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1.1     ! root        1: % -*- LaTeX -*-                (really SLiTeX)
        !             2: 
        !             3: \documentstyle[blackandwhite,landscape,oval,pagenumbers,small]{NRslides}
        !             4: 
        !             5: \def\emph#1{\underline{#1}}
        !             6: 
        !             7: \font\xx=cmbx10
        !             8: \font\yy=cmbx7
        !             9: \font\sf=cmss10
        !            10: 
        !            11: \raggedright
        !            12: 
        !            13: \input trademark
        !            14: \let\tradeNAMfont=\relax
        !            15: \let\tradeORGfont=\relax
        !            16: 
        !            17: \begin{document}
        !            18: 
        !            19: \title {THE OSI CHALLENGE:\\ TRANSITION ASPECTS AND TACTICS}
        !            20: \author        {Marshall T.~Rose\\ NYSERNet, Inc.}
        !            21: \date  {October 25, 1989}
        !            22: \maketitlepage
        !            23: 
        !            24: 
        !            25: \begin{bwslide}
        !            26: \part* {OUTLINE}\bf
        !            27: 
        !            28: \begin{description}
        !            29: \item[PART I:]         MOTIVATION
        !            30: 
        !            31: \item[PART II:]                BACKGROUND
        !            32: 
        !            33: \item[PART III:]       PROTOCOL-BASED APPROACHES
        !            34: 
        !            35: \item[PART IV:]                SERVICE-BASED APPROACHES
        !            36: 
        !            37: \item[PART V:]         EXAMPLES
        !            38: \end{description}
        !            39: \end{bwslide}
        !            40: 
        !            41: 
        !            42: \begin{bwslide}
        !            43: \part  {MOTIVATION}\bf
        !            44: 
        !            45: \begin{nrtc}
        !            46: \item  THERE ARE MANY TCP/IP NETWORKS TODAY; THERE WILL BE MORE TOMORROW
        !            47: 
        !            48: \item  BY THE TIME OSI BECOMES A WORTHWHILE OPERATIONAL ALTERNATIVE,
        !            49:        THERE WILL BE MANY MORE TCP/IP NETWORKS THAN THERE ARE TODAY!
        !            50: 
        !            51: \item  PROBLEM: HOW TO PROTECT INSTALLED BASE?
        !            52: 
        !            53: \item  PROBLEM: HOW TO TRANSITION GRACEFULLY?
        !            54: \end{nrtc}
        !            55: \end{bwslide}
        !            56: 
        !            57: 
        !            58: \begin{bwslide}
        !            59: \ctitle        {GROWTH OF TCP/IP}
        !            60: 
        !            61: \begin{nrtc}
        !            62: \item  SALES OF TCP/IP-BASED TECHNOLOGY
        !            63:     \begin{nrtc}
        !            64:     \item      PARTICULARLY IN EUROPE
        !            65:     \end{nrtc}
        !            66:        CONTINUES TO GROW
        !            67: 
        !            68: \item  SEVERAL TECHNICAL AND MARKET ASPECTS CONTRIBUTE TO THIS PHENOMENA:
        !            69:     \begin{nrtc}
        !            70:     \item      SUPERIORITY OF TCP/IP IN LOWER-LAYER CONNECTIVITY
        !            71: 
        !            72:     \item      MATURITY OF TCP/IP PRODUCTS\\ (e.g., RANGE OF PLATFORMS)
        !            73:     \end{nrtc}
        !            74: 
        !            75: \item  ALTHOUGH OSI WILL DOMINATE, IT DOESN'T YET
        !            76: 
        !            77: \item  HENCE, TCP/IP IS BECOMING MORE FIRMLY ENTRENCHED
        !            78: \end{nrtc}
        !            79: \end{bwslide}
        !            80: 
        !            81: 
        !            82: \begin{bwslide}
        !            83: \ctitle        {FEAR AND LOATHING IN THE MARKET}
        !            84: 
        !            85: \begin{nrtc}
        !            86: \item  F.U.D. IN THE MARKETPLACE:
        !            87: \begin{quote}\em
        !            88: ``All marketing is fear, uncertainty, and doubt.''\\ \raggedleft
        !            89: -- Einar Stefferud, Network Management Associates
        !            90: \end{quote}
        !            91: 
        !            92: \item  WHAT THE VENDORS SAY:
        !            93: \begin{quote}\em
        !            94: ``$\ldots$ protect your investment while assuring a path to an OSI
        !            95: future.''\\ \raggedleft
        !            96: -- Vendor A
        !            97: \end{quote}
        !            98: AND
        !            99: \begin{quote}\em
        !           100: ``$\ldots$ plans for a smooth, painless guaranteed migration to OSI standards
        !           101: as they are approved.''\\ \raggedleft
        !           102: --Vendor B
        !           103: \end{quote}
        !           104: AND
        !           105: \begin{quote}\em
        !           106: ``Once you've scrapped your existing production networks,
        !           107: come to us for OSI.
        !           108: It will be wonderful!''\\ \raggedleft
        !           109: --Vendor C
        !           110: \end{quote}
        !           111: \end{nrtc}
        !           112: \end{bwslide}
        !           113: 
        !           114: 
        !           115: \begin{bwslide}
        !           116: \ctitle        {THE SAD TRUTH}
        !           117: 
        !           118: \begin{quote}\em
        !           119: ``You can't win, and you can't quit, but you \underline{can} reduce the
        !           120: pain.''\\ \raggedleft
        !           121: -- Marshall Rose, NYSERNet, Inc.
