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1.1     ! root        1: % run this through SLiTeX
        !             2: 
        !             3: \documentstyle
        !             4:     [blackandwhite,landscape,oval,pagenumbers,small]{NRslides}
        !             5: 
        !             6: \input trademark
        !             7: 
        !             8: \def\tradeORGfont{\rm}
        !             9: \def\tradeNAMfont{\rm}
        !            10: 
        !            11: \def\tcptpgw/{TCP $\Longleftrightarrow$ TP MAGIC-BOX}
        !            12: 
        !            13: \raggedright
        !            14: 
        !            15: \begin{document}
        !            16: 
        !            17: \title {RECENT DEVELOPMENTS IN\\ MIGRATING TOWARD ISO}
        !            18: \author        {Marshall T.~Rose\\
        !            19:        Computer Science Laboratory\\
        !            20:        Northrop Research and Technology Center}
        !            21: \date  {October 20, 1986}
        !            22: \maketitlepage
        !            23: 
        !            24: 
        !            25: \begin{bwslide}
        !            26: \part* {OUTLINE}\bf
        !            27: 
        !            28: \begin{nrtc}
        !            29: \item  BACKGROUND
        !            30: \item  TOWARD A SOLUTION
        !            31: \item  A DIGRESSION ON THE INTEROPERABILITY OF APPLICATIONS
        !            32: \item  A MIGRATION STRATEGY
        !            33: \item  THE FIRST STEP: ISODE
        !            34: \end{nrtc}
        !            35: \end{bwslide}
        !            36: 
        !            37: 
        !            38: \begin{note}\em
        !            39: i've given a few variants of this talk in the past,
        !            40: so may cover it too quickly!
        !            41: \end{note}
        !            42: 
        !            43: 
        !            44: \begin{bwslide}
        !            45: \part  {BACKGROUND}\bf
        !            46: \begin{nrtc}
        !            47: \item  THE ISO INTERPRETATION OF OSI IS GAINING POPULARITY
        !            48:     \begin{nrtc}
        !            49:     \item      VENDORS (e.g., COS)
        !            50:     \item      USER GROUPS (e.g., MAP/TOP)
        !            51:     \item      INTERNATIONAL COMMUNITY
        !            52:     \end{nrtc}
        !            53: \end{nrtc}
        !            54: \end{bwslide}
        !            55: 
        !            56: 
        !            57: \begin{bwslide}
        !            58: \ctitle        {INFORMAL DEFINITION OF TERMS}
        !            59: 
        !            60: \begin{nrtc}
        !            61: \item  OSI
        !            62: 
        !            63: \item  DDN, ARPA, ISO
        !            64: 
        !            65: \item  SUITE, STACK, WORLD
        !            66: 
        !            67: \item  BLACK-BOX
        !            68: 
        !            69: \item  GATEWAY, MAGIC-BOX
        !            70: \end{nrtc}
        !            71: \end{bwslide}
        !            72: 
        !            73: 
        !            74: \begin{bwslide}
        !            75: \ctitle        {$\ \ \ \ \ \ $ A BIG PROBLEM}
        !            76: \vskip-0.5in
        !            77: \diagram[p]{figure1}
        !            78: \end{bwslide}
        !            79: 
        !            80: 
        !            81: 
        !            82: \begin{note}\em
        !            83: note that ``development'' means design and implementation
        !            84: \end{note}
        !            85: 
        !            86: 
        !            87: \begin{bwslide}
        !            88: \ctitle        {MORE PROBLEMS}
        !            89: 
        !            90: \begin{nrtc}
        !            91: \item  NEED ISO EXPERTISE AND MATURITY (AT ALL LEVELS)
        !            92:     \begin{nrtc}
        !            93:     \item      BUT CAN'T WAIT~---~HAVE REQUIREMENTS NOW!
        !            94: 
        !            95:     \item      AS USUAL, DEVELOPMENT OF APPLICATIONS LAG BEHIND OTHER LAYERS
        !            96:     \end{nrtc}
        !            97: 
        !            98: \item  MIGRATION PREFERABLE TO STARTING FROM SCRATCH
        !            99:     \begin{nrtc}
        !           100:     \item      MANY NEW, MAJOR INVESTMENTS BEING MADE IN CURRENT\\
        !           101:                TECHNOLOGY (e.g., NSFnet, NASA's PROPOSED INTERNET, etc.)
