summaryrefslogtreecommitdiff
path: root/cleopatre/application/spidnetsnmp/doc/rfc/snmpV2/rfc1903.txt
blob: 0ae8dadf9fdb9311d51095674cd13127b43eda95 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
Network Working Group                               SNMPv2 Working Group
Request for Comments: 1903                                       J. Case
Obsoletes: 1443                                      SNMP Research, Inc.
Category: Standards Track                                  K. McCloghrie
                                                     Cisco Systems, Inc.
                                                                 M. Rose
                                            Dover Beach Consulting, Inc.
                                                           S. Waldbusser
                                          International Network Services
                                                            January 1996


                          Textual Conventions
                          for Version 2 of the
              Simple Network Management Protocol (SNMPv2)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Table of Contents

   1. Introduction ................................................    1
   1.1 A Note on Terminology ......................................    2
   2. Definitions .................................................    3
   3. Mapping of the TEXTUAL-CONVENTION macro .....................   19
   3.1 Mapping of the DISPLAY-HINT clause .........................   19
   3.2 Mapping of the STATUS clause ...............................   21
   3.3 Mapping of the DESCRIPTION clause ..........................   21
   3.4 Mapping of the REFERENCE clause ............................   21
   3.5 Mapping of the SYNTAX clause ...............................   22
   4. Security Considerations .....................................   22
   5. Editor's Address ............................................   22
   6. Acknowledgements ............................................   22
   7. References ..................................................   23

1.  Introduction

   A management system contains:  several (potentially many) nodes, each
   with a processing entity, termed an agent, which has access to
   management instrumentation; at least one management station; and, a
   management protocol, used to convey management information between
   the agents and management stations.  Operations of the protocol are
   carried out under an administrative framework which defines



SNMPv2 Working Group        Standards Track                     [Page 1]

RFC 1903             Textual Conventions for SNMPv2         January 1996


   authentication, authorization, access control, and privacy policies.

   Management stations execute management applications which monitor and
   control managed elements.  Managed elements are devices such as
   hosts, routers, terminal servers, etc., which are monitored and
   controlled via access to their management information.

   Management information is viewed as a collection of managed objects,
   residing in a virtual information store, termed the Management
   Information Base (MIB).  Collections of related objects are defined
   in MIB modules.  These modules are written using a subset of OSI's
   Abstract Syntax Notation One (ASN.1) [1], termed the Structure of
   Management Information (SMI) [2].

   When designing a MIB module, it is often useful to define new types
   similar to those defined in the SMI.  In comparison to a type defined
   in the SMI, each of these new types has a different name, a similar
   syntax, but a more precise semantics.  These newly defined types are
   termed textual conventions, and are used for the convenience of
   humans reading the MIB module.  It is the purpose of this document to
   define the initial set of textual conventions available to all MIB
   modules.

   Objects defined using a textual convention are always encoded by
   means of the rules that define their primitive type.  However,
   textual conventions often have special semantics associated with
   them.  As such, an ASN.1 macro, TEXTUAL-CONVENTION, is used to
   concisely convey the syntax and semantics of a textual convention.

   For all textual conventions defined in an information module, the
   name shall be unique and mnemonic, and shall not exceed 64 characters
   in length.  (However, names longer than 32 characters are not
   recommended.) All names used for the textual conventions defined in
   all "standard" information modules shall be unique.

1.1.  A Note on Terminology

   For the purpose of exposition, the original Internet-standard Network
   Management Framework, as described in RFCs 1155 (STD 16), 1157 (STD
   15), and 1212 (STD 16), is termed the SNMP version 1 framework
   (SNMPv1).  The current framework is termed the SNMP version 2
   framework (SNMPv2).









SNMPv2 Working Group        Standards Track                     [Page 2]

RFC 1903             Textual Conventions for SNMPv2         January 1996


2.  Definitions

SNMPv2-TC DEFINITIONS ::= BEGIN

IMPORTS
    ObjectSyntax, TimeTicks
        FROM SNMPv2-SMI;


-- definition of textual conventions

TEXTUAL-CONVENTION MACRO ::=
BEGIN
    TYPE NOTATION ::=
                  DisplayPart
                  "STATUS" Status
                  "DESCRIPTION" Text
                  ReferPart
                  "SYNTAX" Syntax

    VALUE NOTATION ::=
                  value(VALUE Syntax)

    DisplayPart ::=
                  "DISPLAY-HINT" Text
                | empty

    Status ::=
                  "current"
                | "deprecated"
                | "obsolete"

    ReferPart ::=
                  "REFERENCE" Text
                | empty

    -- uses the NVT ASCII character set
    Text ::= """" string """"

    Syntax ::=
                  type(ObjectSyntax)
                | "BITS" "{" Kibbles "}"
    Kibbles ::=
                  Kibble
                | Kibbles "," Kibble
    Kibble ::=
                  identifier "(" nonNegativeNumber ")"




SNMPv2 Working Group        Standards Track                     [Page 3]

RFC 1903             Textual Conventions for SNMPv2         January 1996


END


DisplayString ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "255a"
    STATUS       current
    DESCRIPTION
            "Represents textual information taken from the NVT ASCII
            character set, as defined in pages 4, 10-11 of RFC 854.

