MORIVIATICS
`
`|R COMPUTING, NETWORKING 8: COMMUNICATIONS SPECIALISTS
`
`MAY 1993
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`-- YOUR PROFESSION
`-~ TECHNOLOGY
`- NETWORKING
`what ACS n1eml.>€.-rs
`thunk WI”
`How Nrgel Manse]! won his
`Bridges, routers. gateways.
`race, with a lrttle help from IT be the hot skills of the future.
`What do they alt mean’?
`v DEVELOPMENT
`- BENCHMARK8
`*3;
`— MANAOEMEN1’
`we've: come a long way from Why Japan wants your
`How not to do too much
`MIPS and VUP-.=..
`software.
`
`f-
`
`wrthout oomg too little.
`IPR2015—01176
`
`$5.95
`
`BMC EXHIBIT 2001
`
`SerViceNow V. BMC
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`SERV-BMC-00225183
`
`

`
`
`
`s
`Illput
`18 this a sexist magazine? One
`reader thinks so. Another
`wonders about ‘the real oust of
`downsizing.
`
`Vol 1|IIIIo 3 MAY 1993
`.___:____.______._______._._..
`
`Isl I
`
`
`
`Benchmarks have come a long
`way since the days of MIPS and
`VUPs.Jol1n Tulloch takes a look
`at today's henclurutriting stand-
`
`
`
`
`What do ACS members think
`will be the
`skills in demand
`
`overtltenext e\vyears.lfyou're
`
`a Coboi progrsrntner. perhaps
`you should have a hard think
`
`ahouttltefttture.
`
`
`
`
`
`IN ofllee
`
`as
`
`Ashley Goldswotthy argues the
`oaseforl"l'elitistn.
`
`
`
`
` lflformer "
`
`1
`
`Did you miss anything? A sum-
`mary of all the important news in
`last month's Australian ootnputer
`Dress. By all aocounts. a rather
`quiet month.
`
`
`
`
`DI
`
`:
`
`
`
`
`
`
`
`
`
`
`
`Ltnct In
`to ‘ct
`Keith Power lwkitgu
`
` the risht balance tvmtect p|nn- WWW -M ,_.mdw
`A monthly roundup of ACS
`
`Prod ucllon Editor: John Carlisle
`
`nin3.It‘sofieoacsseofloomueh
`Production Director:
`news. Is it unethical to enter a
`ortoolittle.
`Llchlaxt Brown
`Vendor-run contest?
`Maneell Magic
`Salas Manager: Wendi. Fraser
`Pultllnsltlng Manager: Sally Fryar
` Publisher: Alistair Gordon
`Nigel Manson‘: victory in the
`
`Illustrators: Bob I-‘utcher.
`Gold Cost Indy Raoe was not a
`
`Jane Reid. Laoui Silvestm
`fluke. He was supported by the
`The fitustralisn Computer Society
`most sophisticated racing car
`Presldertttfleofl Dots.-r
`monitoring
`system ever
`\'lee-Presidents: Garry Trirtdcr,
`Bob Ttsdall
`developed.
`
`
`lrnntetllate Past President:
`Man Underwood
`
`National Treasurer: Glen Heinnrh
`Publications Officer: John Hughes
`CIII1!fEl.0l:III1\'! 0|'l|oer:
`
`Ashley Goldsworthy
`wonaartrr ll published by the Strategic
`Publishing Cit-nap Ply Ltd as nurses heart the
`nustnllatt Computer Society. we-mnncr ia
`
`published on the tint Wednesday at each
`muttit. esoepttng January Annual stitu:¢'p-
`don‘-$59[1llsusea).Co§)seaa|edlsu'ihutedfree
`temerrthenefthenuanutancotapaaer society
`
`ll part of Ihelr tnemherslsrp fee. Strnrglc
`Publishing Group Pty Llatl. Level 4. 20-!
`Pltrol is a revolutionary new
`
`Clarutoesl-tsrI.Sydaay NEW 11I!I1Plr (D1156?