        !           102: 
        !           103:     \item      MANY EXISTING SYSTEMS WORK ACCEPTABLY AND/OR HAVE A HEAVY
        !           104:                RE-IMPLEMENTATION COST
        !           105:     \end{nrtc}
        !           106: \end{nrtc}
        !           107: \end{bwslide}
        !           108: 
        !           109: 
        !           110: \begin{bwslide}
        !           111: \ctitle        {OBSERVATIONS}
        !           112: 
        !           113: \begin{nrtc}
        !           114: \item  MANY OF THESE PROBLEMS HAVE PREVIOUSLY BEEN SOLVED, IN\\ DIFFERENT
        !           115:        SETTINGS, WITHOUT LOSS OF GENERALITY
        !           116:     \begin{nrtc}
        !           117:     \item      SOME OF THESE SOLUTIONS ARE QUITE MATURE\\
        !           118:                (STABLE, ROBUST, AND ENJOY A HIGH DEGREE OF VENDOR SUPPORT)
        !           119:     \end{nrtc}
        !           120: 
        !           121: \item  THE ISO STACK IS A STRONGLY LAYERED ARCHITECTURE, WHICH\\ FACILITATES
        !           122:        APPLICATION-INDEPENDENCE OF UNDERLYING\\ PROTOCOLS
        !           123:     \begin{nrtc}
        !           124:     \item      SERVICES ARE IMPORTANT,\\ IMPLEMENTATIONS ARE NOT
        !           125:     \end{nrtc}
        !           126: \end{nrtc}
        !           127: \end{bwslide}
        !           128: 
        !           129: 
        !           130: \begin{bwslide}
        !           131: \part  {TOWARD A SOLUTION}\bf
        !           132: 
        !           133: \begin{nrtc}
        !           134: \item  USE A VENDOR-PROPRIETARY SOLUTION?
        !           135:     \begin{nrtc}
        !           136:     \item      HOW MANY TIMES WILL SYSTEMS HAVE TO BE REWRITTEN?
        !           137: 
        !           138:     \item      HOW MANY INTERIM SOLUTIONS WILL THE VENDORS SELL US?
        !           139:     \end{nrtc}
        !           140: 
        !           141: \item  DEVELOP A MIGRATION STRATEGY!
        !           142:     \begin{nrtc}
        !           143:     \item      ENSURE THAT ANY WORK STARTED TODAY WILL EASILY MIGRATE TO
        !           144:                TOTAL ISO SOLUTIONS, AS THEY BECOME AVAILABLE
        !           145: 
        !           146:     \item      ALLOW FOR THE CO-EXISTENCE OF CURRENTLY OPERATIONAL SYSTEMS
        !           147:     \end{nrtc}
        !           148: \end{nrtc}
        !           149: \end{bwslide}
        !           150: 
        !           151: 
        !           152: \begin{bwslide}
        !           153: \ctitle        {A SOLUTION}
        !           154: 
        !           155: \begin{nrtc}
        !           156: \item  USE TCP/IP AS THE MIGRATION VEHICLE
        !           157:     \begin{nrtc}
        !           158:     \item      OFFER ISO SERVICES ON TOP OF THE DDN PROTOCOL SUITE
        !           159: 
        !           160:     \item      DEVELOP ISO APPLICATIONS NOW IN A LARGE ENVIRONMENT
        !           161: 
        !           162:     \item      NO (OR MINIMAL) RECODING LATER
        !           163:     \end{nrtc}
        !           164: 
        !           165: \item  A FEW ADVANTAGES OF TCP/IP
        !           166:     \begin{nrtc}
        !           167:     \item      ROBUST, MATURE, ETC.
