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1.1     ! root        1: % -*- LaTeX -*-                (really SLiTeX)
        !             2: 
        !             3: \documentstyle[blackandwhite,landscape,oval,pagenumbers,small]{NRslides}
        !             4: 
        !             5: 
        !             6: \font\xx=cmbx10
        !             7: \font\yy=cmbx7
        !             8: 
        !             9: \raggedright
        !            10: 
        !            11: \input trademark
        !            12: \let\tradeNAMfont=\relax
        !            13: \let\tradeORGfont=\relax
        !            14: 
        !            15: \begin{document}
        !            16: 
        !            17: \title {Issues in Transition and Coexistence\\ for TCP/IP to OSI}
        !            18: \author        {Marshall T.~Rose\\ The Wollongong Group, Inc.}
        !            19: \date  {November 29, 1988}
        !            20: \maketitlepage
        !            21: 
        !            22: 
        !            23: \begin{bwslide}
        !            24: \part* {AGENDA}\bf
        !            25: 
        !            26: \begin{description}
        !            27: \item[PART I:]         MOTIVATION
        !            28: 
        !            29: \item[PART II:]                BACKGROUND
        !            30: 
        !            31: \item[PART III:]       PROTOCOL-BASED APPROACHES
        !            32: 
        !            33: \item[PART IV:]                RE-DEFINING THE PROBLEM
        !            34: 
        !            35: \item[PART V:]         SERVICE-BASED APPROACHES
        !            36: 
        !            37: \item[PART VI:]                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: ``$\ldots$ protection of 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: 
        !           105: \item  THE SAD TRUTH:
        !           106: \begin{quote}\em
        !           107: ``You can't win, and you can't quit, but you \underline{can} reduce the
        !           108: pain.''\\ \raggedleft
        !           109: -- Marshall Rose, The Wollongong Group
        !           110: \end{quote}
        !           111: 
        !           112: \end{nrtc}
        !           113: \end{bwslide}
        !           114: 
        !           115: 
        !           116: \begin{bwslide}
        !           117: \part  {BACKGROUND}\bf
        !           118: 
        !           119: \begin{nrtc}
        !           120: \item  CONCEPTS
        !           121: 
        !           122: \item  TERMINOLOGY
        !           123: 
        !           124: \item  HISTORY
        !           125: 
        !           126: \item  METRICS FOR COMPARISON
        !           127: \end{nrtc}
        !           128: \end{bwslide}
        !           129: 
        !           130: 
        !           131: \begin{bwslide}
        !           132: \ctitle        {THE FUNDAMENTAL ASSUMPTION}
        !           133: 
        !           134: \begin{nrtc}
        !           135: \item  TCP/IP IS HERE TODAY, WIDELY INSTALLED, AND USEFUL
        !           136: 
        !           137: \item  OSI WILL EVENTUALLY REPLACE TCP/IP AS THE OFF-THE-SHELF TECHNOLOGY FOR
        !           138:        BUILDING INTEROPERABLE SYSTMS
        !           139: 
        !           140: \item  BOTH WILL BE SIMULTANEOUSLY WIDESPREAD FOR QUITE SOME TIME
        !           141:     \begin{nrtc}
        !           142:     \item      DURING WHICH OSI WILL GAIN DOMINANCE
        !           143:     \end{nrtc}
        !           144: \end{nrtc}
        !           145: \end{bwslide}
        !           146: 
        !           147: 
        !           148: \begin{bwslide}
        !           149: \part* {CONCEPTS}\bf
        !           150: 
        !           151: \begin{nrtc}
        !           152: \item  TRANSITION:
        !           153:     \begin{nrtc}
        !           154:     \item      TO MOVE FROM ONE PROTOCOL SUITE TO ANOTHER
        !           155:     \end{nrtc}
        !           156: 
        !           157: \item  COEXISTENCE:
        !           158:     \begin{nrtc}
        !           159:     \item      TO LIVE TOGETHER WITHOUT HOSTILITY OR CONFLICT DESPITE
        !           160:                DIFFERENCES
        !           161:     \end{nrtc}
        !           162: 
        !           163: \item  MIGRATION:
        !           164:     \begin{nrtc}
        !           165:     \item      TO MOVE BACK AND FORTH, AS THE SEASONS CHANGE
        !           166:     \end{nrtc}
        !           167: \end{nrtc}
        !           168: \end{bwslide}
        !           169: 
        !           170: 
        !           171: \begin{bwslide}
        !           172: \ctitle        {MAPPINGS}
        !           173: 
        !           174: \begin{nrtc}
        !           175: \item  TRANSITION AND COEXISTENCE CAN BE DESCRIBED BY THE MAPPINGS THEY
        !           176:        REQUIRE
        !           177: 
        !           178: \item  SOME MAPPINGS ARE SIMPLE
        !           179:     \begin{nrtc}
        !           180:     \item      i.e., SYNTACTIC CHANGES
        !           181:     \end{nrtc}
        !           182: 
        !           183: \item  SOME MAPPINGS ARE COMPLEX
        !           184:     \begin{nrtc}
        !           185:     \item      i.e., SEMANTIC CHANGES
        !           186:     \end{nrtc}
        !           187: 
        !           188: \item  THE MORE COMPLEX THE MAPPING, THE GREATER THE LOSS OF INFORMATION OR
        !           189:        INTENT
        !           190: \end{nrtc}
        !           191: \end{bwslide}
        !           192: 
        !           193: 
        !           194: \begin{bwslide}
        !           195: \part* {TERMINOLOGY}\bf
        !           196: 
        !           197: \begin{nrtc}
        !           198: \item  WE'LL FAVOR OSI TERMINOLOGY, BUT STILL NEED SOME INTERNET (TCP/IP)
        !           199:        TERMINOLOGY
        !           200: 
        !           201: \item  TWO BASIC TERMS
        !           202:     \begin{nrtc}
        !           203:     \item      GATEWAY: GENERIC TO ANY LEVEL, COMPLEX
        !           204: 
        !           205:     \item      BRIDGE: GENERIC TO ANY LEVEL, SIMPLE
        !           206:     \end{nrtc}
        !           207: \end{nrtc}
        !           208: \end{bwslide}
        !           209: 
        !           210: 
        !           211: \begin{bwslide}
        !           212: \ctitle        {SERVICE SEMANTICS}
        !           213: 
        !           214: \begin{nrtc}
        !           215: \item  STORE-AND-FORWARD
        !           216:     \begin{nrtc}
        !           217:     \item      SERVICE SEMANTICS CARRIED MULTI-HOP VIA FORWARDERS
        !           218:     \end{nrtc}
        !           219: 
        !           220: \item  END-TO-END
        !           221:     \begin{nrtc}
        !           222:     \item      SERVICE SEMANTICS CARRIED FROM ORIGINATOR TO RECIPIENT
        !           223: 
        !           224:     \item      MAY BE SUPPORTED BY AN UNDERYLING STORE-AND-FORWARD SERVICE
        !           225:     \end{nrtc}
        !           226: \end{nrtc}
        !           227: \end{bwslide}
        !           228: 
        !           229: 
        !           230: \begin{bwslide}
        !           231: \ctitle        {SERVICE SEMANTICS (cont.)}
        !           232: 
        !           233: \vskip.5in
        !           234: \diagram[p]{figure3}
        !           235: \end{bwslide}
        !           236: 
        !           237: 
        !           238: \begin{bwslide}
        !           239: \ctitle        {PROTOCOL SUITE}
        !           240: 
        !           241: \begin{nrtc}
        !           242: \item  A COLLECTION OF PROTOCOLS RELATED:
        !           243:     \begin{nrtc}
        !           244:     \item      ADMINISTRATIVELY, BY AN ORGANIZATION\\ (e.g., ISO/IEC); and,
        !           245: 
        !           246:     \item      PHILOSOPHICALLY, BY A REFERENCE MODEL\\ (e.g., the ARM)
        !           247:     \end{nrtc}
        !           248: 
        !           249: \item  FOR OUR PURPOSES, THERE ARE ONLY TWO:
        !           250:     \begin{nrtc}
        !           251:     \item      THE OSI SUITE OF PROTOCOLS
        !           252: 
        !           253:     \item      THE INTERNET SUITE OF PROTOCOLS
        !           254:     \end{nrtc}
        !           255: \end{nrtc}
        !           256: \end{bwslide}
        !           257: 
        !           258: 
        !           259: \begin{bwslide}
        !           260: \ctitle        {APPLICATIONS}
        !           261: 
        !           262: \begin{nrtc}
        !           263: \item  APPLICATION CLASS
        !           264:     \begin{nrtc}
        !           265:     \item      A SET OF APPLICATIONS RELATED TO A PARTICULAR ACTIVITY,
        !           266:                e.g., FILE TRANSFER, IRREGARDLESS OF PROTOCOL SUITE
        !           267:     \end{nrtc}
        !           268: 
        !           269: \item  APPLICATION INSTANCE
        !           270:     \begin{nrtc}
        !           271:     \item      A MEMBER OF AN APPLICATION CLASS SPECIFIC TO A PARTICULAR
        !           272:                PROTOCOL SUITE, e.g., FTAM
        !           273:     \end{nrtc}
        !           274: \end{nrtc}
        !           275: \end{bwslide}
        !           276: 
        !           277: 
        !           278: \begin{bwslide}
        !           279: \part* {HISTORY}\bf
        !           280: 
        !           281: \begin{nrtc}
        !           282: \item  A VERY BRIEF INTRODUCTION TO THE TWO PROTOCOL SUITES
        !           283: 
        !           284: \item  WE'LL ATTEMPT TO TAKE A NON-PARTISAN VIEW (ha!)