            To summarize RFC 854, the NVT ASCII repertoire specifies:

              - the use of character codes 0-127 (decimal)

              - the graphics characters (32-126) are interpreted as
                US ASCII

              - NUL, LF, CR, BEL, BS, HT, VT and FF have the special
                meanings specified in RFC 854

              - the other 25 codes have no standard interpretation

              - the sequence 'CR LF' means newline

              - the sequence 'CR NUL' means carriage-return

              - an 'LF' not preceded by a 'CR' means moving to the
                same column on the next line.

              - the sequence 'CR x' for any x other than LF or NUL is
                illegal.  (Note that this also means that a string may
                end with either 'CR LF' or 'CR NUL', but not with CR.)

            Any object defined using this syntax may not exceed 255
            characters in length."
    SYNTAX       OCTET STRING (SIZE (0..255))


PhysAddress ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1x:"
    STATUS       current
    DESCRIPTION
            "Represents media- or physical-level addresses."
    SYNTAX       OCTET STRING


MacAddress ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "1x:"



SNMPv2 Working Group        Standards Track                     [Page 4]

RFC 1903             Textual Conventions for SNMPv2         January 1996


    STATUS       current
    DESCRIPTION
            "Represents an 802 MAC address represented in the
            `canonical' order defined by IEEE 802.1a, i.e., as if it
            were transmitted least significant bit first, even though
            802.5 (in contrast to other 802.x protocols) requires MAC
            addresses to be transmitted most significant bit first."
    SYNTAX       OCTET STRING (SIZE (6))


TruthValue ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents a boolean value."
    SYNTAX       INTEGER { true(1), false(2) }

TestAndIncr ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents integer-valued information used for atomic
            operations.  When the management protocol is used to specify
            that an object instance having this syntax is to be
            modified, the new value supplied via the management protocol
            must precisely match the value presently held by the
            instance.  If not, the management protocol set operation
            fails with an error of `inconsistentValue'.  Otherwise, if
            the current value is the maximum value of 2^31-1 (2147483647
            decimal), then the value held by the instance is wrapped to
            zero; otherwise, the value held by the instance is
            incremented by one.  (Note that regardless of whether the
            management protocol set operation succeeds, the variable-
            binding in the request and response PDUs are identical.)

            The value of the ACCESS clause for objects having this
            syntax is either `read-write' or `read-create'.  When an
            instance of a columnar object having this syntax is created,
            any value may be supplied via the management protocol.

            When the network management portion of the system is re-
            initialized, the value of every object instance having this
            syntax must either be incremented from its value prior to
            the re-initialization, or (if the value prior to the re-
            initialization is unknown) be set to a pseudo-randomly
            generated value."
    SYNTAX       INTEGER (0..2147483647)


AutonomousType ::= TEXTUAL-CONVENTION



SNMPv2 Working Group        Standards Track                     [Page 5]

RFC 1903             Textual Conventions for SNMPv2         January 1996


    STATUS       current
    DESCRIPTION
            "Represents an independently extensible type identification
            value.  It may, for example, indicate a particular sub-tree
            with further MIB definitions, or define a particular type of
            protocol or hardware."
    SYNTAX       OBJECT IDENTIFIER


InstancePointer ::= TEXTUAL-CONVENTION
    STATUS       obsolete
    DESCRIPTION
            "A pointer to either a specific instance of a MIB object or
            a conceptual row of a MIB table in the managed device.  In
            the latter case, by convention, it is the name of the
            particular instance of the first accessible columnar object
            in the conceptual row.

            The two uses of this textual convention are replaced by
            VariablePointer and RowPointer, respectively."
    SYNTAX       OBJECT IDENTIFIER


VariablePointer ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "A pointer to a specific object instance.  For example,
            sysContact.0 or ifInOctets.3."
    SYNTAX       OBJECT IDENTIFIER


RowPointer ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Represents a pointer to a conceptual row.  The value is the
            name of the instance of the first accessible columnar object
            in the conceptual row.

            For example, ifIndex.3 would point to the 3rd row in the
            ifTable (note that if ifIndex were not-accessible, then
            ifDescr.3 would be used instead)."
    SYNTAX       OBJECT IDENTIFIER


RowStatus ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "The RowStatus textual convention is used to manage the



SNMPv2 Working Group        Standards Track                     [Page 6]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            creation and deletion of conceptual rows, and is used as the
            value of the SYNTAX clause for the status column of a
            conceptual row (as described in Section 7.7.1 of [2].)

