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1.1 root 1: % run this through LaTeX with the appropriate wrapper
2:
3: \dotopic{0}
4: \begin{bwslide}
5: \part {END-TO-END SERVICES}
6: \end{bwslide}
7: \doparts
8:
9:
10: \begin{bwslide}
11: \part* {OUTLINE}\bf
12:
13: \begin{description}
14: \item[PART I:] CONCEPTS
15:
16: \item[PART II:] BUILDING BLOCKS
17:
18: \item[PART III:] ACHIEVING CONNECTIVITY
19:
20: \item[PART IV:] COMPARISON TO TCP/IP
21: \end{description}
22: \end{bwslide}
23:
24:
25: \begin{bwslide}
26: \ctitle {A BIG ACKNOWLEDGEMENT}
27:
28: \begin{nrtc}
29: \item MY INTEREST IN END-TO-END SERVICES IS ONLY AS A USER,
30: NOT A PROVIDER
31:
32: \item AS SUCH, I'D PREFER TO USE THEM AS A BLACK BOX
33:
34: \item UNFORTUNATELY, THIS MODEL DOESN'T WORK IN PRACTICE
35: \begin{nrtc}
36: \item THE LOWER-LAYERS AREN'T HOMOGENEOUS
37: \end{nrtc}
38:
39: \item THE PRACTICAL PERSPECTIVE PRESENTED HERE IS HEAVILY INFLUENCED BY
40: \begin{nrtc}
41: \item STEPHEN E.~KILLE OF UNIVERSITY COLLEGE LONDON
42: \end{nrtc}
43:
44: \item AND HIS PAPER
45: \begin{nrtc}
46: \item ``AN INTERIM APPROACH TO USE OF NETWORK ADDRESSES''
47: \end{nrtc}
48: \end{nrtc}
49: \end{bwslide}
50:
51:
52: \begin{bwslide}
53: \part {CONCEPTS}\bf
54:
55: \begin{nrtc}
56: \item BASIC TERMINOLOGY
57:
58: \item NETWORK SERVICE
59:
60: \item TRANSPORT SERVICE
61: \end{nrtc}
62: \end{bwslide}
63:
64:
65: \begin{bwslide}
66: \part* {BASIC TERMINOLOGY}\bf
67:
68: \begin{nrtc}
69: \item END-TO-END SERVICES RESPONSIBLE FOR
70: \begin{nrtc}
71: \item DATA TRANSFER
72: \end{nrtc}
73:
74: \item APPLICATION SERVICES RESPONSIBLE FOR
75: \begin{nrtc}
76: \item INFORMATION TRANSFER
77: \end{nrtc}
78: \end{nrtc}
79: \end{bwslide}
80:
81:
82: \begin{bwslide}
83: \ctitle {BASIC TERMINOLOGY (cont.)}
84:
85: \begin{nrtc}
86: \item TERMINOLOGY DIFFERS BETWEEN NETWORKING COMMUNITIES
87: \begin{nrtc}
88: \item WE'LL USE ``OSIFIED'' TERMINOLOGY
89: \end{nrtc}
90:
91: \item A NETWORK CONSISTS OF A COLLECTION OF SUBNETWORKS CONNECTED
92: BY INTERMEDIATE SYSTEMS AND POPULATED BY END-SYSTEMS
93:
94: \item DATA TRANSFER OCCURS BETWEEN TWO END-SYSTEMS,
95: POTENTIALLY GOING THROUGH ONE OR MORE INTERMEDIATE-SYSTEMS
96: IF THE END-SYSTEMS RESIDE ON DIFFERENT SUBNETWORKS
97: \end{nrtc}
98: \end{bwslide}
99:
100:
101: \begin{bwslide}
102: \ctitle {THE NETWORK}
103:
104: \vskip.5in
105: \diagram[p]{figureE-2}
106: \end{bwslide}
107:
108:
109: \begin{bwslide}
110: \ctitle {END-SYSTEMs (ES)}
111:
112: \begin{nrtc}
113: \item CONTAIN BOTH:
114: \begin{nrtc}
115: \item THE LOWER-LAYER PROTOCOLS NECESSARY FOR DATA TRANSFER, AND
116:
117: \item THE UPPER-LAYER PROTOCOLS NECESSARY FOR INFORMATION TRANSFER
118: \end{nrtc}
119:
120: \item WHERE THE APPLICATIONS LIVE
121:
122: \item WHAT THE USERS ARE INTERESTED IN
123: \end{nrtc}
124: \end{bwslide}
125:
126:
127: \begin{bwslide}
128: \ctitle {INTERMEDIATE-SYSTEMs (IS)}
129:
130: \begin{nrtc}
131: \item CONTAIN ONLY:
132: \begin{nrtc}
133: \item THE LOWER-LAYER PROTOCOLS NECESSARY FOR DATA TRANSFER
134: \end{nrtc}
135:
136: \item ULTIMATELY CONTAINS HIGHER-LAYER PROTOCOLS TO SUPPORT MANAGEMENT
137:
138: \item IN ADDITION TO PASSING ALONG APPLICATION DATA,
139: INTERMEDIATE-SYSTEMS COOPERATE AMONGST THEMSELVES
140: \begin{nrtc}
141: \item e.g., EXCHANGE ROUTING DATA
142: \end{nrtc}
143: \end{nrtc}
144: \end{bwslide}
145:
146:
147: \begin{bwslide}
148: \part* {NETWORK SERVICE}\bf
149:
150: \begin{nrtc}
151: \item NETWORK SERVICE IS RESPONSIBLE FOR MOVING DATA FROM ONE END-SYSTEM
152: TO ANOTHER
153:
154: \item UNFORTUNATELY, THERE ARE TWO DIFFERENT VIEWS AS TO WHAT THIS MEANS:
155: \begin{nrtc}
156: \item CONNECTION-ORIENTED
157:
158: \item CONNECTIONLESS-MODE
159: \end{nrtc}
160:
161: \item PERHAPS THE GREATEST ``RELIGIOUS'' ISSUE OF THE DECADE
162: \end{nrtc}
163: \end{bwslide}
164:
165:
166: \begin{bwslide}
167: \ctitle {CONNECTION-ORIENTED NETWORK SERVICE\\ (CONS)}
168:
169: \begin{nrtc}
170: \item BASED ON THE NOTION OF ``RESERVATIONS'':
171: \begin{nrtc}
172: \item ON CONNECTION REQUEST, MINIMUM REQUIREMENTS ARE STATED
173: \begin{nrtc}
174: \item (e.g., THROUGHPUT)
175: \end{nrtc}
176:
