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1.1 root 1: % run this through LaTeX with the appropriate wrapper
2:
3: \dotopic{TRANSITION AND\\ COEXISTENCE\\ WITH TCP/IP}
4:
5:
6: \begin{bwslide}
7: \part* {OUTLINE}\bf
8:
9: \begin{description}
10: \item[PART I:] MOTIVATION
11:
12: \item[PART II:] BACKGROUND
13:
14: \item[PART III:] PROTOCOL-BASED APPROACHES
15:
16: \item[PART IV:] SERVICE-BASED APPROACHES
17:
18: \item[PART V:] EXAMPLES
19: \end{description}
20: \end{bwslide}
21:
22:
23: \begin{bwslide}
24: \ctitle {A BIG ACKNOWLEDGEMENT}
25:
26: \begin{nrtc}
27: \item TRANSITION IS MOSTLY SMOKE AND MIRRORS
28:
29: \item THE PRACTICAL PERSPECTIVED PRESENTED HERE IS HEAVILY INFLUENCED BY
30: DISCUSSIONS WITH
31: \begin{nrtc}
32: \item EINAR A.~STEFFERUD (NMA)
33:
34: \item DAVID H.~CROCKER (DEC)
35: \end{nrtc}
36: \end{nrtc}
37: \end{bwslide}
38:
39:
40: \begin{bwslide}
41: \part {MOTIVATION}\bf
42:
43: \begin{nrtc}
44: \item THERE ARE MANY TCP/IP NETWORKS TODAY; THERE WILL BE MORE TOMORROW
45:
46: \item BY THE TIME OSI BECOMES A WORTHWHILE OPERATIONAL ALTERNATIVE,
47: THERE WILL BE MANY MORE TCP/IP NETWORKS THAN THERE ARE TODAY!
48:
49: \item PROBLEM: HOW TO PROTECT INSTALLED BASE?
50:
51: \item PROBLEM: HOW TO TRANSITION GRACEFULLY?
52: \end{nrtc}
53: \end{bwslide}
54:
55:
56: \begin{bwslide}
57: \ctitle {GROWTH OF TCP/IP}
58:
59: \begin{nrtc}
60: \item SALES OF TCP/IP-BASED TECHNOLOGY
61: \begin{nrtc}
62: \item PARTICULARLY IN EUROPE
63: \end{nrtc}
64: CONTINUES TO GROW
65:
66: \item SEVERAL TECHNICAL AND MARKET ASPECTS CONTRIBUTE TO THIS PHENOMENA:
67: \begin{nrtc}
68: \item SUPERIORITY OF TCP/IP IN LOWER-LAYER CONNECTIVITY
69:
70: \item MATURITY OF TCP/IP PRODUCTS\\ (e.g., RANGE OF PLATFORMS)
71: \end{nrtc}
72:
73: \item ALTHOUGH OSI WILL DOMINATE, IT DOESN'T YET
74:
75: \item HENCE, TCP/IP IS BECOMING MORE FIRMLY ENTRENCHED
76: \end{nrtc}
77: \end{bwslide}
78:
79:
80: \begin{bwslide}
81: \ctitle {FEAR AND LOATHING IN THE MARKET}
82:
83: \begin{nrtc}
84: \item F.U.D. IN THE MARKETPLACE:
85: \begin{quote}\em
86: ``All marketing is fear, uncertainty, and doubt.''\\ \raggedleft
87: -- Einar Stefferud, Network Management Associates
88: \end{quote}
89:
90: \item WHAT THE VENDORS SAY:
91: \begin{quote}\em
92: ``$\ldots$ protect your investment while assuring a path to an OSI
93: future.''\\ \raggedleft
94: -- Vendor A
95: \end{quote}
96: AND
97: \begin{quote}\em
98: ``$\ldots$ plans for a smooth, painless guaranteed migration to OSI standards
99: as they are approved.''\\ \raggedleft
100: --Vendor B
101: \end{quote}
102: AND
103: \begin{quote}\em
104: ``Once you've scrapped your existing production networks,
105: come to us for OSI.
106: It will be wonderful!''\\ \raggedleft
107: --Vendor C
108: \end{quote}
109: \end{nrtc}
110: \end{bwslide}
111:
112:
113: \begin{bwslide}
114: \ctitle {THE SAD TRUTH}
115:
116: \begin{quote}\em
117: ``You can't win, and you can't quit, but you \underline{can} reduce the
118: pain.''\\ \raggedleft
119: -- Marshall Rose, PSI, Inc.
