ring has consistently proved to be a superior and robust
technology for corporate networks. Although there have been significant changes in networked
applications over the last fifteen years, Token Ring has kept pace with user needs and has gone through
only two changes since its creation.
The position for Ethernet is very different. Because of inherent weaknesses in the underlying technology,
Ethernet has undergone many changes in its history with each change forcing users to upgrade their
networks and install new equipment. Even now, Ethernet still lacks many important capabilities which
have been present on Token Ring since day one. For example, some Ethernet vendors are suggesting
changes to the Ethernet standard to support larger frames because of the serious problems found in running
Ethernet at gigabit speeds. Similarly, emerging standards, such as 802.1p/q, which are necessary to
support new multimedia applications across Ethernet, involve significant, non-backwards compatible
changes to the Ethernet standard which will result in yet more major upheavals to existing Ethernet
networks.
Token Ring is in a much stronger position for the future. The Token Ring standard is quality of service
(QoS) ready, meaning that a standard Token Ring network will easily support multimedia applications
such as video and voice. And with initiatives, such as High Speed Token Ring, users can rest assured that
their Token Ring networks will support their business application needs well into the future.
Madge Perspective provides a clear strategy for enhancing existing Token Ring networks and taking them
forward into the next millennium. Madge Perspective addresses four key areas of concern for Token Ring
users:
N Scalability: How to scale network performance in all areas of the network, including backbone, server
access and workgroup, through technologies such as High Speed Token Ring, ATM, and workgroup
switching.
N Affordability: How to reduce the cost of Token Ring network by delivering highly integrated, cost
effective solutions both at the desktop and also in the wiring closet.
N Applications: How to unlock the inherent capabilities of Token Ring to support new multimedia
applications such as video, voice and real-time data.
N Integration: How to integrate Token Ring and Ethernet networks together using a common backbone
infrastructure so that information can be freely exchanged.
This paper presents the details of Madge Perspective and discusses how the underlying products from
Madge will make Token Ring networking in the 21st
century a reality.

Madge Perspective
Copyright © 1998 Madge Networks 5
Contents
Executive Summary ........................................................................................................................ 4
Contents.......................................................................................................................................... 5
1. The Historical Choice for Token Ring .................................................................................... 7
1.1 Addressing the Five Key Issues ................................................................................................ 7
(1) Performance and Scalability................................................................................................ 7
(2) Reliability & Robustness .................................................................................................... 7
(3) Network Management ........................................................................................................ 8
(4) Compatibility ..................................................................................................................... 8
(5) Investment Protection......................................................................................................... 9
1.2 Network Evolution................................................................................................................... 9
1.3 Challenges of the New Millennium........................................................................................... 12
Scalability................................................................................................................................ 12
Affordability............................................................................................................................ 12
Application.............................................................................................................................. 12
Integration............................................................................................................................... 12
2. Scalability ................................................................................................................................ 13
2.1 High Speed Token Ring ........................................................................................................... 13
Background ............................................................................................................................. 13
Details of HSTR ...................................................................................................................... 14
HSTR in the Backbone............................................................................................................. 15
2.2 ATM and Token Ring .............................................................................................................. 15
2.3 Madge in the Backbone ............................................................................................................ 16
ATM Strategy.......................................................................................................................... 16
HSTR Strategy......................................................................................................................... 16
2.4 The Token Ring Workgroup..................................................................................................... 16
Stage 1: Micro-segmentation.................................................................................................... 17
Stage 2: Per port switching....................................................................................................... 17
Stage 3: Upgrading to HSTR in the workgroup......................................................................... 17
2.5 Section Summary..................................................................................................................... 18
3 Affordability............................................................................................................................ 19
3.1 Cost of Token Ring Equipment................................................................................................. 20
3.2 Installation and Configuration................................................................................................... 21
3.3 On-going Maintenance and Support.......................................................................................... 21
Management of the desktop...................................................................................................... 23
Management of the network infrastructure................................................................................ 23
Next generation network management...................................................................................... 23
3.4 Section Summary..................................................................................................................... 24
4 Applications............................................................................................................................. 25
4.1 IP on Token Ring ..................................................................................................................... 26
Layer 3 Broadcast Control ....................................................................................................... 26
Layer 3 Switching.................................................................................................................... 26
Madge’s Strategy..................................................................................................................... 27
4.2 Quality of Service on Token Ring............................................................................................. 28
QoS on Token Ring using Token Priority................................................................................. 28
QoS on Ethernet ...................................................................................................................... 29
4.3 Section Summary..................................................................................................................... 30
5 Integration............................................................................................................................... 31
5.1 Token Ring-Ethernet Integration using ATM............................................................................ 32
5.2 Token Ring-Ethernet Integration using HSTR........................................................................... 32
5.3 Section Summary..................................................................................................................... 33
Conclusion...................................................................................................................................... 34

Madge Perspective

Madge Perspective
1. The Historical Choice for Token Ring
Token Ring, as a technology, dates back to the early 1980s. At the time, most corporate information
systems were based around large, expensive, centralized mainframe systems which predominantly were
used to process business transactions. By the time local area networks started appearing, the vast majority
of large corporations were using these types of mainframe-based information systems in the core of their
businesses, making them a critical element in the overall operation of the business.
IBM’s System Network Architecture (SNA) dominated large enterprise networking at the time. Its ability
to offer consistent, predictable and assured network response times had placed it well ahead of alternative
technologies. In fact, even today SNA is still the most widely used protocol for mainframe-based
networking. So, when IBM started examining the technology options for enterprise Local Area Networks
(LANs), the main contender at the time, Ethernet, was quickly rejected. Its variable responsiveness under
load and its inability to provide consistent, assured network response times meant is was a poor choice for
those organizations which had been used to the superior capabilities of SNA.
To meet the needs of organizations which wanted to start deploying LANs, IBM started developing a new
technology which embodied the functionality of SNA but provided the performance and simplicity
expected of PC-based local area networks. This new technology was called Token Ring.
1.1 Addressing the Five Key Issues
Those organizations which were the first to deploy Token Ring in their networks quickly realized that it
provided a powerful solution to the five key issues faced by corporations in their information systems:
(1) Performance and Scalability
Token Ring, from its very outset, was designed to operate in a wide variety of network environments, and
still provide excellent performance even under very heavy load conditions. To be able to do this, the
engineers who designed Token Ring rejected the CSMA/CD access mechanism at the heart of Ethernet
and used a token passing scheme instead. In this superior scheme, access to the shared network is
controlled by a token which is passed from station to station; only the station which has the token at any
given moment is allowed to transmit onto the network. As a result, not only can a Token Ring segment
operate at close to its theoretical capacity, but it can still maintain predictable access times for all stations
on the ring.
In contrast, the random nature of the CSMA/CD scheme in Ethernet means that the network suffers
increasing delays as the demand builds up; if the demand reaches 40-50% of network capacity, almost all
of the 10Mbps bandwidth is consumed by collisions, throughput falls to virtually zero, and access time
effectively extends to infinity.
Token Ring was also designed to operate with large packet sizes. Experience had taught the architects of
Token Ring that processing of network protocols in the end-stations can consume significant amounts of
processor cycles and impact the performance of the applications running. To reduce the impact of the
network, 16Mbps Token Ring can carry up to 18200 byte frames (although most real Token Ring networks
actually operate with 4550 byte frames). In contrast, Ethernet is limited to 1518 byte frames.
Consequently, Token Ring can deliver much greater throughput with less usage of end-station system
resources than equivalent Ethernet networks.
(2) Reliability & Robustness
Most corporate networks carry information which is critical to the overall operation of the business. If,
say, a bank’s network fails, the bank cannot process financial transactions and the effect on the business
can be disastrous. To address this issue, Token Ring was originally designed with maximum reliability
and robustness in mind, and it has served the needs of users well over the last fifteen years.
Each Token Ring end-station has in-bedded intelligence to monitor, detect and attempt recovery of
common network fault conditions. For instance, before a station joins the ring it will perform a lobe test to

Madge Perspective
check the quality of the connection between the adapter and the nearest hub or switch. If there are any
problems with this connection the station will not join the ring, preventing any disruption to the network or
any other attached users.
The predominant architecture used for building a mission critical Token Ring network involves a dual
redundant backbone configuration in which each workgroup ring is bridged or switched to both backbones.
Token Ring’s source routing technology allows the load to be shared between the two backbones to
provide additional network capacity. In the event of a backbone, bridge or switch failure, the end-stations
automatically find a new path across the network to the resources they need through the second backbone.
Network users can continue to operate and do their job oblivious to problems on the network.
Dual redundant backbone offering load sharing capabilities
Although Ethernet does allow similar redundant paths to be built with transparent bridging and the
Spanning Tree Algorithm (STA), the slowness of STA reconfiguration means that users may see several
minutes of downtime and lose connections to network resources before the network reconfigures. In
addition, transparent bridging does not allow load-sharing between multiple paths through the network,
meaning that certain parts of the network can be overloaded while others are idle – only to be brought into
operation when there is a fault. In contrast, Token Ring provides full loading sharing across multiple
parallel paths in the network.
(3) Network Management
Network management is critical in any large mission critical network. Within the design of Token Ring,
several management protocols and mechanisms have been included to improve fault tolerance and make it
easy to identify, locate and resolve network problems.
For instance, every Token Ring station has intelligence which allows it to detect error conditions and
report them to a management station. These MAC-level protocols also allow stations to communicate
with one another to build a picture of the network showing the order of the stations on the ring. Intelligent
hubs can use this information to control access to network resources – for example, preventing
unauthorized stations from physically joining the network – and automatically resolve fault conditions by
removing faulty stations from the network.
(4) Compatibility
The first organizations to choose Token Ring also demanded complete compatibility with their existing
mainframe-based applications. Since Token Ring is based on the same principles as SNA, it delivers
complete compatibility with the installed IBM systems while allowing new applications to be deployed.
For example, many mission critical environments use dual-attach Front End Processors (FEPs) to attach
the mainframe to the network. Since the node address of the mainframe is often hardwired into the
application, these dual attach FEPs are often given the same node addresses (but located on different ring
segments) so that if one FEP fails end-stations can still connect to the mainframe without having to change
the end-station configuration information. In an Ethernet environment, which uses transparent bridging or
switching techniques, it is not possible to deploy multiple FEPs with the same node addresses since, for a
transparent network, a unique node address is required for every station on the network. In contrast,
Load sharing backbone
using Token Ring’s
source-routing technology