        !           122: \end{quote}
        !           123: \end{bwslide}
        !           124: 
        !           125: 
        !           126: \begin{bwslide}
        !           127: \part  {BACKGROUND}\bf
        !           128: 
        !           129: \begin{nrtc}
        !           130: \item  CONCEPTS
        !           131: 
        !           132: \item  TERMINOLOGY
        !           133: 
        !           134: \item  HISTORY
        !           135: 
        !           136: \item  METRICS FOR COMPARISON
        !           137: \end{nrtc}
        !           138: \end{bwslide}
        !           139: 
        !           140: 
        !           141: \begin{bwslide}
        !           142: \ctitle        {THE FUNDAMENTAL ASSUMPTION}
        !           143: 
        !           144: \begin{nrtc}
        !           145: \item  TCP/IP IS HERE TODAY, WIDELY INSTALLED, AND USEFUL
        !           146: 
        !           147: \item  OSI WILL EVENTUALLY REPLACE TCP/IP AS THE OFF-THE-SHELF TECHNOLOGY FOR
        !           148:        BUILDING INTEROPERABLE SYSTMS
        !           149: 
        !           150: \item  BOTH WILL BE SIMULTANEOUSLY WIDESPREAD FOR QUITE SOME TIME
        !           151:     \begin{nrtc}
        !           152:     \item      DURING WHICH OSI WILL GAIN DOMINANCE
        !           153:     \end{nrtc}
        !           154: \end{nrtc}
        !           155: \end{bwslide}
        !           156: 
        !           157: 
        !           158: \begin{bwslide}
        !           159: \part* {CONCEPTS}\bf
        !           160: 
        !           161: \begin{nrtc}
        !           162: \item  TRANSITION:
        !           163:     \begin{nrtc}
        !           164:     \item      TO MOVE FROM ONE PROTOCOL SUITE TO ANOTHER
        !           165:     \end{nrtc}
        !           166: 
        !           167: \item  COEXISTENCE:
        !           168:     \begin{nrtc}
        !           169:     \item      TO LIVE TOGETHER WITHOUT HOSTILITY OR CONFLICT DESPITE
        !           170:                DIFFERENCES
        !           171:     \end{nrtc}
        !           172: 
        !           173: \item  MIGRATION:
        !           174:     \begin{nrtc}
        !           175:     \item      TO MOVE BACK AND FORTH, AS THE SEASONS CHANGE
        !           176:     \end{nrtc}
        !           177: \end{nrtc}
        !           178: \end{bwslide}
        !           179: 
        !           180: 
        !           181: \begin{bwslide}
        !           182: \ctitle        {MAPPINGS}
        !           183: 
        !           184: \begin{nrtc}
        !           185: \item  TRANSITION AND COEXISTENCE CAN BE DESCRIBED BY THE MAPPINGS THEY
        !           186:        REQUIRE
        !           187: 
        !           188: \item  SOME MAPPINGS ARE SIMPLE
        !           189:     \begin{nrtc}
        !           190:     \item      i.e., SYNTACTIC CHANGES
        !           191:     \end{nrtc}
        !           192: 
        !           193: \item  SOME MAPPINGS ARE COMPLEX
        !           194:     \begin{nrtc}
        !           195:     \item      i.e., SEMANTIC CHANGES
        !           196:     \end{nrtc}
        !           197: 
        !           198: \item  THE MORE COMPLEX THE MAPPING, THE GREATER THE LOSS OF INFORMATION OR
        !           199:        INTENT
        !           200: \end{nrtc}
        !           201: \end{bwslide}
        !           202: 
        !           203: 
        !           204: \begin{bwslide}
        !           205: \part* {TERMINOLOGY}\bf
        !           206: 
        !           207: \begin{nrtc}
        !           208: \item  WE'LL FAVOR OSI TERMINOLOGY, BUT STILL NEED SOME INTERNET (TCP/IP)
        !           209:        TERMINOLOGY
        !           210: 
        !           211: \item  TWO BASIC TERMS
        !           212:     \begin{nrtc}
        !           213:     \item      GATEWAY: GENERIC TO ANY LEVEL, COMPLEX
        !           214: 
        !           215:     \item      BRIDGE: GENERIC TO ANY LEVEL, SIMPLE
        !           216:     \end{nrtc}
        !           217: \end{nrtc}
        !           218: \end{bwslide}
        !           219: 
        !           220: 
        !           221: \begin{bwslide}
        !           222: \ctitle        {SERVICE SEMANTICS}
        !           223: 
        !           224: \begin{nrtc}
        !           225: \item  STORE-AND-FORWARD
        !           226:     \begin{nrtc}
        !           227:     \item      SERVICE SEMANTICS CARRIED MULTI-HOP VIA FORWARDERS
        !           228:     \end{nrtc}
        !           229: 
        !           230: \item  END-TO-END
        !           231:     \begin{nrtc}
        !           232:     \item      SERVICE SEMANTICS CARRIED FROM ORIGINATOR TO RECIPIENT
        !           233: 
        !           234:     \item      MAY BE SUPPORTED BY AN UNDERYLING STORE-AND-FORWARD SERVICE
        !           235:     \end{nrtc}
        !           236: \end{nrtc}
        !           237: \end{bwslide}
        !           238: 
        !           239: 
        !           240: \begin{bwslide}
        !           241: \ctitle        {SERVICE SEMANTICS (cont.)}
        !           242: 
        !           243: \vskip.5in
        !           244: \diagram[p]{figureT-3}
        !           245: \end{bwslide}
        !           246: 
        !           247: 
        !           248: \begin{bwslide}
        !           249: \ctitle        {PROTOCOL SUITE}
        !           250: 
        !           251: \begin{nrtc}
        !           252: \item  A COLLECTION OF SERVICES AND PROTOCOLS RELATED:
        !           253:     \begin{nrtc}
        !           254:     \item      ADMINISTRATIVELY, BY AN ORGANIZATION\\ (e.g., ISO/IEC); and,
        !           255: 
        !           256:     \item      PHILOSOPHICALLY, BY A REFERENCE MODEL\\ (e.g., the OSIRM)
        !           257:     \end{nrtc}
        !           258: 
        !           259: \item  FOR OUR PURPOSES, THERE ARE ONLY TWO:
        !           260:     \begin{nrtc}
        !           261:     \item      THE OSI SUITE OF PROTOCOLS
        !           262: 
        !           263:     \item      THE INTERNET SUITE OF PROTOCOLS
        !           264:     \end{nrtc}
        !           265: \end{nrtc}
        !           266: \end{bwslide}
        !           267: 
        !           268: 
        !           269: \begin{bwslide}
        !           270: \ctitle        {APPLICATIONS}
        !           271: 
        !           272: \begin{nrtc}
        !           273: \item  APPLICATION CLASS
        !           274:     \begin{nrtc}
        !           275:     \item      A SET OF APPLICATIONS RELATED TO A PARTICULAR ACTIVITY,
        !           276:                e.g., FILE TRANSFER, IRREGARDLESS OF PROTOCOL SUITE
        !           277:     \end{nrtc}
        !           278: 
        !           279: \item  APPLICATION INSTANCE
        !           280:     \begin{nrtc}
        !           281:     \item      A MEMBER OF AN APPLICATION CLASS SPECIFIC TO A PARTICULAR
        !           282:                PROTOCOL SUITE, e.g., FTAM
        !           283:     \end{nrtc}
        !           284: \end{nrtc}
        !           285: \end{bwslide}
        !           286: 
        !           287: 
        !           288: \begin{bwslide}
        !           289: \part* {HISTORY}\bf
        !           290: 
        !           291: \begin{nrtc}
        !           292: \item  A VERY BRIEF INTRODUCTION TO THE TWO PROTOCOL SUITES
        !           293: 
        !           294: \item  WE'LL ATTEMPT TO TAKE A NON-PARTISAN VIEW (ha!)
        !           295: \end{nrtc}
        !           296: \end{bwslide}
        !           297: 
        !           298: 
        !           299: \begin{bwslide}
        !           300: \ctitle        {INTERNET SUITE}
        !           301: 
        !           302: \begin{nrtc}
        !           303: \item  SPONSORED BY THE U.S.~DoD
        !           304:     \begin{nrtc}
        !           305:     \item      GREW OUT OF EARLY (D)ARPA RESEARCH INTO SURVIVABLE NETWORKS
        !           306:     \end{nrtc}
        !           307:     BASIS FROM THE U.S.~DoD INTERNET ARCHITECTURE MODEL
        !           308: 
        !           309: \item  SPECIFIED IN ``REQUEST FOR COMMENTS'' SERIES (RFCs) AND
        !           310:        U.S.~MILITARY STANDARDS (MILSTDs)
        !           311: 
        !           312: \item  CURRENT GENERATION PRIMARILY BASED ON
        !           313:     \begin{nrtc}
        !           314:     \item      CONNECTION-ORIENTED TRANSPORT SERVICE,
        !           315:                PROVIDED BY THE TCP; AND,
        !           316: 
        !           317:     \item      CONNECTIONLESS-MODE NETWORK SERVICE,
        !           318:                PROVIDED BY THE IP
        !           319:     \end{nrtc}
        !           320: 
        !           321: \item  MAJOR EMPHASIS ON CONNECTIVITY OF DIVERSE SUB-NETWORKS
        !           322:     \begin{nrtc}
        !           323:     \item      EXCELLENT RESEARCH CONTINUES, TO THIS DAY, ON THESE ISSUES
        !           324:     \end{nrtc}
        !           325: \end{nrtc}
        !           326: \end{bwslide}
        !           327: 
        !           328: 
        !           329: \begin{bwslide}
        !           330: \ctitle        {INTERNET SUITE (cont.)}
        !           331: 
        !           332: \begin{nrtc}
        !           333: \item  SEVERAL PRODUCTION APPLICATIONS
        !           334:     \begin{nrtc}
        !           335:     \item      SIMPLE MAIL TRANSFER PROTOCOL (SMTP)
        !           336: 
        !           337:     \item      FILE TRANSFER PROTOCOL (FTP)
        !           338: 
        !           339:     \item      TELNET (VIRTUAL TERMINAL PROTOCOL)
        !           340: 
        !           341:     \item      DOMAIN NAME SYSTEM (DNS)
        !           342:     \end{nrtc}
        !           343:     ALL OF WHICH ARE RATHER SIMPLE
        !           344: 
        !           345: \item  APPLICATIONS CONTAIN THEIR OWN IMPLICIT SESSION AND PRESENTATION
        !           346:        MECHANISMS
        !           347: 
        !           348: \item  NOT SURPRISING, CONSIDERING THAT THESE APPLICATIONS ARE ALL BASED ON
        !           349:        15~YEAR OLD MODELS!