120: \end{quote}
121: \end{bwslide}
122:
123:
124: \begin{bwslide}
125: \part {BACKGROUND}\bf
126:
127: \begin{nrtc}
128: \item CONCEPTS
129:
130: \item TERMINOLOGY
131:
132: \item HISTORY
133:
134: \item METRICS FOR COMPARISON
135: \end{nrtc}
136: \end{bwslide}
137:
138:
139: \begin{bwslide}
140: \ctitle {THE FUNDAMENTAL ASSUMPTION}
141:
142: \begin{nrtc}
143: \item TCP/IP IS HERE TODAY, WIDELY INSTALLED, AND USEFUL
144:
145: \item OSI WILL EVENTUALLY REPLACE TCP/IP AS THE OFF-THE-SHELF TECHNOLOGY FOR
146: BUILDING INTEROPERABLE SYSTMS
147:
148: \item BOTH WILL BE SIMULTANEOUSLY WIDESPREAD FOR QUITE SOME TIME
149: \begin{nrtc}
150: \item DURING WHICH OSI WILL GAIN DOMINANCE
151: \end{nrtc}
152: \end{nrtc}
153: \end{bwslide}
154:
155:
156: \begin{bwslide}
157: \part* {CONCEPTS}\bf
158:
159: \begin{nrtc}
160: \item TRANSITION:
161: \begin{nrtc}
162: \item TO MOVE FROM ONE PROTOCOL SUITE TO ANOTHER
163: \end{nrtc}
164:
165: \item COEXISTENCE:
166: \begin{nrtc}
167: \item TO LIVE TOGETHER WITHOUT HOSTILITY OR CONFLICT DESPITE
168: DIFFERENCES
169: \end{nrtc}
170:
171: \item MIGRATION:
172: \begin{nrtc}
173: \item TO MOVE BACK AND FORTH, AS THE SEASONS CHANGE
174: \end{nrtc}
175: \end{nrtc}
176: \end{bwslide}
177:
178:
179: \begin{bwslide}
180: \ctitle {MAPPINGS}
181:
182: \begin{nrtc}
183: \item TRANSITION AND COEXISTENCE CAN BE DESCRIBED BY THE MAPPINGS THEY
184: REQUIRE
185:
186: \item SOME MAPPINGS ARE SIMPLE
187: \begin{nrtc}
188: \item i.e., SYNTACTIC CHANGES
189: \end{nrtc}
190:
191: \item SOME MAPPINGS ARE COMPLEX
192: \begin{nrtc}
193: \item i.e., SEMANTIC CHANGES
194: \end{nrtc}
195:
196: \item THE MORE COMPLEX THE MAPPING, THE GREATER THE LOSS OF INFORMATION OR
197: INTENT
198: \end{nrtc}
199: \end{bwslide}
200:
201:
202: \begin{bwslide}
203: \part* {TERMINOLOGY}\bf
204:
205: \begin{nrtc}
206: \item WE'LL FAVOR OSI TERMINOLOGY, BUT STILL NEED SOME INTERNET (TCP/IP)
207: TERMINOLOGY
208:
209: \item TWO BASIC TERMS
210: \begin{nrtc}
211: \item GATEWAY: GENERIC TO ANY LEVEL, COMPLEX
212:
213: \item BRIDGE: GENERIC TO ANY LEVEL, SIMPLE
214: \end{nrtc}
215: \end{nrtc}
216: \end{bwslide}
217:
218:
219: \begin{bwslide}
220: \ctitle {SERVICE SEMANTICS}
221:
222: \begin{nrtc}
223: \item STORE-AND-FORWARD
224: \begin{nrtc}
225: \item SERVICE SEMANTICS CARRIED MULTI-HOP VIA FORWARDERS
226: \end{nrtc}
227:
228: \item END-TO-END
229: \begin{nrtc}
230: \item SERVICE SEMANTICS CARRIED FROM ORIGINATOR TO RECIPIENT
231:
232: \item MAY BE SUPPORTED BY AN UNDERYLING STORE-AND-FORWARD SERVICE
233: \end{nrtc}
234: \end{nrtc}
235: \end{bwslide}
236:
237:
238: \begin{bwslide}
239: \ctitle {SERVICE SEMANTICS (cont.)}
240:
241: \vskip.5in
242: \diagram[p]{figureT-3}
243: \end{bwslide}
244:
245:
246: \begin{bwslide}
247: \ctitle {PROTOCOL SUITE}
248:
249: \begin{nrtc}
250: \item A COLLECTION OF SERVICES AND PROTOCOLS RELATED:
251: \begin{nrtc}
252: \item ADMINISTRATIVELY, BY AN ORGANIZATION\\ (e.g., ISO/IEC); and,
253:
254: \item PHILOSOPHICALLY, BY A REFERENCE MODEL\\ (e.g., the OSIRM)
255: \end{nrtc}
256:
257: \item FOR OUR PURPOSES, THERE ARE ONLY TWO:
258: \begin{nrtc}
259: \item THE OSI SUITE OF PROTOCOLS
260:
261: \item THE INTERNET SUITE OF PROTOCOLS
262: \end{nrtc}
263: \end{nrtc}
264: \end{bwslide}
265:
266:
267: \begin{bwslide}
268: \ctitle {APPLICATIONS}
269:
270: \begin{nrtc}
271: \item APPLICATION CLASS
272: \begin{nrtc}
273: \item A SET OF APPLICATIONS RELATED TO A PARTICULAR ACTIVITY,
274: e.g., FILE TRANSFER, IRREGARDLESS OF PROTOCOL SUITE
275: \end{nrtc}
276:
277: \item APPLICATION INSTANCE
278: \begin{nrtc}
279: \item A MEMBER OF AN APPLICATION CLASS SPECIFIC TO A PARTICULAR
280: PROTOCOL SUITE, e.g., FTAM
281: \end{nrtc}
282: \end{nrtc}
283: \end{bwslide}
284:
285:
286: \begin{bwslide}
287: \part* {HISTORY}\bf
288:
289: \begin{nrtc}
290: \item A VERY BRIEF INTRODUCTION TO THE TWO PROTOCOL SUITES
291:
292: \item WE'LL ATTEMPT TO TAKE A NON-PARTISAN VIEW (ha!)