Madge Perspective
Token Ring’s source routing technology allows multiple FEPs to co-exist on the network with the same
address, and will automatically re-route traffic if one FEP fails.
(5) Investment Protection
The original architects of Token Ring were concerned that the technology should be future proof, since
typical corporate installations would comprise many thousands of nodes and upgrading the network to
support any new applications would present significant problems. To achieve this, the architects
considered the many types of applications Token Ring may need to support in the future, including real-
time data, voice and video. To accommodate these new classes of network application they devised a
priority scheme that enabled stations transmitting time-sensitive traffic to pre-empt other stations waiting
to send non-time sensitive data traffic. This token priority scheme, which involves eight different priority
levels, was engineered into the original Token Ring specification and all equipment that conform to the
IEEE 802.5 Token Ring standard support it.
Only now, 15 years after the first Token Ring products started shipping, have the applications started to
appear that can take advantage of this capability. Video conferencing, LAN-based telephony and
multimedia data applications will soon be making effective use of the priority scheme on Token Ring in a
manner which is compatible with the entire installed base of Token Ring equipment.
The problem of how to deliver quality of service across LANs is only now starting to be addressed on
Ethernet. New standards, such as IEEE 802.1p and 802.1q, are being defined which adds information
about priority to the Ethernet packet format. The priority tagging scheme is strikingly similar to Token
Ring. However, whereas all standard Token Ring equipment support priority, the Ethernet priority tag can
only be recognized by new generations of Ethernet equipment, requiring forklift upgrades to existing
Ethernet installations.
1.2 Network Evolution
Since the first Ethernet and Token Ring products appeared on the market, the nature of communications
has changed beyond recognition. Who could have envisaged 15 years ago that PCs would dominate the
office and home environments, that PC-based communications such as email would become so ubiquitous,
and that the Internet would be so pervasive? The demands placed on corporate networks have changed
significantly over this time, and it is worthwhile considering how the different LAN technologies have
responded to these changes.
Changes in applications and the growing impact on the network
Here is a brief overview of the changes which have occurred in networked applications:
Transaction
Processing
Client-Server Applications
Intranets & Web-based
Communications
Multimedia
Communications
1970 1980 1990 2000
Ubiquitous Email
Office Automation
NetworkDemands

Madge Perspective
N 15 years ago, the dominant application running on corporate networks was transaction processing e.g.
cheque processing in banks and insurance claim processing in insurance companies.
N Towards the end of the 1980s saw the emergence of a new breed of client-server applications.
N In the early 1990s email became widely used as a way of sharing and exchanging information.
N Next, office automation emerged as a business tool, coinciding with the wide-scale deployment of PCs
in corporations.
N The last two years have seen the emergence of corporate Intranets, with web-browsers becoming the
universal user interface for these applications.
N And today, a new breed of multimedia communication applications is starting to emerge. Driven by
the penetration of multimedia PCs in the home, corporate PCs now incorporate many of the same
multimedia features allowing video and voice to be deployed to the desktop along with a whole raft of
new interactive multimedia data applications.
These major changes have significantly impacted the LAN by increasing traffic levels and making the
whole environment extremely complex. How LAN technologies, such as Token Ring and Ethernet, have
responded to these changes is now discussed.
Evolution of Ethernet in response to the changing application environment
Ethernet has been through a number of major evolutionary steps over the last fifteen years or so, with the
technology almost re-inventing itself every 2-3 years:
N The first Ethernet LANs comprised multiple shared 10Mbps segments.
N As network traffic levels increased and the limitations of shared 10Mbps became more apparent,
network managers started to segment their shared Ethernet segments into smaller groups of users.
N Next, Ethernet switches started to appear on the market. Initially, these were deployed in the
backbone where network congestion had reached critical levels.
N Over time, switched 10Mbps was pushed out to the workgroup giving each users a dedicated 10Mbps
connection to the switch.
N At the same time, the first 100Mbps products started to appear. Initially, these were used to connect
congested servers into the backbone or to connect switches together.
Smaller shared
segments
Shared
10Mbps
Switched 10Mbps
in backbone
100Mbps in backbone
Switched 10Mbps
to desktop
1Gbps in
backbone
Switched
100Mbps
Impact of application changes on Ethernet
Big
frames
802.1p/q

Madge Perspective
N Recently, 100Mbps has started being run to desktops where 10Mbps is no longer sufficient.
N The first 1Gbps Ethernet products have appeared on the market, principally for connecting switches
together and linking very high performance servers into the network backbone.
N Several vendors have proposed changes to the Ethernet standard to support large frames. This has
been driven by the performance limitations found in Gigabit Ethernet backbones because of the small
packet sizes supported on Ethernet. Obviously, any changes to the Ethernet maximum frame size will
involve considerable hardware changes to any existing Ethernet network.
N Finally, major enhancements to the Ethernet standard have been proposed – for example IEEE 802.1p
and 802.1q – to allow it to carry new types of multimedia network traffic e.g. time sensitive voice and
video traffic. These new standards are not compatible with installed Ethernet equipment and to
deploy them requires a major upgrade to the network.
So, over time, Ethernet has been through several major evolutionary changes – shared to switched,
10Mbps to 100Mbps, 100Mbps to 1Gbps, and now basic changes to the Ethernet frame format – all to
keep pace with the changes in applications running across the network.
Token Ring has more than kept pace with the changing application environment
The story on Token Ring is very different. Because of the foresight of the original architects of Token
Ring, Token Ring has been through substantially fewer changes than Ethernet over the last 15 years – even
though the applications to emerge on Token Ring have been the same as Ethernet. Here are the major
changes which have occurred in Token Ring:
N The change from shared 4Mbps Token Ring to shared 16Mbps Token Ring at the end of the 1980s.
N The arrival of the first backbone Token Ring switches in 1995.
Since its inception, Token Ring has proved to be a substantially more robust technology, being able to
meet changing application and user needs without having to significantly change the underlying
technology. Token Ring has proved to be an excellent investment for those organizations which chose
wisely back in the 1980s.
Smaller shared
segments
Shared
10Mbps
Switched 10Mbps
in backbone
100Mbps in backbone
Switched 10Mbps
to desktop
1Gbps in
backbone
Switched
100Mbps
Big
frames
802.1p/q
Shared
4Mbps
Shared
16Mbps
Switched 16Mbps
in backbone
Incremental
next step...The stable Token Ring
environment

Madge Perspective
1.3 Challenges of the New Millennium
As the new millennium approaches, network managers are faced with new challenges of how to maintain
and develop the network infrastructure and prepare it for the 21st
century. These challenges can be
summarized as follows:
Scalability
Despite Token Ring’s unsurpassed record of keeping pace with network application changes, the next few
years will be critical as increasing traffic loads will stretch the capabilities of 16Mbps Token Ring. A
smooth migration path is required which scales Token Ring bandwidth in all areas of the network,
including the backbone and the workgroup.
Affordability
Although Token Ring has consistently demonstrated that it can evolve to meet changing business
requirements and protect user’s investment, users of Token Ring are constantly looking for more cost-
effective solutions to meet their networking needs.
Application
With the emergence of new business applications which utilize voice, video and real-time data, Token
Ring users are starting to unleash the inherent power of Token Ring to support these new applications.
Integration
The trend over the last few years of mergers and acquisitions has meant that many networks have a
mixture of Token Ring and Ethernet in them. Unfortunately, connecting these disparate networks together
is technically difficult and has performance and cost implications. As this trend continues, an increasing
number of users will be looking for ways to seamlessly integrate Token Ring and Ethernet networks so
that information can be freely shared among users, regardless of their location on the network.
Madge Networks has been developing innovative and technically advanced solutions for Token Ring users
for almost 15 years, and its pedigree in Token Ring networking is second to none. To address the key
challenges of the next millennium, Madge has developed a strategy which will help Token Ring users to
evolve their networks into the future and provide a blueprint for future Token Ring networks. This
strategy is called Madge Perspective¥¥.
The next four sections examine each of the issues above and discuss how Madge Perspective provides the
solution.