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`glfiwan system developed in
`
`lI:m1e.13!ZI. ACN 034 TI! es: ISSN om
`Japan wants you as
`ifdntr. It may mean that ap-
`
`moo. m:‘s- no not 319, ounmeunu NSW
`Plmifiolts management on dis-
`1Il1D.Ht-:I‘JQ,\2'II SE55 FaI:E(.|’J|2I|. IIII
`would you believe that Japan is
`lfibmed networks will never be
`ttllrnasssialtnlfiwrarertrstapa-ntecvssltwtdar
`actively seeking software int-
`"19 time again. we tell: to the
` “mbflhlnd theproduct. andlooit ports? A seminar in Sydney
`a. (.'ca-ntnmtwealtlt emu,» Art mt. Ne
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`19
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`SERV-BMC-00225184
`
`

`
`

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`
`
`What In It?
`What is Patrol. and where has it come from?
`The product's brief history is one of the more
`interesting tales in the long and chequered
`record of software development
`in this
`country.
`To understand Patrol it is necessary to know
`the story of one man. His name is Martin
`Picar-d.
`Picard was born in Italy in 1963. of French
`and Austrian patents. After high school he
`moved to the USA. where he did a combined
`electrical engineering and computer science
`course at Harvard and MIT.
`In 1986 he graduated and joined satellite
`design contractor Ma-Com. where he worked
`on satellite networking. Soon after that he
`moved to Oracle. where he became product
`manager for the SQL"'Net product. and later
`dlrector of networking products.
`Picard took SQL“'Net from nothing to a
`$US23 million a year product in four years.
`Htlw? "It was the first example of a true
`client-server utility and of a true distributed
`database." says Picard. “Oracle was growing
`quickly through that period. and I guess I was
`Justin the right place at the right time."
`lficard says that
`that experience got him
`thinking about the concept of using software
`10 manage software. "But probably more im-
`Pbflttnt was my sailing experience.“
`While working at Oracle. Picard decided he
`Wanted to sail. 'I'hough he had never messed
`lmund in boats. talking to friends who sailed
`E01 him liking the idea. He bought a 34-foot
`El0|'|'|l boat called Orca.
`which sounds a bit like
`Oracle". and jumped
`5l_1'Iiight
`into sailing
`‘Vllltout the usual appren-
`ag.,,hip_
`Typically. he decided
`glifll his first solo sailing
`P Would be
`I‘
`l
`’
`down the NW3.
`West coast. through the
`panama canal. and back
`me to It 1
`.l-I
`ed
`‘bans: arttfhisetrnaftuitz
`0fllcle.and Itrtew that there
`Would be opportunities in
`E'"’°Pt‘- for someone with his skills.
`
`Why Australia?
`Although he arrived almost by accident.
`Picard says he is committed to Australia.
`"The lifestyle here is fantastic. and the
`country has very good software developers.
`The world is a small place nowadays. and a
`software company can
`really be based anywhere.
`“We're not really an
`Australian company. just
`as we are not really an
`American wmpaw The
`location of the develop-
`ment team is irrelevant.
`W
`'
`l
`software
`mfn$;‘_‘.'.“p 5' "
`Picard says that his big
`strength is that he under-
`rand. both nctworltin
`End alaplications. "'I'ltat‘E
`important. because not
`many people do. And my
`long time with Oracle meant that I had some
`important contacts.“
`It was one of these contacts that saw him in
`January I99! in Italy with the large bank
`Banco di Bergamo. an organisation
`renowned for its R&D. The
`wanted a
`networlt authentication server. Whlch was the
`genesis of Patrol. Picard‘s contract with the
`bank allowed him to retain the development
`rights to any systems he was worlting on.
`
`clnll therapy
`3'41 fate stepped in as it often does ‘'I got to
`3:,‘ Panama canal. and it was closed because
`3-" lhe fuss about Noriega. So I decided to
`“P11 Iround and go through the Suez canal.
`"13 Tahiti and Australia.
`M?!’ the time I got to Sydney. the Gulf War
`b1'01ten out and the Suez canal didn't look
`
`SERV-BMC-00225186
`
`ponent of the next generation of network
`management systems, those which will need
`to handle large and heterogeneous networks
`comprising an amorphous mix of applica-
`tions. from databases to transaction process-
`ing monitors. and from financial applications
`to the operating system itself.
`
`too healthy either. And Sydney was such a
`great place l decided to stay a while.“
`The trip had more significance. Being alone
`on a boat for weeks on end provides an une-
`qualled opportunity for extended contempla-
`tion. It was on the trip from San Francisco to
`Sydney that the idea of Patrol was really
`born. “When you are sailing. catching fish
`becomes an important event.