293: \end{nrtc}
294: \end{bwslide}
295:
296:
297: \begin{bwslide}
298: \ctitle {INTERNET SUITE}
299:
300: \begin{nrtc}
301: \item SPONSORED BY THE U.S.~DoD
302: \begin{nrtc}
303: \item GREW OUT OF EARLY (D)ARPA RESEARCH INTO SURVIVABLE NETWORKS
304: \end{nrtc}
305: BASIS FROM THE DoD INTERNET ARCHITECTURE MODEL
306:
307: \item SPECIFIED IN ``REQUEST FOR COMMENTS'' SERIES (RFCs) AND
308: U.S.~MILITARY STANDARDS (MILSTDs)
309:
310: \item CURRENT GENERATION PRIMARILY BASED ON
311: \begin{nrtc}
312: \item CONNECTION-ORIENTED TRANSPORT SERVICE,
313: PROVIDED BY THE TCP; AND,
314:
315: \item CONNECTIONLESS-MODE NETWORK SERVICE,
316: PROVIDED BY THE IP
317: \end{nrtc}
318:
319: \item MAJOR EMPHASIS ON CONNECTIVITY OF DIVERSE SUB-NETWORKS
320: \begin{nrtc}
321: \item EXCELLENT RESEARCH CONTINUES, TO THIS DAY, ON THESE ISSUES
322: \end{nrtc}
323: \end{nrtc}
324: \end{bwslide}
325:
326:
327: \begin{bwslide}
328: \ctitle {INTERNET SUITE (cont.)}
329:
330: \begin{nrtc}
331: \item SEVERAL PRODUCTION APPLICATIONS
332: \begin{nrtc}
333: \item SIMPLE MAIL TRANSFER PROTOCOL (SMTP)
334:
335: \item FILE TRANSFER PROTOCOL (FTP)
336:
337: \item TELNET (VIRTUAL TERMINAL PROTOCOL)
338:
339: \item DOMAIN NAME SYSTEM (DNS)
340: \end{nrtc}
341: ALL OF WHICH ARE RATHER SIMPLE
342:
343: \item APPLICATIONS CONTAIN THEIR OWN IMPLICIT SESSION AND PRESENTATION
344: MECHANISMS
345:
346: \item NOT SURPRISING, CONSIDERING THAT THESE APPLICATIONS ARE ALL BASED ON
347: 15~YEAR OLD MODELS!
348: \end{nrtc}
349: \end{bwslide}
350:
351:
352: \begin{bwslide}
353: \ctitle {INTERNET PROTOCOLS}
354:
355: \vskip.5in
356: \diagram[p]{figureT-4}
357: \end{bwslide}
358:
359:
360: \begin{bwslide}
361: \ctitle {OSI SUITE}
362:
363: \begin{nrtc}
364: \item SPONSORED BY THE INTERNATIONAL COMMUNITY
365: \begin{nrtc}
366: \item IN PARTICULAR THE ISO
367: \end{nrtc}
368: BASIS FROM THE OSI REFERENCE MODEL (OSIRM)
369:
370: \item SPECIFIED IN ``STANDARDS'' (ISO/IEC) AND RECOMMENDATIONS (CCITT)
371:
372: \item BASED ON
373: \begin{nrtc}
374: \item CONNECTION-ORIENTED TRANSPORT SERVICE,
375: PROVIDED BY ONE OF FIVE DIFFERENT TPs; DEPENDING ON
376:
377: \item THE NETWORK SERVICE AVAILABLE (CONS or CLNS)
378: \end{nrtc}
379:
380: \item DIFFICULT TO IDENTIFY THE ``MAJOR'' EMPHASIS
381: \end{nrtc}
382: \end{bwslide}
383:
384:
385: \begin{bwslide}
386: \ctitle {OSI SUITE (cont.)}
387:
388: \begin{nrtc}
389: \item SEVERAL INTERESTING APPLICATIONS
390: \begin{nrtc}
391: \item MESSAGE HANDLING SYSTEMS (MHS)
392:
393: \item FILE TRANSFER, ACCESS AND MANAGEMENT (FTAM)
394:
395: \item VIRTUAL TERMINAL (VT)
396:
397: \item DIRECTORY SERVICES (DS)
398: \end{nrtc}
399:
400: \item APPLICATIONS EVOLVING QUITE HEAVILY OVER THE LAST FEW YEARS
401:
402: \item MUCH MORE AMBITIOUS THAN THEIR INTERNET COUNTERPARTS
403: \end{nrtc}
404: \end{bwslide}
405:
406:
407: \begin{bwslide}
408: %%%\ctitle {OSI PROTOCOLS}
409:
410: %%%\vskip.25in
411: \diagram[p]{figureT-5}
412: \end{bwslide}
413:
414:
415: \begin{bwslide}
416: \ctitle {A BRIEF COMPARISON}
417:
418: \begin{nrtc}
419: \item NOTE THAT CONCERNS DIFFER
420: \begin{nrtc}
421: \item NETWORK USERS: APPLICATION-LEVEL FUNCTIONALITY
422:
423: \item NETWORK ADMINISTRATORS: NETWORK AND TRANSPORT ISSUES
424: \end{nrtc}
425:
426: \item FOR APPLICATIONS, ONCE IMPLEMENTED, THE OSI SUITE IS SUPERIOR
427:
428: \item FOR NETWORK/TRANSPORT ISSUES, AT PRESENT,
429: THE INTERNET SUITE IS SUPERIOR
430: \end{nrtc}
431: \end{bwslide}
432:
433:
434: \begin{bwslide}
435: \part* {METRICS FOR COMPARISON}\bf
436:
437: \begin{nrtc}
438: \item CAN JUDGE A TRANSITION/COEXISTENCE SCHEME USING DIFFERENT
439: CRITERIA
440:
441: \item THE FOUR WE'LL FOCUS ON ARE ALL SUBJECTIVE;
442: \begin{nrtc}
443: \item TECHNICAL SOLUTIONS DO NOT EXIST IN A VACUUM
444:
445: \item THEY MUST BE EVALUATED IN THE CONTEXT OF A TARGET ENVIRONMENT
446: \end{nrtc}
447: \end{nrtc}
448: \end{bwslide}
449:
450:
451: \begin{bwslide}
452: \ctitle {METRICS FOR COMPARISON (cont.)}
453:
454: \begin{nrtc}
455: \item PERFORMANCE:
456: \begin{nrtc}
457: \item THROUGHPUT, LATENCY
458:
459: \item EFFECT ON OTHER APPLICATIONS
460: \end{nrtc}