Madge Perspective
2. Scalability
Token Ring has served the needs of its users well over the last fifteen years. Despite the incessant rise in
network traffic and the revolution in networked applications, Token Ring has consistently provided
corporations with a stable network infrastructure to support their business operations. Only now, as we
move towards the 21st
century, have users started to ask what comes next after 16Mbps Token Ring.
This question has been prompted by slowly emerging problems in three key areas of the Token Ring
network:
N The link between switches in the backbone.
N The connection between servers and the network.
N The Token Ring workgroup.
The traditional solution to the first two problems is to deploy ATM in the backbone. With technologies,
such as LAN Emulation, Token Ring traffic can be seamlessly carried by an ATM backbone, and with
ATM uplinks in Token Ring switches and ATM adapters in the network servers users have a simple
method of building a high performance, scalable backbone. Many Token Ring users world-wide have
built networks on such a design and are benefiting from the improved bandwidth in the backbone.
However, a significant proportion of Token Ring users have shied away from introducing a new
technology into the LAN backbone and prefer a frame-based, rather than a cell-based, solution to their
bandwidth needs. To meet the needs of these users a new technology, called High Speed Token Ring
(HSTR), has emerged that allows native Token Ring to be scaled to 100Mbps, 1Gbps and beyond. HSTR
is changing the landscape of Token Ring and will enable users to stay with their preferred networking
technology well into the next century.
2.1 High Speed Token Ring
Background
High Speed Token Ring (HSTR) is a good example of customer pressure influencing and changing the
plans of vendors. Until the summer of 1997, most vendors’ solutions for scaling bandwidth in the Token
Ring backbone either comprised ATM or some proprietary frame-based system. Although the ATM route
has and will continue to be the preferred solution for many Token Ring users, there is a significant
proportion of Token Ring users who require a standard, frame-based method of scaling performance in the
backbone. Neither ATM nor the single-vendor proprietary solutions meet this need. This groundswell of
customer opinion started appearing in the industry press and by the summer of 1997 it had reach such a
peak that Kevin Tolly, industry analyst and CEO of the Tolly Group, along with Network World magazine
called a meeting of the leading Token Ring vendors. Faced with this huge customer demand for a higher
speed, native Token Ring standard the vendors agreed to start work immediately on High Speed Token
Ring.
To accelerate the process, an industry alliance, called the High Speed Token Ring Alliance, was formed
out of the leading Token Ring vendors. Madge accepted the position of Vice Chair of the alliance with
IBM as the Chair. The objective of the alliance was to quickly develop a technical specification for
HSTR, which the vendors could agree on outside of the normal, usually slow standards making processes.
This has two major benefits: it ensures that vendors products should be interoperable from day one, and it
means that time to market for the first HSTR products is greatly accelerated. From the first meeting in the
summer of 1997 to the first products appearing in the market will be around one year. No other standard –
not even one of the multitude of Ethernet standards – has managed to be defined, agreed by all vendors,
and products developed and manufactured in such a short time period. This clearly shows what is possible
when there is strong customer demand and vendors are willing to collaborate to make something happen.

Madge Perspective
The standards making body for Token Ring is called IEEE 802.5. HSTR is being incorporated into the
802.5 standard to ensure maximum interoperability between HSTR products and avoid proprietary, single
vendor solutions.
The first specification of HSTR is for 100Mbps running over copper cables. Recognizing the amount of
Shielded Twisted Pair (STP) or IBM Type 1 cabling in the Token Ring installed base, the 802.5 committee
is setting out to create a standard that is compatible with both STP and Category 5 UTP cable. Following
closely behind the 100Mbps HSTR over copper standard will be a similar specification for 100Mbps
HSTR over fiber cables. The target for both of these specifications is July 1998.
Meanwhile, work is proceeding in parallel on a specification for 1Gbps HSTR over fiber optic cabling.
This standard is likely to be complete by late 1998 or early 1999.
Details of HSTR
The HSTR standard is based around a number of key Token Ring requirements:
N Native Token Ring frame formats should be preserved throughout. This allows for the simplest and
most cost-effective switched connections between 4 and 16Mbps Token Ring and HSTR, by
eliminating any frame format translations.
N All Token Ring’s native bridging and switching modes should be handled. Support for source
routing, transparent and SRT bridging and switching modes allows for a seamless extension of the
Token Ring environment to higher speeds.
N The HSTR specifications should be based, as far as possible, on existing standards in order to
minimize time to market. At the Physical layer, the 100Mbps and 1Gbps transmission schemes
developed for Fast Ethernet (originally used for FDDI) and Gigabit Ethernet (originally used for Fiber
Channel) are being adapted to support HSTR, while at the Data Link and Media Access Control
layers, the existing 802.5r standard for Dedicated Token Ring with Full Duplex Operation provides
the basis for HSTR.
N HSTR should support all the widely used cable types that are capable of handling 100Mbps and
1Gbps transmission. At 100Mbps, both STP Type 1 and UTP Cat 5 will be supported with lobe
lengths up to 100 meters. Multimode fiber will also be supported. At 1Gbps, HSTR will provide the
same cable compatibility as Gigabit Ethernet over multimode and single mode fiber cables. The
subject of Gigabit transmission over copper cables is still being studied.
N The special features of Token Ring that provide additional robustness and fault tolerance will be
supported in HSTR. For example, the lobe test that Token Ring nodes perform to prove cable integrity
before they insert is preserved in HSTR.
N HSTR should provide a solution for dedicated point-to-point links in a switched Token Ring
environment, and should not set out to address shared media implementations. Creating a shared
media solution for HSTR would delay the standard by many months or even years, and the cost of
switching has fallen to the point where there is no economic justification for a shared media
implementation.
N HSTR will be compatible with the emerging IEEE 802.1q standard for Virtual LAN tagging. Where
Virtual LANs are being used, this standard defines the tags that need to be inserted in each packet on
inter-switch links to identify which VLAN they belong to. The 802.1q specification also defines a
standard way to carry Ethernet packets over HSTR links, and this is expected to assist in situations
where Ethernet workgroups need to be integrated in a predominantly Token Ring environment. More
on this later.

Madge Perspective
HSTR in the Backbone
The first applications for HSTR will be in the backbone for connecting Token Ring switches together, and
linking high performance servers and power-users into the backbone. The jump in performance from
16Mbps to full duplex 100Mbps will provide a significant boost to these areas of the network and alleviate
network congestion problems.
High Speed Token Ring in the LAN backbone
Even those users who have deployed ATM in the backbone for connecting switches together and linking
servers into the network can enhance their networks through HSTR. For example, new file servers being
added to the network can now be located either on the ATM backbone or connected into the Token Ring
network directly with HSTR. Because HSTR is a native Token Ring standard, Token Ring LAN
Emulation fully supports HSTR traffic.
2.2 ATM and Token Ring
So, with all this excitement and momentum behind HSTR, does this mark the death-knell for ATM in
Token Ring networks? Absolutely not! Just like Ethernet, ATM can and does play a critical and strategic
role in many Token Ring networks. ATM is particularly well suited to networks which:
N Consolidate LAN data traffic and synchronous voice traffic from PBXs on the same physical
connection.
N Bring ATM-based Wide Area Network (WAN) connections into the LAN, and where seamless
connectivity is required.
N Provide interconnectivity between Token Ring and Ethernet end-stations, and ATM-based centralized
network services such as file, print, and database services.
N Require uncompromising levels of reliability across the whole network infrastructure.
N Demand the sophisticated levels of quality of service (QoS) only found in ATM.
Many Token Ring networks today do use ATM in the core of the network. These ATM backbones carry
trillions of bytes of data a day to support mission critical applications which are at the heart of many real
businesses around the world.
High Speed
LAN Backbone
High speed
server
connections
High speed
inter-switch
connections
Power User
desktop
connections

Madge Perspective
Looking into the future, these ATM backbones will need to provide two essential ingredients:
N Continued support for Token Ring applications and services: This is particularly important since many
pure Ethernet vendors have turned their back on Token Ring and have ignored the needs of Token
Ring users. As the vendor which lead the Token Ring LAN Emulation initiative at the ATM Forum,
Madge remains at the forefront of Token Ring and ATM initiatives, including resilient LANE services
and LANE 2.0 functionality for mission critical Token Ring backbones. Madge continues to lead the
market into the future.
N Integrated support for both classical Token Ring and High Speed Token Ring services: This addresses
the needs of users which have ATM in the core of their networks today, but are deploying HSTR for
servers or future desktop connections. Here the IEEE 802.5 HSTR standard becomes key – because
HSTR is standard 802.5 Token Ring running at higher speeds, ATM Token Ring LAN Emulation is
fully compatible with HSTR, such that HSTR and ATM can be mixed in the same network. Thus,
network designs in which HSTR-attached servers and power-users co-exist in the same network as
ATM services in the backbone are likely to emerge over the next few years.
ATM and HSTR are not technologies at war: they are complementary technologies which not only co-exist
next to each other, but will form the basis of many Token Ring networks into the 21st
century.
2.3 Madge in the Backbone
ATM Strategy
Madge is fully committed to supporting the backbone needs of Token Ring users. Its range of ATM
backbone solutions – including the Collage 700 series of ATM switches, the Collage 155 ATM adapters,
and the ATM uplinks for its Token Ring switches – have been deployed in many networks around the
world. Madge’s pioneering work on Token Ring LAN Emulation at the ATM Forum ensures that Token
Ring users gain the benefits of ATM in their networks today. Madge’s ATM solutions are particularly
optimized for use in mission critical Token Ring networks, where reliability and stability are paramount.
For example, Madge’s powerful redundant LANE Services ensure the network is not disrupted and users
can continue to work even if critical sections of the network fail. Madge continues to innovate in its ATM
solutions through advanced functionality such as LANE 2.0 and PNNI support.
HSTR Strategy
Through 1998 Madge will be enhancing its backbone solutions with a range of HSTR products for those
Token Ring users who require a frame-based backbone. All Madge Token Ring switches are capable of
supporting HSTR, even the first ones shipped in the middle of 1995. Madge will be offering a range of
HSTR modules for the Ringswitch family of Token Ring switches allowing switches to be meshed into
large, redundant backbone configuration. In addition, Madge will be supplying a 100/16/4 HSTR PCI
adapter for use in servers and power-user applications.
Into 1999 and beyond, Madge plans to enhance its HSTR product portfolio to meet users’ growing
bandwidth needs. During 1999, Madge plans to bring to market a new multi-gigabit member in the
Ringswitch family which will provide a significantly higher density of classical 16/4 and 100Mbps HSTR
ports, as well as offering 1Gbps ports for linking switches together in very high performance Token Ring
backbones. This “Super Ringswitch” will provide the perfect platform for the core of Token Ring
networks in the 21st
century.
2.4 The Token Ring Workgroup
The strategy for the Token Ring workgroup is a little different to that for the backbone because the issues
and problems are different. Most Token Ring workgroups are still based on shared rings, with typically 40
to 60 users on each ring segment. Madge Perspective provides an incremental migration path to more
bandwidth in the workgroup through an easy three-stage process. The rate at which each step is taken will
vary from network to network depending on the needs of the application, and some steps may be missed