        !           285: \end{nrtc}
        !           286: \end{bwslide}
        !           287: 
        !           288: 
        !           289: \begin{bwslide}
        !           290: \ctitle        {INTERNET SUITE}
        !           291: 
        !           292: \begin{nrtc}
        !           293: \item  SPONSORED BY THE U.S.~DoD
        !           294:     \begin{nrtc}
        !           295:     \item      GREW OUT OF EARLY (D)ARPA RESEARCH INTO SURVIVABLE NETWORKS
        !           296:     \end{nrtc}
        !           297:     BASIS FROM THE ARPANET REFERENCE MODEL (ARM)
        !           298: 
        !           299: \item  SPECIFIED IN ``REQUEST FOR COMMENTS'' SERIES (RFCs) AND
        !           300:        U.S.~MILITARY STANDARDS (MILSTDs)
        !           301: 
        !           302: \item  CURRENT GENERATION BASED ON
        !           303:     \begin{nrtc}
        !           304:     \item      CONNECTION-ORIENTED TRANSPORT SERVICE,
        !           305:                PROVIDED BY THE TCP; AND,
        !           306: 
        !           307:     \item      CONNECTIONLESS-MODE NETWORK SERVICE,
        !           308:                PROVIDED BY THE IP
        !           309:     \end{nrtc}
        !           310: 
        !           311: \item  MAJOR EMPHASIS ON CONNECTIVITY OF DIVERSE SUB-NETWORKS
        !           312:     \begin{nrtc}
        !           313:     \item      EXCELLENT RESEARCH CONTINUES, TO THIS DAY, ON THESE ISSUES
        !           314:     \end{nrtc}
        !           315: \end{nrtc}
        !           316: \end{bwslide}
        !           317: 
        !           318: 
        !           319: \begin{bwslide}
        !           320: \ctitle        {INTERNET SUITE (cont.)}
        !           321: 
        !           322: \begin{nrtc}
        !           323: \item  SEVERAL PRODUCTION APPLICATIONS
        !           324:     \begin{nrtc}
        !           325:     \item      SIMPLE MAIL TRANSFER PROTOCOL (SMTP)
        !           326: 
        !           327:     \item      FILE TRANSFER PROTOCOL (FTP)
        !           328: 
        !           329:     \item      TELNET (VIRTUAL TERMINAL PROTOCOL)
        !           330: 
        !           331:     \item      DOMAIN NAME SYSTEM (DNS)
        !           332:     \end{nrtc}
        !           333:     ALL OF WHICH ARE RATHER SIMPLE
        !           334: 
        !           335: \item  APPLICATIONS CONTAIN THEIR OWN IMPLICIT SESSION AND PRESENTATION
        !           336:        MECHANISMS
        !           337: 
        !           338: \item  NOT SURPRISING, CONSIDERING THAT THESE APPLICATIONS ARE ALL BASED ON
        !           339:        15~YEAR OLD MODELS!
        !           340: \end{nrtc}
        !           341: \end{bwslide}
        !           342: 
        !           343: 
        !           344: \begin{bwslide}
        !           345: \ctitle        {INTERNET PROTOCOLS}
        !           346: 
        !           347: \vskip.5in
        !           348: \diagram[p]{figure4}
        !           349: \end{bwslide}
        !           350: 
        !           351: 
        !           352: \begin{bwslide}
        !           353: \ctitle        {OSI SUITE}
        !           354: 
        !           355: \begin{nrtc}
        !           356: \item  SPONSORED BY THE INTERNATIONAL COMMUNITY
        !           357:     \begin{nrtc}
        !           358:     \item      IN PARTICULAR THE ISO
        !           359:     \end{nrtc}
        !           360:     BASIS FROM THE OSI REFERENCE MODEL (OSIRM)
        !           361: 
        !           362: \item  SPECIFIED IN ``STANDARDS'' (ISO/IEC)  AND RECOMMENDATIONS (CCITT)
        !           363: 
        !           364: \item  BASED ON
        !           365:     \begin{nrtc}
        !           366:     \item      CONNECTION-ORIENTED TRANSPORT SERVICE,
        !           367:                PROVIDED BY ONE OF FIVE DIFFERENT TPs; DEPENDING ON
        !           368: 
        !           369:     \item      THE NETWORK SERVICE AVAILABLE (CONS or CLNS)
        !           370:     \end{nrtc}
        !           371: 
        !           372: \item  DIFFICULT TO IDENTIFY THE ``MAJOR'' EMPHASIS
        !           373: \end{nrtc}
        !           374: \end{bwslide}
        !           375: 
        !           376: 
        !           377: \begin{bwslide}
        !           378: \ctitle        {OSI SUITE (cont.)}
        !           379: 
        !           380: \begin{nrtc}
        !           381: \item  SEVERAL INTERESTING APPLICATIONS
        !           382:     \begin{nrtc}
        !           383:     \item      MESSAGE HANDLING SYSTEMS (MHS)
        !           384: 
        !           385:     \item      FILE TRANSFER, ACCESS AND MANAGEMENT (FTAM)
        !           386: 
        !           387:     \item      VIRTUAL TERMINAL (VT)
        !           388: 
        !           389:     \item      DIRECTORY SERVICES (DS)
        !           390:     \end{nrtc}
        !           391: 
        !           392: \item  APPLICATIONS EVOLVING QUITE HEAVILY OVER THE LAST FEW YEARS
        !           393: 
        !           394: \item  MUCH MORE AMBITIOUS THAN THEIR INTERNET COUNTERPARTS
        !           395: \end{nrtc}
        !           396: \end{bwslide}
        !           397: 
        !           398: 
        !           399: \begin{bwslide}
        !           400: \ctitle        {OSI PROTOCOLS}
        !           401: 
        !           402: \vskip.5in
        !           403: \diagram[p]{figure5}
        !           404: \end{bwslide}
        !           405: 
        !           406: 
        !           407: \begin{bwslide}
        !           408: \ctitle        {A BRIEF COMPARISON}
        !           409: 
        !           410: \begin{nrtc}
        !           411: \item  NOTE THAT CONCERNS DIFFER
        !           412:     \begin{nrtc}
        !           413:     \item      NETWORK USERS: APPLICATION-LEVEL FUNCTIONALITY
        !           414: 
        !           415:     \item      NETWORK ADMINISTRATORS: NETWORK AND TRANSPORT ISSUES
        !           416:     \end{nrtc}
        !           417: 
        !           418: \item  FOR APPLICATIONS, ONCE IMPLEMENTED, THE OSI SUITE IS SUPERIOR
        !           419: 