        !           350: \end{nrtc}
        !           351: \end{bwslide}
        !           352: 
        !           353: 
        !           354: \begin{bwslide}
        !           355: \ctitle        {INTERNET PROTOCOLS}
        !           356: 
        !           357: \vskip.5in
        !           358: \diagram[p]{figureT-4}
        !           359: \end{bwslide}
        !           360: 
        !           361: 
        !           362: \begin{bwslide}
        !           363: \ctitle        {OSI SUITE}
        !           364: 
        !           365: \begin{nrtc}
        !           366: \item  SPONSORED BY THE INTERNATIONAL COMMUNITY
        !           367:     \begin{nrtc}
        !           368:     \item      IN PARTICULAR THE ISO
        !           369:     \end{nrtc}
        !           370:     BASIS FROM THE OSI REFERENCE MODEL (OSIRM)
        !           371: 
        !           372: \item  SPECIFIED IN ``STANDARDS'' (ISO/IEC)  AND RECOMMENDATIONS (CCITT)
        !           373: 
        !           374: \item  BASED ON
        !           375:     \begin{nrtc}
        !           376:     \item      CONNECTION-ORIENTED TRANSPORT SERVICE,
        !           377:                PROVIDED BY ONE OF FIVE DIFFERENT TPs; DEPENDING ON
        !           378: 
        !           379:     \item      THE NETWORK SERVICE AVAILABLE (CONS or CLNS)
        !           380:     \end{nrtc}
        !           381: 
        !           382: \item  DIFFICULT TO IDENTIFY THE ``MAJOR'' EMPHASIS
        !           383: \end{nrtc}
        !           384: \end{bwslide}
        !           385: 
        !           386: 
        !           387: \begin{bwslide}
        !           388: \ctitle        {OSI SUITE (cont.)}
        !           389: 
        !           390: \begin{nrtc}
        !           391: \item  SEVERAL INTERESTING APPLICATIONS
        !           392:     \begin{nrtc}
        !           393:     \item      MESSAGE HANDLING SYSTEMS (MHS)
        !           394: 
        !           395:     \item      FILE TRANSFER, ACCESS AND MANAGEMENT (FTAM)
        !           396: 
        !           397:     \item      VIRTUAL TERMINAL (VT)
        !           398: 
        !           399:     \item      DIRECTORY SERVICES (DS)
        !           400:     \end{nrtc}
        !           401: 
        !           402: \item  APPLICATIONS EVOLVING QUITE HEAVILY OVER THE LAST FEW YEARS
        !           403: 
        !           404: \item  MUCH MORE AMBITIOUS THAN THEIR INTERNET COUNTERPARTS
        !           405: \end{nrtc}
        !           406: \end{bwslide}
        !           407: 
        !           408: 
        !           409: \begin{bwslide}
        !           410: %%%\ctitle     {OSI PROTOCOLS}
        !           411: 
        !           412: %%%\vskip.25in
        !           413: \diagram[p]{figureT-5}
        !           414: \end{bwslide}
        !           415: 
        !           416: 
        !           417: \begin{bwslide}
        !           418: \ctitle        {A BRIEF COMPARISON}
        !           419: 
        !           420: \begin{nrtc}
        !           421: \item  NOTE THAT CONCERNS DIFFER
        !           422:     \begin{nrtc}
        !           423:     \item      NETWORK USERS: APPLICATION-LEVEL FUNCTIONALITY
        !           424: 
        !           425:     \item      NETWORK ADMINISTRATORS: NETWORK AND TRANSPORT ISSUES
        !           426:     \end{nrtc}
        !           427: 
        !           428: \item  FOR APPLICATIONS, ONCE IMPLEMENTED, THE OSI SUITE IS SUPERIOR
        !           429: 
        !           430: \item  FOR NETWORK/TRANSPORT ISSUES, AT PRESENT,
        !           431:        THE INTERNET SUITE IS SUPERIOR
        !           432: \end{nrtc}
        !           433: \end{bwslide}
        !           434: 
        !           435: 
        !           436: \begin{bwslide}
        !           437: \part* {METRICS FOR COMPARISON}\bf
        !           438: 
        !           439: \begin{nrtc}
        !           440: \item  CAN JUDGE A TRANSITION/COEXISTENCE SCHEME USING DIFFERENT
        !           441:        CRITERIA
        !           442: 
        !           443: \item  THE FOUR WE'LL FOCUS ON ARE ALL SUBJECTIVE;
        !           444:     \begin{nrtc}
        !           445:     \item      TECHNICAL SOLUTIONS DO NOT EXIST IN A VACUUM
        !           446: 
        !           447:     \item      THEY MUST BE EVALUATED IN THE CONTEXT OF A TARGET ENVIRONMENT
        !           448:     \end{nrtc}
        !           449: \end{nrtc}
        !           450: \end{bwslide}
        !           451: 
        !           452: 
        !           453: \begin{bwslide}
        !           454: \ctitle        {METRICS FOR COMPARISON (cont.)}
        !           455: 
        !           456: \begin{nrtc}
        !           457: \item  PERFORMANCE:
        !           458:     \begin{nrtc}
        !           459:     \item      THROUGHPUT, LATENCY
        !           460: 
        !           461:     \item      EFFECT ON OTHER APPLICATIONS
        !           462:     \end{nrtc}
        !           463: 
        !           464: \item  FLEXIBILITY:
        !           465:     \begin{nrtc}
        !           466:     \item      RANGE OF APPLICABILITY
        !           467:     \end{nrtc}
        !           468: \end{nrtc}
        !           469: \end{bwslide}
        !           470: 
        !           471: 
        !           472: \begin{bwslide}
        !           473: \ctitle        {METRICS FOR COMPARISON (cont.)}
        !           474: 
        !           475: \begin{nrtc}
        !           476: \item  TRANSPARENCY:
        !           477:     \begin{nrtc}
        !           478:     \item      USAGE CONTINUITY
        !           479: 
        !           480:     \item      SEAMLESS USER INTERFACE
        !           481:     \end{nrtc}
        !           482: 
        !           483: \item  AMENABILITY:
        !           484:     \begin{nrtc}
        !           485:     \item      MANAGEABILITY
        !           486:     \end{nrtc}
        !           487: \end{nrtc}
        !           488: \end{bwslide}
        !           489: 
        !           490: 
        !           491: \begin{bwslide}
        !           492: \ctitle        {SEVERAL CANDIDATES}
        !           493: 
        !           494: \begin{nrtc}
        !           495: \item  PROTOCOL-BASED APPROACHES
        !           496:     \begin{nrtc}
        !           497:     \item      DUAL STACK
        !           498: 
        !           499:     \item      APPLICATION GATEWAYS
        !           500: 
        !           501:     \item      TRANSPORT GATEWAYS
        !           502:     \end{nrtc}
        !           503: 
        !           504: \item  SERVICE-BASED APPROACHES
        !           505:     \begin{nrtc}
        !           506:     \item      TRANSPORT-SERVICE BRIDGES
        !           507: 