Madge Perspective
out altogether. The benefit of this strategy, however, is a smooth, risk free path to greater bandwidth in the
workgroup with minimal disruption to the network users.
Stage 1: Micro-segmentation
The first step to greater bandwidth in the workgroup is to segment the workgroup ring into smaller rings,
therefore increasing the average available bandwidth per user. For example, on a 60 user ring the average
available bandwidth per user is 16MbpsO60 or 0.267Mbps. By splitting the ring into six rings of 10 users,
bandwidth is increased by a factor of six to 1.6Mbps.
Interconnection between the new, multi-ring segments is provided by a micro-segmentation switch, such
as Madge’s Smart Ringswitch Express. A high speed uplink from the multi-segmented workgroup to the
backbone is provided using 100Mbps High Speed Token Ring or 155Mbps ATM.
For even smaller ring segments, the GroupSwitch module for the Ringswitch family provides an even
better solution. The 20-port GroupSwitch module combines the functionality of a hub with a switch on a
single Ringswitch module, with each group of 5 hub ports sharing the same switch port. This integrated
solution is ideal for new segmented workgroups since an additional hub is no longer required. Used in the
Ringswitch Plus, a high density of workgroup connections can be achieved in a single chassis.
Stage 2: Per port switching
The process of splitting the workgroup rings into smaller and smaller rings can continue until there is just
one user on each port of the switch. In this case, there is a dedicated link between the adapter and the
switch, which means it can be operated as a dedicated, full duplex connection with bi-directional 16Mbps
traffic flows between the adapter and switch. The maximum aggregate bandwidth per user rises to
32Mbps – a 120 times increases from the original 60 user workgroup ring. This staggering increase in
workgroup performance is simply achieved by upgrading the wiring closet to a per-port workgroup switch
– the installed network adapters in the PCs remain untouched.
Micro-segmentation and per-port switching in the Token Ring workgroup
Madge continues to innovate and pioneer in desktop connectivity. Madge was the first vendor to ship full
duplex drivers for its adapters, offering them for free to existing Madge customers – any customer with a
Smart Ringnode adapter can load the driver onto an existing adapter and achieved 32Mbps full duplex
operation without any additional cost.
Similarly, Madge is pioneering in workgroup switching technology and plans to delivering to market later
in 1998 the world’s most advanced stackable workgroup switch designed specifically for cost sensitive
workgroup applications.
Stage 3: Upgrading to HSTR in the workgroup
With the huge bandwidth jump in stage 2, it will be sometime before Token Ring users will want even
greater bandwidth in the workgroup. But this time will come and again HSTR provides the ideal solution.
Micro-segmentation
to split workgroup rings
into smaller rings
Per-port switching
with one user on
each port of the switch

Madge Perspective
The specification of HSTR being worked on by the HSTR Alliance and the IEEE 802.5 Token Ring
standards making body is for dedicated links only. There are good reasons for this. The first applications
for HSTR will be in the backbone where switching has become the dominant technology. Also, by
avoiding the complexities of shared Token Ring, HSTR can be delivered to market quickly and at an
attractive price point. Currently, there are no plans to develop a shared HSTR standard; the hope – which
is based on historical data and a good understanding of how Token Ring technology is evolving – is that
the cost of switched 100Mbps connections will decline so rapidly that the differential between shared
100Mbps and switched 100Mbps in the workgroup will become negligible. When faced with the choice of
shared vs. switched at similar price points, the user is always likely to choose switched, since it offers
substantially better performance with many other important advantages.
So, the long-term future of Token Ring in the workgroup is switched 100Mbps HSTR to the desktop with
a very high speed uplink, such as 1Gbps HSTR, into the backbone. To facilitate this, a low cost 100Mbps
HSTR workgroup switch is required along with very low cost 100Mbps HSTR adapters. The first HSTR
products to appear in the market during 1998 are unlikely serve this purpose, because they are targeted at
the backbone. However, during 1999 and into 2000, the first true desktop HSTR products are likely to
start appearing.
Even though many Token Ring users are unlikely to deploy switched 100Mbps to their desktops for a
number of years, they can start planning for eventual HSTR deployment by carefully designing their
backbone and selecting the right adapters for their PCs. For example, when the first low cost, 100/16/4
client adapters start appearing in 1999 – which can be connected to a classical 16/4 Token Ring or a
100Mbps HSTR network – users can start deploying them in their networks at 16Mbps; when they are
ready to deploy 100Mbps HSTR to the desktop they only have to change the switch in the wiring closet
and not touch the adapters installed in their PCs. This is an extremely simple way of upgrading the
network to very high speeds with no disruption to individual network users.
Madge is committed to HSTR in the workgroup as a long-term strategy for Token Ring users. As part of
the Madge Perspective strategy, Madge plans to bring to market 100/16/4 HSTR adapters which can be
used both in servers and client environments, at an affordable price point. Similarly, Madge is driving
forward the capabilities of workgroup switching to allow 100Mbps switched HSTR to be a realistic
workgroup technology in the future.
2.5 Section Summary
The previous sections discussed, in detail, the immediate and long-term problems faced by network
managers in trying to driver greater bandwidth across their Token Ring networks. For the backbone, two
solutions are now available to Token Ring users: ATM and High Speed Token Ring. Both technologies
have their own unique capabilities and benefits, and both provide real solutions to actual network
problems. Madge is at the forefront of these two technologies with its Collage series of ATM switches and
its Ringswitch range of Token Ring backbone switches. Madge has a clear roadmap for both High Speed
Token Ring and ATM to address Token Ring user needs well into the next century.
The story for the workgroup is a little different. Token Ring switching is only now starting to emerge as a
workgroup technology. Madge is pioneering workgroup switching through a range of workgroup
switching solutions, including the Ringswitch Express, designed for micro-segmentation applications, and
a new, very low cost per-port workgroup switch, for wide-scale deployment of switched Token Ring to
every desktop. In the next century, 100Mbps HSTR will emerge as the long-term desktop technology for
Token Ring users and Madge, with is powerful switching technology and unbeatable track record in
innovation, intends to lead this market forward as well.

Madge Perspective
3 Affordability
Token Ring has historically been viewed as an expensive technology, with equipment costs “perceived” to
be many times higher than Ethernet. The reality of this is very different. This section discusses why.
Firstly, Token Ring equipment costs have been falling rapidly over the last few years and the difference
between Token Ring and Ethernet costs is significantly less than it was. Unfortunately, people’s
perceptions take much longer to change and, as a result, Token Ring is still viewed as being significantly
more expensive than Ethernet. For example, in the March 30 1998 edition of Network World Magazine,
Scott Bradner wrote an article about Token Ring vs. Ethernet with one of his arguments being:
“The disparity in cost between Ethernet and token ring is just too great. For example, 4M/16M
bit/sec token-ring PC interfaces cost more than six times as much as 100M bit/sec full-duplex
Ethernet interfaces.”
In fact, reality is much different. At the time of going to press, the suggested retail price for a 3Com
10/100 Ethernet PCI adapter is $116, whereas Madge’s own Presto PCI Token Ring adapter retails for
$169 – a difference significantly less than 6 times! (Suggested retail prices are used here to give a fair
comparison between vendors.) Over the last two years prices have fallen significantly, as shown in the
figure below.
Token Ring adapters have become significantly more affordable
Another argument used is that: “Ethernet comes for free on the PC motherboard, whereas Token Ring is a
cost option”. In fact, many Ethernet users have evaluated using the built-in Ethernet chipset but have
consistently decided a separate Ethernet NIC card is the much better approach. The reasons for this
include the cost of maintaining multiple drivers across the corporate network, since each chipset requires
its own specific driver; if the PC standard is changed a new chipset will be introduced into the network
increasing maintenance and support costs for the network and attached peripherals; and the management
overhead associated with managing multiple types of embedded NICs can be prohibitive. As a
consequence, most corporations using Ethernet still purchase separate Ethernet adapters, so the cost
difference between Ethernet and Token Ring is not so great.
Finally, when examining the cost of a network it is important to realize that the capital equipment cost is
not the whole story and, in fact, there are many other costs associated with supplying corporate IT
services. Gartner Group studies indicate that the biggest cost actually comes from on-going maintenance
and support, which can account for up to 80% of the total cost of a system over its life-time. The
combined cost of the capital equipment and the installation and configuration of the equipment only comes
to around 20% of the total cost of the system. Hence, when examining the cost of a new system it is very
Lowest retail price of a Token Ring PCI adapter in the US
0
50
100
150
200
250
300
350
1996 1997 1998
US$