        !           420: \item  FOR NETWORK/TRANSPORT ISSUES, THE INTERNET SUITE IS SUPERIOR:
        !           421:     \begin{nrtc}
        !           422:     \item      TSDU(PACKET) ORIENTATION PREVENTS USE OF SOPHISTICATED
        !           423:                CONGESTION COLLAPSE ALGORITHMS
        !           424: 
        !           425:     \item      SIMPLISTIC RETRANSMISSION ALGORITHMS
        !           426: 
        !           427:     \item      INAPPROPRIATE END-TO-END CHECKSUM
        !           428:     \end{nrtc}
        !           429: \end{nrtc}
        !           430: \end{bwslide}
        !           431: 
        !           432: 
        !           433: \begin{bwslide}
        !           434: \part* {METRICS FOR COMPARISON}\bf
        !           435: 
        !           436: \begin{nrtc}
        !           437: \item  CAN JUDGE A TRANSITION/COEXISTENCE SCHEME USING DIFFERENT
        !           438:        CRITERIA
        !           439: 
        !           440: \item  THE FOUR WE'LL FOCUS ON ARE ALL SUBJECTIVE;
        !           441:     \begin{nrtc}
        !           442:     \item      TECHNICAL SOLUTIONS DO NOT EXIST IN A VACUUM
        !           443: 
        !           444:     \item      THEY MUST BE EVALUATED IN THE CONTEXT OF A TARGET ENVIRONMENT
        !           445:     \end{nrtc}
        !           446: \end{nrtc}
        !           447: \end{bwslide}
        !           448: 
        !           449: 
        !           450: \begin{bwslide}
        !           451: \ctitle        {METRICS FOR COMPARISON (cont.)}
        !           452: 
        !           453: \begin{nrtc}
        !           454: \item  PERFORMANCE:
        !           455:     \begin{nrtc}
        !           456:     \item      THROUGHPUT, LATENCY
        !           457: 
        !           458:     \item      EFFECT ON OTHER APPLICATIONS
        !           459:     \end{nrtc}
        !           460: 
        !           461: \item  FLEXIBILITY:
        !           462:     \begin{nrtc}
        !           463:     \item      RANGE OF APPLICABILITY
        !           464:     \end{nrtc}
        !           465: \end{nrtc}
        !           466: \end{bwslide}
        !           467: 
        !           468: 
        !           469: \begin{bwslide}
        !           470: \ctitle        {METRICS FOR COMPARISON (cont.)}
        !           471: 
        !           472: \begin{nrtc}
        !           473: \item  TRANSPARENCY:
        !           474:     \begin{nrtc}
        !           475:     \item      USAGE CONTINUITY
        !           476: 
        !           477:     \item      SEAMLESS USER INTERFACE
        !           478:     \end{nrtc}
        !           479: 
        !           480: \item  AMENABILITY:
        !           481:     \begin{nrtc}
        !           482:     \item      MANAGEABILITY
        !           483:     \end{nrtc}
        !           484: \end{nrtc}
        !           485: \end{bwslide}
        !           486: 
        !           487: 
        !           488: \begin{bwslide}
        !           489: \ctitle        {SEVERAL CANDIDATES}
        !           490: 
        !           491: \begin{nrtc}
        !           492: \item  PROTOCOL-BASED APPROACHES
        !           493:     \begin{nrtc}
        !           494:     \item      DUAL STACK
        !           495: 
        !           496:     \item      APPLICATION GATEWAYS
        !           497: 
        !           498:     \item      TRANSPORT GATEWAYS
        !           499:     \end{nrtc}
        !           500: 
        !           501: \item  SERVICE-BASED APPROACHES
        !           502:     \begin{nrtc}
        !           503:     \item      TRANSPORT-SERVICE BRIDGES
        !           504: 
        !           505:     \item      NETWORK TUNNELS
        !           506:     \end{nrtc}
        !           507: 
        !           508: \item  NONE OF THESE TECHNIQUES ARE SPECIFIC TO THE PROBLEM OF
        !           509:     \begin{nrtc}
        !           510:     \item      INTERNET $\mapsto$ OSI
        !           511:     \end{nrtc}
        !           512: \end{nrtc}
        !           513: \end{bwslide}
        !           514: 
        !           515: 
        !           516: \begin{bwslide}
        !           517: \part  {PROTOCOL-BASED APPROACHES}\bf
        !           518: 
        !           519: \begin{nrtc}
        !           520: \item  THE ``STANDARD'' METHODS USED TO INTERCONNECT DIFFERENT
        !           521:        PROTOCOL STACKS
        !           522: 
        !           523: \item  THESE EMPHASIZE THE PROTOCOLS IN EACH STACK
        !           524: 
        !           525: \item  HENCE THEY REINFORCE THE BOUNDARIES BETWEEN TCP/IP AND OSI
        !           526: \end{nrtc}
        !           527: \end{bwslide}
        !           528: 
        !           529: 
        !           530: \begin{bwslide}
        !           531: \part* {DUAL STACK}\bf
        !           532: 
        !           533: \begin{nrtc}
        !           534: \item  PUT BOTH PROTOCOL SUITES IN ALL HOSTS
        !           535: 
        !           536: \item  WORKS WELL, IF YOU CAN CHANGE EVERYTHING ON THE NETWORK
        !           537: \begin{quote}\em
        !           538: ``Nice work, if you can get it.''\\ \raggedleft
        !           539: -- Groucho Marx, Monkey Business, Paramount Pictures (1931)
        !           540: \end{quote}
        !           541: \end{nrtc}
        !           542: \end{bwslide}
        !           543: 
        !           544: 
        !           545: \begin{bwslide}
        !           546: \ctitle        {DUAL STACK (cont.)}
        !           547: 
        !           548: \vskip.5in
        !           549: \diagram[p]{figure1}
        !           550: \end{bwslide}
        !           551: 
        !           552: 
        !           553: \begin{bwslide}
        !           554: \ctitle        {TALKING TO UNI-STACK HOSTS}
        !           555: 
        !           556: \begin{nrtc}
        !           557: \item  QUESTION: HOW TO DECIDE WHICH APPLICATION INSTANCE,
        !           558:     \begin{nrtc}
        !           559:     \item      APPL-$\alpha$ OR APPL-$\gamma$,
        !           560:     \end{nrtc}
        !           561:        TO USE?