        !           168: 
        !           169:     \item      VENDOR SUPPORT
        !           170: 
        !           171:     \item      LARGE BODY OF EXPERTISE
        !           172: 
        !           173:     \item      SIMILAR ARCHITECTURE
        !           174:     \end{nrtc}
        !           175: \end{nrtc}
        !           176: \end{bwslide}
        !           177: 
        !           178: 
        !           179: \begin{note}\em
        !           180: assume everyone already knows about tcp/ip here$\ldots$
        !           181: 
        !           182: if not, we're in big trouble
        !           183: \end{note}
        !           184: 
        !           185: 
        !           186: \begin{bwslide}
        !           187: \ctitle        {PHILOSOPHY}
        !           188: 
        !           189: \begin{nrtc}
        !           190: \item  COMPLEMENTARY CO-EXISTENCE:
        !           191:     \begin{nrtc}
        !           192:     \item      UTILIZE TCP/IP FUNCTIONALITY NOT CURRENTLY IN ISO\\
        !           193:                (ROUTING, ETC.)
        !           194: 
        !           195:     \item      GAIN EXPERIENCE IN THE NUMEROUS EXISTING TCP/IP WORLDS
        !           196: 
        !           197:     \item      UTILIZE ISO FUNCTIONALITY AS IT BECOMES AVAILABLE
        !           198:     \end{nrtc}
        !           199: 
        !           200: \item  DEVELOP APPLICATIONS IN AN \underline{EVOLUTIONARY},
        !           201:        NOT \underline{REVOLUTIONARY}, FASHION
        !           202: 
        !           203: \item  WANT TO BE CONSISTENT WITH ISO'S DIRECTION,
        !           204:        BUT WANT TO GET WORK DONE NOW
        !           205: \end{nrtc}
        !           206: \end{bwslide}
        !           207: 
        !           208: 
        !           209: \begin{note}\em
        !           210: aside on arpa applications:
        !           211: 
        !           212: \begin{nrtc}
        !           213: \item  most are 15+ years old (sans domains)
        !           214: \item  each application ``rolls its own'' syntax
        !           215: \item  the netascii legacy
        !           216: \end{nrtc}  
        !           217: \end{note}
        !           218: 
        !           219: 
        !           220: \begin{bwslide}
        !           221: \ctitle        {$\ \ \ \ \ \ $ WHERE TO JOIN THEM?}
        !           222: \vskip-0.5in
        !           223: \diagram[p]{figure2}
        !           224: \end   {bwslide}
        !           225: 
        !           226: 
        !           227: \begin{bwslide}
        !           228: \ctitle        {COMPARISON OF THE TCP AND TP4}
        !           229: 
        !           230: \begin{nrtc}
        !           231: \item  THE TCP IS STREAM-ORIENTED, THE TP4 IS PACKET-ORIENTED
        !           232: 
        !           233: \item  THE TCP COALESCES SIMULTANEOUS CONNECTIONS
        !           234: 
        !           235: \item  THE TCP HAS AN ``URGENCY'' CONCEPT, THE TP4 HAS ``EXPEDITED''
        !           236: 
        !           237: \item  THE TCP HAS A GRACEFUL CLOSE
        !           238: \end{nrtc}
        !           239: \end{bwslide}
        !           240: 
        !           241: 
        !           242: \begin{bwslide}
        !           243: \ctitle        {APPROACH}
        !           244: 
        !           245: \begin{nrtc}
        !           246: \item  USE \underline{INTERFACE TRANSLATION} ABOVE TCP/IP
        !           247:     \begin{nrtc}
        !           248:     \item      USE A WRAPPER TO MAKE THE NATIVE TCP INTERFACE APPEAR TO BE
        !           249:                THE TP4 INTERFACE
        !           250: 
        !           251:     \item      SAME SERVICE OFFERED TO USERS
        !           252: 
        !           253:     \item      ENTIRELY DIFFERENT IMPLEMENTATION OF THOSE SERVICES
        !           254:     \end{nrtc}
        !           255: \end{nrtc}
        !           256: \end{bwslide}
        !           257: 
        !           258: 