Madge Perspective
important to examine all aspects of the system, not just how much individual components will cost to
purchase.
This is where Token Ring has a real lead over Ethernet. As discussed in section 1, over the last fifteen
years Token Ring has consistently delivered a stable networking environment to corporations despite the
significant changes in applications running across the network. In contrast, Ethernet has gone through
many major upheavals in the same time period which has forced Ethernet users to periodically replace
equipment and upgrade the network to the latest Ethernet technology. Token Ring provides substantially
better investment protection than Ethernet.
Madge has been pioneering in all areas of product and technology to reduce the total cost of Token Ring
networking by addressing three main areas:
N Reducing equipment costs
N Reducing installation and configuration costs
N Reducing maintenance and support costs
Each of these areas will now be examined in more detail.
3.1 Cost of Token Ring Equipment
At the heart of most computers and networking equipment are Application Specific Integrated Circuits
(ASICs). ASICs are highly integrated pieces of silicon which have been developed to perform a specific
function. For example, an ASIC is typically found on standard Token Ring adapters to process the frames
coming off the network, handle the low level MAC functions which keep the ring running, handle error
conditions, and pass data traffic from the network up to the PC memory and processor. The quality of the
ASIC – how well it is designed and the level of integration – can have a significant impact on the
performance and cost of a device. Generally, the more components that are integrated onto an ASIC the
lower the cost of the device.
ASICs are either supplied by ASIC vendors, which have developed general purpose ASICs for use in
different vendors products, or are developed by vendors for use in their own products. For example, the
Token Ring chips described above can be sourced from an ASIC vendor, such as Texas Instruments, or a
number of key Token Ring vendors, such as Madge and IBM, have developed their own.
Owning core silicon technology is actually the key to winning the cost battle. Madge has been developing
Token Ring and switching ASICs since the early 1990s and has invested many millions of dollars in this
technology. Its Token Ring silicon, called RingRunner_, started shipping in 1995 in the Smart
Ringswitch and Blue+ adapter products. Since then major enhancements have been made – including
significant cost reductions – enabling Madge to launch the lowest priced adapter, called Presto PCI, onto
the market in April 1997.
LevelofIntegration
RingRunner
(Blue+ & Ringswitch)
RingRunner K1
(Presto PCI)
RingRunner K2
(Next generation PCI adapters)
RingRunner K3
(First generation HSTR products)
RingRunner HSTR
(Next generation HSTR products)
Madge Token Ring silicon roadmap

Madge Perspective
Madge has a detailed roadmap for the continued development of the RingRunner technology which will
enable Madge to keep pace with changes in the market. For example, its fourth generation RingRunner
chip will appear on the first HSTR adapter and will be the first time 16/4 and 100Mbps operation will be
combined on a single chip. In addition, Madge is busily working on a 100/16/4 chip which integrates even
more of the components on a 100/16/4 adapter, enabling a substantially lower priced 100/16/4 HSTR
adapter to appear in 1999 for desktop applications.
Madge is also applying this silicon technology in its latest range of switching products which will enable
workgroup switching to be widely deployed across the whole corporate environment at an affordable cost
to Token Ring users.
3.2 Installation and Configuration
Installation and configuration costs are often the most understated part of the overall cost of an information
system. When new equipment or a new technology is deployed in a network, the time taken learning,
installing, configuring, and optimizing the system can be considerable – and this adds to the overall costs
of running the network.
Five years ago, it was normal for network managers to spend days, or even weeks, testing, installing and
configuring network equipment such as adapters, hubs and bridges. Today, most network managers spend
their time planning for the future, deploying new applications, and trying to deliver the best possible
services to their network users. Spending time on these relatively “simple” parts of the network is now
longer an option.
Madge recognized this many years ago, and has been pioneering the concept of Plug-and-Play on all of its
network equipment. For example, the Presto PCI Token Ring adapter has been designed with installation
and set-up in mind, so that when installing in, say, a Windows 95 or Windows NT environment the user
has only to make one or two mouse clicks to get the driver installed and ready to run. The installation
software automatically decides the configuration parameters required to optimize the driver for a particular
environment. Presto PCI was measured by the Tolly Group, a New Jersey-based independent network
testing and consulting firm, and this what they reported:
The Madge Presto PCI adapter was by far the easiest adapter to install, of all the Token Ring
adapters evaluated by The Tolly Group. It was surprising just how difficult the other products
were to install and configure, especially with Windows NT 4.0. The Madge Presto PCI has the
most comprehensive documentation and support utilities and offers high value with no
degradation in performance, compared to other vendors' products.
Similarly, the latest hub and switch solutions from Madge have been designed with Plug-and-Play
operating in mind. For the example, the Ringswitch Express is the easiest Token Ring switch to install
with the minimal amount of set-up required to get a switched network up-and-running.
This concept is being applied to all of Madge’s future products, from the desktop to the backbone.
Madge’s strategy is to make Token Ring networking as easy to use as possible.
3.3 On-going Maintenance and Support
As discussed previously, maintenance and support costs form the largest part of the total cost of an
information system, with perhaps up to 80% of the overall cost of the system during its lifetime being
associated with this type of activity. As a result, minimizing operational and support costs can have a
dramatic impact on the total cost of an information system.
Token Ring delivers substantial benefits in large corporate environments, since the technology has many
embedded functions which aid in the management and control of the network. In fact, this is one of the
major reasons why Token Ring has been deployed so widely in corporate environments.

Madge Perspective
A good example of what Token Ring delivers in terms management and control is the Token Ring Media
Access Control or MAC which is built into every Token Ring end-station. Unlike Ethernet, the Token
Ring MAC is an extremely sophisticated entity which performs many functions, including:
N Lobe tests: As part of the normal process of joining the ring, an adapter tests the quality of the
connection between it and the local hub or switch port. It does this by sending frames along the wire
between it and the local hub or switch, and making sure that the frames are not corrupted when they
are received back on the adapter. Only once the adapter is sure of the quality of the connection will it
physically open the relay in the hub or switch port to join the rest of the network.
N Ring polls: Each station can determine its position on the ring using a process called a ring poll.
Basically, this involves a station sending a special frame containing its own MAC address. This frame
is received by the next adjacent, down-stream station which then knows the address of its immediate
upstream neighbour. The process continues around the ring until every station knows who is
immediately upstream of it on the ring. This information is used by network management programs to
build topological maps of the network with the locations of all the stations on it.
N Active monitor: The active monitor is a special station on the ring which performs important tasks,
such as generating the timing clock for signals on the wire and initiating processes such as the ring
poll. In some LAN technologies, this type of activity would require an additional, specific station on
the network performing all of these tasks. Token Ring allows any station on the ring to become the
active monitor, and all IEEE 802.5 compliant adapters are capable of being the active monitor. Token
Ring provides a voting process which selects which station is to be the active monitor. This avoids
additional equipment having to be added to the network, and means if the active monitor leaves the
network (e.g. the PC is turned off) another station is automatically assigned as the new active monitor
and the ring continues to operate normally.
N Remove station: There is a type of MAC frame defined for removing stations from the network. If a
Token Ring end-station receives this type of frame, it automatically removes itself from the network.
All IEEE 802.5 adapters, including the very first adapters shipped in the mid 1980s, support this
function. This very powerful management tool gives the network manager complete control over who
has access to network resources.
N Soft errors: In certain circumstances – for example, when a cable is of poor quality or is located to
sources of electromagnetic interference – the quality of the signal on the network may be degraded
and frames can become corrupted. When this happens, the network stations generate a special type of
MAC frame called a soft error. These are designed to alert the network manager of intermittent
problems which are impacting the performance of the ring. Several different types of soft error are
defined to provide the network manager with some insight into the cause of the problem.
N Hard errors: A hard error or beacon condition occurs when the ring completely stops carrying data.
For example, if a cable is broken, the station downstream of the fault detects that it has stopped
receiving a valid signal and will send a beacon frame to alert the network manager of the problem.
The source MAC address and type of beacon frame can be used to isolate the location and cause of the
problem. Intelligent Token Ring hubs use this information to automatically remove faulty stations or
by-pass broken cables on the ring.
Although these advanced functions at the heart of Token Ring go a long way to provide network managers
with the tools they need to manage and support the network, there exists management packages which are
able to process this information and provide the network manager with even more sophisticated
management and control over the network. In addition, new emerging management standards, particularly
at the desktop, are set to revolutionise the corporate networking environment. The next few sections will
examine these in more detail.