177: \item IF REQUEST IS GRANTED, THESE RESOURCES ARE RESERVED FOR THE
178: CONNECTION'S DURATION
179: \end{nrtc}
180:
181: \item CO-MODE SERVICE PRIMITIVES
182: \begin{nrtc}
183: \item N-CONNECT: CONNECTION ESTABLISHMENT
184:
185: \item N-DATA (N-DATA-ACKNOWLEDGE): DATA TRANSFER
186:
187: \item N-EXPEDITED-DATA: EXPEDITED DATA TRANSFER
188:
189: \item N-DISCONNECT: CONNECTION RELEASE
190:
191: \item N-RESET: CONNECTION RESYNCHRONIZATION
192: \end{nrtc}
193: \end{nrtc}
194: \end{bwslide}
195:
196:
197: \begin{bwslide}
198: \ctitle {CONS (cont.)}
199:
200: \begin{nrtc}
201: \item GOOD POINTS:
202: \begin{nrtc}
203: \item LOW OVERHEAD FOR DATA TRANSIT
204:
205: \item IMMUNITY FROM OTHER NETWORK TRAFFIC
206:
207: \item ACCOUNTABILITY
208: \end{nrtc}
209:
210: \item BAD POINTS:
211: \begin{nrtc}
212: \item HIGH OVERHEAD FOR CONNECTION ESTABLISHMENT
213:
214: \item QUESTIONABLE RECOVERY CHARACTERISTICS
215:
216: \item IF RESOURCES ARE RESERVED, BUT NOT IN USE,
217: NEW CONNECTION REQUESTS ARE DENIED
218: \end{nrtc}
219: \end{nrtc}
220: \end{bwslide}
221:
222:
223: \begin{bwslide}
224: \ctitle {CONNECTIONLESS-MODE NETWORK SERVICE\\ (CLNS)}
225:
226: \begin{nrtc}
227: \item BASED ON THE NOTION OF ``COME AS YOU ARE'':
228: \begin{nrtc}
229: \item NO CONNECTION REQUEST, JUST SEND DATA
230:
231: \item TRANSPORT MUST DYNAMICALLY DETERMINE IF REQUIREMENTS ARE
232: BEING MET
233: \end{nrtc}
234:
235: \item CL-MODE SERVICE PRIMITIVES
236: \begin{nrtc}
237: \item N-UNITDATA: DATA TRANSFER
238: \end{nrtc}
239: \end{nrtc}
240: \end{bwslide}
241:
242:
243: \begin{bwslide}
244: \ctitle {CLNS (cont.)}
245:
246: \begin{nrtc}
247: \item GOOD POINTS:
248: \begin{nrtc}
249: \item LESS DELAY FOR INITIAL DATA TRANSIT
250:
251: \item POTENTIALLY MORE ROBUST WITH CHANGES IN THE NETWORK
252:
253: \item SQUEEZES ``LAST DROP'' FROM AVAILABLE RESOURCES
254: \end{nrtc}
255:
256: \item BAD POINTS:
257: \begin{nrtc}
258: \item HIGHER OVERHEAD FOR DATA TRANSIT IF MULTIPLE SUBNETWORKS
259: ARE INVOLVED
260:
261: \item REQUIRES WELL-BEHAVED USERS TO PREVENT OVER-SUBSCRIPTION
262: \end{nrtc}
263: \end{nrtc}
264: \end{bwslide}
265:
266:
267: \begin{bwslide}
268: \part* {TRANSPORT SERVICE}
269:
270: \begin{nrtc}
271: \item TRANSPORT SERVICE IS RESPONSIBLE FOR MOVING DATA FROM ONE END-SYSTEM
272: TO ANOTHER~---~RELIABLY
273: \begin{nrtc}
274: \item (WE'RE CONSIDERING ONLY CO-MODE TRANSPORT SERVICE)
275: \end{nrtc}
276:
277: \item IF CO-MODE NETWORK SERVICE IS USED, THIS IS TRIVIAL
278:
279: \item OTHERWISE, SOPHISTICATED ALGORITHMS ARE REQUIRED IN PROTOCOLS
280: WHICH IMPLEMENT TRANSPORT SERVICE
281: \end{nrtc}
282: \end{bwslide}
283:
284:
285: \begin{bwslide}
286: \ctitle {TRANSPORT SERVICE (cont.)}
287:
288: \begin{nrtc}
289: \item IMPORTANT IMPLICATION:\\
290: \begin{nrtc}
291: \item AVAILABLE NETWORK SERVICE DETERMINES WHICH
292: TRANSPORT PROTOCOL CAN BE USED
293:
294: \item HOWEVER, WHEN INITIATING A CONNECTION,
295: TRANSPORT SERVICE IS ACTIVE PRIOR TO NETWORK SERVICE!
296: \end{nrtc}
297: \end{nrtc}
298: \end{bwslide}
299:
300:
301: \begin{bwslide}
302: \ctitle {CHOICE OF NETWORK SERVICE}
303:
304: \begin{nrtc}
305: \item CHOICE OF NETWORK SERVICE IS ECO-POLITICAL NOT TECHNICAL
306: \begin{nrtc}
307: \item EITHER APPROACH CAN BE MADE TO WORK WELL
308: \end{nrtc}
309:
310: \item CO-MODE NETWORK SERVICE IS MORE SUITED TOWARDS A COMMON-CARRIER MODEL
311: \begin{nrtc}
312: \item ACCOUNTABILITY AND ISOLATION
313: \end{nrtc}
314: THIS IS TYPIFIED BY PUBLIC DATA NETWORKS
315:
316: \item CL-MODE NETWORK SERVICE IS MORE GENERAL
317: \begin{nrtc}
318: \item ADAPTABILITY AND COOPERATION
319: \end{nrtc}
320: THIS IS TYPIFIED BY CLOSED COMMUNITY NETWORKS
321:
322: \item HOWEVER, THE TWO APPROACHES DON'T MIX WELL
323: \end{nrtc}
324: \end{bwslide}
325:
326:
327: \begin{bwslide}
328: \part {BUILDING BLOCKS}\bf
329:
330: \begin{nrtc}
331: \item ADDRESS FORMATS
332:
333: \item NETWORK BINDING
334:
335: \item TRANSPORT PROTOCOLS
336:
337: \item APPLICATION USE OF END-TO-END SERVICES
338:
339: \item EMULATION OF OSI END-TO-END SERVICES
340: \end{nrtc}
341: \end{bwslide}
342:
343:
344: \begin{bwslide}
345: \part* {ADDRESS FORMATS}\bf
346:
347: \begin{nrtc}