        !           562: 
        !           563: \item  TWO ANSWERS:
        !           564:     \begin{nrtc}
        !           565:     \item      DEPEND ON THE USER TO KNOW AND INVOKE THE RIGHT PROGRAM
        !           566: 
        !           567:     \item      DEVELOP A GENERIC APPLICATION WHICH SUPPORTS BOTH CLASSES
        !           568:     \end{nrtc}
        !           569: 
        !           570: \item  IN THE LATTER CASE, NEED AN UP-TO-DATE DIRECTORY TO DO THIS RELIABLY
        !           571: \end{nrtc}
        !           572: \end{bwslide}
        !           573: 
        !           574: 
        !           575: \begin{bwslide}
        !           576: \ctitle        {GENERIC APPLICATION INSTANCE}
        !           577: 
        !           578: \vskip.5in
        !           579: \diagram[p]{figure6}
        !           580: \end{bwslide}
        !           581: 
        !           582: 
        !           583: \begin{bwslide}
        !           584: \ctitle        {AN IMPLEMENTATION OF DUAL-STACK}
        !           585: 
        !           586: \begin{nrtc}
        !           587: \item  ENVIRONMENT: \unix/~SVR3 (STREAMS)
        !           588: 
        !           589: \item  ACCESS TO LOWER-LAYER PROTOCOLS VIA TRANSPORT LAYER INTERFACE (TLI)
        !           590: 
        !           591: \item  NOTE THAT ALTHOUGH TLI PROVIDES A UNIFORM INTERFACE,
        !           592:        IT DOES NOT PROVIDE A UNIFORM SERVICE:
        !           593:     \begin{nrtc}
        !           594:     \item      PACKET- vs. STREAM-ORIENTATION
        !           595: 
        !           596:     \item      GRACEFUL RELEASE
        !           597: 
        !           598:     \item      EXPEDITED vs. URGENT DATA
        !           599: 
        !           600:     \item      ADDRESSING
        !           601:     \end{nrtc}
        !           602: \end{nrtc}
        !           603: \end{bwslide}
        !           604: 
        !           605: 
        !           606: \begin{bwslide}
        !           607: \ctitle        {GENERIC APPLICATION INSTANCE}
        !           608: 
        !           609: \vskip.5in
        !           610: \diagram[p]{figure11}
        !           611: \end{bwslide}
        !           612: 
        !           613: 
        !           614: \begin{bwslide}
        !           615: \ctitle        {SCORECARD}
        !           616: 
        !           617: \begin{nrtc}
        !           618: \item  PERFORMANCE: NO DEGRADATION
        !           619: 
        !           620: \item  FLEXIBILITY: GOOD
        !           621: 
        !           622: \item  TRANSPARENCY:
        !           623:     \begin{nrtc}
        !           624:     \item      ASSUMING REMOTE SYSTEM SUPPORTS AT LEAST ONE OF THE PROTOCOL
        !           625:                STACKS, THEN HIGH TRANSPARENCY BY USING COMMON SERVICE
        !           626:                INTERFACE
        !           627:     \end{nrtc}
        !           628: 
        !           629: \item  AMENABILITY:
        !           630:     \begin{nrtc}
        !           631:     \item      BOTH END- AND INTERMEDIATE-SYSTEMS MUST RUN BOTH PROTOCOLS
        !           632: 
        !           633:     \item      INTRODUCES ADMINISTRATIVE PROBLEMS AS THERE ARE NOW TWO
        !           634:                LOGICAL NETWORKS
        !           635:        \begin{nrtc}
        !           636:        \item   MANAGEMENT OF BOTH \underline{PLUS} CONTENTION BETWEEN THEM
        !           637:        \end{nrtc}
        !           638:     \end{nrtc}
        !           639: \end{nrtc}
        !           640: \end{bwslide}
        !           641: 
        !           642: 
        !           643: \begin{bwslide}
        !           644: \part* {APPLICATION GATEWAYS}\bf
        !           645: 
        !           646: \begin{nrtc}
        !           647: \item  A WELL-KNOWN, BUT LITTLE-UNDERSTOOD TECHNOLOGY
        !           648:     \begin{nrtc}
        !           649:     \item      USED IN MESSAGE HANDLING QUITE A BIT
        !           650:     \end{nrtc}
        !           651: 
        !           652: \item  MOST ARE QUITE TERRIBLE
        !           653: \begin{quote}\em
        !           654: ``Sometimes when you try to turn an apple into an orange you get back a
        !           655: lemon.''\\ \raggedleft
        !           656: -- Michael Padlipsky, The Elements of Networking Style (1985)
        !           657: \end{quote}
        !           658: \end{nrtc}
        !           659: \end{bwslide}
        !           660: 
        !           661: 
        !           662: \begin{bwslide}
        !           663: \ctitle        {APPLICATION GATEWAYS (cont.)}
        !           664: 
        !           665: \vskip.5in
        !           666: \diagram[p]{figure2}
        !           667: \end{bwslide}
        !           668: 
        !           669: 
        !           670: \begin{bwslide}
        !           671: \ctitle        {IMPERFECT MAPPINGS}
        !           672: 
        !           673: \begin{nrtc}
        !           674: \item  BECAUSE THEY ARE AT THE HIGHEST LAYER IN THE STACK,
        !           675:        APPLICATION GATEWAYS TEND TO PERFORM SEMANTIC MAPPINGS
        !           676: 
        !           677: \item  THESE ARE ACCOMPANIED BY A LOSS OF INFORMATION
        !           678: 
        !           679: \item  SOMETIMES THE LOSS IS ONLY ANNOYING
        !           680:     \begin{nrtc}
        !           681:     \item      e.g., ``FUNNY LOOKING'' MAIL ADDRESSES
        !           682:     \end{nrtc}
        !           683: 
        !           684: \item  SOMETIMES THE LOSS IS CATASTROPHIC
        !           685:     \begin{nrtc}
        !           686:     \item      e.g., ROUTING LOOPS
        !           687:     \end{nrtc}
        !           688: \end{nrtc}
        !           689: \end{bwslide}
        !           690: 
        !           691: 
        !           692: \begin{bwslide}
        !           693: \ctitle        {AN IMPLEMENATION OF APPLICATION-GATEWAY}
        !           694: 
        !           695: \begin{nrtc}
        !           696: \item  TWO KINDS OF IMPLEMENATIONS
        !           697: 
        !           698: \item  STAGING (TRUE STORE-AND-FORWARD):
        !           699:     \begin{nrtc}
        !           700:     \item      TOP-LEVEL PROTOCOL TRANSACTIONS ARE GROUPED AT THE GATEWAY
        !           701: 
        !           702:     \item      REQUIRES LOCAL STORAGE, BUT MAY PERMIT BETTER MAPPINGS
        !           703:     \end{nrtc}
        !           704: 
        !           705: \item  IN-SITU (VIRTUAL END-TO-END):
        !           706:     \begin{nrtc}
        !           707:     \item      NO PROTOCOL TRANSACTIONS ARE GROUPED
        !           708: 
        !           709:     \item      MAPPINGS ARE ``ON THE FLY''\\ (AND PERHAPS LESS PRECISE)
        !           710: 
        !           711:     \item      END-TO-END RESPONSE IS FASTER
        !           712:     \end{nrtc}
        !           713: \end{nrtc}
        !           714: \end{bwslide}
        !           715: 
        !           716: 
        !           717: \begin{bwslide}
        !           718: \ctitle        {A STAGING IMPLEMENTATION}
        !           719: 
        !           720: \vskip.5in
        !           721: \diagram[p]{figure12}
        !           722: \end{bwslide}
        !           723: 
        !           724: 
        !           725: \begin{bwslide}
        !           726: \ctitle        {AN IN-SITU IMPLEMENTATION}
        !           727: 
        !           728: \vskip.5in
        !           729: \diagram[p]{figure13}
        !           730: \end{bwslide}
        !           731: 
        !           732: 
        !           733: \begin{bwslide}
        !           734: \ctitle        {SCORECARD}
        !           735: 
        !           736: \begin{nrtc}
        !           737: \item  PERFORMANCE: USUALLY POOR, BUT ACCEPTABLE FOR STORE-AND-FORWARD
        !           738:        APPLICATIONS
        !           739:     \begin{nrtc}