        !           508:     \item      NETWORK TUNNELS
        !           509:     \end{nrtc}
        !           510: 
        !           511: \item  NONE OF THESE TECHNIQUES ARE SPECIFIC TO THE PROBLEM OF
        !           512:     \begin{nrtc}
        !           513:     \item      INTERNET $\mapsto$ OSI
        !           514:     \end{nrtc}
        !           515: \end{nrtc}
        !           516: \end{bwslide}
        !           517: 
        !           518: 
        !           519: \begin{bwslide}
        !           520: \part  {PROTOCOL-BASED APPROACHES}\bf
        !           521: 
        !           522: \begin{nrtc}
        !           523: \item  THE ``STANDARD'' METHODS USED TO INTERCONNECT DIFFERENT
        !           524:        PROTOCOL STACKS
        !           525: 
        !           526: \item  THESE EMPHASIZE THE PROTOCOLS IN EACH STACK
        !           527: 
        !           528: \item  HENCE THEY REINFORCE THE BOUNDARIES BETWEEN TCP/IP AND OSI
        !           529: \end{nrtc}
        !           530: \end{bwslide}
        !           531: 
        !           532: 
        !           533: \begin{bwslide}
        !           534: \part* {DUAL STACK}\bf
        !           535: 
        !           536: \begin{nrtc}
        !           537: \item  PUT BOTH PROTOCOL SUITES IN ALL HOSTS
        !           538: 
        !           539: \item  WORKS WELL, IF YOU CAN CHANGE EVERYTHING ON THE NETWORK
        !           540: \begin{quote}\em
        !           541: ``Nice work, if you can get it.''\\ \raggedleft
        !           542: -- Groucho Marx, Monkey Business, Paramount Pictures (1931)
        !           543: \end{quote}
        !           544: \end{nrtc}
        !           545: \end{bwslide}
        !           546: 
        !           547: 
        !           548: \begin{bwslide}
        !           549: \ctitle        {DUAL STACK (cont.)}
        !           550: 
        !           551: \vskip.5in
        !           552: \diagram[p]{figureT-1}
        !           553: \end{bwslide}
        !           554: 
        !           555: 
        !           556: \begin{bwslide}
        !           557: \ctitle        {TALKING TO UNI-STACK HOSTS}
        !           558: 
        !           559: \begin{nrtc}
        !           560: \item  QUESTION: HOW TO DECIDE WHICH APPLICATION INSTANCE,
        !           561:     \begin{nrtc}
        !           562:     \item      APPL-$\alpha$ OR APPL-$\gamma$,
        !           563:     \end{nrtc}
        !           564:        TO USE?
        !           565: 
        !           566: \item  TWO ANSWERS:
        !           567:     \begin{nrtc}
        !           568:     \item      DEPEND ON THE USER TO KNOW AND INVOKE THE RIGHT PROGRAM
        !           569: 
        !           570:     \item      DEVELOP A GENERIC APPLICATION WHICH SUPPORTS BOTH CLASSES
        !           571:     \end{nrtc}
        !           572: 
        !           573: \item  IN THE LATTER CASE, NEED AN UP-TO-DATE DIRECTORY TO DO THIS RELIABLY
        !           574: \end{nrtc}
        !           575: \end{bwslide}
        !           576: 
        !           577: 
        !           578: \begin{bwslide}
        !           579: \ctitle        {GENERIC APPLICATION INSTANCE}
        !           580: 
        !           581: \vskip.5in
        !           582: \diagram[p]{figureT-6}
        !           583: \end{bwslide}
        !           584: 
        !           585: 
        !           586: \begin{bwslide}
        !           587: \ctitle        {AN IMPLEMENTATION OF DUAL-STACK}
        !           588: 
        !           589: \begin{nrtc}
        !           590: \item  ENVIRONMENT: \unix/~SVR3 (STREAMS)
        !           591: 
        !           592: \item  ACCESS TO LOWER-LAYER PROTOCOLS VIA TRANSPORT LAYER INTERFACE (TLI)
        !           593: 
        !           594: \item  NOTE THAT ALTHOUGH TLI PROVIDES A UNIFORM INTERFACE,
        !           595:        IT DOES NOT PROVIDE A UNIFORM SERVICE:
        !           596:     \begin{nrtc}
        !           597:     \item      PACKET- vs. STREAM-ORIENTATION
        !           598: 
        !           599:     \item      GRACEFUL RELEASE
        !           600: 
        !           601:     \item      EXPEDITED vs. URGENT DATA
        !           602: 
        !           603:     \item      ADDRESSING
        !           604:     \end{nrtc}
        !           605: \end{nrtc}
        !           606: \end{bwslide}
        !           607: 
        !           608: 
        !           609: \begin{bwslide}
        !           610: \ctitle        {GENERIC APPLICATION INSTANCE}
        !           611: 
        !           612: \vskip.5in
        !           613: \diagram[p]{figureT-11}
        !           614: \end{bwslide}
        !           615: 
        !           616: 
        !           617: \begin{bwslide}
        !           618: \ctitle        {SCORECARD}
        !           619: 
        !           620: \begin{nrtc}
        !           621: \item  PERFORMANCE: NO DEGRADATION
        !           622: 
        !           623: \item  FLEXIBILITY: GOOD
        !           624: 
        !           625: \item  TRANSPARENCY:
        !           626:     \begin{nrtc}
        !           627:     \item      ASSUMING REMOTE SYSTEM SUPPORTS AT LEAST ONE OF THE PROTOCOL
        !           628:                STACKS, THEN HIGH TRANSPARENCY BY USING COMMON SERVICE
        !           629:                INTERFACE
        !           630:     \end{nrtc}
        !           631: 
        !           632: \item  AMENABILITY:
        !           633:     \begin{nrtc}
        !           634:     \item      BOTH END- AND INTERMEDIATE-SYSTEMS MUST RUN BOTH PROTOCOLS
        !           635: 
        !           636:     \item      INTRODUCES ADMINISTRATIVE PROBLEMS AS THERE ARE NOW TWO
        !           637:                LOGICAL NETWORKS
        !           638:        \begin{nrtc}
        !           639:        \item   MANAGEMENT OF BOTH \underline{PLUS} CONTENTION BETWEEN THEM
        !           640:        \end{nrtc}
        !           641:     \end{nrtc}
        !           642: \end{nrtc}
        !           643: \end{bwslide}
        !           644: 
        !           645: 
        !           646: \begin{bwslide}
        !           647: \part* {APPLICATION GATEWAYS}\bf
        !           648: 
        !           649: \begin{nrtc}
        !           650: \item  A WELL-KNOWN, BUT LITTLE-UNDERSTOOD TECHNOLOGY
        !           651:     \begin{nrtc}
        !           652:     \item      USED IN MESSAGE HANDLING QUITE A BIT
        !           653:     \end{nrtc}
        !           654: 
        !           655: \item  MOST ARE QUITE TERRIBLE
        !           656: \begin{quote}\em
        !           657: ``Sometimes when you try to turn an apple into an orange you get back a
        !           658: lemon.''\\ \raggedleft
        !           659: -- Michael Padlipsky, The Elements of Networking Style (1985)