348: \item HIERARHICALLY STRUCTURED
349: \begin{nrtc}
350: \item ADDRESSING DOMAINS, SUB-DOMAINS
351:
352: \item UNAMBIGUOUS PREFIXES
353: \end{nrtc}
354:
355: \item MAIN GOAL: FACILITATE ALLOCATION
356:
357: \item NO IMPLICATIONS ON ``WHERE IT IS'' OR ``HOW TO GET THERE''
358: \begin{nrtc}
359: \item BUT STRUCTURE MAY FACILITATE ROUTING DECISIONS
360: \end{nrtc}
361: \end{nrtc}
362: \end{bwslide}
363:
364:
365: \begin{bwslide}
366: \ctitle {ADDRESS FORMATS (cont.)}
367:
368: \begin{nrtc}
369: \item AN ADDRESSING AUTHORITY DEFINES STRUCTURE OF DOMAIN
370: \begin{nrtc}
371: \item TERMED AN ABSTRACT SYNTAX
372: \end{nrtc}
373: AND ALSO ALLOCATES VALUES
374:
375: \item A TRANSFER SYNTAX DEFINES HOW ADDRESSES ARE ENCODED
376: \end{nrtc}
377: \end{bwslide}
378:
379:
380: \begin{bwslide}
381: \ctitle {TOP-LEVEL}
382:
383: \begin{nrtc}
384: \item ADDRESS IS DIVIDED INTO TWO PARTS:
385: \begin{nrtc}
386: \item INITIAL DOMAIN PART (IDP), AND
387:
388: \item DOMAIN SPECIFIC PART (DSP)
389: \end{nrtc}
390: \end{nrtc}
391:
392: \diagram[p]{figureE-3}
393: \end{bwslide}
394:
395:
396: \begin{bwslide}
397: \ctitle {TOP-LEVEL (cont.)}
398:
399: \begin{nrtc}
400: \item AUTHORITY AND FORMAT IDENTIFIER (AFI) DEFINES HOW
401: \begin{nrtc}
402: \item IDI IS INTERPRETED, AND
403:
404: \item HOW DSP IS FORMATTED (DECIMAL/BINARY ABSTRACT SYNTAX)
405: \end{nrtc}
406:
407: \item INITIAL DOMAIN IDENTIFIER (IDI) SAYS WHO OWNS THE DSP
408: \begin{nrtc}
409: \item MIGHT BE VARIABLE LENGTH
410:
411: \item MIGHT HAVE (SIGNIFICANT) LEADING ZEROS
412: \end{nrtc}
413:
414: \item DOMAIN SPECIFIC PART (DSP) IS JUST THAT
415: \end{nrtc}
416: \end{bwslide}
417:
418:
419: \begin{bwslide}
420: \ctitle {EXAMPLE 1:\\ X.121 ADDRESS}
421:
422: \begin{nrtc}
423: \item AN X.121 ADDRESS MAY BE ENCODED USING
424: \begin{nrtc}
425: \item AFI = 36
426:
427: \item IDI = X.121 ADDRESS (UP TO 14~DIGITS)
428: \end{nrtc}
429: \end{nrtc}
430:
431: \diagram[p]{figureE-4}
432: \end{bwslide}
433:
434:
435: \begin{bwslide}
436: \ctitle {EXAMPLE 2:\\ ICD ADDRESS}
437:
438: \begin{nrtc}
439: \item AN INTERNATIONALLY RECOGNIZED ENTITY MAY ALLOCATE ADDRESSES USING
440: \begin{nrtc}
441: \item AFI = 47
442:
443: \item IDI = INTERNATIONAL CODE DESIGNATOR (4~DIGITS)
444: \end{nrtc}
445: \end{nrtc}
446:
447: \diagram[p]{figureE-5}
448: \end{bwslide}
449:
450:
451: \begin{bwslide}
452: \ctitle {EXAMPLE 3:\\ LOCAL ADDRESS}
453:
454: \begin{nrtc}
455: \item ANYONE MIGHT USE A ``LOCAL'' ADDRESSING FORMAT
456: \begin{nrtc}
457: \item AFI = 49
458:
459: \item IDI = NULL (0~DIGITS)
460: \end{nrtc}
461: \end{nrtc}
462:
463: \diagram[p]{figureE-6}
464: \end{bwslide}
465:
466:
467: \begin{bwslide}
468: \part* {NETWORK BINDING}\bf
469:
470: \begin{nrtc}
471: \item HOW DOES DATA GO FROM ORIGINATING TO DESTINATION END-SYSTEM?
472: \begin{nrtc}
473: \item i.e., HOW IS ROUTING ACCOMPLISHED?
474: \end{nrtc}
475:
476: \item NETWORK SERVICE AT ORIGINATING END-SYSTEM DECIDES ``NEXT HOP''
477:
478: \item IF DESTINATION END-SYSTEM IS ON SAME SUBNETWORK,
479: THEN NEXT HOP IS DESTINATION END-SYSTEM
480:
481: \item OTHERWISE, NEXT HOP IS AN INTERMEDIATE SYSTEM (ON THE SAME SUBNETWORK)
482: WHICH IS ``CLOSER'' TO THE DESTINATION END-SYSTEM
483: \end{nrtc}
484: \end{bwslide}
485:
486:
487: \begin{bwslide}
488: \ctitle {DETERMINING THE NEXT HOP}
489:
490: \begin{nrtc}
491: \item NETWORK ADDRESSES DO NOT CONTAIN ROUTING INFORMATION
492: \begin{nrtc}
493: \item IN THEORY, AT LEAST
494: \end{nrtc}
495:
496: \item INTERMEDIATE-SYSTEMS MAINTAIN ROUTING TABLES WHICH TELL
497: ``HOW TO GET THERE''
498:
499: \item SO, ONCE THE DESTINATION END-SYSTEM'S SUBNETWORK HAS BEEN REACHED,
500: NEED A WAY OF DETERMINING ``WHERE IT IS'' ON A PARTICULAR
501: SUBNETWORK
502: \end{nrtc}
503: \end{bwslide}
504:
505:
506: \begin{bwslide}
507: \ctitle {SUBNETWORK POINT OF ATTACHMENT (SNPA)}
508:
509: \begin{nrtc}
510: \item A NODE (ES or IS) IS ATTACHED TO A SUBNETWORK AT A
511: \begin{nrtc}
512: \item SUBNETWORK POINT OF ATTACHMENT (SNPA)
513: \end{nrtc}
514:
515: \item A LOCAL DIRECTORY IS USED TO MAP BETWEEN A NETWORK ADDRESS
516: AND ITS CORRESPONDING SNPA
517: \begin{nrtc}
518: \item NOT THE OSI DIRECTORY (LUCKY FOR US!)