461:
462: \item FLEXIBILITY:
463: \begin{nrtc}
464: \item RANGE OF APPLICABILITY
465: \end{nrtc}
466: \end{nrtc}
467: \end{bwslide}
468:
469:
470: \begin{bwslide}
471: \ctitle {METRICS FOR COMPARISON (cont.)}
472:
473: \begin{nrtc}
474: \item TRANSPARENCY:
475: \begin{nrtc}
476: \item USAGE CONTINUITY
477:
478: \item SEAMLESS USER INTERFACE
479: \end{nrtc}
480:
481: \item AMENABILITY:
482: \begin{nrtc}
483: \item MANAGEABILITY
484: \end{nrtc}
485: \end{nrtc}
486: \end{bwslide}
487:
488:
489: \begin{bwslide}
490: \ctitle {SEVERAL CANDIDATES}
491:
492: \begin{nrtc}
493: \item PROTOCOL-BASED APPROACHES
494: \begin{nrtc}
495: \item DUAL STACK
496:
497: \item APPLICATION GATEWAYS
498:
499: \item TRANSPORT GATEWAYS
500: \end{nrtc}
501:
502: \item SERVICE-BASED APPROACHES
503: \begin{nrtc}
504: \item TRANSPORT-SERVICE BRIDGES
505:
506: \item NETWORK TUNNELS
507: \end{nrtc}
508:
509: \item NONE OF THESE TECHNIQUES ARE SPECIFIC TO THE PROBLEM OF
510: \begin{nrtc}
511: \item INTERNET $\mapsto$ OSI
512: \end{nrtc}
513: \end{nrtc}
514: \end{bwslide}
515:
516:
517: \begin{bwslide}
518: \part {PROTOCOL-BASED APPROACHES}\bf
519:
520: \begin{nrtc}
521: \item THE ``STANDARD'' METHODS USED TO INTERCONNECT DIFFERENT
522: PROTOCOL STACKS
523:
524: \item THESE EMPHASIZE THE PROTOCOLS IN EACH STACK
525:
526: \item HENCE THEY REINFORCE THE BOUNDARIES BETWEEN TCP/IP AND OSI
527: \end{nrtc}
528: \end{bwslide}
529:
530:
531: \begin{bwslide}
532: \part* {DUAL STACK}\bf
533:
534: \begin{nrtc}
535: \item PUT BOTH PROTOCOL SUITES IN ALL HOSTS
536:
537: \item WORKS WELL, IF YOU CAN CHANGE \underline{EVERYTHING} ON THE NETWORK
538: \begin{quote}\em
539: ``Nice work, if you can get it.''\\ \raggedleft
540: -- Groucho Marx, Monkey Business, Paramount Pictures (1931)
541: \end{quote}
542: \end{nrtc}
543: \end{bwslide}
544:
545:
546: \begin{bwslide}
547: \ctitle {DUAL STACK (cont.)}
548:
549: \vskip.5in
550: \diagram[p]{figureT-1}
551: \end{bwslide}
552:
553:
554: \begin{bwslide}
555: \ctitle {TALKING TO UNI-STACK HOSTS}
556:
557: \begin{nrtc}
558: \item QUESTION: HOW TO DECIDE WHICH APPLICATION INSTANCE,
559: \begin{nrtc}
560: \item APPL-$\alpha$ OR APPL-$\gamma$,
561: \end{nrtc}
562: TO USE?
563:
564: \item TWO ANSWERS:
565: \begin{nrtc}
566: \item DEPEND ON THE USER TO KNOW AND INVOKE THE RIGHT PROGRAM
567:
568: \item DEVELOP A GENERIC APPLICATION WHICH SUPPORTS BOTH CLASSES
569: \end{nrtc}
570:
571: \item IN THE LATTER CASE, NEED AN UP-TO-DATE DIRECTORY TO DO THIS RELIABLY
572: \end{nrtc}
573: \end{bwslide}
574:
575:
576: \begin{bwslide}
577: \ctitle {GENERIC APPLICATION INSTANCE}
578:
579: \vskip.5in
580: \diagram[p]{figureT-6}
581: \end{bwslide}
582:
583:
584: \begin{bwslide}
585: \ctitle {AN IMPLEMENTATION OF DUAL-STACK}
586:
587: \begin{nrtc}
588: \item ENVIRONMENT: \unix/~SVR3 (STREAMS)
589:
590: \item ACCESS TO LOWER-LAYER PROTOCOLS VIA TRANSPORT LAYER INTERFACE (TLI)
591:
592: \item NOTE THAT ALTHOUGH TLI PROVIDES A UNIFORM INTERFACE,
593: IT DOES NOT PROVIDE A UNIFORM SERVICE:
594: \begin{nrtc}
595: \item PACKET- vs. STREAM-ORIENTATION
596:
597: \item GRACEFUL RELEASE
598:
599: \item EXPEDITED vs. URGENT DATA
600:
601: \item ADDRESSING
602: \end{nrtc}
603: \end{nrtc}
604: \end{bwslide}
605:
606:
607: \begin{bwslide}
608: \ctitle {GENERIC APPLICATION INSTANCE}
609:
610: \vskip.5in
611: \diagram[p]{figureT-11}
612: \end{bwslide}
613:
614:
615: \begin{bwslide}
616: \ctitle {SCORECARD}
617:
618: \begin{nrtc}
619: \item PERFORMANCE: NO DEGRADATION
620:
621: \item FLEXIBILITY: GOOD
622:
623: \item TRANSPARENCY:
624: \begin{nrtc}
625: \item ASSUMING REMOTE SYSTEM SUPPORTS AT LEAST ONE OF THE PROTOCOL
626: STACKS, THEN HIGH TRANSPARENCY BY USING COMMON SERVICE
627: INTERFACE
628: \end{nrtc}
629:
630: \item AMENABILITY:
631: \begin{nrtc}
632: \item BOTH END- AND INTERMEDIATE-SYSTEMS MUST RUN BOTH PROTOCOLS
633:
634: \item INTRODUCES ADMINISTRATIVE PROBLEMS AS THERE ARE NOW TWO
635: LOGICAL NETWORKS
636: \begin{nrtc}
637: \item MANAGEMENT OF BOTH \underline{PLUS} CONTENTION BETWEEN THEM
638: \end{nrtc}
639: \end{nrtc}
640: \end{nrtc}
641: \end{bwslide}
642:
643:
644: \begin{bwslide}
645: \part* {APPLICATION GATEWAYS}\bf
646:
647: \begin{nrtc}
648: \item A WELL-KNOWN, BUT LITTLE-UNDERSTOOD TECHNOLOGY
649: \begin{nrtc}
650: \item USED IN MESSAGE HANDLING QUITE A BIT
651: \end{nrtc}
652:
653: \item MOST ARE QUITE TERRIBLE
654: \begin{quote}\em
655: ``Sometimes when you try to turn an apple into an orange you get back a
656: lemon.''\\ \raggedleft
657: -- Michael Padlipsky, The Elements of Networking Style (1985)
658: \end{quote}
659: \end{nrtc}
660: \end{bwslide}
661:
662:
663: \begin{bwslide}
664: \ctitle {APPLICATION GATEWAYS (cont.)}
665:
666: \vskip.5in
667: \diagram[p]{figureT-2}
668: \end{bwslide}
669:
670:
671: \begin{bwslide}
672: \ctitle {IMPERFECT MAPPINGS}
673:
674: \begin{nrtc}
675: \item BECAUSE THEY ARE AT THE HIGHEST LAYER IN THE STACK,
676: APPLICATION GATEWAYS TEND TO PERFORM SEMANTIC MAPPINGS
677:
678: \item THESE ARE ACCOMPANIED BY A LOSS OF INFORMATION
679:
680: \item SOMETIMES THE LOSS IS ONLY ANNOYING
681: \begin{nrtc}
682: \item e.g., ``FUNNY LOOKING'' MAIL ADDRESSES
683: \end{nrtc}
684:
685: \item SOMETIMES THE LOSS IS CATASTROPHIC
686: \begin{nrtc}
687: \item e.g., ROUTING LOOPS
688: \end{nrtc}
689: \end{nrtc}
690: \end{bwslide}
691:
692:
693: \begin{bwslide}
694: \ctitle {AN IMPLEMENATION OF APPLICATION-GATEWAY}
695:
696: \begin{nrtc}
697: \item TWO KINDS OF IMPLEMENATIONS
698:
699: \item STAGING (TRUE STORE-AND-FORWARD):
700: \begin{nrtc}
701: \item TOP-LEVEL PROTOCOL TRANSACTIONS ARE GROUPED AT THE GATEWAY
702:
703: \item REQUIRES LOCAL STORAGE, BUT MAY PERMIT BETTER MAPPINGS
704: \end{nrtc}
705:
706: \item IN-SITU (VIRTUAL END-TO-END):
707: \begin{nrtc}
708: \item NO PROTOCOL TRANSACTIONS ARE GROUPED
709:
710: \item MAPPINGS ARE ``ON THE FLY''\\ (AND PERHAPS LESS PRECISE)
711:
712: \item END-TO-END RESPONSE IS FASTER
713: \end{nrtc}
714: \end{nrtc}
715: \end{bwslide}
716:
717:
718: \begin{bwslide}
719: \ctitle {INVOKING THE GATEWAY}
720:
721: \vskip1.5in
722: \begin{verbatim}
723: % ftp file-gateway
724: Name (file-gateway:asterix): obelix@osi-host
725: Password:
726: \end{verbatim}
727: \end{bwslide}
728:
729:
730: \begin{bwslide}
731: \ctitle {A STAGING IMPLEMENTATION}
732:
733: \vskip.5in
734: \diagram[p]{figureT-12}
735: \end{bwslide}
736:
737:
738: \begin{bwslide}
739: \ctitle {AN IN-SITU IMPLEMENTATION}
740:
741: \vskip.5in
742: \diagram[p]{figureT-13}
743: \end{bwslide}
744:
745:
746: \begin{bwslide}
747: \ctitle {SCORECARD}
748:
749: \begin{nrtc}
750: \item PERFORMANCE: USUALLY POOR, BUT ACCEPTABLE FOR STORE-AND-FORWARD
751: APPLICATIONS
752: \begin{nrtc}
753: \item TYPICALLY ALSO INTRODUCES ADDITIONAL NETWORK TRAFFIC
754: \end{nrtc}
755:
756: \item FLEXIBILITY: NONE; EACH A-GWY IS A SPECIAL-PURPOSE SOFTWARE BOX
757:
758: \item TRANSPARENCY:
759: \begin{nrtc}
760: \item TO SERVICE: OFTEN LOSES SIGNIFICANT FUNCTIONALITY
761:
762: \item TO USERS: POSSIBLE, BUT NOT LIKELY (e.g., IN AN FTAM/FTP A-GWY,
763: USERS EMBED HOSTNAMES IN FILENAMES)
764: \end{nrtc}
765:
766: \item AMENABILITY:
767: \begin{nrtc}
768: \item REQUIRES NO END-SYSTEM MODIFICATION
769:
770: \item MAY INTRODUCE ADMINISTRATIVE PROBLEMS
771: \end{nrtc}
772: \end{nrtc}
773: \end{bwslide}
774:
775:
776: \begin{bwslide}
777: \part* {TRANSPORT GATEWAYS}\bf
778:
779: \begin{nrtc}
780: \item IDEA: GATEWAY AT THE TRANSPORT LAYER SO AS TO AVOID NEEDING
781: MULTIPLE APPLICATION GATEWAYS
782: \begin{quote}\em
783: ``We could do it, but it would be wrong.''\\ \raggedleft
784: -- Richard Nixon, The Watergate Tapes (1974)
785: \end{quote}
786:
787: \item ALTHOUGH THE OSI (TP4) AND INTERNET (TCP) TRANSPORT PROTOCOLS DIFFER,
788: THE SERVICE IS QUITE SIMILAR
789:
790: \item HENCE, IT IS TECHNICALLY FEASIBLE TO PERFORM THE MAPPINGS
791: \begin{nrtc}
792: \item (ALTHOUGH IT'S A LOT OF HARD WORK)
793: \end{nrtc}
794: \end{nrtc}
795: \end{bwslide}
796:
797:
798: \begin{bwslide}
799: \ctitle {TRANSPORT GATEWAYS (cont.)}
800:
801: \vskip.5in
802: \diagram[p]{figureT-14}
803: \end{bwslide}
804:
805:
806: \begin{bwslide}
807: \ctitle {THE OBVIOUS QUESTION}
808:
809: \begin{nrtc}
810: \item WHAT APPLICATION DO YOU RUN WHEN USING THIS?