        !           259: \begin{bwslide}
        !           260: \ctitle        {ISO TRANSPORT SERVICES ON TOP OF THE TCP}
        !           261: 
        !           262: \diagram[p]{figure5}
        !           263: \end{bwslide}
        !           264: 
        !           265: 
        !           266: \begin{bwslide}
        !           267: \ctitle        {SUMMARY OF THE MAGIC-BOX PROTOCOL}
        !           268: 
        !           269: \begin{nrtc}
        !           270: \item  OBSERVATIONS
        !           271:     \begin{nrtc}
        !           272:     \item      ALL THE REALLY HARD PARTS ARE ALREADY DONE BY THE\\ TCP
        !           273:                (i.e., THE MAJORITY OF THE TRANSPORT PROTOCOL\\ FUNCTIONALITY)
        !           274: 
        !           275:     \item      THE TRANSPORT INTERFACING REMAINS TO BE DONE
        !           276:     \end{nrtc}
        !           277: 
        !           278: \item  USES AN EFFICIENT PACKETIZATION PROTOCOL\\
        !           279:        (GOING THE OTHER WAY IS A LOT HARDER)
        !           280: 
        !           281: \item  QUALITY OF SERVICE~---~FOR FURTHER STUDY
        !           282: \end{nrtc}
        !           283: \end{bwslide}
        !           284: 
        !           285: 
        !           286: \begin{bwslide}
        !           287: \ctitle        {ISSUE: MANAGEMENT OF THE ADDRESS SPACE}
        !           288: 
        !           289: THE CLEVER APPROACH:
        !           290: \begin{small}
        !           291: \[\begin{tabular}{rlc}
        !           292:        $<$NSAP ID$>$&          $\longleftrightarrow$&  $<$IP address$>$\\
        !           293:        $<$TSAP selector, SSAP selector, PSAP selector$>$&
        !           294:                                $\longleftrightarrow$&  $<$TCP port$>$
        !           295: \end{tabular}\]
        !           296: \end{small}
        !           297: 
        !           298: \begin{nrtc}
        !           299: \item  SUGGESTS THAT THE TP CAN BE RUN DIRECTLY ABOVE THE DDN IP PROTOCOL
        !           300: \end{nrtc}
        !           301: \end{bwslide}
        !           302: 
        !           303: 
        !           304: 
        !           305: \begin{bwslide}
        !           306: \ctitle        {MANAGEMENT OF THE ADDRESS SPACE (cont.)}
        !           307: 
        !           308: \begin{nrtc}
        !           309: \item  THE TCP PORT SPACE IS TOO LIMITED
        !           310: 
        !           311: \item  THE SIMPLE SOLUTION:\\
        !           312:        USE A SINGLE HARD-WIRED MAGIC-BOX PORT FOR THE TCP
        !           313: \end{nrtc}
        !           314: \end{bwslide}
        !           315: 
        !           316: 
        !           317: \begin{bwslide}
        !           318: \ctitle        {ISSUE: EXPEDITED DATA}
        !           319: 
        !           320: THREE WAYS TO TRY IT:
        !           321: \begin{nrtc}
        !           322: \item  ONE TCP CONNECTION\\
        !           323:        BORDERLINE COMPLIANCE
        !           324: 
        !           325: \item  ONE TCP CONNECTION WITH URGENCY TO SIGNAL EXPEDITED DATA
        !           326: 
        !           327: \item  TWO TCP CONNECTIONS, ONE WITH BETTER IP QOS\\
        !           328:        COMPLICATED PROTOCOL NEEDED TO GUARANTEE COMPLIANCE
        !           329: \end{nrtc}
        !           330: \end{bwslide}
        !           331: 
        !           332: 
        !           333: \begin{bwslide}
        !           334: \ctitle        {EXPEDITED DATA (cont.)}
        !           335: 
        !           336: \begin{nrtc}
        !           337: \item  NOT ALL TCP IMPLEMENTATIONS CORRECTLY HANDLE URGENCY IN THE
        !           338:        DEGENERATE CASES
        !           339: 
        !           340: \item  NOT ALL IP IMPLEMENTATIONS ACTUALLY IMPLEMENT QOS
        !           341: 
        !           342: \item  THE SIMPLE SOLUTION:\\
        !           343:        USE A SINGLE CONNECTION SINCE THIS IS THE LEAST COMPLEX CHOICE
        !           344: \end{nrtc}
        !           345: \end{bwslide}