`I rigged up a
`fishing line attached to a bell. which you
`might call an event-driven alert. That ship's
`bell was Patrol L0."
`The key to any great software product. as
`with most other inventions. is the idea rather
`than the execution. "With Patrol. the concept
`was the difficult thing.“ says Picard. "By
`comparison. the coding and the rest of the
`product development has been relatively
`straightforward."
`When he arrived in Australia. Picard and
`Orca were put into quarantine at Neutral Bay.
`Ken Jacobs. an old Oracle colleague and the
`company's director of database marketing.
`was in Sydney for an Oracle conference (the
`I990 users‘ conference in Adelaide). He saw
`the Orca and suggested Picard attend the con-
`ference. '‘It was like I had never been away."
`says Picartl. "I was straight baclt into the
`Oracle scene." But he didn't want to rejoin
`the company after the freedom of the high
`seas. and he set himself up as an independent
`Oracle consultant. specialising in distributed
`systems. He called his company Distributed
`Data Systems. And all the time he was think-
`ing a lot about the fish and the bell and the
`concept that became Patrol.
`
`T I
`
`t was on the trip
`from San Francisco
`IO Sydney tltaflht’
`{deg ofpggy-of was
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`

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` _j_
`INDEPTH
`
`When he returned to Australia. which by
`this time he had decided to make his home.
`Picard began working with OTC and KPMG
`to further develop Patrol. They acted as spon-
`sors. and were early users of the system.
`From the start the development team com-
`prised only three developers. though eight are
`now working on the product. Key members
`0? l.he team have been Kirill Tatarinov. who
`Worked on the Russian space progratn and
`was lead graphics developer of the Fibronics
`network management system. and Dave Bon-
`flell. one of the system's chief architects and
`a leading distributed systems and process
`control developer.
`“Our sales revenue is still ramping up.“ says
`Picard. “but we actually made money on the
`flevelopment because of the way we funded
`It. We have pre-sold the software to alpha and
`beta sites. who have been happy to work that
`Way because they have been able to use even
`lhe early versions immediately."
`
`Formal raleaaa
`ln September
`[992 Patrol was formally
`released. Oracle is marketing the product in the
`Aflia-Pacific region. and Picard has set up of-
`rlfies in San Francisco (at Redwood City. near
`Oracle) antl New York City. Further develop-
`ment funds have come from the pre-payment
`Dfmyaltles by Oracle Australia. which has also
`Sllpported the company through the provision
`01' ofliee support and developrrtent facilities.
`
`Patrol is described as “a distributed systems
`manager designed to give administrators the
`necessary tool for automating the manage-
`ment of systems they support.“ It can act as a
`front end to an enterprise-wide network
`management system. or to just a few worksta-
`tions and sewers.
`Patrol is a client-server application. The ar-
`chitectures comprises a console. multiple
`secondary displays. and remote service
`“agents" that reside on the managed applica-
`tions. The software is architeeted to support
`de facto open systems standards like TCP,-'lP
`and OSF.-’Molil' and emerging standards like
`DCE (Distributed Computing Environment)
`and DME (Distributed Management En-
`virortment).
`"Until now the whole thing has cost about a
`million dollars to develop." says Picard. ''In
`terms of software development. that is not a
`lot of money. But it‘s a well known fact that
`there is no relationship between resources
`and quality in software development.
`"We're still alter good developers. espe-
`cially people who are good at graphics and
`other leading-edge technologies. Anybody
`out there interested?"
`In its short life. Patrol has garnered an im-
`pressive list of users. Telccom Australia
`heads a group of 15 or so Australian govem-
`ment depanments and inslrumentalities. and
`there are many private users. including Coca-
`Cola Amalil.
`
`installations in
`There are now 150 Patrol
`North America. though most of these are only
`trialling the product. Name users include
`Northern Telecom. Goldman Sachs. and
`Shell. A major European user is CERN. the
`European nuclear research centre based in
`Switzerland.
`Picard is softly spoken. but with a bundle of
`self-confidence that never quite comes
`through as arrogance. He is not yet 30 years
`old. Now that Patrol seems poised on the
`edge of greatness. how does he see the fu-
`ture?
`‘'1 think we have a two-year window of
`opportunity before a serious competitor ap-
`pears. We have already started doing a lot of
`work with VARS (valued-added resellers).