811: \begin{nrtc}
812: \item CAN'T RUN INTERNET APPLICATIONS IN THE OSI NETWORK,
813: SINCE THE TRANSPORT GATEWAY YIELDS OSI TRANSPORT SEMANTICS
814:
815: \item CAN'T RUN OSI APPLICATIONS IN THE INTERNET NETWORK,
816: SINCE THE TRANSPORT GATEWAY YIELDS INTERNET TRANSPORT SEMANTICS
817: \end{nrtc}
818:
819: \item THIS APPROACH FAILS BECAUSE IT PRESENTS DIFFERENT SERVICE SEMANTICS
820: IN EACH NETWORK
821: \end{nrtc}
822: \end{bwslide}
823:
824:
825: \begin{bwslide}
826: \part {SERVICE-BASED APPROACHES}\bf
827:
828: \begin{nrtc}
829: \item BY THE TIME OSI-BASED NETWORKS ARE TRULY WIDESPREAD,
830: TCP/IP-BASED NETWORKS WILL ALREADY OFFER A MIX OF SERVICES:
831: \begin{nrtc}
832: \item SUCH AS FTAM AND MHS, IN ADDITION TO FTP AND SMTP
833: \end{nrtc}
834:
835: \item IN OTHER WORDS, PERHAPS THE TRANSITION TO OSI BEGINS WITH NEW
836: APPLICATIONS ON HOSTS AND NO CHANGES TO THE NETWORK
837: \end{nrtc}
838: \end{bwslide}
839:
840:
841: \begin{bwslide}
842: \ctitle {WOULD THIS REALLY HAPPEN?}
843:
844: \begin{nrtc}
845: \item RECALL THAT USERS ARE INTERESTED IN \underline{SERVICES} NOT
846: \underline{PROTOCOLS}
847:
848: \item THE OSI APPLICATIONS ARE MUCH RICHER THAN THEIR INTERNET COUNTERPARTS
849:
850: \item IN CONTRAST, AT THE LOWER-LAYERS THE INTERNET SUITE ``WORKS BETTER''
851: \begin{nrtc}
852: \item AS SUCH, IT IS UNLIKELY TO BE REPLACED BY THE OSI LOWER-LAYERS
853: FOR QUITE SOME TIME
854: \end{nrtc}
855: \end{nrtc}
856: \end{bwslide}
857:
858:
859: \begin{bwslide}
860: \ctitle {OBSERVATION}
861:
862: \begin{nrtc}
863: \item GIVEN THE ABOVE ASSUMPTION, IT SHOULD BE NOTED THAT:
864: \begin{nrtc}
865: \item WE HAVE TWO COMMUNITIES USING THE SAME APPLICATIONS
866: (OSI), AND
867:
868: \item ONLY THE UNDERLYING ``TS-STACK'' WILL DIFFER BETWEEN THE TWO:
869: \begin{nrtc}
870: \item IN THE OSI COMMUNITY: TP4/CLNP/$\ldots$
871:
872: \item IN THE TCP COMMUNITY: RFC1006/TCP/IP/$\ldots$
873: \end{nrtc}
874: \end{nrtc}
875:
876: \item THIS LEADS US TO POSTULATE AN INTERESTING COEXISTENCE
877: STRATEGY:
878: \begin{nrtc}
879: \item LET'S RUN OSI APPLICATIONS, END-TO-END, BETWEEN THE TWO
880: \end{nrtc}
881:
882: \item IN A SENSE, THIS IS A HYBRID OF THE TWO PREVIOUS APPROACHES,
883: INTENDED TO MINIMIZE THE DISADVANTAGES OF EACH
884: \begin{nrtc}
885: \item SAME APPLICATION PROTOCOL,\\
886: BUT DIFFERENT UNDERYLING LAYERS
887: \end{nrtc}
888: \end{nrtc}
889: \end{bwslide}
890:
891:
892: \begin{bwslide}
893: \part* {TRANSPORT-SERVICE BRIDGES}\bf
894:
895: \begin{nrtc}
896: \item INTRODUCE A TRANSPORT ENTITY CALLED THE ``TS-BRIDGE''
897: \begin{quote}\em
898: ``Users are interested in services, not protocols.''\\ \raggedleft
899: -- Marshall Rose, The Open Book (1990)
900: \end{quote}
901:
902: \item THE TS-BRIDGE ``COPIES'' SERVICE PRIMITIVES FROM ONE TS-STACK TO THE
903: OTHER, e.g.:
904: \begin{nrtc}
905: \item UPON RECEIVING A T-CONNECT.INDICATION PRIMITIVE FROM ONE
906: TS-STACK,
907:
908: \item IT ISSUES A T-CONNECT.REQUEST PRIMITIVE TO THE OTHER TS-STACK
909: \end{nrtc}
910:
911: \item AS DISCUSSED EARLIER, THIS TECHNOLOGY IS USED FOR CONNECTIVITY BETWEEN
912: DIFFERENT OSI COMMUNITIES
913: \end{nrtc}
914: \end{bwslide}
915:
916:
917: \begin{bwslide}
918: \ctitle {TRANSPORT-SERVICE BRIDGES (cont.)}
919:
920: \vskip.5in
921: \diagram[p]{figureT-9}
922: \end{bwslide}
923:
924:
925: \begin{bwslide}
926: \ctitle {CONS vs. CLNS CONNECTIVITY}
927:
928: \vskip.5in
929: \diagram[p]{figureT-19}
930: \end{bwslide}
931:
932:
933: \begin{bwslide}
934: \ctitle {THE TS-BRIDGE AND THE OSI MODEL\\ (REVIEW)}