        !           346: 
        !           347: 
        !           348: \begin{bwslide}
        !           349: \ctitle        {COMPARISON TO OTHER APPROACHES}
        !           350: 
        !           351: \begin{nrtc}
        !           352: \item  THE ARCHIVAL REFERENCE: [PGREE86]
        !           353: 
        !           354: \item  PROTOCOL TRANSLATION: \tcptpgw/ [IGROE86]
        !           355:     \begin{nrtc}
        !           356:     \item      ANALYZE ESMs FOR EACH
        !           357:     \item      IDENTIFY SUBSET OF COMMON SERVICES
        !           358:     \item      BUILD ESM FOR MAGIC-BOX
        !           359:     \end{nrtc}
        !           360: \end{nrtc}
        !           361: \end{bwslide}
        !           362: 
        !           363: 
        !           364: \begin{bwslide}
        !           365: \ctitle        {WHAT IS THE PRACTICAL VALUE?}
        !           366: 
        !           367: \begin{nrtc}
        !           368: \item  STILL NO COMMONALITY FOR APPLICATIONS
        !           369:     \begin{nrtc}
        !           370:     \item      DDN APPLICATIONS STILL WANT TCP SERVICES\\
        !           371:                SO CAN'T RUN DDN STUFF IN THE ISO WORLD
        !           372: 
        !           373:     \item      ISO APPLICATIONS STILL WANT ISO SERVICES\\
        !           374:                SO CAN'T RUN ISO STUFF IN THE DDN WORLD
        !           375:     \end{nrtc}
        !           376: 
        !           377: \item  ONE WORLD HAS TO IMPLEMENT THE OTHER WORLD'S STACK
        !           378: \end{nrtc}
        !           379: \end{bwslide}
        !           380: 
        !           381: 
        !           382: \begin{note}\em
        !           383: but, isn't this criticism also true of our work?
        !           384: 
        !           385: yes.
        !           386: \end{note}
        !           387: 
        !           388: 
        !           389: \begin{bwslide}
        !           390: \part  {A DIGRESSION ON THE INTEROPERABILITY OF APPLICATIONS}\bf
        !           391: 
        !           392: CAN WE DO EITHER OF THESE?
        !           393: \begin{nrtc}
        !           394: \item  ACHIEVE INTEROPERABILITY BETWEEN SIMILAR APPLICATIONS\\ (e.g., MAIL)
        !           395: 
        !           396: \item  MOVE AN APPLICATION FROM ONE PROTOCOL SUITE TO ANOTHER
        !           397: \end{nrtc}
        !           398: \end{bwslide}
        !           399: 
        !           400: 
        !           401: \begin{bwslide}
        !           402: \ctitle        {ABSTRACT VIEW OF AN ENTITY}
        !           403: 
        !           404: \diagram[p]{figure7}
        !           405: \end{bwslide}
        !           406: 
        !           407: 
        !           408: \begin{bwslide}
        !           409: \ctitle        {APPROACH \#1: BUILD AN APPLICATION MAGIC-BOX}
        !           410: 
        !           411: PROBLEM: SERVICES OFFERED USUALLY VARY DRAMATICALLY
        !           412: 
        !           413: \vspace{0.25in}
        !           414: \diagram[p]{figure3}
        !           415: \vspace{0.25in}
        !           416: 
        !           417: E.G., MAIL, CONSIDER [SKILL86]
        !           418: \end{bwslide}
        !           419: 
        !           420: 
        !           421: \begin{note}\em
        !           422: The acid test is moving data through the magic-box and back again w/o loss
        !           423: of information
        !           424: 
        !           425: padlipsky: ``sometimes when you try to turn an apple into an orange you get
        !           426: back a lemon''
        !           427: \end{note}
        !           428: 
        !           429: 
        !           430: \begin{bwslide}
        !           431: \ctitle        {APPROACH \#2: MIGRATE THE APPLICATION}
        !           432: 
        !           433: PROBLEM: SERVICES REQUIRED USUALLY VARY DRAMATICALLY
        !           434: 
        !           435: \vspace{0.25in}
        !           436: \diagram[p]{figure4}