`And Patrol allows VARS to build highly
`graphical network-aware front ends to exist-
`ing tools and existing system knowledge."
`Picard said.
`"That will be an important pan of our fu-
`ture. but probably not as significant as our
`relationship with major vendors. who we
`believe will OEM the product as integral
`components of their own systems manage-
`ment products."
`Picard is after bigger things. After all. he
`has moved on to a 60 foot (20m) boat. "Patrol
`dominates my life at the moment. but there
`are many other challenges."
`Perhaps we will learn what they are after his
`next solo yachting marathon.
`Parameter:
`Parameters can be displayed a naugea. graphs or also
`boxaa {providing textual WarI'llI'|fi|.} By dalaull. parameters
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`suchandatabasestanup.
`
`SERV-BMC-00225188
`
`

`
`INDEPTH
`
`l-low Patrol works
`Patrol uses a point and click GUI interface to
`manage many different systems simul-
`taneously. by allowing the administrator to
`select and send a command to many objects
`at once. This can include operating systems
`management. or SQL commands on multiple
`databases. Any tool normally used to access
`the database can be used. Patrol provides the
`graphical interface to allow the user to con-
`nect that tool to any object.
`The system also has the ability to simul-
`taneously monitor multiple applications on
`multiple machines. Each object can be as-
`signed an icon. which changes colour or
`shape to refelect its status. Parameters can
`also be mapped against elapsed time. These
`capabilities can then be used to generate
`detailed reports showing the progress of an
`entire corporate system. or any component of
`it. The report can be automatically compiled
`and faxed or e-mailed to the right recipients.
`
`The Patrol eonoolo
`The console is the central display environ-
`ment responsible for collecting rules and
`commands from the user and sending them to
`the agents. It also displays a real-time picture
`of the status of all machines and applications
`being managed.
`The console uses an X Server with arecom-
`mended 32 Mbytes of RAM. though Patrol
`itself needs only 2 Mbytes. It also requires 10
`Mbytes of disk storage. The Patrol console
`shows all defined components of it dis-
`tributed system as icons. These components
`can be hardware as well as software. The
`colour of the icon signals its status: a crushed
`database. for example. will flash red.
`
`them. and how to determine their status. The
`agent must also know how to evaluate the
`information to determine ifalarm or recovery
`actions are warranted.
`
`The Inter-application language
`Patrol uses its own object-oriented language,
`independent of the underlying transport
`mechanisms. to pass messages between the
`console and the agents.
`The software is designed to provide a logi-
`cal view of all hardware and software in the
`system. Patrol itself is written in C and CH-.
`but its dynamic scripting capability allows
`objects to be defined through any series of
`commands native to the hardware or software
`being monitored. The language is portable
`across networks. operating systems and
`remote procedure call (RPC) mechanisms.
`Each item of hanlware or software is dis-
`played as an icon. When these are defined.
`Patrol runs an application discovery proce-
`dure, detennining the attributes of the object.
`A hierarchy then deten-nines how objects
`within Patrol behave. allowing groups of ob-
`jects to be operated on simultaneously. It treats
`the entire network as a single logical entity.
`and doesn't try to draw the underlying topol-
`ogy. Users of network management applica-
`tions like HP Opcnview or Sun Net Manager
`can navigate into Patrol transparently.
`
`The system parameter concept
`The system is parameter-driven, allowing it to
`recognise the symptoms of possible problems
`and to provide a way of graphically displaying
`any system details. Parameters are commands
`that Patrol knows how to issue and whose
`results are automatically analysed to determine
`if an alarm or a recovery action should be
`generated.
`Patrol agent:
`issuing
`It can monitor a parameter.
`Each processor to be managed must run an
`recovery actions until the problem is fixed or
`agent. a “teaming engine" that monitors all
`a human alerted. Parameters can be defined
`activity within that machine. An agent re-
`for the operating system. for a database using
`quires 200 ltbytes of RAM and 2 Mbytes of
`disk storage.
`SQL. or for any other application using its
`native language or interface.
`Agents receive rt.t|e definitions and service
`Parameters can be dis-
`requests from the console.
`and send event nteasagaes T played as graphs. simulated
`analogue gauges. test. and in
`to the console. They ea-
`OCLIIG Ilfld ECl'Id|.llC $5013
`I! number Of other f{.'lI'|T|llI5.