            The status column has six defined values:

                 - `active', which indicates that the conceptual row is
                 available for use by the managed device;

                 - `notInService', which indicates that the conceptual
                 row exists in the agent, but is unavailable for use by
                 the managed device (see NOTE below);

                 - `notReady', which indicates that the conceptual row
                 exists in the agent, but is missing information
                 necessary in order to be available for use by the
                 managed device;

                 - `createAndGo', which is supplied by a management
                 station wishing to create a new instance of a
                 conceptual row and to have its status automatically set
                 to active, making it available for use by the managed
                 device;

                 - `createAndWait', which is supplied by a management
                 station wishing to create a new instance of a
                 conceptual row (but not make it available for use by
                 the managed device); and,

                 - `destroy', which is supplied by a management station
                 wishing to delete all of the instances associated with
                 an existing conceptual row.

            Whereas five of the six values (all except `notReady') may
            be specified in a management protocol set operation, only
            three values will be returned in response to a management
            protocol retrieval operation:  `notReady', `notInService' or
            `active'.  That is, when queried, an existing conceptual row
            has only three states:  it is either available for use by
            the managed device (the status column has value `active');
            it is not available for use by the managed device, though
            the agent has sufficient information to make it so (the
            status column has value `notInService'); or, it is not
            available for use by the managed device, and an attempt to
            make it so would fail because the agent has insufficient
            information (the state column has value `notReady').





SNMPv2 Working Group        Standards Track                     [Page 7]

RFC 1903             Textual Conventions for SNMPv2         January 1996


                                     NOTE WELL

                 This textual convention may be used for a MIB table,
                 irrespective of whether the values of that table's
                 conceptual rows are able to be modified while it is
                 active, or whether its conceptual rows must be taken
                 out of service in order to be modified.  That is, it is
                 the responsibility of the DESCRIPTION clause of the
                 status column to specify whether the status column must
                 not be `active' in order for the value of some other
                 column of the same conceptual row to be modified.  If
                 such a specification is made, affected columns may be
                 changed by an SNMP set PDU if the RowStatus would not
                 be equal to `active' either immediately before or after
                 processing the PDU.  In other words, if the PDU also
                 contained a varbind that would change the RowStatus
                 value, the column in question may be changed if the
                 RowStatus was not equal to `active' as the PDU was
                 received, or if the varbind sets the status to a value
                 other than 'active'.


            Also note that whenever any elements of a row exist, the
            RowStatus column must also exist.



























SNMPv2 Working Group        Standards Track                     [Page 8]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            To summarize the effect of having a conceptual row with a
            status column having a SYNTAX clause value of RowStatus,
            consider the following state diagram:


                                         STATE
              +--------------+-----------+-------------+-------------
              |      A       |     B     |      C      |      D
              |              |status col.|status column|
              |status column |    is     |      is     |status column
    ACTION    |does not exist|  notReady | notInService|  is active
--------------+--------------+-----------+-------------+-------------
set status    |noError    ->D|inconsist- |inconsistent-|inconsistent-
column to     |       or     |   entValue|        Value|        Value
createAndGo   |inconsistent- |           |             |
              |         Value|           |             |
--------------+--------------+-----------+-------------+-------------
set status    |noError  see 1|inconsist- |inconsistent-|inconsistent-
column to     |       or     |   entValue|        Value|        Value
createAndWait |wrongValue    |           |             |
--------------+--------------+-----------+-------------+-------------
set status    |inconsistent- |inconsist- |noError      |noError
column to     |         Value|   entValue|             |
active        |              |           |             |
              |              |     or    |             |
              |              |           |             |
              |              |see 2   ->D|          ->D|          ->D
--------------+--------------+-----------+-------------+-------------
set status    |inconsistent- |inconsist- |noError      |noError   ->C
column to     |         Value|   entValue|             |
notInService  |              |           |             |
              |              |     or    |             |      or
              |              |           |             |
              |              |see 3   ->C|          ->C|wrongValue
--------------+--------------+-----------+-------------+-------------
set status    |noError       |noError    |noError      |noError
column to     |              |           |             |
destroy       |           ->A|        ->A|          ->A|          ->A
--------------+--------------+-----------+-------------+-------------
set any other |see 4         |noError    |noError      |see 5
column to some|              |           |             |
value         |              |      see 1|          ->C|          ->D
--------------+--------------+-----------+-------------+-------------

            (1) goto B or C, depending on information available to the
            agent.





SNMPv2 Working Group        Standards Track                     [Page 9]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            (2) if other variable bindings included in the same PDU,
            provide values for all columns which are missing but
            required, then return noError and goto D.