        !           740:     \item      TYPICALLY ALSO INTRODUCES ADDITIONAL NETWORK TRAFFIC
        !           741:     \end{nrtc}
        !           742: 
        !           743: \item  FLEXIBILITY: NONE; EACH A-GWY IS A SPECIAL-PURPOSE SOFTWARE BOX
        !           744: 
        !           745: \item  TRANSPARENCY: 
        !           746:     \begin{nrtc}
        !           747:     \item      TO SERVICE: OFTEN LOSES SIGNIFICANT FUNCTIONALITY
        !           748: 
        !           749:     \item      TO USERS: POSSIBLE, BUT NOT LIKELY (e.g., IN AN FTAM/FTP A-GWY,
        !           750:                USERS EMBED HOSTNAMES IN FILENAMES)
        !           751:     \end{nrtc}
        !           752: 
        !           753: \item  AMENABILITY:
        !           754:     \begin{nrtc}
        !           755:     \item      REQUIRES NO END-SYSTEM MODIFICATION
        !           756: 
        !           757:     \item      MAY INTRODUCE ADMINISTRATIVE PROBLEMS
        !           758:     \end{nrtc}
        !           759: \end{nrtc}
        !           760: \end{bwslide}
        !           761: 
        !           762: 
        !           763: \begin{bwslide}
        !           764: \part* {TRANSPORT GATEWAYS}\bf
        !           765: 
        !           766: \begin{nrtc}
        !           767: \item  IDEA: GATEWAY AT THE TRANSPORT LAYER SO AS TO AVOID NEEDING
        !           768:        MULTIPLE APPLICATION GATEWAYS
        !           769: \begin{quote}\em
        !           770: ``We could do it, but it would be wrong.''\\ \raggedleft
        !           771: -- Richard Nixon
        !           772: \end{quote}
        !           773: 
        !           774: \item  ALTHOUGH THE OSI (TP4) AND INTERNET (TCP) TRANSPORT PROTOCOLS DIFFER,
        !           775:        THE SERVICE IS QUITE SIMILAR
        !           776: 
        !           777: \item  HENCE, IT IS TECHNICALLY FEASIBLE TO PERFORM THE MAPPINGS
        !           778:     \begin{nrtc}
        !           779:     \item      (ALTHOUGH IT'S A LOT OF HARD WORK)
        !           780:     \end{nrtc}
        !           781: \end{nrtc}
        !           782: \end{bwslide}
        !           783: 
        !           784: 
        !           785: \begin{bwslide}
        !           786: \ctitle        {TRANSPORT GATEWAYS (cont.)}
        !           787: 
        !           788: \vskip.5in
        !           789: \diagram[p]{figure14}
        !           790: \end{bwslide}
        !           791: 
        !           792: 
        !           793: \begin{bwslide}
        !           794: \ctitle        {THE OBVIOUS QUESTION}
        !           795: 
        !           796: \begin{nrtc}
        !           797: \item  WHAT APPLICATION DO YOU RUN WHEN USING THIS?
        !           798:     \begin{nrtc}
        !           799:     \item      CAN'T RUN INTERNET APPLICATIONS IN THE OSI NETWORK,
        !           800:                SINCE THE TRANSPORT GATEWAY YIELDS OSI TRANSPORT SEMANTICS
        !           801: 
        !           802:     \item      CAN'T RUN OSI APPLICATIONS IN THE INTERNET NETWORK,
        !           803:                SINCE THE TRANSPORT GATEWAY YIELDS INTERNET TRANSPORT SEMANTICS
        !           804:     \end{nrtc}
        !           805: 
        !           806: \item  THIS APPROACH FAILS BECAUSE IT PRESENTS DIFFERENT SERVICE SEMANTICS
        !           807:        IN EACH NETWORK
        !           808: \end{nrtc}
        !           809: \end{bwslide}
        !           810: 
        !           811: 
        !           812: \begin{bwslide}
        !           813: \part  {RE-DEFINING THE PROBLEM}\bf
        !           814: 
        !           815: \begin{nrtc}
        !           816: \item  BY THE TIME OSI-BASED NETWORKS ARE TRULY WIDESPREAD,
        !           817:        TCP/IP-BASED NETWORKS WILL ALREADY OFFER A MIX OF SERVICES:
        !           818:     \begin{nrtc}
        !           819:     \item      SUCH AS FTAM AND MHS, IN ADDITION TO FTP AND SMTP
        !           820:     \end{nrtc}
        !           821: 
        !           822: \item  IN OTHER WORDS, THE TRANSITION TO OSI BEGINS WITH NEW APPLICATIONS ON
        !           823:        HOSTS AND NO CHANGES TO THE NETWORK
        !           824: \end{nrtc}
        !           825: \end{bwslide}
        !           826: 
        !           827: 
        !           828: \begin{bwslide}
        !           829: \ctitle        {WOULD THIS REALLY HAPPEN?}
        !           830: 
        !           831: \begin{nrtc}
        !           832: \item  RECALL THAT USERS ARE INTERESTED IN \underline{SERVICES} NOT
        !           833:        \underline{PROTOCOLS}
        !           834: 
        !           835: \item  THE OSI APPLICATIONS ARE MUCH RICHER THAN THEIR INTERNET COUNTERPARTS
        !           836: 
        !           837: \item  IN CONTRAST, AT THE LOWER-LAYERS THE INTERNET SUITE ``WORKS BETTER''
        !           838:     \begin{nrtc}
        !           839:     \item      AS SUCH, IT IS UNLIKELY TO BE REPLACED BY THE OSI LOWER-LAYERS
        !           840:                FOR QUITE SOME TIME
        !           841:     \end{nrtc}
        !           842: \end{nrtc}
        !           843: \end{bwslide}
        !           844: 
        !           845: 
        !           846: \begin{bwslide}
        !           847: \ctitle        {ONLY ONE LITTLE PROBLEM$\ldots$}
        !           848: 
        !           849: \begin{nrtc}
        !           850: \item  HOW TO RUN THE OSI UPPER-LAYERS IN A TCP/IP-BASED NETWORK?
        !           851: 
        !           852: \item  A SOLUTION IS OFFERED BY LAYERING
        !           853:     \begin{nrtc}
        !           854:     \item      THE OSI TRANSPORT \underline{SERVICE} IS VERY SIMPLE
        !           855: 
        !           856:     \item      CAN WE PROVIDE AN EMULATION OF THAT SERVICE USING TCP?
        !           857:     \end{nrtc}
        !           858: \end{nrtc}
        !           859: \end{bwslide}
        !           860: 
        !           861: 
        !           862: \begin{bwslide}
        !           863: \ctitle        {SERVICE EMULATOR AT TRANSPORT}
        !           864: 
        !           865: \vskip.5in
        !           866: \diagram[p]{figure7}
        !           867: \end{bwslide}
        !           868: 
        !           869: 
        !           870: \begin{bwslide}
        !           871: \ctitle        {THE OSI TRANSPORT SERVICE}
        !           872: 
        !           873: \begin{nrtc}
        !           874: \item  ALTHOUGH THE SERVICE IS VERY SIMPLE, THERE ARE ACTUALLY FIVE DIFFERENT
        !           875:        ISO PROTOCOLS WHICH CAN BE USED (TP0$\ldots$TP4)
        !           876: 
        !           877: \item  PROTOCOLS CAN BE DIVIDED INTO TWO CLASSES, BASED ON THE UNDERLYING
        !           878:        NETWORK SERVICE
        !           879:     \begin{nrtc}
        !           880:     \item      A CONNECTION-ORIENTED NETWORK SERVICE (CONS), e.g., X.25
        !           881:                
        !           882: 
        !           883:     \item      A CONNECTIONLESS-MODE NETWORK SERVICE (CLNS), e.g., CLNP
        !           884:     \end{nrtc}
        !           885: \end{nrtc}
        !           886: \end{bwslide}
        !           887: 
        !           888: 
        !           889: \begin{bwslide}
        !           890: \ctitle        {OSI TRANSPORT SERVICES\\ ON TOP OF THE DoD TCP}
        !           891: 
        !           892: \begin{nrtc}
        !           893: \item  IDEA: TAKE THE SIMPLEST PROTOCOL (TP0) AND DEFINE A MAPPING ONTO
        !           894:        THE DoD TCP
        !           895: 
        !           896: \item{}        [RFC983], PUBLISHED IN APRIL OF 1986, WAS A FIRST ATTEMPT AT THIS
        !           897: 
        !           898: \item  TWO VERSIONS AND 13 MONTHS LATER, [RFC1006] GOT IT RIGHT, TELLING
        !           899:        ``HOW TO SPEAK TP0 OVER THE TCP''
        !           900: 
        !           901: \item  NOTE: THIS APPROACH IS NOT UNIQUE TO TCP/IP-BASED NETWORKS!