`based
`on
`pre-set
`parameters. and initiate
`recovery actions when
`_ rreoessary.
`Knowledge modules
`A ltey component of Patrol
`is its library of knowledge
`modules. profiles which are built up of each
`component on the network. The system comes
`with a standard library. for popular hardware
`and soflware. which can be added to by the
`user. Patrol can load several knowledge
`modules at once. allowing it to recognise and
`manage many different systems.
`Agents are supplied with knowledge by the
`console. This knowledge explains how to
`identify application instances. how to access
`
`Pgfrof “$95 “S own
`object-oriented
`language.
`fndgpendeng offhg
`.
`""dmy'"3 ""’”P°"
`mechanisms.
`
`Oporltlnp
`environments
`Patrol is cunently available
`on Hewlett-Packard. IBM.
`Motorola. Silicon Graphics.
`Seqttent. and Sun Unis
`workstations. DEC. DO and
`SCO Unix are currently under development.
`as are versions for VMS and Netware.
`
`Coat
`Like most software. the price varies enor-
`mously according to the configuration. A
`typical system with it console and live agents
`costs around 525.000. Low~end systems start
`at around $6000. Patrol can be contacted on
`(02) 963 1445.
`El
`
`°
`
`SERV-BMC-00225189
`
`INFORMA'l"IC8 May 1993 _
`
`

`
`

`
`
`
`INDEPTH
`
`The meaning of
`
`internetworking Refers to the process of mnnecting two
`
`to enable
`together
`or more networks
`devices on one network to communicate with devices on another network.
`
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`lnternetworking refers to the connection of
`separate networks into one larger network. It
`has become one of the fastest growing areas of
`the IT industry, but many of its concepts are still
`not widely understood. Scott Petty provides a
`guide to internetworking for the intelligent
`layman.
`
`lJ11.'l:l~ ‘in its allies: l=« nlln:~
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`
`omputer technology new pet»
`meates the very heart of the opera-
`tional structure and methodology
`of most organisations.
`In most
`large companies and government depart-
`ments. their computing platform forms the
`cornerstone of their corporate communica-
`tions systems.
`Realising the need to maximise their often
`huge investments in IT. these orgnttisatiotts are
`demanding better levels of integration,
`availability and productivity from their cont-
`puting environtnents. No longer can it com-
`puter system simply provide ftttancial pro-
`cessing applications. It must now also provide
`such items as personal productivity tools. cont~
`rrtunieations capabilities such as electronic
`Understanding the largon
`messaging. and workflow applications.
`lnternetworking is not the simplest or easiest
`The recession has also produced corporate
`directives to rein in out—ot’-control IT budgets.
`area of the computing industry to understand.
`It has created some complex jargon that can
`This has further driven network growth. as
`batnboozle users trying to devise migration
`organisations look for lower cost alternatives
`strategies around internetworking. Under-
`to traditional enterprise computing.
`standing these underlying terms is critical to
`As the nuntber of applications and plat-
`teaming what can be achieved with today's
`forrns has grown. so has the need to tie them
`intemetworlting technology.
`all
`together. A major ittternetworlting in-
`l he in lti ultlctl I'll.
`Me"
`The term “internetvvorking" refers to the
`dustry has musltroomed. providing a fabric to
`al ill in llitillillil lltlli-lll;'~.
`process of connecting two or tnore networks
`provide information flow between users and
`together to enable devices on one network to
`applications regardless of the underlying
`eontntunicate with devices on another net-
`platform. The building of heterogeneous net-
`worlt. The rationale for internctworlting
`ilrt:;ttt> ull ill ti :1 .ll lit lib‘ lL"l'€l\. nail;
`vvorlt environments. or intcmetworking. has
`resulted from the inability of most typical
`becorne one of the fastest growing pans of the
`treat. an pttnllitzt in iiliilliiilltli
`types of networks to satisfy the communica-
`IT industry.
`tions requirements of an organisation. That
`'35 per
`According to Forrester Research.
`is. a local area network (LAN) provides com-
`cent of Fortune 500 companies in the USA
`llitl ltnalil,‘ lt'= llllttlillli Dcliillllti It-.
`l|.!‘Jlii\
`munications within a relatively small
`already have some forth of inlemetworlting.