        !           660: \end{quote}
        !           661: \end{nrtc}
        !           662: \end{bwslide}
        !           663: 
        !           664: 
        !           665: \begin{bwslide}
        !           666: \ctitle        {APPLICATION GATEWAYS (cont.)}
        !           667: 
        !           668: \vskip.5in
        !           669: \diagram[p]{figureT-2}
        !           670: \end{bwslide}
        !           671: 
        !           672: 
        !           673: \begin{bwslide}
        !           674: \ctitle        {IMPERFECT MAPPINGS}
        !           675: 
        !           676: \begin{nrtc}
        !           677: \item  BECAUSE THEY ARE AT THE HIGHEST LAYER IN THE STACK,
        !           678:        APPLICATION GATEWAYS TEND TO PERFORM SEMANTIC MAPPINGS
        !           679: 
        !           680: \item  THESE ARE ACCOMPANIED BY A LOSS OF INFORMATION
        !           681: 
        !           682: \item  SOMETIMES THE LOSS IS ONLY ANNOYING
        !           683:     \begin{nrtc}
        !           684:     \item      e.g., ``FUNNY LOOKING'' MAIL ADDRESSES
        !           685:     \end{nrtc}
        !           686: 
        !           687: \item  SOMETIMES THE LOSS IS CATASTROPHIC
        !           688:     \begin{nrtc}
        !           689:     \item      e.g., ROUTING LOOPS
        !           690:     \end{nrtc}
        !           691: \end{nrtc}
        !           692: \end{bwslide}
        !           693: 
        !           694: 
        !           695: \begin{bwslide}
        !           696: \ctitle        {AN IMPLEMENATION OF APPLICATION-GATEWAY}
        !           697: 
        !           698: \begin{nrtc}
        !           699: \item  TWO KINDS OF IMPLEMENATIONS
        !           700: 
        !           701: \item  STAGING (TRUE STORE-AND-FORWARD):
        !           702:     \begin{nrtc}
        !           703:     \item      TOP-LEVEL PROTOCOL TRANSACTIONS ARE GROUPED AT THE GATEWAY
        !           704: 
        !           705:     \item      REQUIRES LOCAL STORAGE, BUT MAY PERMIT BETTER MAPPINGS
        !           706:     \end{nrtc}
        !           707: 
        !           708: \item  IN-SITU (VIRTUAL END-TO-END):
        !           709:     \begin{nrtc}
        !           710:     \item      NO PROTOCOL TRANSACTIONS ARE GROUPED
        !           711: 
        !           712:     \item      MAPPINGS ARE ``ON THE FLY''\\ (AND PERHAPS LESS PRECISE)
        !           713: 
        !           714:     \item      END-TO-END RESPONSE IS FASTER
        !           715:     \end{nrtc}
        !           716: \end{nrtc}
        !           717: \end{bwslide}
        !           718: 
        !           719: 
        !           720: \begin{bwslide}
        !           721: \ctitle        {INVOKING THE GATEWAY}
        !           722: 
        !           723: \vskip1.5in
        !           724: \begin{verbatim}
        !           725: % ftp file-gateway
        !           726: Name (file-gateway:asterix): obelix@osi-host
        !           727: Password:
        !           728: \end{verbatim}
        !           729: \end{bwslide}
        !           730: 
        !           731: 
        !           732: \begin{bwslide}
        !           733: \ctitle        {A STAGING IMPLEMENTATION}
        !           734: 
        !           735: \vskip.5in
        !           736: \diagram[p]{figureT-12}
        !           737: \end{bwslide}
        !           738: 
        !           739: 
        !           740: \begin{bwslide}
        !           741: \ctitle        {AN IN-SITU IMPLEMENTATION}
        !           742: 
        !           743: \vskip.5in
        !           744: \diagram[p]{figureT-13}
        !           745: \end{bwslide}
        !           746: 
        !           747: 
        !           748: \begin{bwslide}
        !           749: \ctitle        {SCORECARD}
        !           750: 
        !           751: \begin{nrtc}
        !           752: \item  PERFORMANCE: USUALLY POOR, BUT ACCEPTABLE FOR STORE-AND-FORWARD
        !           753:        APPLICATIONS
        !           754:     \begin{nrtc}
        !           755:     \item      TYPICALLY ALSO INTRODUCES ADDITIONAL NETWORK TRAFFIC
        !           756:     \end{nrtc}
        !           757: 
        !           758: \item  FLEXIBILITY: NONE; EACH A-GWY IS A SPECIAL-PURPOSE SOFTWARE BOX
        !           759: 
        !           760: \item  TRANSPARENCY: 
        !           761:     \begin{nrtc}
        !           762:     \item      TO SERVICE: OFTEN LOSES SIGNIFICANT FUNCTIONALITY
        !           763: 
        !           764:     \item      TO USERS: POSSIBLE, BUT NOT LIKELY (e.g., IN AN FTAM/FTP A-GWY,
        !           765:                USERS EMBED HOSTNAMES IN FILENAMES)
        !           766:     \end{nrtc}
        !           767: 
        !           768: \item  AMENABILITY:
        !           769:     \begin{nrtc}
        !           770:     \item      REQUIRES NO END-SYSTEM MODIFICATION
        !           771: 
        !           772:     \item      MAY INTRODUCE ADMINISTRATIVE PROBLEMS
        !           773:     \end{nrtc}
        !           774: \end{nrtc}
        !           775: \end{bwslide}
        !           776: 
        !           777: 
        !           778: \begin{bwslide}
        !           779: \part* {TRANSPORT GATEWAYS}\bf
        !           780: 
        !           781: \begin{nrtc}
        !           782: \item  IDEA: GATEWAY AT THE TRANSPORT LAYER SO AS TO AVOID NEEDING
        !           783:        MULTIPLE APPLICATION GATEWAYS
        !           784: \begin{quote}\em
        !           785: ``We could do it, but it would be wrong.''\\ \raggedleft
        !           786: -- Richard Nixon, The Watergate Tapes (1974)
        !           787: \end{quote}
        !           788: 
        !           789: \item  ALTHOUGH THE OSI (TP4) AND INTERNET (TCP) TRANSPORT PROTOCOLS DIFFER,
        !           790:        THE SERVICE IS QUITE SIMILAR
        !           791: 
        !           792: \item  HENCE, IT IS TECHNICALLY FEASIBLE TO PERFORM THE MAPPINGS
        !           793:     \begin{nrtc}
        !           794:     \item      (ALTHOUGH IT'S A LOT OF HARD WORK)
        !           795:     \end{nrtc}
        !           796: \end{nrtc}
        !           797: \end{bwslide}
        !           798: 
        !           799: 
        !           800: \begin{bwslide}
        !           801: \ctitle        {TRANSPORT GATEWAYS (cont.)}
        !           802: 
        !           803: \vskip.5in
        !           804: \diagram[p]{figureT-14}
        !           805: \end{bwslide}
        !           806: 
        !           807: 
        !           808: \begin{bwslide}
        !           809: \ctitle        {THE OBVIOUS QUESTION}
        !           810: 
        !           811: \begin{nrtc}
        !           812: \item  WHAT APPLICATION DO YOU RUN WHEN USING THIS?