935:
936: \begin{nrtc}
937: \item THE TS-BRIDGE IS A LEVEL-FOUR ROUTER
938:
939: \item POTENTIAL PROBLEMS:
940: \begin{nrtc}
941: \item THE TS-BRIDGE MAINTAINS STATE AS TO THE EXISTING CONNECTIONS
942:
943: \item TWO CHECKSUMS, AND NEITHER REALLY END-TO-END
944:
945: \item \underline{MAY} THWART SOPHISTICATED BACK-PRESSURE TECHNIQUES
946: \end{nrtc}
947: \end{nrtc}
948: \end{bwslide}
949:
950:
951: \begin{bwslide}
952: \ctitle {AN IMPLEMENTATION OF THE TS-BRIDGE}
953:
954: \begin{nrtc}
955: \item FIRST DEMONSTRATION IN FEBRUARY, 1988
956: \begin{nrtc}
957: \item TP4/CLNP to RFC1006/TCP
958: \end{nrtc}
959:
960: \item ANOTHER IMPLEMENTATION IN EUROPE IS HANDLING
961: \begin{nrtc}
962: \item TP0/X.25 to RFC1006/TCP
963: \end{nrtc}
964: \end{nrtc}
965: \end{bwslide}
966:
967:
968: \begin{bwslide}
969: \ctitle {SCORECARD}
970:
971: \begin{nrtc}
972: \item PERFORMANCE: FAIR
973:
974: \item FLEXIBILITY: HIGH; INDEPENDENT OF ANY APPLICATION
975:
976: \item TRANSPARENCY: TOTAL
977:
978: \item AMENABILITY:
979: \begin{nrtc}
980: \item TCP END-SYSTEMS MUST RUN ``NEW'' PROTOCOLS
981: \begin{nrtc}
982: \item BUT, NO MODIFICATIONS REQUIRED TO END-SYSTEM KERNELS
983: \end{nrtc}
984:
985: \item MAY INTRODUCE ADMINISTRATIVE PROBLEMS
986: \end{nrtc}
987: \end{nrtc}
988: \end{bwslide}
989:
990:
991: \begin{bwslide}
992: \part* {NETWORK TUNNELS}\bf
993:
994: \begin{nrtc}
995: \item IDEA: ENCAPSULATE CLNP INSIDE OF IP, TREATING IP AS SIMPLY A DATA LINK
996: PROTOCOL
997: \begin{quote}\em
998: ``Encapsulation complies with the layering concept, but violates the notion
999: of absolute levels.''\\ \raggedleft
1000: -- Danny Cohen and Jon Postel, ``The ISO Reference Model and Other Protocol
1001: Architectures'' (1983)
1002: \end{quote}
1003:
1004: \item NS-TUNNEL PERFORMS AS A ROUTER, REMOVING ONE DATA LINK HEADER AND
1005: ADDING ANOTHER
1006:
1007: \item METHOD SPECIFIED IN [RFC1070]
1008:
1009: \item ADDRESS MAPPINGS SPECIFIED IN [RFC1069]
1010: \end{nrtc}
1011: \end{bwslide}
1012:
1013:
1014: \begin{bwslide}
1015: \ctitle {TUNNELING}
1016:
1017: \vskip.5in
1018: \diagram[p]{figureT-18}
1019: \end{bwslide}
1020:
1021:
1022: \begin{bwslide}
1023: \ctitle {NETWORK TUNNELS}
1024:
1025: \vskip.5in
1026: \diagram[p]{figureT-10}
1027: \end{bwslide}
1028:
1029:
1030: \begin{bwslide}
1031: \ctitle {INTERESTING FEATURES}
1032:
1033: \begin{nrtc}
1034: \item NO STATE MAINTAINED BY NS-TUNNEL
1035:
1036: \item A TRUE END-TO-END CHECKSUM
1037: \end{nrtc}
1038: \end{bwslide}
1039:
1040:
1041: \begin{bwslide}
1042: \ctitle {POTENTIAL PROBLEMS}
1043:
1044: \begin{nrtc}
1045: \item REQUIRES COMMON HIGHER-LEVEL PROTOCOLS (TRANSPORT AND ABOVE) ON BOTH
1046: END-SYSTEMS, BUT DOES NOT REQUIRE ALL INTERVENING ROUTERS TO USE THE
1047: SAME NETWORK PROTOCOL
1048:
1049: \item THE TCP END-SYSTEM IMPLEMENTATION CHOICES ARE SIMILAR TO NETBIOS OVER
1050: TCP [RFC1001/1002]
1051: \end{nrtc}
1052: \end{bwslide}
1053:
1054:
1055: \begin{bwslide}
1056: \ctitle {AN IMPLEMENATION OF AN NS-TUNNEL}
1057:
1058: \begin{nrtc}
1059: \item HAVEN'T SEE ANY YET
1060: \begin{nrtc}
1061: \item BUT WILL BE IN 4.4BSD UNIX
1062: \end{nrtc}
1063:
1064: \item NEED A LOT OF CLNP-BASED NETWORKS BEFORE THIS IS OF USE
1065:
1066: \item SO THIS WILL HAPPEN AT THE END OF THE TRANSITION PERIOD
1067: \end{nrtc}
1068: \end{bwslide}
1069:
1070:
1071: \begin{bwslide}
1072: \ctitle {SCORECARD}
1073:
1074: \begin{nrtc}
1075: \item PERFORMANCE: NO WORSE THAN TYPICAL CLNP-ROUTER (AND PROBABLY A LOT
1076: BETTER TOO!)