Madge Perspective
Management of the desktop
Microsoft has been pioneering management of the corporate desktop with initiatives such as the PC9x
specifications. PC9x details the functions and operation of peripheral devices, such as network interface
cards, which are installed in a Windows environment.
In addition, the PC98 specification includes an operation called OnNow for remotely updating a PC’s
installed applications and operating system while the machine is not in use. OnNow is very similar to the
older Wake-on-LAN specification. For example, it is often convenient for applications to be updated
overnight or over the weekend when the user is not in the office. With OnNow, the network manager can
send a special request to the network adapter to wake-up the PC. When the application update is complete,
another request can be sent to the PC to power into a special hibernation state. As a result, updates and
upgrades can be performed centrally, across the network, during out-of-office hours with no disruption to
network users.
Madge is committed to supporting these emerging desktop management standards. Its next generation of
Token Ring adapters will provide full support for desktop management standards such as PC97 and PC98,
as well as the remote wake-up standard such as OnNow and Wake-on-LAN.
Management of the network infrastructure
Back in 1992, Madge was one of the first vendors to pioneer graphical management of Token Ring
networks with its TrueView management software. Based on Madge’s own experience of managing and
supporting its internal corporate Token Ring network, TrueView provided comprehensive and powerful
management of the Token Ring infrastructure through a simple, easy-to-use graphical interface.
Since then, TrueView has evolved significantly and now provides extensive management of both shared
and switch Token Ring networks, as well as ATM. It has also evolved into a multi-platform system that
can run on both Windows and UNIX systems, and can be integrated with a wide range of third party
network management platforms such as HP OpenView and IBM NetView/AIX.
One of TrueView’s strengths is that it has been completely written from scratch for Token Ring. Most
other vendors management systems have been written for Ethernet and then ported over to Token Ring.
Because of this approach, TrueView utilizes all of the embedded functions of Token Ring (see above) to
provide extremely detailed information about the status of the network and attached stations, and can
significantly reduce the time taken to isolate and resolve network problems.
TrueView will continue to evolve to meet the changing nature of Token Ring network. Its advanced
functions for the management and control of switched Token Ring environments will become increasingly
important as switching becomes more prevalent in the backbone and emerges as a widely-deployed
desktop technology.
Next generation network management
As networks evolve from shared to switched, the role of the switch in the management of the network
becomes critical. The switches become the heart of the network, through which all communications flow.
For the network manager to have complete control over the switched infrastructure, the core network
switches need to be endowed with sufficient management functions.
The Remote Monitoring or RMON standard was designed to allow network devices to provide network
management information in a standard and coherent way. Because of Token Ring’s inherent management
capabilities, the information provided by the Token Ring network can be significantly more sophisticated
than many Ethernet networks. Because of this, the RMON standard has been enhanced with extra groups
specifically designed for the management of Token Ring networks, and which directly link in with the in-
built management functions of Token Ring.
Madge is the only Token Ring switch vendor to support these additional Token Ring enhancements to the
RMON standard. Its Ringswitch family supports the full Token Ring RMON standard to provide

Madge Perspective
unparalleled levels of management over the switched Token Ring infrastructure – information that is vital
to maintain critical network services in a switched Token Ring environment.
High Speed Token Ring switch ports operate in the same way as 16/4Mbps ports, since the same
IEEE802.5 MAC is used in both cases. Therefore RMON (including the Token Ring extensions) extends
to HSTR backbones, whether they are running at 100Mbps or gigabit speeds. Thus, as the network
backbone scales to higher speeds Madge’s switch solutions will continue to provide their unparalleled
levels of network management.
3.4 Section Summary
A lot of ground has been covered in this section. The cost of networking is not just the cost of the network
equipment. Independent studies have shown that the true cost of network comprises equipment costs,
installation and set-up costs, and on-going maintenance and support costs. The latter can cost up to 80%
of the overall cost of the system over its life-time. Thus, even though the cost of Token Ring equipment
may be higher than Ethernet, the overall cost of the system may be lower because of Token Ring’s
superior management functions.
The perception is that Token Ring equipment costs significantly more than Ethernet. The reality is far
from this. Madge is continuing to drive down the costs of Token Ring networking through innovations in
component integration and silicon technology, such that the premium for Token Ring equipment continues
to fall. For example, the premium for Madge’s Presto PCI adapter is less than 45% above a 10/100 adapter
from 3Com. As this technology innovation continues, the per user costs for Token Ring are likely to
continue to fall.
Token Ring continues to deliver a long term return on investment. Unlike Ethernet, it has not required
regular re-investment in the infrastructure as traffic demands and patterns have changed. The advanced
architecture of Token Ring will ensure that it continues to deliver exceptional return on investment for the
foreseeable future. This is a major factor when considering on-going network support costs.
Madge is also taking the lead in driving down the other costs associated with networking. It is pioneering
plug-and-play operation on all of its products to significantly reduce the time taken to install and configure
new network equipment. Similarly, with its leading edge network management technology, it is
continuing to drive down the costs associated with maintaining and supporting the network.
As switching becomes more prevalent in the Token Ring network and becomes the preferred connection
for desktops, management and control of the switched infrastructure will be key to maintaining network
services. Madge’s pioneering work with the Token Ring extensions to RMON and extending these to
work across 100Mbps and gigabit speed High Speed Token Ring will form the basis for Token Ring
network management in the 21st
century.

Madge Perspective
4 Applications
The last fifteen years have seen enormous changes in the applications which are run across local area
networks. From the early days of transaction processing applications, Token Ring has kept pace with the
changes in networked applications and is now used in many thousands of corporate networks world-wide
to deliver a wide range of services to the corporate desktop.
The next five years are likely to see radical changes in the types of applications run across the network.
Many organizations are starting to deploy Web browser technologies and corporate intranets to standardize
information flow across the whole organization; collaborative applications, such as white-boarding and
application sharing, in which multiple users share ideas and information are becoming increasingly
utilized; desktop video conferencing is starting to become an important business tool in many companies;
and LAN-based telephony is beginning to be tested in many networks.
These trends raise two important issues for Token Ring users:
N Firstly, the importance of IP in corporate Token Ring networks is going to change substantially over
the next few years. For historical reasons, Token Ring networks have tended to support a much wider
range of protocols than Ethernet. It is not uncommon to find multiple protocols, including IPX, SNA,
NetBIOS and IP, running on the same Token Ring network. As corporations converge around web-
based applications and Intranets, IP is likely to become the dominant protocol over the next few years.
For example, Novell, once the bastion of the IPX protocol, is providing native IP support in the latest
version of its Network Operating System, NetWare 5. Although the other protocols are unlikely to
disappear completely, their importance will fade over time. With this shift in the protocol make-up on
the network, it is important for Token Ring users to have a clear strategy for the wide-scale
deployment of IP while maintaining on-going support for “legacy” protocols.
N The second issue comes from the emergence of multimedia applications. A revolution has occurred in
the domestic PC market, with even the most basic of PCs now providing support for sound, voice and
video. These multimedia functions are starting to appear at the corporate desktop, and business
applications are being developed to take full advantage of them. Current data applications, such email
and printing, operate well on today’s LANs because they are not particularly sensitive to the delays
inherent in most networks. In contrast, real-time video conferencing and voice telephony are very
sensitive to delays and their operation can be seriously impacted if the network becomes particularly
busy and delays build up. For networks to support these new types of applications, enhancements are
needed so that they can provide different levels of service depending on the type of application. The
provision of quality of service on Token Ring will become increasingly important as these
applications are deployed across the organization.
Network support services needed for new classes of applications
IP
broadcast
mgt
services
IP
switching
services
Real-time
network
services
Standard data
applications
New video, voice &
real-time data applications
Client-server,
email, office
automation,...
Web browser
applications
Voice Video Real-time
data
IP data service Real-time IP (RTP, RSVP)
Network
support
services

Madge Perspective
The next few sections discuss these issues in more detail and show how Token Ring, through Madge
Perspective, is evolving to provide the right solution.
4.1 IP on Token Ring
Layer 3 Broadcast Control
The wide-scale deployment of IP on Token Ring has two important implications for network design.
Firstly, as with any other protocol, IP-based applications generate broadcast traffic – without broadcasts
these applications would not be able to locate important services on the network and would be unable to
operate correctly. As networks become increasingly flatter, with meshes of layer-2 switches used to
connect ring segments together, the amount of broadcast traffic will increase significantly as broadcast
frames are propagated across the network by the switches.
Madge’s solution to this problem is to build layer-3 broadcast control function into its Token Ring
switches. This technology, called Active Broadcast Control or ABC, enables the Ringswitch family to
monitor all broadcast traffic and make intelligent decisions on where to forward them to. It does this by
building an internal map of the network and automatically determining where the different network
services are located. So, if a broadcast frame is received on one port, the Ringswitch can decide which
port it really needs to be forwarded to rather than just duplicating it on every port. Thus ABC dramatically
reduces the level of broadcast traffic in the network and ensures critical computing power is not wasted
with unnecessary traffic. Madge’s ABC technology supports all the major networking protocols, including
IPX, IP and NetBIOS.
Active Broadcast Control (ABC) in the Madge Ringswitch family
ABC is a very effective tool in large switched LANs, avoiding all the configuration and administration
overheads, and the performance degradations associated with a router-based network. Tests show that
each Ringswitch can remove up to 90% of ARE broadcasts, as well as reduce IP and NetBIOS broadcasts
by more than 40%. With multiple Ringswitches in a network, their combined filtering actions are
cumulative providing even greater levels of broadcast suppression. Madge’s ABC is self optimizing on
each Ringswitch in the network, requiring no intervention from the network manager.
Layer 3 Switching
Secondly, a potential problem with IP comes from its addressing scheme and how organizations connect
into the Internet. IP’s limited address space means that many organizations are forced into deploying
multiple IP subnets across the LAN, with relatively small numbers of users in each subnet. Although
communication within a subnet can be performed with each user exchanging data directly across a layer-2
switch, information exchanges between users on different subnets requires a layer 3 device such as a
router. (To overcome this problem, many organizations have started using private IP addressing schemes
Port 1 Port 2 Port 3 Port 4
Layer 2 switching engine
(SR, T, SRT+)
NetBIOS,
3270, SNA,
IP, IPX,...
Ringswitch Switching Engine
Active Broadcast Control
(ABC) engine