            (3) if other variable bindings included in the same PDU,
            provide values for all columns which are missing but
            required, then return noError and goto C.

            (4) at the discretion of the agent, the return value may be
            either:

                 inconsistentName:  because the agent does not choose to
                 create such an instance when the corresponding
                 RowStatus instance does not exist, or

                 inconsistentValue:  if the supplied value is
                 inconsistent with the state of some other MIB object's
                 value, or

                 noError: because the agent chooses to create the
                 instance.

            If noError is returned, then the instance of the status
            column must also be created, and the new state is B or C,
            depending on the information available to the agent.  If
            inconsistentName or inconsistentValue is returned, the row
            remains in state A.

            (5) depending on the MIB definition for the column/table,
            either noError or inconsistentValue may be returned.

            NOTE: Other processing of the set request may result in a
            response other than noError being returned, e.g.,
            wrongValue, noCreation, etc.


                              Conceptual Row Creation

            There are four potential interactions when creating a
            conceptual row:  selecting an instance-identifier which is
            not in use; creating the conceptual row; initializing any
            objects for which the agent does not supply a default; and,
            making the conceptual row available for use by the managed
            device.







SNMPv2 Working Group        Standards Track                    [Page 10]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            Interaction 1: Selecting an Instance-Identifier

            The algorithm used to select an instance-identifier varies
            for each conceptual row.  In some cases, the instance-
            identifier is semantically significant, e.g., the
            destination address of a route, and a management station
            selects the instance-identifier according to the semantics.

            In other cases, the instance-identifier is used solely to
            distinguish conceptual rows, and a management station
            without specific knowledge of the conceptual row might
            examine the instances present in order to determine an
            unused instance-identifier.  (This approach may be used, but
            it is often highly sub-optimal; however, it is also a
            questionable practice for a naive management station to
            attempt conceptual row creation.)

            Alternately, the MIB module which defines the conceptual row
            might provide one or more objects which provide assistance
            in determining an unused instance-identifier.  For example,
            if the conceptual row is indexed by an integer-value, then
            an object having an integer-valued SYNTAX clause might be
            defined for such a purpose, allowing a management station to
            issue a management protocol retrieval operation.  In order
            to avoid unnecessary collisions between competing management
            stations, `adjacent' retrievals of this object should be
            different.

            Finally, the management station could select a pseudo-random
            number to use as the index.  In the event that this index
            was already in use and an inconsistentValue was returned in
            response to the management protocol set operation, the
            management station should simply select a new pseudo-random
            number and retry the operation.

            A MIB designer should choose between the two latter
            algorithms based on the size of the table (and therefore the
            efficiency of each algorithm).  For tables in which a large
            number of entries are expected, it is recommended that a MIB
            object be defined that returns an acceptable index for
            creation.  For tables with small numbers of entries, it is
            recommended that the latter pseudo-random index mechanism be
            used.








SNMPv2 Working Group        Standards Track                    [Page 11]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            Interaction 2: Creating the Conceptual Row

            Once an unused instance-identifier has been selected, the
            management station determines if it wishes to create and
            activate the conceptual row in one transaction or in a
            negotiated set of interactions.

            Interaction 2a: Creating and Activating the Conceptual Row

            The management station must first determine the column
            requirements, i.e., it must determine those columns for
            which it must or must not provide values.  Depending on the
            complexity of the table and the management station's
            knowledge of the agent's capabilities, this determination
            can be made locally by the management station.  Alternately,
            the management station issues a management protocol get
            operation to examine all columns in the conceptual row that
            it wishes to create.  In response, for each column, there
            are three possible outcomes:

                 - a value is returned, indicating that some other
                 management station has already created this conceptual
                 row.  We return to interaction 1.

                 - the exception `noSuchInstance' is returned,
                 indicating that the agent implements the object-type
                 associated with this column, and that this column in at
                 least one conceptual row would be accessible in the MIB
                 view used by the retrieval were it to exist. For those
                 columns to which the agent provides read-create access,
                 the `noSuchInstance' exception tells the management
                 station that it should supply a value for this column
                 when the conceptual row is to be created.

                 - the exception `noSuchObject' is returned, indicating
                 that the agent does not implement the object-type
                 associated with this column or that there is no
                 conceptual row for which this column would be
                 accessible in the MIB view used by the retrieval.  As
                 such, the management station can not issue any
                 management protocol set operations to create an
                 instance of this column.

            Once the column requirements have been determined, a
            management protocol set operation is accordingly issued.
            This operation also sets the new instance of the status
            column to `createAndGo'.