        !           437: \end{bwslide}
        !           438: 
        !           439: 
        !           440: \begin{bwslide}
        !           441: \ctitle        {THE RECURRING THEME}
        !           442: 
        !           443: GENERAL UTILITY REQUIRES THAT PROTOCOL CONVERSION OCCUR AT EVERY LAYER
        !           444: IN WHICH THE SUITES CAN BE CONNECTED
        !           445: \end{bwslide}
        !           446: 
        !           447: 
        !           448: \begin{bwslide}
        !           449: \ctitle        {THE RECURRING THEME (cont.)}
        !           450: 
        !           451: SO TO INTEROPERATE MAIL (FOR EXAMPLE), WE NEED ONE OF:
        !           452: \begin{nrtc}
        !           453: \item  SMTP IN BOTH WORLDS
        !           454: 
        !           455: \item  P1 IN BOTH WORLDS
        !           456: 
        !           457: \item  SMTP AND P1 RUNNING IN THE \tcptpgw/\\
        !           458:        (REALLY AN APPLICATION RELAY)
        !           459: \end{nrtc}
        !           460: IN ADDITION TO THE \tcptpgw/
        !           461: \end{bwslide}
        !           462: 
        !           463: 
        !           464: \begin{note}\em
        !           465: all three choices are hard from above (services offered)
        !           466: 
        !           467: all three choices are hard from below (services required)
        !           468: \end{note}
        !           469: 
        !           470: 
        !           471: \begin{bwslide}
        !           472: \ctitle        {DOES INTERFACE TRANSLATION HELP?}
        !           473: 
        !           474: \begin{nrtc}
        !           475: \item  BOTH GIVE THE SAME END-RESULT
        !           476: 
        !           477: \item  \underline{INTERFACE} TRANSLATION REQUIRES SIMILAR FUNCTIONALITY
        !           478:        BETWEEN THE TWO \underline{SERVICES} IN QUESTION
        !           479: 
        !           480: \item  \underline{PROTOCOL} TRANSLATION REQUIRES SIMILAR FUNCTIONALITY\\
        !           481:        BETWEEN THE TWO \underline{PROTOCOLS} IN QUESTION
        !           482: 
        !           483: \item  HENCE, OPTIMALITY DEPENDS ON CONTEXT
        !           484: \end{nrtc}
        !           485: \end{bwslide}
        !           486: 
        !           487: 
        !           488: \begin{note}\em
        !           489: in other words,
        !           490: neither approach makes applications interoperate
        !           491: 
        !           492: there is no free lunch!
        !           493: \end{note}
        !           494: 
        !           495: 
        !           496: \begin{bwslide}
        !           497: \ctitle        {BENEFITS IN OUR CONTEXT}
        !           498: 
        !           499: \begin{nrtc}
        !           500: \item  SHORT-TERM: EASY TO IMPLEMENT
        !           501: 
        !           502: \item  MEDIUM-TERM:
        !           503:     \begin{nrtc}
        !           504:     \item      ANY FUTURE WORK IS DONE IN ONE STACK, BUT WILL RUN IN BOTH
        !           505:                WORLDS
        !           506: 
        !           507:     \item      APPLICATION DESIGNERS CAN USE AN ISO-APPLICATIONS\\ FRAMEWORK
        !           508:                IN THE NUMEROUS EXISTING TCP/IP WORLDS
        !           509:     \end{nrtc}
        !           510: 
        !           511: \item  LONG-TERM: PROVIDES THE BASIS FOR A MIGRATION STRATEGY
        !           512: \end{nrtc}
        !           513: \end{bwslide}
        !           514: 
        !           515: 
        !           516: \begin{bwslide}
        !           517: \part  {A MIGRATION STRATEGY}\bf
        !           518: 
        !           519: \begin{nrtc}
        !           520: \item  THREE PHASES FROM THE DDN SUITE TO THE ISO SUITE
        !           521: 
        !           522: \item  ASSUMES AN EXISTING (AND HOPEFULLY) EXTENSIVE TCP/IP\\
        !           523:        INTERNET IN PLACE
        !           524: 
        !           525: \item  REQUIRES ALL NEW HOSTS TO SPEAK TCP/IP UNTIL PHASE THREE