519: \end{nrtc}
520:
521: \item THE PROBLEM:
522: \begin{nrtc}
523: \item ROUTING IS A NETWORK-WIDE FUNCTION,
524:
525: \item SO INFORMATION MUST BE COHERENT NETWORK-WIDE
526: \end{nrtc}
527: \end{nrtc}
528: \end{bwslide}
529:
530:
531: \begin{bwslide}
532: \ctitle {MAPPING TO SNPA}
533:
534: \begin{nrtc}
535: \item TWO WAYS TO ACHIEVE DYNAMIC MAPPINGS
536:
537: \item RUN A PROTOCOL ON THE SUBNETWORK
538: \begin{nrtc}
539: \item e.g., AN ADDRESS RESOLUTION PROTOCOL
540: \end{nrtc}
541:
542: \item USE A LOCAL TABLE
543:
544: \item OTHERWISE MUST EMBED THE SNPA IN THE NETWORK ADDRESS
545: \begin{nrtc}
546: \item LOSES A LOT OF FLEXIBILITY
547: \end{nrtc}
548: \end{nrtc}
549: \end{bwslide}
550:
551:
552: \begin{bwslide}
553: \part* {TRANSPORT PROTOCOLS}\bf
554:
555: \begin{nrtc}
556: \item AVAILABLE NETWORK SERVICE DETERMINES CHOICE OF TRANSPORT PROTOCOL
557:
558: \item OSI PROVIDES 5 TRANSPORT PROTOCOLS, TP0--TP4
559: \begin{nrtc}
560: \item CLASSES 0--3 WORKS WITH A CO-MODE NETWORK SERVICE
561:
562: \item CLASS 4 WORKS WITH BOTH CO/CL-MODE NETWORK SERVICES
563: \end{nrtc}
564: \end{nrtc}
565: \end{bwslide}
566:
567:
568: \begin{bwslide}
569: \ctitle {NETWORK CLASSES}
570:
571: \begin{nrtc}
572: \item ``A'' --- LOW LOSS, ERRORS SIGNALLED
573:
574: \item ``B'' --- ERRORS SIGNALLED
575:
576: \item ``C'' --- ERRORS NOT SIGNALLED
577: \begin{nrtc}
578: \item LOSS
579:
580: \item DUPLICATION
581:
582: \item RE-ORDERING
583:
584: \item CORRUPTION
585: \end{nrtc}
586: OF DATA
587: \end{nrtc}
588: \end{bwslide}
589:
590:
591: \begin{bwslide}
592: \ctitle {PROTOCOLS USING\\ CO-MODE NETWORK SERVICE}
593:
594: \begin{nrtc}
595: \item TP0: SIMPLE CLASS
596: \begin{nrtc}
597: \item NOTHING MORE THAN TRANSPORT ADDRESSING AND SEGMENTATION
598:
599: \item ``A'' NETWORKS
600: \end{nrtc}
601:
602: \item TP1: BASIC ERROR RECOVERY CLASS
603: \begin{nrtc}
604: \item RECOVER FROM NETWORK RESETS (MAY INVOLVE RE-ROUTING)
605:
606: \item ``B'' NETWORKS
607: \end{nrtc}
608: \end{nrtc}
609: \end{bwslide}
610:
611:
612: \begin{bwslide}
613: \ctitle {PROTOCOLS USING\\ CO-MODE NETWORK SERVICE (cont.)}
614:
615: \begin{nrtc}
616: \item TP2: MULTIPLEXING CLASS
617: \begin{nrtc}
618: \item MULTIPLEX OVER A SINGLE NETWORK CONNECTION
619:
620: \item OPTIONAL FLOW CONTROL
621:
622: \item ``A'' NETWORKS
623: \end{nrtc}
624:
625: \item TP3: ERROR RECOVERY AND MULTIPLEXING CLASS
626: \begin{nrtc}
627: \item ALL OF THE ABOVE
628:
629: \item ``B'' NETWORKS
630: \end{nrtc}
631: \end{nrtc}
632: \end{bwslide}
633:
634:
635: \begin{bwslide}
636: \ctitle {PROTOCOLS WHICH CAN USE\\ CL-MODE NETWORK SERVICE}
637:
638: \begin{nrtc}
639: \item TP4: ERROR DETECTION AND RECOVERY CLASS
640: \begin{nrtc}
641: \item RELIABILITY THROUGH RETRANSMISSION
642:
643: \item ``C'' NETWORKS
644: \end{nrtc}
645: \end{nrtc}
646: \end{bwslide}
647:
648:
649: \begin{bwslide}
650: \part* {APPLICATION USE OF END-TO-END SERVICES}\bf
651:
652: \begin{nrtc}
653: \item APPLICATION IDENTIFIES APPLICATION ENTITY WHICH PROVIDES
654: DESIRED SERVICE
655: \begin{nrtc}
656: \item e.g., AN FTAM APPLICATION IDENTIFIES A FILESTORE SERVICE
657: PROVIDED BY A PARTICULAR APPLICATION ENTITY
658: \end{nrtc}
659:
660: \item THE APPLICATION ENTITY IS IDENTIFIED BY ITS DISTINGUISHED NAME IN
661: THE OSI DIRECTORY
662: \end{nrtc}
663: \end{bwslide}
664:
665:
666: \begin{bwslide}
667: \ctitle {STEP 1:\\ MAP DISTINGUISHED NAME\\ TO PRESENTATION ADDRESS}
668:
669: \begin{nrtc}
670: \item ESTABLISH ASSOCIATION TO DIRECTORY SERVICE AGENT (DSA)
671: USING DIRECTORY ACCESS PROTOCOL (DAP)
672:
673: \item RETRIEVE THE \verb"presentationAddress" ATTRIBUTE FROM
674: THE OBJECT WITH THE GIVEN DISTINGUISHED NAME
675: \end{nrtc}
676:
677: \begin{quote}\small\begin{verbatim}
678: PSAPaddr ::=
679: SEQUENCE {
680: pSelector[0]
681: OCTET STRING
682: OPTIONAL,
683:
684: sSelector[1]
685: OCTET STRING
686: OPTIONAL,
687:
688: tSelector[2]
689: OCTET STRING
690: OPTIONAL,
691:
692: nAddresses[3]
693: SET OF OCTET STRING
694: }
695: \end{verbatim}\end{quote}
696: \end{bwslide}
697:
698:
699: \begin{bwslide}
700: \ctitle {STEP 2:\\ DETERMINE USE OF NETWORK ADDRESSES}
701:
702: \begin{nrtc}
703: \item PRESENTATION ADDRESS IS GIVEN TO THE ASSOCIATION CONTROL SERVICE
704: ELEMENT (ACSE), WHICH ESTABLISHES THE ASSOCIATION
705:
706: \item ACSE PASSES THE ADDRESS TO THE PRESENTATION SERVICE,
707: WHICH USES THE PRESENTATION SELECTOR
708:
709: \item THE REMAINDER IS GIVEN TO THE SESSION SERVICE,
710: WHICH USES THE SESSION SELECTOR
711:
712: \item THE REMAINDER IS GIVEN TO THE TRANSPORT SERVICE
713: \end{nrtc}
714: \end{bwslide}
715:
716:
717: \begin{bwslide}
718: \ctitle {STEP 2 (cont.)}
719:
720: \begin{nrtc}
721: \item TRANSPORT SERVICE LOOKS AT EACH NETWORK ADDRESS AND MUST DECIDE
722: \begin{nrtc}
723: \item WHICH MODE NETWORK SERVICE WILL BE USED FOR THIS ADDRESS
724: \end{nrtc}
725:
726: \item TRANSPORT SERVICE SELECTS A TRANSPORT PROTOCOL BASED ON THE
727: DERIVED NETWORK SERVICE AND THE COMMUNICATIONS QUALITY OF SERVICE (QOS)
728: DESIRED BY THE APPLICATION
729:
730: \item THIS COMBINATION
731: \begin{nrtc}
732: \item (NETWORK SERVICE+TRANSPORT PROTOCOL)
733: \end{nrtc}
734: IS TERMED A
735: \begin{nrtc}
736: \item TRANSPORT SERVICE STACK (TS-STACK)
737: \end{nrtc}
738: \end{nrtc}
739: \end{bwslide}
740:
741:
742: \begin{bwslide}
743: \ctitle {STILL MORE ON\\ STEP 2}
744:
745: \begin{nrtc}
746: \item IN MANY ENVIRONMENTS ONLY A SINGLE MODE OF NETWORK SERVICE AND A
747: SINGLE TRANSPORT PROTOCOL ARE AVAILABLE
748:
749: \item THIS IMPLIES THAT ONLY A SUBSET (OR PERHAPS NONE) OF THE
750: NETWORK ADDRESSES WILL BE USABLE AT THE ORIGINATING END-SYSTEM
751: \end{nrtc}
752: \end{bwslide}
753:
754:
755: \begin{bwslide}
756: \ctitle {STEP 3:\\ ORDER NETWORK ADDRESSES}
757:
758: \begin{nrtc}
759: \item THE NETWORK ADDRESSES ARE THEN ORDERED BY PREFERENCE
760:
761: \item PREFERENCE IS BASED BOTH ON COMMUNICATIONS-QOS AND ``CLOSENESS''
762: OF NETWORK ADDRESSES
763:
764: \item FOR EXAMPLE:
765: \begin{nrtc}
766: \item TWO NETWORK ADDRESSES, EACH IMPLYING A CO-MODE NETWORK
767: SERVICE, MIGHT BE PRESENT
768:
769: \item ONE OF THE NETWORK ADDRESS MIGHT BELONG TO A PRIVATE
770: NETWORK, WHILST THE OTHER BELONGS TO A PDN
771:
772: \item THE TRANSPORT SERVICE MIGHT PREFER THE PRIVATE NETWORK,
773: FOR COST REASONS
774: \end{nrtc}
775: \end{nrtc}
776: \end{bwslide}
777:
778:
779: \begin{bwslide}
780: \ctitle {STEP 4:\\ ATTEMPT CONNECTIONS}
781:
782: \begin{nrtc}
783: \item FOR EACH NETWORK ADDRESS:
784: \begin{nrtc}
785: \item THE APPROPRIATE TRANSPORT PROTOCOL ENGINE IS STARTED,
786: AND THE NETWORK SERVICE INVOKED
787:
788: \item ONCE A TRANSPORT CONNECTION IS ESTABLISHED,
789: THE REMAINDER OF THE NETWORK ADDRESSES ARE IGNORED
790: \end{nrtc}
791: \end{nrtc}
792: \end{bwslide}
793:
794:
795: \begin{bwslide}
796: \part* {EMULATION OF OSI END-TO-END SERVICES}\bf
797:
798: \begin{nrtc}
799: \item IS IT POSSIBLE TO PROVIDE
800:
801: \item A SOLUTION IS OFFERED BY LAYERING
802: \begin{nrtc}
803: \item THE OSI TRANSPORT \underline{SERVICE} IS VERY SIMPLE
804: \end{nrtc}
805:
806: \item CAN WE BUILD TS-STACKS USING NON-OSI PROTOCOLS?
807: \end{nrtc}
808: \end{bwslide}
809:
810:
811: \begin{bwslide}
812: \ctitle {SERVICE EMULATOR AT TRANSPORT}
813:
814: \vskip.5in
815: \diagram[p]{figureE-13}
816: \end{bwslide}
817:
818:
819: \begin{bwslide}
820: \ctitle {APPROACH:\\ TRANSPORT SERVICE CONVERGENCE PROTOCOL}
821:
822: \begin{nrtc}
823: \item USE THE CONNECTION-ORIENTED TRANSPORT SERVICE PROVIDED BY
824: THE NON-OSI PROTOCOL SUITE
825:
826: \item DEFINE A ``TSCP'' WHICH SMOOTHS OVER THE DIFFERENCES IN THE SERVICES
827: OFFERED
828: \begin{nrtc}
829: \item IN PRACTICE, THESE ARE QUITE SMALL
830: \end{nrtc}
831:
832: \item FOR EXAMPLE, THE RFC1006 METHOD DEFINES A TSCP FOR TCP/IP NETWORKS
833: \end{nrtc}
834: \end{bwslide}
835:
836:
837: \begin{bwslide}
838: \ctitle {OSI TRANSPORT SERVICES\\ ON TOP OF THE DoD TCP (cont.)}
839:
840: \vskip.25in
841: \diagram[p]{figureE-14}
842: \end{bwslide}
843:
844:
845: \begin{bwslide}
846: \part {ACHIEVING CONNECTIVITY}\bf
847:
848: \begin{nrtc}
849: \item THE REAL WORLD OF OSI
850:
851: \item INTERIM USE OF NETWORK ADDRESSES
852:
853: \item TRANSPORT BRIDGING
854: \end{nrtc}
855: \end{bwslide}
856:
857:
858: \begin{bwslide}
859: \ctitle {NOW THE HARD PART}
860:
861: \begin{nrtc}
862: \item A LOT OF FLEXIBILITY IS AVAILABLE
863:
864: \item BUT PRACTICALLY, CAN THIS BE MADE TO WORK?
865: \end{nrtc}
866: \end{bwslide}
867:
868:
869: \begin{bwslide}
870: \part* {THE REAL WORLD OF OSI}\bf
871:
872: \begin{nrtc}
873: \item THE ``REAL WORLD'' DEPENDS ENTIRELY WHERE YOU LIVE
874:
875: \item A COMMUNITY IS A COLLECTION OF END-SYSTEMS SHARING COMPATIBLE
876: TS-STACKS AND CONNECTED TOGETHER
877:
878: \item WHAT KIND OF OSI COMMUNITIES EXIST TODAY?