SNMPv2 Working Group        Standards Track                    [Page 12]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            When the agent processes the set operation, it verifies that
            it has sufficient information to make the conceptual row
            available for use by the managed device.  The information
            available to the agent is provided by two sources:  the
            management protocol set operation which creates the
            conceptual row, and, implementation-specific defaults
            supplied by the agent (note that an agent must provide
            implementation-specific defaults for at least those objects
            which it implements as read-only).  If there is sufficient
            information available, then the conceptual row is created, a
            `noError' response is returned, the status column is set to
            `active', and no further interactions are necessary (i.e.,
            interactions 3 and 4 are skipped).  If there is insufficient
            information, then the conceptual row is not created, and the
            set operation fails with an error of `inconsistentValue'.
            On this error, the management station can issue a management
            protocol retrieval operation to determine if this was
            because it failed to specify a value for a required column,
            or, because the selected instance of the status column
            already existed.  In the latter case, we return to
            interaction 1.  In the former case, the management station
            can re-issue the set operation with the additional
            information, or begin interaction 2 again using
            `createAndWait' in order to negotiate creation of the
            conceptual row.

                                     NOTE WELL

                 Regardless of the method used to determine the column
                 requirements, it is possible that the management
                 station might deem a column necessary when, in fact,
                 the agent will not allow that particular columnar
                 instance to be created or written.  In this case, the
                 management protocol set operation will fail with an
                 error such as `noCreation' or `notWritable'.  In this
                 case, the management station decides whether it needs
                 to be able to set a value for that particular columnar
                 instance.  If not, the management station re-issues the
                 management protocol set operation, but without setting
                 a value for that particular columnar instance;
                 otherwise, the management station aborts the row
                 creation algorithm.

            Interaction 2b: Negotiating the Creation of the Conceptual
            Row

            The management station issues a management protocol set
            operation which sets the desired instance of the status



SNMPv2 Working Group        Standards Track                    [Page 13]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            column to `createAndWait'.  If the agent is unwilling to
            process a request of this sort, the set operation fails with
            an error of `wrongValue'.  (As a consequence, such an agent
            must be prepared to accept a single management protocol set
            operation, i.e., interaction 2a above, containing all of the
            columns indicated by its column requirements.)  Otherwise,
            the conceptual row is created, a `noError' response is
            returned, and the status column is immediately set to either
            `notInService' or `notReady', depending on whether it has
            sufficient information to make the conceptual row available
            for use by the managed device.  If there is sufficient
            information available, then the status column is set to
            `notInService'; otherwise, if there is insufficient
            information, then the status column is set to `notReady'.
            Regardless, we proceed to interaction 3.

            Interaction 3: Initializing non-defaulted Objects

            The management station must now determine the column
            requirements.  It issues a management protocol get operation
            to examine all columns in the created conceptual row.  In
            the response, for each column, there are three possible
            outcomes:

                 - a value is returned, indicating that the agent
                 implements the object-type associated with this column
                 and had sufficient information to provide a value.  For
                 those columns to which the agent provides read-create
                 access (and for which the agent allows their values to
                 be changed after their creation), a value return tells
                 the management station that it may issue additional
                 management protocol set operations, if it desires, in
                 order to change the value associated with this column.

                 - the exception `noSuchInstance' is returned,
                 indicating that the agent implements the object-type
                 associated with this column, and that this column in at
                 least one conceptual row would be accessible in the MIB
                 view used by the retrieval were it to exist. However,
                 the agent does not have sufficient information to
                 provide a value, and until a value is provided, the
                 conceptual row may not be made available for use by the
                 managed device.  For those columns to which the agent
                 provides read-create access, the `noSuchInstance'
                 exception tells the management station that it must
                 issue additional management protocol set operations, in
                 order to provide a value associated with this column.




SNMPv2 Working Group        Standards Track                    [Page 14]

RFC 1903             Textual Conventions for SNMPv2         January 1996


                 - the exception `noSuchObject' is returned, indicating
                 that the agent does not implement the object-type
                 associated with this column or that there is no
                 conceptual row for which this column would be
                 accessible in the MIB view used by the retrieval.  As
                 such, the management station can not issue any
                 management protocol set operations to create an
                 instance of this column.

            If the value associated with the status column is
            `notReady', then the management station must first deal with
            all `noSuchInstance' columns, if any.  Having done so, the
            value of the status column becomes `notInService', and we
            proceed to interaction 4.

            Interaction 4: Making the Conceptual Row Available

            Once the management station is satisfied with the values
            associated with the columns of the conceptual row, it issues
            a management protocol set operation to set the status column
            to `active'.  If the agent has sufficient information to
            make the conceptual row available for use by the managed
            device, the management protocol set operation succeeds (a
            `noError' response is returned).  Otherwise, the management
            protocol set operation fails with an error of
            `inconsistentValue'.


                                     NOTE WELL

                 A conceptual row having a status column with value
                 `notInService' or `notReady' is unavailable to the
                 managed device.  As such, it is possible for the
                 managed device to create its own instances during the
                 time between the management protocol set operation
                 which sets the status column to `createAndWait' and the
                 management protocol set operation which sets the status
                 column to `active'.  In this case, when the management
                 protocol set operation is issued to set the status
                 column to `active', the values held in the agent
                 supersede those used by the managed device.