        !           526: 
        !           527: \end{nrtc}
        !           528: \end{bwslide}
        !           529: 
        !           530: 
        !           531: \begin{bwslide}
        !           532: \ctitle        {PHASE ONE:\\ BUILD ISO DEVELOPMENT ENVIRONMENT}
        !           533: 
        !           534: \begin{nrtc}
        !           535: \item  BEGIN WORKING ON ISO APPLICATIONS
        !           536: 
        !           537: \item  MAGIC-BOX OFFERS TP4 SERVICE
        !           538: 
        !           539: \item  DEVELOP DDN/ISO USER AGENTS
        !           540:     \begin{nrtc}
        !           541:     \item      COMMON USER-INTERFACE
        !           542: 
        !           543:     \item      USE EITHER DDN OR ISO APPLICATION SERVICE, AS AVAILABLE
        !           544: 
        !           545:     \item      NAME(DIRECTORY) SERVICE DETERMINES CHOICE OF STACK
        !           546:     \end{nrtc}
        !           547: \end{nrtc}
        !           548: \end{bwslide}
        !           549: 
        !           550: 
        !           551: \begin{note}\em
        !           552: for example, the symbolics filesystem interface
        !           553: \end{note}
        !           554: 
        !           555: 
        !           556: \begin{bwslide}
        !           557: \ctitle        {PHASE TWO:\\ EXPERIMENT WITH MIGRATION ENGINES}
        !           558: 
        !           559: \begin{nrtc}
        !           560: \item  START USING HOSTS WITH BOTH ISO AND DDN STACKS
        !           561: 
        !           562: \item  TEST APPLICATIONS IN A ``PURE'' ISO ENVIRONMENT
        !           563: 
        !           564: \item  DO IP-LEVEL ROUTERS TO FORM TWO LOGICAL INTERNETS
        !           565: \end{nrtc}
        !           566: \end{bwslide}
        !           567: 
        !           568: 
        !           569: \begin{bwslide}
        !           570: \ctitle        {PHASE THREE:\\ DEPLOY MIGRATION ENGINES}
        !           571: 
        !           572: \begin{nrtc}
        !           573: \item  RELATIVELY INEXPENSIVE (AT FIRST) TO KEEP SOME DDN-ONLY HOSTS
        !           574: 
        !           575: \item  USER AGENTS BEGIN TO SPEAK ISO ONLY
        !           576: 
        !           577: \item  NEW HOSTS CAN BE ISO ONLY
        !           578: \end{nrtc}
        !           579: \end{bwslide}
        !           580: 
        !           581: 
        !           582: \begin{bwslide}
        !           583: \ctitle {LAN--BASED MIGRATION TO NATIVE ISO}
        !           584: \vskip-0.5in
        !           585: \diagram[p]{figure6}
        !           586: \end{bwslide}
        !           587: 
        !           588: 
        !           589: \begin{note}\em
        !           590: so, our plan is to attack things from the top,
        !           591: while others attack from the bottom$\ldots$
        !           592: \end{note}
        !           593: 
        !           594: 
        !           595: \begin{bwslide}
        !           596: \part  {THE FIRST STEP:\\ ISODE}\bf
        !           597: 
        !           598: \begin{nrtc}
        !           599: \item  AN OPENLY AVAILABLE ISO DEVELOPMENT
        !           600:        ENVIRONMENT HAS BEEN IMPLEMENTED AT NRTC
        !           601: 
        !           602: \item  CODED ENTIRELY IN C
        !           603: \end{nrtc}
        !           604: \end{bwslide}
        !           605: 
        !           606: 
        !           607: \begin{bwslide}
        !           608: \ctitle        {OPERATING ENVIRONMENTS}
        !           609: 
        !           610: \begin{nrtc}
        !           611: \item  4.2\bsd/ \unix/
        !           612: \item  SVR2 AT\&T \unix/ WITH AN EXCELAN \exos/~8044 TCP/IP PACKAGE
        !           613: \item  \vax//\vms/ RELEASE 4.4 WITH AN \exos/ CARD (UNDER DEVELOPMENT)
        !           614: \item  \pcdos/ WITH THE MIT PC-IP SOFTWARE (UNDER NEGOTIATION)
        !           615: \end{nrtc}
        !           616: 
        !           617: \end{bwslide}