        !           813:     \begin{nrtc}
        !           814:     \item      CAN'T RUN INTERNET APPLICATIONS IN THE OSI NETWORK,
        !           815:                SINCE THE TRANSPORT GATEWAY YIELDS OSI TRANSPORT SEMANTICS
        !           816: 
        !           817:     \item      CAN'T RUN OSI APPLICATIONS IN THE INTERNET NETWORK,
        !           818:                SINCE THE TRANSPORT GATEWAY YIELDS INTERNET TRANSPORT SEMANTICS
        !           819:     \end{nrtc}
        !           820: 
        !           821: \item  THIS APPROACH FAILS BECAUSE IT PRESENTS DIFFERENT SERVICE SEMANTICS
        !           822:        IN EACH NETWORK
        !           823: \end{nrtc}
        !           824: \end{bwslide}
        !           825: 
        !           826: 
        !           827: \begin{bwslide}
        !           828: \part  {SERVICE-BASED APPROACHES}\bf
        !           829: 
        !           830: \begin{nrtc}
        !           831: \item  BY THE TIME OSI-BASED NETWORKS ARE TRULY WIDESPREAD,
        !           832:        TCP/IP-BASED NETWORKS WILL ALREADY OFFER A MIX OF SERVICES:
        !           833:     \begin{nrtc}
        !           834:     \item      SUCH AS FTAM AND MHS, IN ADDITION TO FTP AND SMTP
        !           835:     \end{nrtc}
        !           836: 
        !           837: \item  IN OTHER WORDS, PERHAPS THE TRANSITION TO OSI BEGINS WITH NEW
        !           838:        APPLICATIONS ON HOSTS AND NO CHANGES TO THE NETWORK
        !           839: \end{nrtc}
        !           840: \end{bwslide}
        !           841: 
        !           842: 
        !           843: \begin{bwslide}
        !           844: \ctitle        {WOULD THIS REALLY HAPPEN?}
        !           845: 
        !           846: \begin{nrtc}
        !           847: \item  RECALL THAT USERS ARE INTERESTED IN \underline{SERVICES} NOT
        !           848:        \underline{PROTOCOLS}
        !           849: 
        !           850: \item  THE OSI APPLICATIONS ARE MUCH RICHER THAN THEIR INTERNET COUNTERPARTS
        !           851: 
        !           852: \item  IN CONTRAST, AT THE LOWER-LAYERS THE INTERNET SUITE ``WORKS BETTER''
        !           853:     \begin{nrtc}
        !           854:     \item      AS SUCH, IT IS UNLIKELY TO BE REPLACED BY THE OSI LOWER-LAYERS
        !           855:                FOR QUITE SOME TIME
        !           856:     \end{nrtc}
        !           857: \end{nrtc}
        !           858: \end{bwslide}
        !           859: 
        !           860: 
        !           861: \begin{bwslide}
        !           862: \ctitle        {OBSERVATION}
        !           863: 
        !           864: \begin{nrtc}
        !           865: \item  GIVEN THE ABOVE ASSUMPTION, IT SHOULD BE NOTED THAT:
        !           866:     \begin{nrtc}
        !           867:     \item      WE HAVE TWO COMMUNITIES USING THE SAME APPLICATIONS
        !           868:                (OSI), AND
        !           869: 
        !           870:     \item      ONLY THE UNDERLYING ``TS-STACK'' WILL DIFFER BETWEEN THE TWO:
        !           871:        \begin{nrtc}
        !           872:        \item   IN THE OSI COMMUNITY: TP4/CLNP/$\ldots$
        !           873: 
        !           874:        \item   IN THE TCP COMMUNITY: RFC1006/TCP/IP/$\ldots$
        !           875:        \end{nrtc}
        !           876:     \end{nrtc}
        !           877: 
        !           878: \item  THIS LEADS US TO POSTULATE AN INTERESTING COEXISTENCE
        !           879:        STRATEGY:
        !           880:     \begin{nrtc}
        !           881:     \item      LET'S RUN OSI APPLICATIONS, END-TO-END, BETWEEN THE TWO
        !           882:     \end{nrtc}
        !           883: 
        !           884: \item  IN A SENSE, THIS IS A HYBRID OF THE TWO PREVIOUS APPROACHES,
        !           885:        INTENDED TO MINIMIZE THE DISADVANTAGES OF EACH
        !           886:     \begin{nrtc}
        !           887:        \item   SAME APPLICATION PROTOCOL,\\
        !           888:                BUT DIFFERENT UNDERYLING LAYERS
        !           889:     \end{nrtc}
        !           890: \end{nrtc}
        !           891: \end{bwslide}
        !           892: 
        !           893: 
        !           894: \begin{bwslide}
        !           895: \part* {TRANSPORT-SERVICE BRIDGES}\bf
        !           896: 
        !           897: \begin{nrtc}
        !           898: \item  INTRODUCE A TRANSPORT ENTITY CALLED THE ``TS-BRIDGE''
        !           899: \begin{quote}\em
        !           900: ``Users are interested in services, not protocols.''\\ \raggedleft
        !           901: -- Marshall Rose, NYSERNet, Inc.
        !           902: \end{quote}
        !           903: 
        !           904: \item  ALTHOUGH MANY DIFFERENT TS-STACKS EXIST,
        !           905:        THEY ALL PROVIDE THE SAME TRANSPORT SERVICE
        !           906: 
        !           907: \item  SO, IT IS STRAIGHT-FORWARD TO BUILD A BOX THAT:
        !           908:     \begin{nrtc}
        !           909:     \item      KNOWS NOTHING ABOUT TRANSPORT PROTOCOLS, BUT
        !           910: 
        !           911:     \item      KNOWS HOW TO USE THE RELATIVELY SIMPLE OSI TRANSPORT SERVICE
        !           912:     \end{nrtc}
        !           913: \end{nrtc}
        !           914: \end{bwslide}
        !           915: 
        !           916: 
        !           917: \begin{bwslide}
        !           918: \ctitle        {TRANSPORT-SERVICE BRIDGES (cont.)}
        !           919: 
        !           920: \begin{nrtc}
        !           921: \item  THE TS-BRIDGE ``COPIES'' SERVICE PRIMITIVES FROM ONE TS-STACK TO THE
        !           922:        OTHER, e.g.:
        !           923:     \begin{nrtc}
        !           924:     \item      UPON RECEIVING A T-CONNECT.INDICATION PRIMITIVE FROM ONE
        !           925:                TS-STACK,
        !           926: 
        !           927:     \item      IT ISSUES A T-CONNECT.REQUEST PRIMITIVE TO THE OTHER TS-STACK
        !           928:     \end{nrtc}
        !           929: \end{nrtc}
        !           930: \end{bwslide}
        !           931: 
        !           932: 
        !           933: \begin{bwslide}
        !           934: \ctitle        {TRANSPORT-SERVICE BRIDGES (cont.)}
        !           935: 
        !           936: \vskip.5in
        !           937: \diagram[p]{figureT-9}
        !           938: \end{bwslide}
        !           939: 
        !           940: 
        !           941: \begin{bwslide}
        !           942: \ctitle        {CONS vs. CLNS CONNECTIVITY}
        !           943: 
        !           944: \vskip.5in
        !           945: \diagram[p]{figureT-19}
        !           946: \end{bwslide}
        !           947: 
        !           948: 
        !           949: \begin{bwslide}
        !           950: \ctitle        {USE OF THE TS-BRIDGE (cont.)}
        !           951: 
        !           952: \begin{nrtc}
        !           953: \item  ENCODE THE NETWORK ADDRESS AND TRANSPORT SELECTOR AS AN OCTET STRING,
        !           954:        CALL THIS THE NEW TRANSPORT SELECTOR
        !           955: 
        !           956: \item  USE THE NETWORK ADDRESS OF THE TS-BRIDGE FOR THE REMAINING STEPS