        !           902: \end{nrtc}
        !           903: \end{bwslide}
        !           904: 
        !           905: 
        !           906: \begin{bwslide}
        !           907: \ctitle        {OSI TRANSPORT SERVICES\\ ON TOP OF THE DoD TCP (cont.)}
        !           908: 
        !           909: \vskip.25in
        !           910: \diagram[p]{figure8}
        !           911: \end{bwslide}
        !           912: 
        !           913: 
        !           914: \begin{bwslide}
        !           915: \part  {SERVICE-BASED APPROACHES}\bf
        !           916: 
        !           917: \begin{nrtc}
        !           918: \item  BACK TO OUR PREDICATION:
        !           919:     \begin{nrtc}
        !           920:     \item      TCP/IP-BASED NETWORKS WILL OFFER A MIX OF SERVICES
        !           921:     \end{nrtc}
        !           922: \end{nrtc}
        !           923: \end{bwslide}
        !           924: 
        !           925: 
        !           926: \begin{bwslide}
        !           927: \ctitle        {OBSERVATION}
        !           928: 
        !           929: \begin{nrtc}
        !           930: \item  GIVEN THE ABOVE ASSUMPTION, IT SHOULD BE NOTED THAT:
        !           931:     \begin{nrtc}
        !           932:     \item      WE HAVE TWO COMMUNITIES USING THE SAME APPLICATIONS
        !           933:                (OSI), AND
        !           934: 
        !           935:     \item      ONLY THE UNDERLYING ``TS-STACK'' WILL DIFFER BETWEEN THE TWO:
        !           936:        \begin{nrtc}
        !           937:        \item   IN THE OSI COMMUNITY: TP4/CLNP/$\ldots$
        !           938: 
        !           939:        \item   IN THE TCP COMMUNITY: [RFC1006]/TCP/IP/$\ldots$
        !           940:        \end{nrtc}
        !           941:     \end{nrtc}
        !           942: 
        !           943: \item  THIS LEADS US TO POSTULATE AN INTERESTING COEXISTENCE
        !           944:        STRATEGY:
        !           945:     \begin{nrtc}
        !           946:     \item      LET'S RUN OSI APPLICATIONS, END-TO-END, BETWEEN THE TWO
        !           947:     \end{nrtc}
        !           948: 
        !           949: \item  IN A SENSE, THIS IS A HYBRID OF THE TWO PREVIOUS APPROACHES,
        !           950:        INTENDED TO MINIMIZE THE DISADVANTAGES OF EACH
        !           951:     \begin{nrtc}
        !           952:        \item   SAME APPLICATION PROTOCOL,\\
        !           953:                BUT DIFFERENT UNDERYLING LAYERS
        !           954:     \end{nrtc}
        !           955: \end{nrtc}
        !           956: \end{bwslide}
        !           957: 
        !           958: 
        !           959: \begin{bwslide}
        !           960: \part* {TRANSPORT-SERVICE BRIDGES}\bf
        !           961: 
        !           962: \begin{nrtc}
        !           963: \item  INTRODUCE A TRANSPORT ENTITY CALLED THE ``TS-BRIDGE''
        !           964: \begin{quote}\em
        !           965: ``Users are interested in services, not protocols.''\\ \raggedleft
        !           966: -- Marshall Rose, The Wollongong Group
        !           967: \end{quote}
        !           968: 
        !           969: \item  THE TS-BRIDGE ``COPIES'' SERVICE PRIMITIVES FROM ONE COMMUNITY TO THE
        !           970:        OTHER, e.g.:
        !           971:     \begin{nrtc}
        !           972:     \item      UPON RECEIVING A T-CONNECT.INDICATION PRIMITIVE FROM ONE
        !           973:                TS-STACK,
        !           974: 
        !           975:     \item      IT ISSUES A T-CONNECT.REQUEST PRIMITIVE TO THE OTHER TS-STACK
        !           976:     \end{nrtc}
        !           977: \end{nrtc}
        !           978: \end{bwslide}
        !           979: 
        !           980: 
        !           981: \begin{bwslide}
        !           982: \ctitle        {TRANSPORT-SERVICE BRIDGES (cont.)}
        !           983: 
        !           984: \vskip.5in
        !           985: \diagram[p]{figure9}
        !           986: \end{bwslide}
        !           987: 
        !           988: 
        !           989: \begin{bwslide}
        !           990: \ctitle        {THE TS-BRIDGE AND THE OSI MODEL}
        !           991: 
        !           992: \begin{nrtc}
        !           993: \item  THE TS-BRIDGE IS A LEVEL-FOUR ROUTER
        !           994: 
        !           995: \item  POTENTIAL PROBLEMS:
        !           996:     \begin{nrtc}
        !           997:     \item      THE TS-BRIDGE MAINTAINS STATE AS TO THE EXISTING CONNECTIONS
        !           998: 
        !           999:     \item      TWO CHECKSUMS, AND NEITHER REALLY END-TO-END
        !          1000: 
        !          1001:     \item      \underline{MAY} THWART SOPHISTICATED BACK-PRESSURE TECHNIQUES
        !          1002:     \end{nrtc}
        !          1003: \end{nrtc}
        !          1004: \end{bwslide}
        !          1005: 
        !          1006: 
        !          1007: \begin{bwslide}
        !          1008: \ctitle        {TRANSPARENT USE OF TS-BRIDGES}
        !          1009: 
        !          1010: \begin{nrtc}
        !          1011: \item  BY JUDICIOUS USE OF DIRECTORY SERVICES, SELECTION OF THE
        !          1012:        TS-BRIDGE CAN BE MADE TRANSPARENT ON BOTH ENDPOINTS
        !          1013: 
        !          1014: \item  CONSIDER A ``TYPICAL'' PRESENTATION ADDRESS:
        !          1015: \[\begin{tabular}{ll}
        !          1016: network address:&      CLNP 470005001700$\ldots$5301\\
        !          1017: transport selector:&   1\\
        !          1018: session selector:&     ``FTAM''\\
        !          1019: presentation selector:&        null
        !          1020: \end{tabular}\]
        !          1021: 
        !          1022: \item  A SLIGHTLY DIFFERENT ENTRY IS RETURNED FOR HOSTS IN THE
        !          1023:        OPPOSITE COMMUNITY:
        !          1024: \[\begin{tabular}{ll}
        !          1025: network address:&      ts-bridge's network address\\
        !          1026: transport selector:&   \begin{tabular}[t]{ll}
        !          1027:                        network address:&
        !          1028:                                CLNP 47 $\ldots$\\
        !          1029:                        transport selector:&     1
        !          1030:                        \end{tabular}\\
        !          1031: session selector:&     ``FTAM''\\
        !          1032: presentation selector:&        null
        !          1033: \end{tabular}\]
        !          1034: \end{nrtc}
        !          1035: \end{bwslide}
        !          1036: 
        !          1037: 
        !          1038: \begin{bwslide}
        !          1039: \ctitle        {ANOTHER PROBLEM SOLVED:\\ ISO CONS versus CLNS}
        !          1040: 
        !          1041: \begin{nrtc}
        !          1042: \item  IN GENERAL, THE TS-BRIDGE SHOWS HOW TO PERFORM
        !          1043:        ``IMPEDENCE MATCHING'' BETWEEN TWO PROTOCOLS WHICH OFFER THE