        !           618: 
        !           619: 
        !           620: \begin{bwslide}
        !           621: \ctitle        {SOFTWARE}
        !           622: 
        !           623: \begin{nrtc}
        !           624: \item  TRANSPORT: IMPLEMENTS VERSION~2 OF THE MAGIC-BOX PROTOCOL
        !           625: 
        !           626: \item  SESSION: BCS, BAS, BSS, EXPEDITED
        !           627: 
        !           628: \item  PRESENTATION: ASN.1 ENCODING
        !           629: 
        !           630: 
        !           631: \item  APPLICATION: 
        !           632:     \begin{nrtc}
        !           633:     \item      ROS (REMOTE OPERATIONS)
        !           634: 
        !           635:     \item      RTS (RELIABLE TRANSFER)
        !           636: 
        !           637:     \item      ASN.1 SPECIFICATION PARSER FOR THE AUTOMATIC GENERATION OF
        !           638:                APDU PARSERS
        !           639:     \end{nrtc}
        !           640: 
        !           641: \item  PLANNED FOR THE NEXT RELEASE:
        !           642:     \begin{nrtc}
        !           643:     \item      MAP/TOP VERSION~3.0 COMPATIBILITY\\
        !           644:                (WHEN THAT STABILIZES)
        !           645: 
        !           646:     \item      APPLICATION SERVICE ELEMENTS (ASE) SUPPORT
        !           647: 
        !           648:     \item      ISO PRESENTATION PROTOCOL
        !           649:     \end{nrtc}
        !           650: \end{nrtc}
        !           651: \end{bwslide}
        !           652: 
        !           653: 
        !           654: \begin{bwslide}
        !           655: \ctitle        {PERFORMANCE OBSERVATIONS}
        !           656: 
        !           657: \begin{nrtc}
        !           658: \item  ALTHOUGH NOT PRODUCTION SOFTWARE,
        !           659:        CODED WITH AN EYE\\ TOWARD EFFICIENCY
        !           660: 
        !           661: \item  INITIAL BENCHMARKING SUGGESTS THROUGHPUT RATES VERY CLOSE TO RAW TCP
        !           662:        FOR BOTH TRANSPORT AND SESSION ECHO AND SINK ENTITIES
        !           663: 
        !           664: \item  AT THE APPLICATION INTERFACE,
        !           665:        PERFORMANCE IS ONLY 10\%-12\% WORSE THAN RAW TCP
        !           666: 
        !           667: \item  RESULTS PRIMARILY DUE TO MINIMIZED BYTE-COPYING BETWEEN\\
        !           668:        LAYERS
        !           669: \end{nrtc}
        !           670: \end{bwslide}
        !           671: 
        !           672: 
        !           673: \begin{bwslide}
        !           674: \ctitle        {FOR FURTHER READING}
        !           675: 
        !           676: \begin{nrtc}
        !           677: \item  REQUEST FOR COMMENTS 983 [DCASS86]
        !           678: 
        !           679: \item  ISO TRANSPORT SERVICES ON TOP OF THE TCP\\
        !           680:        COMPUTER NETWORKS AND ISDN SYSTEMS JOURNAL (TO APPEAR)
        !           681: 
        !           682: \item  REQUEST FOR COMMENTS 987 [SKILL86]\\
        !           683:        MAPPING BETWEEN X.400 AND RFC822
        !           684: 
        !           685: \item  PROTOCOL CONVERSION [PGREE86]\\
        !           686:        IEEE TRANSACTIONS ON COMMUNICATION\\
        !           687:        VOLUME 34, NUMBER 3, MARCH 1986
        !           688: 
        !           689: \item  CONVERSION BETWEEN THE TCP AND ISO TRANSPORT$\ldots$
        !           690:        [IGROE86]\\
        !           691:        IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS\\
        !           692:        VOLUME 4, NUMBER 2, MARCH 1986
        !           693: 
        !           694: \item  MOVING FROM DOD TO ISO PROTOCOLS: A FIRST STEP [MWITT86]\\
        !           695:        ACM COMPUTER COMMUNICATIONS REVIEW\\
        !           696:        VOLUME 16, NUMBER 2, APRIL/MAY 1986
        !           697: \end{nrtc}
        !           698: \end{bwslide}
        !           699: 
        !           700: 
        !           701: \end{document}

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