879: \end{nrtc}
880: \end{bwslide}
881:
882:
883: \begin{bwslide}
884: \ctitle {COMMUNITY 1:\\ INTERNATIONAL X.25}
885:
886: \begin{nrtc}
887: \item X.121 FORMAT ADDRESSES ARE USED
888:
889: \item NETWORK PROTOCOL IS X.25(80) WHICH DOES NOT PROVIDE TRUE
890: OSI NETWORK SERVICE
891: \begin{nrtc}
892: \item EVENTUALLY UPGRADING TO X.25(84)
893: \end{nrtc}
894:
895: \item TP0 IS FAVORED TRANSPORT PROTOCOL
896:
897: \item TS-STACKS:
898: \end{nrtc}
899:
900: \diagram[p]{figureE-7}
901: \end{bwslide}
902:
903:
904: \begin{bwslide}
905: \ctitle {COMMUNITY 2:\\ PRIVATE X.25}
906:
907: \begin{nrtc}
908: \item SIMILAR TO INTERNATIONAL X.25 COMMUNITY,
909: BUT OWNED BY A PARTICULAR ENTERPRISE
910: \begin{nrtc}
911: \item e.g., THE U.K.~JOINT ACADEMIC NETWORK (JANET)
912: \end{nrtc}
913:
914: \item ADDRESSES ARE X.121-BASED, BUT ARE PRIVATELY ALLOCATED
915: \begin{nrtc}
916: \item THUS THE X.121 NETWORK ADDRESS FORMAT CAN'T BE USED
917: \end{nrtc}
918:
919: \item TS-STACKS:
920: \end{nrtc}
921:
922: \diagram[p]{figureE-7}
923: \end{bwslide}
924:
925:
926: \begin{bwslide}
927: \ctitle {COMMUNITY 3:\\ VARIANT U.S. USE OF X.25}
928:
929: \begin{nrtc}
930: \item X.25 TREATED AS A SUBNETWORK PROTOCOL
931:
932: \item CL-MODE NETWORK SERVICE RUN OVER THIS
933:
934: \item TS-STACKS:
935: \end{nrtc}
936:
937: \diagram[p]{figureE-9}
938: \end{bwslide}
939:
940:
941: \begin{bwslide}
942: \ctitle {COMMUNITY 4:\\ CONS-BASED LANS}
943:
944: \begin{nrtc}
945: \item CO-MODE NETWORK SERVICE OFFERRED OVER 8802 SUBNETWORK
946:
947: \item BASICALLY ``X.25 OVER ETHERNET'' (LLC2)
948:
949: \item TS-STACKS:
950: \end{nrtc}
951:
952: \diagram[p]{figureE-10}
953: \end{bwslide}
954:
955:
956: \begin{bwslide}
957: \ctitle {COMMUNITY 5:\\ CLNS-BASED LANS}
958:
959: \begin{nrtc}
960: \item CL-MODE NETWORK SERVICE OFFERRED OVER 8802 SUBNETWORK
961:
962: \item COMMONLY TERMED ``MAP/TOP LANs'' (LLC1)
963:
964: \item TS-STACKS:
965: \end{nrtc}
966:
967: \diagram[p]{figureE-11}
968: \end{bwslide}
969:
970:
971: \begin{bwslide}
972: \ctitle {COMMUNITY 6:\\ TCP/IP-BASED INTERNET USING RFC1006}
973:
974: \begin{nrtc}
975: \item RFC1006 DEFINES A MAPPING FROM THE OSI TRANSPORT SERVICE ONTO THE DoD
976: TCP
977: \begin{nrtc}
978: \item (A TRANSPORT SERVICE CONVERGENCE PROTOCOL)
979: \end{nrtc}
980:
981: \item PROBLEM: WHAT FORMAT TO USE NETWORK ADDRESS?
982:
983: \item TS-STACKS:
984: \end{nrtc}
985:
986: \diagram[p]{figureE-12}
987: \end{bwslide}
988:
989:
990: \begin{bwslide}
991: \ctitle {COMMUNITY 7:\\ TCP/IP-BASED LAN USING RFC1006}
992:
993: \begin{nrtc}
994: \item SIMILAR TO INTERNET COMMUNITY,
995: BUT ON AN ISOLATED TCP/IP LAN
996: \begin{nrtc}
997: \item e.g., A CAMPUS NETWORK RUNNING TCP/IP LOCALLY AND HAVING A
998: CONNECTION TO A PDN
999: \end{nrtc}
1000:
1001: \item TS-STACKS:
1002: \end{nrtc}
1003:
1004: \diagram[p]{figureE-12}
1005: \end{bwslide}
1006:
1007:
1008: \begin{bwslide}
1009: \ctitle {COMMUNITY INTEROPERATION}
1010:
1011: \begin{nrtc}
1012: \item SO, THERE ARE (AT LEAST) SEVEN DIFFERENT COMMUNITIES IN THE OSI WORLD
1013:
1014: \item IDEALLY WOULD LIKE THIS INTERWORKING MATRIX:
1015: \end{nrtc}
1016:
1017: \diagram[p]{figureE-15}
1018: \end{bwslide}
1019:
1020:
1021: \begin{bwslide}
1022: \ctitle {COMMUNITY INTEROPERATION (cont.)}
1023:
1024: \begin{nrtc}
1025: \item COMMUNITY 7 IS ISOLATED BY LACK OF CONNECTIVITY
1026: \end{nrtc}
1027:
1028: \diagram[p]{figureE-16}
1029: \end{bwslide}
1030:
1031:
1032: \begin{bwslide}
1033: \ctitle {COMMUNITY INTEROPERATION (cont.)}
1034:
1035: \begin{nrtc}
1036: \item PRIVATE X.25 AND RFC1006--BASED COMMUNITIES NEED DIFFERENT ADDRESS
1037: SPACE
1038: \end{nrtc}
1039:
1040: \diagram[p]{figureE-17}
1041: \end{bwslide}
1042:
1043:
1044: \begin{bwslide}
1045: \ctitle {REAL WORLD CONNECTIVITY MATRIX}
1046:
1047: \begin{nrtc}
1048: \item IN PRACTICE, CONS-BASED LANS DON'T INTEROPERATE WITH CONS-BASED WANS
1049: \begin{nrtc}
1050: \item ROUTING OF CONS-BASED SUBNETWORKS ISN'T WIDELY IMPLEMENTED
1051: OUTSIDE OF X.75
1052: \end{nrtc}
1053: \end{nrtc}
1054:
1055: \diagram[p]{figureE-18}
1056: \end{bwslide}
1057:
1058:
1059: \begin{bwslide}
1060: \ctitle {COMMUNITY INTEROPERATION (cont.)}
1061:
1062: \begin{nrtc}
1063: \item CLNS-BASED AND CONS-BASED TS-STACKS DON'T ALWAYS INTEROPERATE