`
`24
`INFORMATICS May [993
`
`this high level of saturation does not
`But
`imply stagnation. Many companies are in the
`midst of major network redesigns. away from
`bridging and toward routing.
`A second segment fuelling internetworlting
`growth are the traditional IBM environments.
`who are moving from hierarchical SNA trel-
`worits toward new corporate networks utilis-
`ing client-server technology. By gaining a
`significant slice of this marketplace. interact-
`working is building a very solid base among
`users.
`
`If market projections are accurate then the
`internctworking vendors can expect to enjoy
`even stronger demand for their products over
`the next few years.
`
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`SERV-BMC-00225191
`
`

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`
`INDEPTH .
`
`05! model and intemetworklng devices
`
`
`
`geographic area. while wide area networks
`(WANs) provide a ntethod for connecting
`users over long distances at relatively slow
`speeds.
`lntcrnctworking also involves enhancing
`lite power of a network by allowing it to be
`Segmented into multiple pieces l'or localisa-
`tion of traffic. thereby providing higher over-
`all bandwidth availability.
`Intemetworking has grown hand-in-hand
`with structured cabling systems revolving
`around intel I igcnt hubs and other manageable
`devices that allow greater network reliability
`and l'lexil'Iility. Without each other these two
`Segtncnts would not have grown as sig-
`nificantly as they have. For this reason it is
`fair to combine them into one group.
`These two areas oI' internetworking also
`define the product mix. For |.ANl'l-AN and
`I-Ahifltost
`interconnection there are three
`Popular types of communications Jevices:
`bridges. routers and gateways. I-"or creating a
`ntulti-segment network in a large building.
`Intelligent hubs are used. In Ittost there is a
`mixture of Intelligent hubs. bridges. routers
`find gateways. and in some cases the hubs
`Include the functionality of the other three
`communieations devices.
`
`to establish larger segments.
`LAN modules are only the beginning. Add-
`in cards also carry bridges. routers. network
`management. protocol analysers. single
`board computers and Unix workstations. It is
`possible to connect
`individual cards or
`separate hubs together using El bridge or a
`water. thus segmenting the network for bet-
`ter performance and management.
`By mixing add-in boards. network desig-
`ners are afforded near-unlimited flex ihility in
`network design. However.
`the largest ad-
`vantage of structured cabling systems based
`around hubs is fault tolerance and manage-
`ment. Since each individual node connects to
`its own LAN port. it is possible to manipulate
`that port and therefore node.
`For instance. a node can be disconnected
`from the network if it is submitting corrupt
`data before it causes a network failure. With
`management software. network ad-
`ministrators can analyse and manipulate data
`How. network performance and errors front a
`central console. This combination of
`manageability and resilience greatly reduces
`the cost of supporting large networks.
`
`What is a bridge?
`A bridge traditionally connects or extends
`similar l,ANs {for example Token Ring to
`Token Ring or Ethernet to Ethemet) as well
`as LANs to WANs (known as a remote
`bridge). A bridge operates at the physical and
`data link Layers of the ISO-OSI reference
`model. commonly referred to as the media
`access control tMAC} level.
`As data traverses it LAN. the bridge reads
`the destination address contained in each
`packet and determines if it should transmit
`the packet on to another LAN or whether to
`ignore it. This process is known as filtering.
`and is often used as a benchmark to the per-
`formance of a bridge.
`To determine whether or not a packet des-
`tination is on the current LAN or on a dif-
`ferent LAN requires the bridge either to build
`tables based upon examination of the packet
`now or on the examination and response to
`int'ormation in each packet. The first method
`is referred to as transparent bridging. while
`
`the second is known as source routing.
`Local bridges transmit traffic between
`geographically close networks such as be-
`tween floors of a building. Typically a local
`bridge will contain two LAN interconnection
`ports such as IOBASE-T ports. in most cases
`they are used to segment a large LAN into
`smaller parts that improves network perfor-
`matter: by basically increasing the bandwidth
`available to individual workstations.
`Remote bridges transmit data between
`geographically distant LANs. such as be-
`tween oflice buildings. Typically they will
`contain one LAN connection port. such as an
`Ethernet IOBASE-T port. and a WAN port
`that allows the bridge to be connected to an
`external transport device such as an ISDN
`link or ){.25 packet switched network.
`
`What Is a router?