            If the management station is prevented from setting the
            status column to `active' (e.g., due to management station
            or network failure) the conceptual row will be left in the
            `notInService' or `notReady' state, consuming resources
            indefinitely.  The agent must detect conceptual rows that
            have been in either state for an abnormally long period of



SNMPv2 Working Group        Standards Track                    [Page 15]

RFC 1903             Textual Conventions for SNMPv2         January 1996


            time and remove them.  It is the responsibility of the
            DESCRIPTION clause of the status column to indicate what an
            abnormally long period of time would be.  This period of
            time should be long enough to allow for human response time
            (including `think time') between the creation of the
            conceptual row and the setting of the status to `active'.
            In the absense of such information in the DESCRIPTION
            clause, it is suggested that this period be approximately 5
            minutes in length.  This removal action applies not only to
            newly-created rows, but also to previously active rows which
            are set to, and left in, the notInService state for a
            prolonged period exceeding that which is considered normal
            for such a conceptual row.


                             Conceptual Row Suspension

            When a conceptual row is `active', the management station
            may issue a management protocol set operation which sets the
            instance of the status column to `notInService'.  If the
            agent is unwilling to do so, the set operation fails with an
            error of `wrongValue'.  Otherwise, the conceptual row is
            taken out of service, and a `noError' response is returned.
            It is the responsibility of the DESCRIPTION clause of the
            status column to indicate under what circumstances the
            status column should be taken out of service (e.g., in order
            for the value of some other column of the same conceptual
            row to be modified).


                              Conceptual Row Deletion

            For deletion of conceptual rows, a management protocol set
            operation is issued which sets the instance of the status
            column to `destroy'.  This request may be made regardless of
            the current value of the status column (e.g., it is possible
            to delete conceptual rows which are either `notReady',
            `notInService' or `active'.)  If the operation succeeds,
            then all instances associated with the conceptual row are
            immediately removed."


    SYNTAX       INTEGER {
                     -- the following two values are states:
                     -- these values may be read or written
                     active(1),
                     notInService(2),




SNMPv2 Working Group        Standards Track                    [Page 16]

RFC 1903             Textual Conventions for SNMPv2         January 1996


                     -- the following value is a state:
                     -- this value may be read, but not written
                     notReady(3),

                     -- the following three values are
                     -- actions: these values may be written,
                     --   but are never read
                     createAndGo(4),
                     createAndWait(5),
                     destroy(6)
                 }


TimeStamp ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "The value of the sysUpTime object at which a specific
            occurrence happened.  The specific occurrence must be
            defined in the description of any object defined using this
            type."
    SYNTAX       TimeTicks


TimeInterval ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "A period of time, measured in units of 0.01 seconds."
    SYNTAX       INTEGER (0..2147483647)


DateAndTime ::= TEXTUAL-CONVENTION
    DISPLAY-HINT "2d-1d-1d,1d:1d:1d.1d,1a1d:1d"
    STATUS       current
    DESCRIPTION
            "A date-time specification.

            field  octets  contents                  range
            -----  ------  --------                  -----
              1      1-2   year                      0..65536
              2       3    month                     1..12
              3       4    day                       1..31
              4       5    hour                      0..23
              5       6    minutes                   0..59
              6       7    seconds                   0..60
                           (use 60 for leap-second)
              7       8    deci-seconds              0..9
              8       9    direction from UTC        '+' / '-'
              9      10    hours from UTC            0..11



SNMPv2 Working Group        Standards Track                    [Page 17]

RFC 1903             Textual Conventions for SNMPv2         January 1996


             10      11    minutes from UTC          0..59

            For example, Tuesday May 26, 1992 at 1:30:15 PM EDT would be
            displayed as:

                             1992-5-26,13:30:15.0,-4:0

            Note that if only local time is known, then timezone
            information (fields 8-10) is not present."
    SYNTAX       OCTET STRING (SIZE (8 | 11))


StorageType ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
            "Describes the memory realization of a conceptual row.  A
            row which is volatile(2) is lost upon reboot.  A row which
            is either nonVolatile(3), permanent(4) or readOnly(5), is
            backed up by stable storage.  A row which is permanent(4)
            can be changed but not deleted.  A row which is readOnly(5)
            cannot be changed nor deleted.

            If the value of an object with this syntax is either
            permanent(4) or readOnly(5), it cannot be modified.
            Conversely, if the value is either other(1), volatile(2) or
            nonVolatile(3), it cannot be modified to be permanent(4) or
            readOnly(5).