        !           957: 
        !           958: \item  WHEN TS-BRIDGE RECEIVES CONNECTION,
        !           959:        IT SIMPLY DECODES TRANSPORT SELECTOR TO FIND ADDRESS OF
        !           960:        DESTINATION END-SYSTEM
        !           961: \end{nrtc}
        !           962: \end{bwslide}
        !           963: 
        !           964: 
        !           965: \begin{bwslide}
        !           966: \ctitle        {TS-BRIDGE ADDRESSING}
        !           967: 
        !           968: \vskip.5in
        !           969: \diagram[p]{figureT-20}
        !           970: \end{bwslide}
        !           971: 
        !           972: 
        !           973: \begin{bwslide}
        !           974: \ctitle        {THE TS-BRIDGE AND THE OSI MODEL}
        !           975: 
        !           976: \begin{nrtc}
        !           977: \item  THE TS-BRIDGE IS A LEVEL-FOUR ROUTER
        !           978: 
        !           979: \item  POTENTIAL PROBLEMS:
        !           980:     \begin{nrtc}
        !           981:     \item      THE TS-BRIDGE MAINTAINS STATE AS TO THE EXISTING CONNECTIONS
        !           982: 
        !           983:     \item      TWO CHECKSUMS, AND NEITHER REALLY END-TO-END
        !           984: 
        !           985:     \item      \underline{MAY} THWART SOPHISTICATED BACK-PRESSURE TECHNIQUES
        !           986:     \end{nrtc}
        !           987: \end{nrtc}
        !           988: \end{bwslide}
        !           989: 
        !           990: 
        !           991: \begin{bwslide}
        !           992: \ctitle        {AN IMPLEMENTATION OF THE TS-BRIDGE}
        !           993: 
        !           994: \begin{nrtc}
        !           995: \item  FIRST DEMONSTRATION IN FEBRUARY, 1988
        !           996:     \begin{nrtc}
        !           997:     \item      TP4/CLNP to RFC1006/TCP
        !           998:     \end{nrtc}
        !           999: 
        !          1000: \item  ANOTHER IMPLEMENTATION IN EUROPE IS HANDLING
        !          1001:     \begin{nrtc}
        !          1002:     \item      TP0/X.25 to RFC1006/TCP
        !          1003:     \end{nrtc}
        !          1004: \end{nrtc}
        !          1005: \end{bwslide}
        !          1006: 
        !          1007: 
        !          1008: \begin{bwslide}
        !          1009: \ctitle        {SCORECARD}
        !          1010: 
        !          1011: \begin{nrtc}
        !          1012: \item  PERFORMANCE: FAIR; WHEN TS-BRIDGE IS MADE INTO A KERNEL-RESIDENT
        !          1013:        STREAMS MODULE IT SHOULD IMPROVE DRAMATICALLY
        !          1014: 
        !          1015: \item  FLEXIBILITY: HIGH; INDEPENDENT OF ANY APPLICATION
        !          1016: 
        !          1017: \item  TRANSPARENCY: TOTAL
        !          1018: 
        !          1019: \item  AMENABILITY:
        !          1020:     \begin{nrtc}
        !          1021:     \item      TCP END-SYSTEMS MUST RUN ``NEW'' PROTOCOLS
        !          1022:        \begin{nrtc}
        !          1023:        \item   BUT, NO MODIFICATIONS REQUIRED TO END-SYSTEM KERNELS
        !          1024:        \end{nrtc}
        !          1025: 
        !          1026:     \item      MAY INTRODUCE ADMINISTRATIVE PROBLEMS
        !          1027:     \end{nrtc}
        !          1028: \end{nrtc}
        !          1029: \end{bwslide}
        !          1030: 
        !          1031: 
        !          1032: \begin{bwslide}
        !          1033: \part* {NETWORK TUNNELS}\bf
        !          1034: 
        !          1035: \begin{nrtc}
        !          1036: \item  IDEA: ENCAPSULATE CLNP INSIDE OF IP, TREATING IP AS SIMPLY A DATA LINK
        !          1037:        PROTOCOL
        !          1038: \begin{quote}\em
        !          1039: ``Encapsulation complies with the layering concept, but violates the notion
        !          1040: of absolute levels.''\\ \raggedleft
        !          1041: -- Danny Cohen and Jon Postel, ``The ISO Reference Model and Other Protocol
        !          1042: Architectures'' (1983)
        !          1043: \end{quote}
        !          1044: 
        !          1045: \item  NS-TUNNEL PERFORMS AS A ROUTER, REMOVING ONE DATA LINK HEADER AND
        !          1046:        ADDING ANOTHER
        !          1047: 
        !          1048: \item  METHOD SPECIFIED IN [RFC1070]
        !          1049: 
        !          1050: \item  ADDRESS MAPPINGS SPECIFIED IN [RFC1069] 
        !          1051: \end{nrtc}
        !          1052: \end{bwslide}
        !          1053: 
        !          1054: 
        !          1055: \begin{bwslide}
        !          1056: \ctitle        {TUNNELING}
        !          1057: 
        !          1058: \vskip.5in
        !          1059: \diagram[p]{figureT-18}
        !          1060: \end{bwslide}
        !          1061: 
        !          1062: 
        !          1063: \begin{bwslide}
        !          1064: \ctitle        {NETWORK TUNNELS}
        !          1065: 
        !          1066: \vskip.5in
        !          1067: \diagram[p]{figureT-10}
        !          1068: \end{bwslide}
        !          1069: 
        !          1070: 
        !          1071: \begin{bwslide}
        !          1072: \ctitle        {INTERESTING FEATURES}
        !          1073: 
        !          1074: \begin{nrtc}
        !          1075: \item  NO STATE MAINTAINED BY NS-TUNNEL
        !          1076: 
        !          1077: \item  A TRUE END-TO-END CHECKSUM
        !          1078: \end{nrtc}
        !          1079: \end{bwslide}
        !          1080: 
        !          1081: 
        !          1082: \begin{bwslide}
        !          1083: \ctitle        {POTENTIAL PROBLEMS}
        !          1084: 
        !          1085: \begin{nrtc}
        !          1086: \item  REQUIRES COMMON HIGHER-LEVEL PROTOCOLS (TRANSPORT AND ABOVE) ON BOTH
        !          1087:        END-SYSTEMS, BUT DOES NOT REQUIRE ALL INTERVENING ROUTERS TO USE THE
        !          1088:        SAME NETWORK PROTOCOL
        !          1089: 
        !          1090: \item  THE TCP END-SYSTEM IMPLEMENTATION CHOICES ARE SIMILAR TO NETBIOS OVER
        !          1091:        TCP [RFC1001/1002]
        !          1092: \end{nrtc}
        !          1093: \end{bwslide}
        !          1094: 
        !          1095: 
        !          1096: \begin{bwslide}
        !          1097: \ctitle        {AN IMPLEMENATION OF AN NS-TUNNEL}
        !          1098: 
        !          1099: \begin{nrtc}
        !          1100: \item  HAVEN'T SEE ANY YET
        !          1101:     \begin{nrtc}
        !          1102:     \item      BUT WILL BE IN 4.4BSD UNIX
        !          1103:     \end{nrtc}
        !          1104: 
        !          1105: \item  NEED A LOT OF CLNP-BASED NETWORKS BEFORE THIS IS OF USE
        !          1106: 
        !          1107: \item  SO THIS WILL HAPPEN AT THE END OF THE TRANSITION PERIOD
        !          1108: \end{nrtc}
        !          1109: \end{bwslide}
        !          1110: 
        !          1111: 
        !          1112: \begin{bwslide}
        !          1113: \ctitle        {SCORECARD}
        !          1114: 
        !          1115: \begin{nrtc}
        !          1116: \item  PERFORMANCE: NO WORSE THAN TYPICAL CLNP-ROUTER (AND PROBABLY A LOT
        !          1117:        BETTER TOO!)