Madge Perspective
within their local network, with an address translation gateway providing public addressed access and
firewall to external IP and Internet resources.)
Despite the router approach having been adequate for many Token Ring users, it does have limitations
which are becoming increasingly critical as the level of IP deployment rises. For example, routers employ
complex layer 3 routing engines to forward traffic between networks. These complex engines typically
make the router extremely expensive and limit its overall performance. In addition, if all inter-subnet
traffic is going via a single router port (what is commonly called a one-legged router design), this port can
become the bottleneck in the network reducing the overall performance of the network.
A better design would be to incorporate layer-3 forwarding functions into the main switches in the
network. This would remove the need for additional routers for inter-subnet communications, as well as
provide a better platform for the wide-scale deployment of IP on Token Ring. A multilayer switch
architecture combines the simplicity and performance of layer-2 switching with the inter-subnet
forwarding capabilities found in layer-3 routers. Of course, this architecture does not completely alleviate
the need for routers in the network, since they are still extremely useful for connecting LANs into a diverse
set of Wide Area Networks. The architecture proposed here involves deploying multilayer switches in the
core of the LAN backbone, with routers located on the edge of the network providing connectivity into the
WAN.
Layer-3 switching in the Smart Ringswitch Plus
Madge’s Strategy
Madge’s strategy involves evolving its award winning Ringswitch backbone switching platform to match
the future needs of Token Ring users. Specifically, Madge plans to add multilayer switching functions
into the Ringswitch Plus solution, allowing it to switch standard Token Ring traffic at layer-2 at the same
time switch inter-subnet IP traffic at layer-3. This functionality is planned to start shipping in the first half
of 1999. The combination of multilayer switching and Madge’s unique Active Broadcast Control
technology on the Ringswitch Plus platform will provide Token Ring users with the most comprehensive
switching solution on the market that will meet their IP networking needs well into the next century.
Port 1 Port 2 Port 3 Port 4
(SR, T, SRT+)
NetBIOS,
3270, SNA,
IP, IPX,...
Ringswitch Switching Engine
Active Broadcast Control
(ABC) engine
(IP between subnets)
IP between
subnets

Madge Perspective
4.2 Quality of Service on Token Ring
QoS on Token Ring using Token Priority
As well as delivering classical data application services to the corporate desktop, over the next few years
Token Ring will have to evolve to support a whole raft of emerging voice, video and real-time data
applications. To be able to do this Token Ring has to be able to deliver different levels of service across
the network depending on the type of application running. How frame-based networks deliver these
various levels of services is of great debate at the moment, but, as we shall see, Token Ring provides the
best answer.
As discussed in the first section, the original architects of Token Ring designed the technology with the
future in mind. They had the foresight back in the 1980s to realize that LANs would one day be carrying a
multitude of different traffic types and so they designed into the original Token Ring a method of
delivering quality of service (QoS) across Token Ring LANs. So advanced was this thinking that only
now is this capability being taken advantage of by emerging multimedia applications.
All Token Ring frames have a special field in the header called the priority field. This field can take any
value between 0 and 7, with 0 being the lowest priority and 7 the highest. Normally, data applications
transmit at priority 0; internetworking devices such as bridges and switches typically uses 4; 7 is reserved
for MAC frames. When a station wants to transmit onto the ring, it queues up a frame with a particular
priority. If this queued frame has a higher priority than the other queued frames on the ring, then the
station can claim the next free token ahead of the other stations on the ring and immediately transmit the
frame onto the ring. With this scheme, stations running time critical applications, such as real-time video
conferencing, can transmit ahead of stations running non-time sensitive applications, such as Web
browsing and file printing.
Token Ring’s priority scheme in action
The bandwidth ReSerVation Protocol (RSVP) provides a standard method for applications to request a
specific level of service from the network. The end-station driver software maps these RSVP requests to a
specific priority level on the wire. Subsequent IP datagrams from the application are then transmitted at
the required priority level. This scheme allows multiple applications running in the end-station to request
different classes of service (i.e. different priority levels) on the network. The two highest, unused priority
levels on Token Ring (levels 5 and 6) can map directly to the classes of service provided by RSVP.
Station
currently
transmitting
Station
currently
transmitting
Stations
waiting to
transmit
Stations
waiting to
transmit
Station with higher
priority packet can
grab token next
Station with higher
priority packet can
grab token next

Madge Perspective
Accessing Token Ring’s priority scheme using IP
Delivering different classes of service to the Token Ring desktop is only half of the story. The next
problem is how to extend these classes of service across the whole network. To do this requires two
advanced functions in the switch:
N The switch has to be able to propagate high priorities between its ports, so that if a frame is received
on one port at, say, priority 5, it is re-transmitted on the outbound port at the same priority.
N The switch has to have multiple internal queues which allow high priority frames to jump ahead of
low priority ones on the output port.
Both of these key functions are already supported in Madge’s Smart Ringswitch range of backbone
switches, making them ready for voice, video and real-time data applications.
End-to-end QoS on Token Ring
QoS on Ethernet
The IEEE standards making body has also been examining the issue of how to deliver quality of service in
frame-based networks. The main driver for this is the lack of QoS functions in Ethernet networks. Unlike
Token Ring, Ethernet has no priority scheme which means it does not perform well in a multiservice
networking environment – Ethernet cannot distinguish between the different types of networked
applications.
To solve this problem the IEEE 802.1p and 802.1q groups have been working on some enhancements to
the Ethernet standard. One of these enhancements includes modifications to the Ethernet header to add a
3-bit priority field. Just like Token Ring, this priority field can take a value of between 0 and 7, with the
higher value being associated with a higher priority. Under this scheme, Ethernet users can enjoy the QoS
features that have been present on Token Ring since the mid 1980s.
IP
protocol
stack
IP
protocol
stack
Adapter card
driver
Adapter card
driver
NDIS 5
Data
packets
Video
packets
RSVP
messages
Priority
= 0
Priority
= 6
TR
Switch
TR
Switch
TR
Switch
TR
Switch
Support for
multiple
priority queues
Support for
multiple
priority queues

Madge Perspective
However, there is a snag. The new Ethernet frame formats defined by 802.1q are incompatible with the
current Ethernet standard. This means that organizations deploying 802.1q will have to replace all their
existing network equipment – adapters, hubs, switches and even routers – with 802.1q compliant
equipment. This is a major upheaval to the network, and one which will cost Ethernet users dearly. Token
Ring, on the other hand, is completely multimedia ready because it was designed from day one with
multiservice networks in mind. Consequently, Token Ring users can deploy the new multimedia
applications with minimal changes to the network infrastructure. This is yet another example of the
superior investment protection provide by Token Ring.
4.3 Section Summary
Token Ring is well prepared for the future. Its inherent ability to support emerging voice, video and real-
time data applications through its priority scheme will protect user’s investment and significantly prolong
the life of their Token Ring network. In contrast, Ethernet has had to be significantly enhanced to allow it
to provide the same quality of service functions as Token Ring. Unfortunately for Ethernet users, these
enhancements are not backward compatible and will require significant portions of the network to be
replaced.
Madge Perspective provides a clear strategy for the deployment of these new multiservice applications in
the network. Support for multiple queues and priority passing in the Ringswitch family allow time
sensitive traffic to be fast-tracked across the whole network. Enhancements to the end-station driver
software will allow RSVP requests to be mapped to priority on the wire, allowing multiple applications
with different network service requirements to be run concurrently.
IP is becoming increasingly used in Token Ring networks, driven by the wide-scale deployment of
corporate Intranets and web-based applications. Madge’s two pronged approach to solving the limitations
of IP will enable Token Ring users to deploy IP with minimal impact on network performance. Madge’s
Active Broadcast Control technology running in its Ringswitch family of switches is used by many Token
Ring sites to limit the impact of broadcast traffic from a wide range of protocols including IP. Combined
with Madge’s plans to implement multilayer switching in the Ringswitch platform for simple, fast layer-3
inter-subnet communications, Madge provides Token Ring users with an unbeatable solution for the future
of their networks.