            Every usage of this textual convention is required to
            specify the columnar objects which a permanent(4) row must
            at a minimum allow to be writable."
    SYNTAX       INTEGER {
                     other(1),       -- eh?
                     volatile(2),    -- e.g., in RAM
                     nonVolatile(3), -- e.g., in NVRAM
                     permanent(4),   -- e.g., partially in ROM
                     readOnly(5)     -- e.g., completely in ROM
                 }


TDomain ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
          "Denotes a kind of transport service.

          Some possible values, such as snmpUDPDomain, are defined in
          'Transport Mappings for Version 2 of the Simple Network
          Management Protocol (SNMPv2)'."



SNMPv2 Working Group        Standards Track                    [Page 18]

RFC 1903             Textual Conventions for SNMPv2         January 1996


    SYNTAX       OBJECT IDENTIFIER


TAddress ::= TEXTUAL-CONVENTION
    STATUS       current
    DESCRIPTION
          "Denotes a transport service address.

          For snmpUDPDomain, a TAddress is 6 octets long, the initial 4
          octets containing the IP-address in network-byte order and the
          last 2 containing the UDP port in network-byte order.  Consult
          'Transport Mappings for Version 2 of the Simple Network
          Management Protocol (SNMPv2)' for further information on
          snmpUDPDomain."
    SYNTAX       OCTET STRING (SIZE (1..255))


END

3.  Mapping of the TEXTUAL-CONVENTION macro

   The TEXTUAL-CONVENTION macro is used to convey the syntax and
   semantics associated with a textual convention.  It should be noted
   that the expansion of the TEXTUAL-CONVENTION macro is something which
   conceptually happens during implementation and not during run-time.

   For all descriptors appearing in an information module, the
   descriptor shall be unique and mnemonic, and shall not exceed 64
   characters in length.  (However, descriptors longer than 32
   characters are not recommended.)  Further, the hyphen is not allowed
   as a character in the name of any textual convention.

3.1.  Mapping of the DISPLAY-HINT clause

   The DISPLAY-HINT clause, which need not be present, gives a hint as
   to how the value of an instance of an object with the syntax defined
   using this textual convention might be displayed.  The DISPLAY-HINT
   clause may be present if and only if the syntax has an underlying
   primitive type of INTEGER or OCTET STRING.  (Note, however, that the
   semantics defined for a particular syntax can cause the use of
   DISPLAY-HINT for that syntax to make no sense, e.g., for Counter32
   [2].)

   When the syntax has an underlying primitive type of INTEGER, the hint
   consists of an integer-format specification, containing two parts.
   The first part is a single character suggesting a display format,
   either: 'x' for hexadecimal, or 'd' for decimal, or 'o' for octal, or
   'b' for binary.  The second part is always omitted for 'x', 'o' and



SNMPv2 Working Group        Standards Track                    [Page 19]

RFC 1903             Textual Conventions for SNMPv2         January 1996


   'b', and need not be present for 'd'.  If present, the second part
   starts with a hyphen and is followed by a decimal number, which
   defines the implied decimal point when rendering the value.  For
   example:

     Hundredths ::= TEXTUAL-CONVENTION
         DISPLAY-HINT "d-2"
         ...
         SYNTAX     INTEGER (0..10000)

   suggests that a Hundredths value of 1234 be rendered as "12.34"

   When the syntax has an underlying primitive type of OCTET STRING, the
   hint consists of one or more octet-format specifications.  Each
   specification consists of five parts, with each part using and
   removing zero or more of the next octets from the value and producing
   the next zero or more characters to be displayed.  The octets within
   the value are processed in order of significance, most significant
   first.

   The five parts of a octet-format specification are:

(1)  the (optional) repeat indicator; if present, this part is a `*',
     and indicates that the current octet of the value is to be used as
     the repeat count.  The repeat count is an unsigned integer (which
     may be zero) which specifies how many times the remainder of this
     octet-format specification should be successively applied.  If the
     repeat indicator is not present, the repeat count is one.

(2)  the octet length: one or more decimal digits specifying the number
     of octets of the value to be used and formatted by this octet-
     specification.  Note that the octet length can be zero.  If less
     than this number of octets remain in the value, then the lesser
     number of octets are used.

(3)  the display format, either:  `x' for hexadecimal, `d' for decimal,
     `o' for octal, or `a' for ascii.  If the octet length part is
     greater than one, and the display format part refers to a numeric
     format, then network-byte ordering (big-endian encoding) is used
     interpreting the octets in the value.

(4)  the (optional) display separator character; if present, this part
     is a single character which is produced for display after each
     application of this octet-specification; however, this character is
     not produced for display if it would be immediately followed by the
     display of the repeat terminator character for this octet-
     specification.  This character can be any character other than a
     decimal digit and a `*'.