1077:
1078: \item FLEXIBILITY: HIGH (INDEPENDENT OF ANY APPLICATION)
1079:
1080: \item TRANSPARENCY: TOTAL
1081:
1082: \item AMENABILITY: TCP END-SYSTEMS MUST RUN BOTH TRANSPORT PROTOCOLS
1083: \end{nrtc}
1084: \end{bwslide}
1085:
1086:
1087: \begin{bwslide}
1088: \part {EXAMPLES}\bf
1089:
1090: \begin{nrtc}
1091: \item DoD OSI IMPLEMENTATION PLAN
1092:
1093: \item GENERIC EXAMPLE
1094:
1095: \item CONCLUSIONS
1096: \end{nrtc}
1097: \end{bwslide}
1098:
1099:
1100: \begin{bwslide}
1101: \part* {DoD OSI\\ IMPLEMENTATION PLAN}\bf
1102:
1103: \begin{nrtc}
1104: \item IMPLEMENT CAPABILITY TO USE OSI IN DoD INTERNETWORK ENVIRONMENT
1105: \begin{nrtc}
1106: \item OSI-POSIX PROJECT
1107: \end{nrtc}
1108:
1109: \item PROVIDE THE CAPABILITY FOR DoD AND OSI PROTOCOLS TO INTEROPERATE
1110: \begin{nrtc}
1111: \item FTAM-FTP GATEWAY
1112:
1113: \item MHS-SMTP GATEWAY
1114: \end{nrtc}
1115: \end{nrtc}
1116: \end{bwslide}
1117:
1118:
1119: \begin{bwslide}
1120: \ctitle {OSI-POSIX PROJECT}
1121:
1122: \begin{nrtc}
1123: \item GOAL: ACCELLERATE THE UBIQUITY OF OSI
1124:
1125: \item APPROACH: OPENLY AVAILABLE, COMPLETE OSI IMPLEMENTATION FOR NEXT MAJOR
1126: RELEASE OF BERKELEY \unix/
1127:
1128: \item FOR MORE DETAILS:
1129: \begin{quote}
1130: OSI PROTOCOLS WITHIN AN OPENLY AVAILABLE, POSIX-CONFORMANT, BERKELEY UNIX
1131: ENVIRONMENT
1132: \end{quote}
1133: APPEARING IN ConneXions, OCTOBER, 1988
1134: \end{nrtc}
1135: \end{bwslide}
1136:
1137:
1138: \begin{bwslide}
1139: \diagram[p]{figureT-15}
1140: \end{bwslide}
1141:
1142:
1143: \begin{bwslide}
1144: \diagram[p]{figureT-16}
1145: \end{bwslide}
1146:
1147:
1148: \begin{bwslide}
1149: \part* {GENERIC EXAMPLE}\bf
1150:
1151: \begin{nrtc}
1152: \item TWO PRONGS:
1153: \begin{nrtc}
1154: \item FAVOR USE OF OSI APPLICATIONS OVER TCP ON LAN MESH
1155:
1156: \item LOCATE APPLICATION GATEWAYS AND A TS-BRIDGE ON ALL NODES
1157: WITH WAN ATTACHMENETS
1158: \end{nrtc}
1159:
1160: \item AWAIT OSI LOWER-LAYERS TO BECOME COMPETITIVE
1161: \end{nrtc}
1162: \end{bwslide}
1163:
1164:
1165: \begin{bwslide}
1166: \ctitle {GENERIC EXAMPLE (cont.)}
1167:
1168: \begin{nrtc}
1169: \item EACH ATTACHMENT LOCUS SHOULD SUPPORT COEXISTENCE SERVICES
1170:
1171: \item IF RESOURCES PERMIT, SELECT ONE OTHER SYSTEM TO SUPPORT THESE
1172: SERVICES FOR USE BY LOCAL UNI-STACK HOSTS
1173:
1174: \item THIS ``COVERS ALL BASES'' BY HANDLING ALL POSSIBLE OSI COMBINATIONS
1175: WITH A BIT OF EXTRA REDUNDANCY
1176:
1177: \item MIGHT REQUIRE A BIT OF SOPHISTICATED USE FROM THE DIRECTORY
1178: \end{nrtc}
1179: \end{bwslide}
1180:
1181:
1182: \begin{bwslide}
1183: \ctitle {A LAN OF MANY COLORS}
1184:
1185: \vskip.5in
1186: \diagram[p]{figureT-17}
1187: \end{bwslide}
1188:
1189:
1190: \begin{bwslide}
1191: \part* {CONCLUSIONS}\bf
1192:
1193: \begin{quote}\em
1194: ``Optimality differs according to context.''\\ \raggedleft
1195: -- Michael Padlipsky, The Elements of Networking Style (1985)
1196: \end{quote}
1197: \end{bwslide}
1198:
1199:
1200: \begin{bwslide}
1201: \ctitle {CONCLUSIONS (cont.)}
1202:
1203: \begin{nrtc}
1204: \item TCP/IP-BASED NETWORKS WILL OFFER OSI APPLICATIONS
1205:
1206: \item COEXISTENCE IN THE SHORT TERM:
1207: \begin{nrtc}
1208: \item TS-BRIDGE MINIMIZES SOFTWARE INVESTMENT
1209: \end{nrtc}
1210:
1211: \item COEXISTENCE IN THE LONG TERM:
1212: \begin{nrtc}
1213: \item NS-TUNNEL MAXIMIZES PERFORMANCE AND ROBUSTNESS
1214: \end{nrtc}
1215:
1216: \item IF/WHEN THERE ARE NO MORE TCP/IP-BASED NETWORKS, THEN THE
1217: COEXISTENCE PERIOD IS OVER, AND TRANSITION IS A NON-ISSUE!
1218: \end{nrtc}
1219: \end{bwslide}
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