1064: \begin{nrtc}
1065: \item IT IS NOT ENOUGH TO START WITH TP4 AND DOWN-NEGOTIATE
1066: \end{nrtc}
1067: \end{nrtc}
1068:
1069: \diagram[p]{figureE-19}
1070: \end{bwslide}
1071:
1072:
1073: \begin{bwslide}
1074: \ctitle {THE MYTH OF TRANSPORT NEGOTIATION}
1075:
1076: \begin{nrtc}
1077: \item IF INITIATOR SELECTS TP4, MUST ALSO DECIDE CONS/CLNS
1078: \begin{nrtc}
1079: \item IF CLNS IS USED, THEN MUST STAY WITH TP4
1080:
1081: \item IF CLNS ISN'T USED, THEN CAN'T TALK TO CLNS-BASED LAN
1082: \end{nrtc}
1083: \end{nrtc}
1084: \end{bwslide}
1085:
1086:
1087: \begin{bwslide}
1088: \part* {INTERIM USE OF NETWORK ADDRESSES}\bf
1089:
1090: \begin{nrtc}
1091: \item WANT TO ACCOMODATE ALL OSI COMMUNITIES IN OSI DIRECTORY
1092:
1093: \item PROBLEM: ALL ADDRESSES MUST CONFORM TO DIRECTORY DEFINED SYNTAX
1094:
1095: \item PROBLEM: ALL ADDRESSES MUST BE GLOBALLY UNIQUE YET LOCALLY
1096: INTERPRETABLE
1097: \end{nrtc}
1098: \end{bwslide}
1099:
1100:
1101: \begin{bwslide}
1102: \ctitle {CONFORMANCE TO\\ DIRECTORY DEFINED SYNTAX}
1103:
1104: \begin{nrtc}
1105: \item A PROBLEM FOR THE PRIVATE X.25 AND RFC1006--BASED COMMUNITIES
1106:
1107: \item TAKE A PART OF THE SPACE ASSIGNED TO TELEX ADDRESSES
1108: \begin{nrtc}
1109: \item NO ONE WILL USE TELEX AFI FOR NETWORK ADDRESSES
1110: \end{nrtc}
1111:
1112: \item SUB-DIVIDE THIS ADDRESS SPACE FOR EACH COMMUNITY, e.g.,
1113: \begin{nrtc}
1114: \item AFI = 54
1115:
1116: \item IDI = 00728722
1117: \end{nrtc}
1118: \end{nrtc}
1119:
1120: \diagram[p]{figureE-8}
1121: \end{bwslide}
1122:
1123:
1124: \begin{bwslide}
1125: \ctitle {INTERPRETATION OF ADDRESSES}
1126:
1127: \begin{nrtc}
1128: \item FROM EACH NETWORK ADDRESS
1129: \begin{nrtc}
1130: \item COMMUNITY (TS-STACK, IDENTITY OF NETWORK) MUST BE DEDUCIBLE
1131:
1132: \item NETWORK-SPECIFIC INFORMATION (i.e., SNPA) MUST BE DEDUCIBLE
1133: \end{nrtc}
1134: \end{nrtc}
1135: \end{bwslide}
1136:
1137:
1138: \begin{bwslide}
1139: \part* {TRANSPORT BRIDGING}\bf
1140:
1141: \begin{nrtc}
1142: \item PROBLEM: SUPPOSE THE ORIGINATING END-SYSTEM DETERMINES THAT
1143: IT IS IN A DIFFERENT COMMUNITY THAN THE DESTINATION END-SYSTEM
1144:
1145: \item FROM A PURIST PERSPECTIVE:
1146: \begin{nrtc}
1147: \item INTEROPERATION CAN NOT OCCUR!
1148: \end{nrtc}
1149:
1150: \item FROM A PRAGMATIC PERSPECTIVE:
1151: \begin{nrtc}
1152: \item IGNORE THE CURSED MODEL AND BUILD A LEVEL-4 RELAY
1153: \end{nrtc}
1154: \end{nrtc}
1155: \end{bwslide}
1156:
1157:
1158: \begin{bwslide}
1159: \ctitle {TS-BRIDGES}
1160:
1161: \begin{nrtc}
1162: \item ALTHOUGH MANY DIFFERENT TS-STACKS EXIST,
1163: THEY ALL PROVIDE THE SAME TRANSPORT SERVICE
1164:
1165: \item SO, IT IS STRAIGHT-FORWARD TO BUILD A BOX THAT:
1166: \begin{nrtc}
1167: \item KNOWS NOTHING ABOUT TRANSPORT PROTOCOLS, BUT
1168:
1169: \item KNOWS HOW TO USE THE RELATIVELY SIMPLE OSI TRANSPORT SERVICE
1170: \end{nrtc}
1171:
1172: \item A TS-BRIDGE ``COPIES'' SERVICE PRIMITIVES FROM ONE TS-STACK TO THE
1173: OTHER, e.g.,
1174: \begin{nrtc}
1175: \item UPON RECEIVING A T-CONNECT.INDICATION PRIMITIVE FROM ONE
1176: TS-STACK,
1177:
1178: \item IT ISSUES A T-CONNECT.REQUEST PRIMITIVE TO THE OTHER TS-STACK
1179: \end{nrtc}
1180: \end{nrtc}
1181: \end{bwslide}
1182:
1183:
1184: \begin{bwslide}
1185: \ctitle {TS-BRIDGES (cont.)}
1186:
1187: \vskip.5in
1188: \diagram[p]{figureE-1}
1189: \end{bwslide}
1190:
1191:
1192: \begin{bwslide}
1193: \ctitle {THE PROBLEMS OF LEVEL-4 RELAYS}
1194:
1195: \begin{nrtc}
1196: \item THE TS-BRIDGE MAINTAINS STATE AS TO THE EXISTING CONNECTIONS
1197:
1198: \item EACH TS-STACK PROVIDES A CHECKSUM,
1199: NEITHER OF WHICH IS REALLY END-TO-END
1200: \begin{nrtc}
1201: \item (CHECKSUM AT EITHER TRANSPORT OR NETWORK SERVICE)
1202: \end{nrtc}
1203:
1204: \item THIS ALSO DEFEATS TRANSPORT-LEVEL ENCRYPTION
1205:
1206: \item \underline{MAY} THWART SOPHISTICATED BACK-PRESSURE TECHNIQUES
1207: \end{nrtc}
1208: \end{bwslide}
1209:
1210:
1211: \begin{bwslide}
1212: \ctitle {USE OF THE TS-BRIDGE}
1213:
1214: \begin{nrtc}
1215: \item MUST NOW SUBTLY MODIFY TRANSPORT SERVICE OF ORIGINATING END-SYSTEM
1216: \begin{nrtc}
1217: \item STEP 2: DETERMINE USE OF NETWORK ADDRESSES
1218: \end{nrtc}
1219:
1220: \item IF NO USABLE NETWORK ADDRESSES ARE AVAILABLE
1221:
1222: \item THEN SELECT A TS-BRIDGE WHICH SERVICES THE OSI COMMUNITY FOR ONE OF
1223: THE NETWORK ADDRESSES
1224: \begin{nrtc}
1225: \item RECALL, OSI COMMUNITY EQUALS TS-STACK PLUS CONNECTIVITY
1226: \end{nrtc}
1227: \end{nrtc}
1228: \end{bwslide}
1229:
1230:
1231: \begin{bwslide}
1232: \ctitle {USE OF THE TS-BRIDGE (cont.)}
1233:
1234: \begin{nrtc}
1235: \item ENCODE THE NETWORK ADDRESS AND TRANSPORT SELECTOR AS AN OCTET STRING,
1236: CALL THIS THE NEW TRANSPORT SELECTOR
1237:
1238: \item USE THE NETWORK ADDRESS OF THE TS-BRIDGE FOR THE REMAINING STEPS
1239:
1240: \item WHEN TS-BRIDGE RECEIVES CONNECTION,
1241: IT SIMPLY DECODES TRANSPORT SELECTOR TO FIND ADDRESS OF
1242: DESTINATION END-SYSTEM
1243: \end{nrtc}
1244: \end{bwslide}
1245:
1246:
1247: \begin{bwslide}
1248: \ctitle {TS-BRIDGE ADDRESSING}
1249:
1250: \vskip.5in
1251: \diagram[p]{figureE-20}
1252: \end{bwslide}
1253:
1254:
1255: \begin{bwslide}
1256: \part {COMPARISON TO TCP/IP}\bf
1257:
1258: \begin{nrtc}
1259: \item NETWORK SERVICE
1260:
1261: \item TRANSPORT SERVICE
1262: \end{nrtc}
1263: \end{bwslide}
1264:
1265:
1266: \begin{bwslide}
1267: \ctitle {COMPARISONS}
1268:
1269: \begin{nrtc}
1270: \item ALL COMPARISONS ARE PARTISAN IN NATURE
1271:
1272: \item HOWEVER, WITHOUT BIAS OR LOSS OF GENERALITY,\\ I CAN HONESTLY STATE:
1273: \begin{nrtc}
1274: \item THE OSI LOWER-LAYERS ARE CURRENTLY INCOHERENT
1275: \end{nrtc}
1276: \end{nrtc}
1277: \end{bwslide}
1278:
1279:
1280: \begin{bwslide}
1281: \part* {NETWORK SERVICE}\bf
1282:
1283: \begin{nrtc}
1284: \item THE INTERNET PROTOCOL (IP) PROVIDES A CL-NETWORK SERVICE
1285: \begin{nrtc}
1286: \item SIMILAR TO CLNP,\\ BUT MUCH MORE EFFICIENT
1287: \end{nrtc}
1288:
1289: \item THE LEAST COMMON DENOMINATOR, USABLE OVER BOTH WANs AND LANs
1290: \begin{nrtc}
1291: \item BEST EFFORT DELIVERY
1292:
1293: \item RELIABILITY RESPONSIBILITY OF TRANSPORT SERVICE
1294: \end{nrtc}
1295: \end{nrtc}
1296: \end{bwslide}
1297:
1298:
1299: \begin{bwslide}
1300: \ctitle {ARE TWO OSI NETWORK SERVICES\\ ONE TOO MANY?}
1301:
1302: \begin{nrtc}
1303: \item IN A WORD: YES
1304:
1305: \item OSI COMMUNITIES ARE SEPERATED BY TS-STACKS AND CONNECTIVITY
1306:
1307: \item CONNECTIVITY ISN'T A TECHNICAL ISSUE
1308:
1309: \item BUT, TS-STACKS ARE, SO:
1310: \begin{nrtc}
1311: \item IF THERE WAS A SINGLE NETWORK SERVICE,
1312: THEN THERE COULD BE A SINGLE TRANSPORT PROTOCOL
1313: \end{nrtc}
1314: \end{nrtc}
1315: \end{bwslide}
1316:
1317:
1318: \begin{bwslide}
1319: \part* {TRANSPORT SERVICE}\bf
1320:
1321: \begin{nrtc}
1322: \item THE TRANSMISSION CONTROL PROTOCOL (TCP) PROVIDES A CO-TRANSPORT
1323: SERVICE
1324:
1325: \item SEVERAL DIFFERENCES FROM THE OSI TRANSPORT SERVICE
1326: \begin{nrtc}
1327: \item TCP IS STREAM-ORIENTED
1328:
1329: \item TCP USES GRACEFUL RELEASE
1330:
1331: \item TCP USES URGENT DATA
1332: \end{nrtc}
1333:
1334: \item THESE ARE DIFFERENCES, NOT PROS AND CONS
1335: \end{nrtc}
1336: \end{bwslide}
1337:
1338:
1339: \begin{bwslide}
1340: \ctitle {COMPARISON OF PROTOCOLS}
1341:
1342: \begin{nrtc}
1343: \item REALLY CAN COMPARE ONLY THE TCP AND TP4
1344:
1345: \item TP4 PACKET ORIENTATION PREVENTS USE OF SOPHISTICATED CONGESTION
1346: COLLAPSE ALGORITHMS
1347:
1348: \item TP4 PACKET ORIENTATION HELPS BUFFER MANAGEMENT,
1349: POSSIBLY MORE EFFICIENT
1350:
1351: \item TP4 RETRANSMISSION ALGORITHMS ARE SIMPLISTIC
1352:
1353: \item TP4 END-TO-END CHECKSUM IS INAPPROPRIATE
1354: \end{nrtc}
1355: \end{bwslide}
1356:
1357:
1358: \begin{bwslide}
1359: \ctitle {TRANSPORT BRIDGING}
1360:
1361: \begin{nrtc}
1362: \item UNNECESSARY IN TCP/IP WORLD
1363: \begin{nrtc}
1364: \item COMMON NETWORK PROTOCOL
1365:
1366: \item UNIFORM NETWORK ADDRESS FORMAT
1367: \end{nrtc}
1368: \end{nrtc}
1369: \end{bwslide}
1370:
1371:
1372: \begin{bwslide}
1373: \part* {CONCLUSIONS}\bf
1374:
1375: \begin{nrtc}
1376: \item DEPRESSING
1377: \begin{nrtc}
1378: \item WORLD-WIDE OSI ``CAN'T HAPPEN''
1379:
1380: \item THIS WILL CURTAIL USE OF WONDERFUL APPLICATIONS
1381: \end{nrtc}
1382:
1383: \item FORTUNATELY, CLOSED COMMUNITIES WILL BE RELATIVELY IMMUNE
1384: \end{nrtc}
1385: \end{bwslide}
1386:
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