SNMPv2 Working Group        Standards Track                    [Page 20]

RFC 1903             Textual Conventions for SNMPv2         January 1996


(5)  the (optional) repeat terminator character, which can be present
     only if the display separator character is present and this octet-
     specification begins with a repeat indicator; if present, this part
     is a single character which is produced after all the zero or more
     repeated applications (as given by the repeat count) of this
     octet-specification.  This character can be any character other
     than a decimal digit and a `*'.

   Output of a display separator character or a repeat terminator
   character is suppressed if it would occur as the last character of
   the display.

   If the octets of the value are exhausted before all the octet-format
   specification have been used, then the excess specifications are
   ignored.  If additional octets remain in the value after interpreting
   all the octet-format specifications, then the last octet-format
   specification is re-interpreted to process the additional octets,
   until no octets remain in the value.

3.2.  Mapping of the STATUS clause

   The STATUS clause, which must be present, indicates whether this
   definition is current or historic.

   The values "current", and "obsolete" are self-explanatory.  The
   "deprecated" value indicates that the definition is obsolete, but
   that an implementor may wish to support the use of this textual
   convention to foster interoperability with older implementations.

3.3.  Mapping of the DESCRIPTION clause

   The DESCRIPTION clause, which must be present, contains a textual
   definition of the textual convention, which provides all semantic
   definitions necessary for implementation, and should embody any
   information which would otherwise be communicated in any ASN.1
   commentary annotations associated with the object.

   Note that, in order to conform to the ASN.1 syntax, the entire value
   of this clause must be enclosed in double quotation marks, and
   therefore cannot itself contain double quotation marks, although the
   value may be multi-line.

3.4.  Mapping of the REFERENCE clause

   The REFERENCE clause, which need not be present, contains a textual
   cross-reference to a related item defined in some other published
   work.




SNMPv2 Working Group        Standards Track                    [Page 21]

RFC 1903             Textual Conventions for SNMPv2         January 1996


3.5.  Mapping of the SYNTAX clause

   The SYNTAX clause, which must be present, defines abstract data
   structure corresponding to the textual convention.  The data
   structure must be one of the alternatives defined in the ObjectSyntax
   CHOICE or the BITS construct (see section 7.1 in [2]).

4.  Security Considerations

   Security issues are not discussed in this memo.

5.  Editor's Address

   Keith McCloghrie
   Cisco Systems, Inc.
   170 West Tasman Drive
   San Jose, CA  95134-1706
   US

   Phone: +1 408 526 5260
   EMail: kzm@cisco.com

6.  Acknowledgements

   This document is the result of significant work by the four major
   contributors:

   Jeffrey D. Case (SNMP Research, case@snmp.com)
   Keith McCloghrie (Cisco Systems, kzm@cisco.com)
   Marshall T. Rose (Dover Beach Consulting, mrose@dbc.mtview.ca.us)
   Steven Waldbusser (International Network Services, stevew@uni.ins.com)

   In addition, the contributions of the SNMPv2 Working Group are
   acknowledged.  In particular, a special thanks is extended for the
   contributions of:

     Alexander I. Alten (Novell)
     Dave Arneson (Cabletron)
     Uri Blumenthal (IBM)
     Doug Book (Chipcom)
     Kim Curran (Bell-Northern Research)
     Jim Galvin (Trusted Information Systems)
     Maria Greene (Ascom Timeplex)
     Iain Hanson (Digital)
     Dave Harrington (Cabletron)
     Nguyen Hien (IBM)
     Jeff Johnson (Cisco Systems)
     Michael Kornegay (Object Quest)



SNMPv2 Working Group        Standards Track                    [Page 22]

RFC 1903             Textual Conventions for SNMPv2         January 1996


     Deirdre Kostick (AT&T Bell Labs)
     David Levi (SNMP Research)
     Daniel Mahoney (Cabletron)
     Bob Natale (ACE*COMM)
     Brian O'Keefe (Hewlett Packard)
     Andrew Pearson (SNMP Research)
     Dave Perkins (Peer Networks)
     Randy Presuhn (Peer Networks)
     Aleksey Romanov (Quality Quorum)
     Shawn Routhier (Epilogue)
     Jon Saperia (BGS Systems)
     Bob Stewart (Cisco Systems, bstewart@cisco.com), chair
     Kaj Tesink (Bellcore)
     Glenn Waters (Bell-Northern Research)
     Bert Wijnen (IBM)

7.  References

[1]  Information processing systems - Open Systems Interconnection -
     Specification of Abstract Syntax Notation One (ASN.1),
     International Organization for Standardization.  International
     Standard 8824, (December, 1987).

[2]  SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and
     S. Waldbusser, "Structure of Management Information for Version 2
     of the Simple Network Management Protocol (SNMPv2)", RFC 1902,
     January 1996.
























SNMPv2 Working Group        Standards Track                    [Page 23]