        !          1044:        SAME SERVICE INTERFACE, e.g., OUR USE IS:
        !          1045:     \begin{nrtc}
        !          1046:     \item      PROTOCOLS: TP4/CLNP AND TP0/TCP
        !          1047: 
        !          1048:     \item      SERVICE: OSI TRANSPORT SERVICE
        !          1049:     \end{nrtc}
        !          1050: 
        !          1051: \item  THIS IS SUSPICIOUSLY SIMILAR TO THE ISO TP4/CLNS vs. TP0/CONS PROBLEM:
        !          1052:     \begin{nrtc}
        !          1053:     \item      PROTOCOLS: TP4/CLNP AND TP0/X.25
        !          1054: 
        !          1055:     \item      SERVICE: OSI TRANSPORT SERVICE
        !          1056:     \end{nrtc}
        !          1057: 
        !          1058: \item  THE TS-BRIDGE WILL ALSO WORK IN THIS ENVIRONMENT WITHOUT
        !          1059:        MEANINGFUL LOSS OF GENERALITY:
        !          1060:     \begin{nrtc}
        !          1061:     \item      EXPEDITED DATA IS NEGOTIATED AWAY, AND
        !          1062: 
        !          1063:     \item      INITIAL USER DATA RESULTS IN DISCONNECT
        !          1064:     \end{nrtc}
        !          1065: \end{nrtc}
        !          1066: \end{bwslide}
        !          1067: 
        !          1068: 
        !          1069: \begin{bwslide}
        !          1070: \ctitle        {AN IMPLEMENTATION OF THE TS-BRIDGE}
        !          1071: 
        !          1072: \begin{nrtc}
        !          1073: \item  AT UNIFORUM IN FEBRUARY, 1988, THE
        !          1074:     \begin{nrtc}
        !          1075:     \item      TP4/CLNP to TP0/TCP
        !          1076:     \end{nrtc}
        !          1077:     ``IMPEDENCE MATCHING'' WAS DEMONSTRATED
        !          1078: 
        !          1079: \item  CURRENTLY, ALL THREE TS-STACKS
        !          1080:     \begin{nrtc}
        !          1081:     \item      TP4/CLNP, TP0/X.25, TP0/TCP
        !          1082:     \end{nrtc}
        !          1083:     ARE BEING BRIDGED (ON A SINGLE HOST)
        !          1084: \end{nrtc}
        !          1085: \end{bwslide}
        !          1086: 
        !          1087: 
        !          1088: \begin{bwslide}
        !          1089: \ctitle        {SCORECARD}
        !          1090: 
        !          1091: \begin{nrtc}
        !          1092: \item  PERFORMANCE: FAIR; WHEN TS-BRIDGE IS MADE INTO A KERNEL-RESIDENT
        !          1093:        STREAMS MODULE IT SHOULD IMPROVE DRAMATICALLY
        !          1094: 
        !          1095: \item  FLEXIBILITY: HIGH; INDEPENDENT OF ANY APPLICATION
        !          1096: 
        !          1097: \item  TRANSPARENCY: TOTAL
        !          1098: 
        !          1099: \item  AMENABILITY:
        !          1100:     \begin{nrtc}
        !          1101:     \item      TCP END-SYSTEMS MUST RUN ``NEW'' PROTOCOLS
        !          1102:        \begin{nrtc}
        !          1103:        \item   BUT, NO MODIFICATIONS REQUIRED TO END-SYSTEM KERNELS
        !          1104:        \end{nrtc}
        !          1105: 
        !          1106:     \item      MAY INTRODUCE ADMINISTRATIVE PROBLEMS (WHICH SHOULD BE SOLVED
        !          1107:                DYNAMICALLY BY DIRECTORY SERVICES)
        !          1108:     \end{nrtc}
        !          1109: \end{nrtc}
        !          1110: \end{bwslide}
        !          1111: 
        !          1112: 
        !          1113: \begin{bwslide}
        !          1114: \part* {NETWORK TUNNELS}\bf
        !          1115: 
        !          1116: \begin{nrtc}
        !          1117: \item  IDEA: ENCAPSULATE CLNP INSIDE OF IP, TREATING IP AS SIMPLY A DATA LINK
        !          1118:        PROTOCOL
        !          1119: \begin{quote}\em
        !          1120: ``Encapsulation complies with the layering concept, but violates the notion
        !          1121: of absolute levels.''\\ \raggedleft
        !          1122: -- Danny Cohen and Jon Postel, ``The ISO Reference Model and Other Protocol
        !          1123: Architectures'' (1983)
        !          1124: \end{quote}
        !          1125: 
        !          1126: \item  NS-TUNNEL PERFORMS AS A ROUTER, REMOVING ONE DATA LINK HEADER AND
        !          1127:        ADDING ANOTHER
        !          1128: \end{nrtc}
        !          1129: \end{bwslide}
        !          1130: 
        !          1131: 
        !          1132: \begin{bwslide}
        !          1133: \ctitle        {TUNNELING}
        !          1134: 
        !          1135: \vskip.5in
        !          1136: \diagram[p]{figure18}
        !          1137: \end{bwslide}
        !          1138: 
        !          1139: 
        !          1140: \begin{bwslide}
        !          1141: \ctitle        {NETWORK TUNNELS}
        !          1142: 
        !          1143: \vskip.5in
        !          1144: \diagram[p]{figure10}
        !          1145: \end{bwslide}
        !          1146: 
        !          1147: 
        !          1148: \begin{bwslide}
        !          1149: \ctitle        {INTERESTING FEATURES}
        !          1150: 
        !          1151: \begin{nrtc}
        !          1152: \item  NO STATE MAINTAINED BY NS-TUNNEL
        !          1153: 
        !          1154: \item  A TRUE END-TO-END CHECKSUM
        !          1155: \end{nrtc}
        !          1156: \end{bwslide}
        !          1157: 
        !          1158: 
        !          1159: \begin{bwslide}
        !          1160: \ctitle        {POTENTIAL PROBLEMS}
        !          1161: 
        !          1162: \begin{nrtc}
        !          1163: \item  REQUIRES COMMON HIGHER-LEVEL PROTOCOLS (TRANSPORT AND ABOVE) ON BOTH
        !          1164:        END-SYSTEMS, BUT DOES NOT REQUIRE ALL INTERVENING ROUTERS TO USE THE
        !          1165:        SAME NETWORK PROTOCOL
        !          1166: 
        !          1167: \item  THE TCP END-SYSTEM IMPLEMENTATION CHOICES ARE SIMILAR TO NETBIOS OVER
        !          1168:        TCP [RFC1001/1002]
        !          1169: \end{nrtc}
        !          1170: \end{bwslide}
        !          1171: 
        !          1172: 
        !          1173: \begin{bwslide}
        !          1174: \ctitle        {AN IMPLEMENATION OF AN NS-TUNNEL}
        !          1175: 
        !          1176: \begin{nrtc}
        !          1177: \item  HAVEN'T SEE ANY YET
        !          1178: 
        !          1179: \item  REALLY NEED A LOT OF CLNP-BASED NETWORKS BEFORE THIS IS OF USE
        !          1180: 
        !          1181: \item  THIS WILL HAPPEN AT THE END OF THE TRANSITION PERIOD
        !          1182: \end{nrtc}
        !          1183: \end{bwslide}
        !          1184: 
        !          1185: 
        !          1186: \begin{bwslide}
        !          1187: \ctitle        {SCORECARD}
        !          1188: 
        !          1189: \begin{nrtc}
        !          1190: \item  PERFORMANCE: NO WORSE THAN TYPICAL CLNP-ROUTER (AND PROBABLY A LOT
        !          1191:        BETTER TOO!)