`A router operates at the network layer of the
`[S0-OSI model. which enables this device to
`provide a higher level of connectivity than
`that obtainable using bridges. The key dif-
`ferences bctween bridges and routers are in
`the areas of intelligent distribution of infor-
`mation and protocol dependency.
`The router is capable of evaluating the net-
`work environment. considering network traf-
`fie and other factors such as the fastest. most
`direct routes aside from the packet address
`alone. This factor makes routers highly reli-
`able. as they can send data via alternate paths.
`The ability to provide “best path" transport
`also equates to better WAN utilisation and
`cost efficiency.
`Routers are similar to bridges in that they
`can operate in a local or remote mode or
`support both modes. In a local mode. routers
`function as intelligent bridges and have the
`ability to convert packet frames from one
`type of network topology to another. such as
`Ethernet to Token Ring. When operated in
`remote mode. routers perform the same
`functionality but use WAN technologies as
`their communications method.
`
`Bridging versus routing
`Choosing whether to use a bridge or ll meter
`is not always easy. There are some simple
`
`intelligent hubs and structured cabling
`M a corporate network grows it is important
`lhat the physical media in the network be
`flexible. yet organised. A structured cabling
`Plan based around intelligent hubs results in
`long-term savings. because it allows
`manageability for today and flexibility for
`“Pension. rtot just for next week. but for
`Years.
`When reduced to essentials. a hub consists
`Of a chassis tbacltplanel that accepts add-in
`Cttrds and modules. The simplest ol' these
`“flfds are those equipped with LAN ports. In
`it rudimentary configuration. cable runs from
`3 desktop to a LAN port. which means the
`hub structures both Ethernet and Token Ring
`"1 '3 Physical star. Typically. all of the users
`Connected to one add-in card are considered
`*0 be on the same logical segment. More than
`011:: card can be linked through the bacltplanc
`
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`'NF0It1tt.t'rIcs May I-J93
`
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`SERV-BMC-00225192
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`m:1:
`
`guidelines to follow to facilitate tlte choice.
`On the one hand. bridges are traditionally
`less expensive and provide high throughput
`because of smaller processing overheads.
`There simple design also means they are
`easier to install and manage. But connecting
`dissimilar networks via bridges often com-
`promises network functionality. Bridges also
`suffer from “broadcast storms". a protocol or
`address error that causes the network to be
`flooded with unwanted traffic which not only
`slows the network but also increases costs on
`WAN links.
`Routers. on the other hand. can evaluate
`factors such traffic use and best path informa-
`tion to ensure that the network bandwidth is
`used efficiently. Routers can also create "fire
`walls" that ensure traffic is not passed to
`unwanted areas of the network. This is par-
`ticularly useful for minimising the effects of
`errors and broadcast infonnation.
`However. routers are normally more dif-
`ficult to install and manage than bridges. and
`as they work at level three of the OSI model
`they require support for specific protocols.
`Therefore in a mixed Novell Netware and
`Unix environment one would require a router
`that supports both IPXISPX and TCPIIP. Un-
`fortunately sortie protocols such as NetBl0S
`(NetBEUl) and DECnet LAT are not
`routable.
`Many of these problems have. however. been
`addressed through multi-protocol bridging
`
`routers thatcombinethe
`functionality and intel-
`ligence of routers with
`the ease of use and
`protocol
`independence
`of bridges. Most inter-
`networking manufac-
`turers.
`including
`Synoptics. Proteon and
`Retix. offer bridging
`routers that provide net-
`work designers with
`flexibility and security
`when planning network
`suategies for the futtue.
`
`
`
`gateway mtrst perform such functions as char-
`acter code conversion. screen attribute conver-
`sion. and mapping of keys to generate different
`key codes when other keys are pressed.
`The internetwork of a company should be
`viewed as one of the basic elements of a
`corporate network infrastructure. To a town
`planner, infrastructure means highways.
`roads and bridges. To an architect. it means
`the foundation and framework of a building.
`For networking. internetworking is the in-
`frastructure that allows communications be-
`tween groups of users utilising a range of
`tools that increase the productivity of the
`companies employees.
`
`
`Scot‘iPettyisCom Tedr ConI'riuni:atii.'.vrs'
`iedrnrioairrisrirarlngmanager.
`
`What is a gateway?
`The most complex of the three common inter-
`networking devices is t