Madge Perspective
5 Integration
Back in the 1980s, most organizations standardized on a single networking technology, whether it was
Token Ring or Ethernet. However, over time, this situation gradually changed as companies merged with
other companies, and their application needs changed, such that today many companies have a mixture of
Token Ring and Ethernet in the same network.
Providing connectivity between Token Ring and Ethernet networks is not a simple matter. As discussed in
section 1, there are significant differences between Token Ring and Ethernet. For example, Token Ring
can support very large frame sizes with most Token Ring networks running 4kbyte frames. In contrast,
Ethernet’s maximum frame size is 1.5kbytes. As a result, it is not possible to transmit a large Token Ring
frame across a standard Ethernet network. To overcome this problem, the Token Ring frame size would
have to be reduced to that of Ethernet, which would involve re-configuring every Token Ring end-station.
This is not a desirable solution.
In addition, the address bit ordering sequence on Token Ring is completely different to that of Ethernet.
As a result, every frame passing between Token Ring and Ethernet must be completely analysed and any
addresses modified to the new bit ordering scheme. This is very complex to implement – since it involves
the internetworking device recognizing and understanding every protocol on the network – and it adds
significant processing overhead to the internetworking device.
Finally, the bridging schemes for Token Ring and Ethernet are very different. Token Ring source routing
allows fully redundant paths to be built across the network by adding to the Token Ring frame information
about the route it should take across the network. Ethernet uses a transparent bridging scheme in which
the bridges or switches decide where the frame should go based on its destination MAC address. Because
Ethernet does not define a field in its header for source routing information, the problem arises of what to
do with the Token Ring source routing field as the frame passes from Token Ring to Ethernet.
There have been several attempts in the past to solve these problems. Translational bridges have been
developed by vendors, such as IBM, which bridge at layer 2 between Token Ring and Ethernet and have
processors for handling the protocol specific bit fix-ups and source route caching (the source route field is
stripped from the frame and stored in a table as the frame goes from Token Ring to Ethernet; when a reply
is sent in the opposite direction, the source route field is added back to the frame before it is transmitted
onto the Token Ring network). Unfortunately, because of the amount of processing required to handle
these complex activities, the Token Ring-to-Ethernet performance has typically been very slow. In
addition, the frame size problem still remains. Needless to say, these types of device have not been widely
deployed.
The more widely used method of linking Token Ring and Ethernet networks is to use a router. Since
routers operate at layer 3, they are able to handle the addressing issues fairly easily within the normal
routing process. However, apart from being an expensive solution, routing only solves the problem for
routable protocols such as IP and IPX. As discussed above, most Token Ring networks have a diverse
range of protocols running on them, including SNA and NetBIOS. These are non-routable protocols
which mean they cannot be handled at layer 3 – a layer 2 device is required. Some routers do provide
support for these non-routable protocols, but it is through a translational bridging or proprietary
encapsulation scheme which suffer from the same problems described above.
Various schemes have been proposed by vendors for solving these problems. The schemes typically
include modifying the Ethernet standard to support large frames, and then encapsulating the Token Ring
frames within an Ethernet frame. Unfortunately, these schemes are completely proprietary and will only
work on that vendor’s equipment, so users adopting them will be completely locked into a non-standard,
single vendor solution.
Madge firmly believes that users should have complete freedom to choose their networking partner, and
that single vendor, proprietary solutions are bad for users and bad for the industry as a whole. Madge
continues to promote a standards-based, open approach to networking which will take users into the 21st
century without locking them into dead-end, proprietary technologies.

Madge Perspective
Madge Perspective provides two standards-based approaches for solving the Token Ring-Ethernet
integration problem, one using ATM in the core of the network and the other using High Speed Token
Ring. These are now discussed in more detail.
5.1 Token Ring-Ethernet Integration using ATM
For several years now, ATM has provided an excellent platform for the integration of Token Ring and
Ethernet networks. Through LAN Emulation (LANE), the ATM network can be used to emulate both
Token Ring and Ethernet networks, allowing concurrent transport of Token Ring and Ethernet traffic
across an ATM backbone. LANE also allows network attached devices, such as ATM adapters in servers,
to appear as both emulated Token Ring and Ethernet end-stations. Hence, within this design, users located
on either the Token Ring or Ethernet network can access centralized network resources located on the
ATM backbone.
Because LANE can emulate both Token Ring and Ethernet LANs, the differences between Token Ring and
Ethernet are avoided. Thus, source routing, large frames and the Token Ring address bit ordering scheme
are completely supported by the emulated Token Ring LAN.
Madge has been supplying ATM solutions for a number of years and has won several awards for its ATM
products. The Collage 700 series of ATM switches provide a powerful solution to those Token Ring users
which are deploying ATM in their backbone. As the first vendor to support standards-based Token Ring
LANE, Madge is uniquely positioned to support Token Ring users’ ATM needs both now and in the future.
Combined with its award winning server adapter, Madge has a complete solution for the ATM backbone.
5.2 Token Ring-Ethernet Integration using HSTR
The High Speed Token Ring standard is being defined with Token Ring-Ethernet integration in mind.
Through the use of IEEE 802.1q, which provides a standard-based method for encapsulating one
technology in another, it is possible to encapsulate Ethernet frames in Token Ring frames for transport
across a common HSTR backbone. Unlike encapsulation of Token Ring in Ethernet, because Token
Ring’s maximum frame size is substantially greater than that of Ethernet, the problem of how to
encapsulate the largest possible Ethernet frame in a Token Ring frame does not arise – Token Ring can
easily handle it. Similarly, the other problems associated with Token Ring in Ethernet encapsulation –
such as what to do with the source routing information – no longer matter if the encapsulation is done the
other way around.
Thus, using HSTR and 802.1q it is possible to build a common frame-based backbone that can carry both
Token Ring and Ethernet traffic. HSTR is demonstrating itself to be a superior technology, not only for
pure Token Ring networks but also for mixed Token Ring and Ethernet networks. The main benefit of this
HSTR approach is that it uses open standards rather than vendor specific, proprietary technologies, and
therefore provides a much clearer path into the 21st
century.
Token Ring-Ethernet integration using HSTR and 802.1q
HSTR & 802.1q
used to carry
Ethernet frames
on backbone
HSTR & 802.1q
used to carry
Ethernet frames
on backbone
Additional 802.1q
drivers required
in server
Additional 802.1q
drivers required
in server
Fast Ethernet
Interface on
Smart Ringswitch
Plus
Fast Ethernet
Interface on
Smart Ringswitch
Plus

Madge Perspective
To use HSTR as the core of the Token Ring and Ethernet network, an entry point is required from Ethernet
into the HSTR backbone. This can be provided either through HSTR uplinks for Ethernet switches, or
through support for Ethernet in Token Ring backbone switches. Madge’s strategy includes the addition of
Fast Ethernet interfaces to the Ringswitch platform as well as providing the 802.1q encapsulation of
Ethernet in Token Ring frames in the switch.
For shared services located on the HSTR backbone, Madge plans to provide an 802.1q compatible driver
for its HSTR adapters which will de-encapsulate the Ethernet frames from the Token Ring frames before
passing to the high level applications. Just as with LANE, simultaneous Token Ring and Ethernet stacks
can be supported by one HSTR adapter.
5.3 Section Summary
Many networks have a mixture of Token Ring and Ethernet in them. Providing seamless connectivity
between these disparate networking types is difficult and technically complex. Some vendors have
proposed solutions to this problem, but these are completely proprietary and will lock users into a single
vendor solution.
Madge Perspective provides two standards-based solutions to this problem. The first utilizes ATM and
LAN Emulation to build a common backbone infrastructure which will support both Token Ring and
Ethernet traffic. The second utilizes High Speed Token Ring and the 802.1q to carry both Token Ring and
Ethernet across a common frame-based based backbone. Using these approaches, the problem of how to
connect Token Ring and Ethernet together are alleviated.

Madge Perspective
Conclusion
Token Ring has consistently proved to be a reliable and robust technology for corporate networks. Despite
the huge changes in networked applications which have occurred in the last fifteen years, Token Ring has
kept pace with user needs and has only undergone two changes since its creation in the mid-1980s.
The story for Ethernet is much worse. Because of the inherent weaknesses in Ethernet technology,
Ethernet has been through many major changes in the same period, forcing Ethernet users to upgrade their
networks and install new equipment every two years or so. Even now, Ethernet still lacks many important
capabilities which have been present in Token Ring since its creation.
Token Ring is in a much stronger position for the future. Through enhancements, such as High Speed
Token Ring, users can significantly extend the life of their Token Ring network and scale to gigabit speeds
without having to change to any new technologies.
Madge Perspective delivers a clear strategy for the future of Token Ring. By addressing the four major
concerns of Token Ring users – how to scale network performance, how to make Token Ring networking
more affordable, how to support new applications such voice, video and real-time, and how to integrate
Token Ring and Ethernet networks together – Madge Perspective delivers a powerful case for Token Ring
networking well into the future.

Madge Networks
EUROPE, MIDDLE EAST & AFRICA
Madge Networks Ltd
Wexham Springs
Framewood Road, Wexham
Slough SL3 6PJ
England
Tel: +44 1753 661000
Fax: +44 1753 661011
Internet: http://www.madge.com
AMERICAS
Madge Networks Inc
2314 North First Street
San Jose,
CA 95131-1011
United States
Tel: +1 408 955 0700
Fax: +1 408 955 0970
ASIA PACIFIC
Madge Networks Pty
Suite 4B
15 Orion Road
Lane Cove NSW 2066
Australia
Tel: +61 2 9936 1700
Fax: +61 2 9936 1799
Madge Networks reserves the right to change specifications without notice.
Madge, Madge Perspective, the Madge logo and Smart Ringswitch are trademarks, and in some jurisdictions may be registered trademarks, of Madge Networks or its affiliated
companies. Other trademarks appearing in this document are the property of their respective owners.
© Copyright 1998 Madge Networks. All Rights Reserved.
60000xxx 7/98

Madge Perspective

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