        !          1192: 
        !          1193: \item  FLEXIBILITY: HIGH (INDEPENDENT OF ANY APPLICATION)
        !          1194: 
        !          1195: \item  TRANSPARENCY: TOTAL
        !          1196: 
        !          1197: \item  AMENABILITY: TCP END-SYSTEMS MUST RUN BOTH TRANSPORT PROTOCOLS
        !          1198: \end{nrtc}
        !          1199: \end{bwslide}
        !          1200: 
        !          1201: 
        !          1202: \begin{bwslide}
        !          1203: \part  {EXAMPLES}\bf
        !          1204: 
        !          1205: \begin{nrtc}
        !          1206: \item  DoD OSI IMPLEMENTATION PLAN
        !          1207: 
        !          1208: \item  GENERIC EXAMPLE
        !          1209: 
        !          1210: \item  CONCLUSIONS
        !          1211: \end{nrtc}
        !          1212: \end{bwslide}
        !          1213: 
        !          1214: 
        !          1215: \begin{bwslide}
        !          1216: \part* {DoD OSI\\ IMPLEMENTATION PLAN}\bf
        !          1217: 
        !          1218: \begin{nrtc}
        !          1219: \item  IMPLEMENT CAPABILITY TO USE OSI IN DoD INTERNETWORK ENVIRONMENT
        !          1220:     \begin{nrtc}
        !          1221:     \item      OSI-POSIX PROJECT
        !          1222:     \end{nrtc}
        !          1223: 
        !          1224: \item  PROVIDE THE CAPABILITY FOR DoD AND OSI PROTOCOLS TO INTEROPERATE
        !          1225:     \begin{nrtc}
        !          1226:     \item      FTAM-FTP GATEWAY
        !          1227: 
        !          1228:     \item      MHS-SMTP GATEWAY
        !          1229:     \end{nrtc}
        !          1230: \end{nrtc}
        !          1231: \end{bwslide}
        !          1232: 
        !          1233: 
        !          1234: \begin{bwslide}
        !          1235: \ctitle        {OSI-POSIX PROJECT}
        !          1236: 
        !          1237: \begin{nrtc}
        !          1238: \item  GOAL: ACCELLERATE THE UBIQUITY OF OSI
        !          1239: 
        !          1240: \item  APPROACH: OPENLY AVAILABLE, COMPLETE OSI IMPLEMENTATION FOR NEXT MAJOR
        !          1241:        RELEASE OF BERKELEY \unix/
        !          1242: 
        !          1243: \item  FOR MORE DETAILS:
        !          1244: \begin{quote}
        !          1245: OSI PROTOCOLS WITHIN AN OPENLY AVAILABLE, POSIX-CONFORMANT, BERKELEY UNIX
        !          1246: ENVIRONMENT
        !          1247: \end{quote}
        !          1248: APPEARING IN ConneXions, OCTOBER, 1988
        !          1249: \end{nrtc}
        !          1250: \end{bwslide}
        !          1251: 
        !          1252: 
        !          1253: \begin{bwslide}
        !          1254: \diagram[p]{figure15}
        !          1255: \end{bwslide}
        !          1256: 
        !          1257: 
        !          1258: \begin{bwslide}
        !          1259: \diagram[p]{figure16}
        !          1260: \end{bwslide}
        !          1261: 
        !          1262: 
        !          1263: \begin{bwslide}
        !          1264: \part* {GENERIC EXAMPLE}\bf
        !          1265: 
        !          1266: \begin{nrtc}
        !          1267: \item  TWO PRONGS:
        !          1268:     \begin{nrtc}
        !          1269:     \item      FAVOR USE OF OSI APPLICATIONS OVER TCP ON LAN MESH
        !          1270: 
        !          1271:     \item      LOCATE APPLICATION GATEWAYS AND A TS-BRIDGE ON ALL NODES
        !          1272:                WITH WAN ATTACHMENETS
        !          1273:     \end{nrtc}
        !          1274: 
        !          1275: \item  AWAIT OSI LOWER-LAYERS TO BECOME COMPETITIVE
        !          1276: \end{nrtc}
        !          1277: \end{bwslide}
        !          1278: 
        !          1279: 
        !          1280: \begin{bwslide}
        !          1281: \ctitle        {GENERIC EXAMPLE (cont.)}
        !          1282: 
        !          1283: \begin{nrtc}
        !          1284: \item  EACH ATTACHMENT LOCUS SHOULD SUPPORT COEXISTENCE SERVICES
        !          1285: 
        !          1286: \item  IF RESOURCES PERMIT, SELECT ONE OTHER SYSTEM TO SUPPORT THESE
        !          1287:        SERVICES FOR USE BY LOCAL UNI-STACK HOSTS
        !          1288: 
        !          1289: \item  THIS ``COVERS ALL BASES'' BY HANDLING ALL POSSIBLE OSI COMBINATIONS
        !          1290:        WITH A BIT OF EXTRA REDUNDANCY
        !          1291: 
        !          1292: \item  MIGHT REQUIRE A BIT OF SOPHISTICATED USE FROM THE DIRECTORY
        !          1293: \end{nrtc}
        !          1294: \end{bwslide}
        !          1295: 
        !          1296: 
        !          1297: \begin{bwslide}
        !          1298: \ctitle        {A LAN OF MANY COLORS}
        !          1299: 
        !          1300: \vskip.5in
        !          1301: \diagram[p]{figure17}
        !          1302: \end{bwslide}
        !          1303: 
        !          1304: 
        !          1305: \begin{bwslide}
        !          1306: \part* {CONCLUSIONS}\bf
        !          1307: 
        !          1308: \begin{quote}\em
        !          1309: ``Optimality differs according to context.''\\ \raggedleft
        !          1310: -- Michael Padlipsky, The Elements of Networking Style (1985)
        !          1311: \end{quote}
        !          1312: \end{bwslide}
        !          1313: 
        !          1314: 
        !          1315: \begin{bwslide}
        !          1316: \ctitle        {CONCLUSIONS (cont.)}
        !          1317: 
        !          1318: \begin{nrtc}
        !          1319: \item  TCP/IP-BASED NETWORKS WILL OFFER OSI APPLICATIONS
        !          1320: 
        !          1321: \item  COEXISTENCE IN THE SHORT TERM:
        !          1322:     \begin{nrtc}
        !          1323:     \item      TS-BRIDGE MINIMIZES SOFTWARE INVESTMENT
        !          1324:     \end{nrtc}
        !          1325: 
        !          1326: \item  COEXISTENCE IN THE LONG TERM:
        !          1327:     \begin{nrtc}
        !          1328:     \item      NS-TUNNEL MAXIMIZES PERFORMANCE AND ROBUSTNESS
        !          1329:     \end{nrtc}
        !          1330: 
        !          1331: \item  IF/WHEN THERE ARE NO MORE TCP/IP-BASED NETWORKS, THEN THE
        !          1332:        COEXISTENCE PERIOD IS OVER, AND TRANSITION IS A NON-ISSUE!
        !          1333: \end{nrtc}
        !          1334: \end{bwslide}
        !          1335: 
        !          1336: 
        !          1337: \end{document}

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