        !          1118: 
        !          1119: \item  FLEXIBILITY: HIGH (INDEPENDENT OF ANY APPLICATION)
        !          1120: 
        !          1121: \item  TRANSPARENCY: TOTAL
        !          1122: 
        !          1123: \item  AMENABILITY: TCP END-SYSTEMS MUST RUN BOTH TRANSPORT PROTOCOLS
        !          1124: \end{nrtc}
        !          1125: \end{bwslide}
        !          1126: 
        !          1127: 
        !          1128: \begin{bwslide}
        !          1129: \part  {EXAMPLES}\bf
        !          1130: 
        !          1131: \begin{nrtc}
        !          1132: \item  U.S.~DoD OSI IMPLEMENTATION PLAN
        !          1133: 
        !          1134: \item  GENERIC EXAMPLE
        !          1135: 
        !          1136: \item  CONCLUSIONS
        !          1137: \end{nrtc}
        !          1138: \end{bwslide}
        !          1139: 
        !          1140: 
        !          1141: \begin{bwslide}
        !          1142: \part* {U.S.~DoD OSI\\ IMPLEMENTATION PLAN}\bf
        !          1143: 
        !          1144: \begin{nrtc}
        !          1145: \item  IMPLEMENT CAPABILITY TO USE OSI IN DoD INTERNETWORK ENVIRONMENT
        !          1146:     \begin{nrtc}
        !          1147:     \item      OSI-POSIX PROJECT
        !          1148:     \end{nrtc}
        !          1149: 
        !          1150: \item  PROVIDE THE CAPABILITY FOR U.S.~DoD AND OSI PROTOCOLS TO INTEROPERATE
        !          1151:     \begin{nrtc}
        !          1152:     \item      FTAM-FTP GATEWAY
        !          1153: 
        !          1154:     \item      MHS-SMTP GATEWAY
        !          1155:     \end{nrtc}
        !          1156: \end{nrtc}
        !          1157: \end{bwslide}
        !          1158: 
        !          1159: 
        !          1160: \begin{bwslide}
        !          1161: \ctitle        {OSI-POSIX PROJECT}
        !          1162: 
        !          1163: \begin{nrtc}
        !          1164: \item  GOAL: ACCELLERATE THE UBIQUITY OF OSI
        !          1165: 
        !          1166: \item  APPROACH: OPENLY AVAILABLE, COMPLETE OSI IMPLEMENTATION FOR NEXT MAJOR
        !          1167:        RELEASE OF BERKELEY \unix/
        !          1168: 
        !          1169: \item  FOR MORE DETAILS:
        !          1170: \begin{quote}
        !          1171: OSI PROTOCOLS WITHIN AN OPENLY AVAILABLE, POSIX-CONFORMANT, BERKELEY UNIX
        !          1172: ENVIRONMENT
        !          1173: \end{quote}
        !          1174: APPEARING IN ConneXions, OCTOBER, 1988
        !          1175: \end{nrtc}
        !          1176: \end{bwslide}
        !          1177: 
        !          1178: 
        !          1179: \begin{bwslide}
        !          1180: \diagram[p]{figureT-15}
        !          1181: \end{bwslide}
        !          1182: 
        !          1183: 
        !          1184: \begin{bwslide}
        !          1185: \diagram[p]{figureT-16}
        !          1186: \end{bwslide}
        !          1187: 
        !          1188: 
        !          1189: \begin{bwslide}
        !          1190: \part* {GENERIC EXAMPLE}\bf
        !          1191: 
        !          1192: \begin{nrtc}
        !          1193: \item  TWO PRONGS:
        !          1194:     \begin{nrtc}
        !          1195:     \item      FAVOR USE OF OSI APPLICATIONS OVER TCP ON LAN MESH
        !          1196: 
        !          1197:     \item      LOCATE APPLICATION GATEWAYS AND A TS-BRIDGE ON ALL NODES
        !          1198:                WITH WAN ATTACHMENETS
        !          1199:     \end{nrtc}
        !          1200: 
        !          1201: \item  AWAIT OSI LOWER-LAYERS TO BECOME COMPETITIVE
        !          1202: \end{nrtc}
        !          1203: \end{bwslide}
        !          1204: 
        !          1205: 
        !          1206: \begin{bwslide}
        !          1207: \ctitle        {GENERIC EXAMPLE (cont.)}
        !          1208: 
        !          1209: \begin{nrtc}
        !          1210: \item  EACH ATTACHMENT LOCUS SHOULD SUPPORT COEXISTENCE SERVICES
        !          1211: 
        !          1212: \item  IF RESOURCES PERMIT, SELECT ONE OTHER SYSTEM TO SUPPORT THESE
        !          1213:        SERVICES FOR USE BY LOCAL UNI-STACK HOSTS
        !          1214: 
        !          1215: \item  THIS ``COVERS ALL BASES'' BY HANDLING ALL POSSIBLE OSI COMBINATIONS
        !          1216:        WITH A BIT OF EXTRA REDUNDANCY
        !          1217: 
        !          1218: \item  MIGHT REQUIRE A BIT OF SOPHISTICATED USE FROM THE DIRECTORY
        !          1219: \end{nrtc}
        !          1220: \end{bwslide}
        !          1221: 
        !          1222: 
        !          1223: \begin{bwslide}
        !          1224: \ctitle        {A LAN OF MANY COLORS}
        !          1225: 
        !          1226: \vskip.5in
        !          1227: \diagram[p]{figureT-17}
        !          1228: \end{bwslide}
        !          1229: 
        !          1230: 
        !          1231: \begin{bwslide}
        !          1232: \part* {CONCLUSIONS}\bf
        !          1233: 
        !          1234: \begin{quote}\em
        !          1235: ``Optimality differs according to context.''\\ \raggedleft
        !          1236: -- Michael Padlipsky, The Elements of Networking Style (1985)
        !          1237: \end{quote}
        !          1238: \end{bwslide}
        !          1239: 
        !          1240: 
        !          1241: \begin{bwslide}
        !          1242: \ctitle        {CONCLUSIONS (cont.)}
        !          1243: 
        !          1244: \begin{nrtc}
        !          1245: \item  TCP/IP-BASED NETWORKS WILL OFFER OSI APPLICATIONS
        !          1246: 
        !          1247: \item  COEXISTENCE IN THE SHORT TERM:
        !          1248:     \begin{nrtc}
        !          1249:     \item      TS-BRIDGE MINIMIZES SOFTWARE INVESTMENT
        !          1250:     \end{nrtc}
        !          1251: 
        !          1252: \item  COEXISTENCE IN THE LONG TERM:
        !          1253:     \begin{nrtc}
        !          1254:     \item      NS-TUNNEL MAXIMIZES PERFORMANCE AND ROBUSTNESS
        !          1255:     \end{nrtc}
        !          1256: 
        !          1257: \item  IF/WHEN THERE ARE NO MORE TCP/IP-BASED NETWORKS, THEN THE
        !          1258:        COEXISTENCE PERIOD IS OVER, AND TRANSITION IS A NON-ISSUE!
        !          1259: \end{nrtc}
        !          1260: \end{bwslide}
        !          1261: 
        !          1262: \end{document}

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