RFC1443 - Textual Conventions for version 2 of the Simple Network Management Pro

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　　Network Working Group J. Case
Request for Comments: 1443 SNMP Research, Inc.
K. McCloghrie
Hughes LAN Systems
M. Rose
Dover Beach Consulting, Inc.
S. Waldbusser
Carnegie Mellon University
April 1993

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

Status of this Memo

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

Table of Contents

1 Introduction .......................................... 2
1.1 A Note on Terminology ............................... 3
2 Definitions ........................................... 4
3 Mapping of the TEXTUAL-CONVENTION macro ............... 22
3.1 Mapping of the DISPLAY-HINT clause .................. 22
3.2 Mapping of the STATUS clause ........................ 24
3.3 Mapping of the DESCRIPTION clause ................... 24
3.4 Mapping of the REFERENCE clause ..................... 24
3.5 Mapping of the SYNTAX clause ........................ 24
4 Acknowledgements ...................................... 26
5 References ............................................ 30
6 Security Considerations ............................... 31
7 Authors' Addresses .................................... 31

RFC1443 Textual Conventions for SNMPv2 April 1993

1. Introduction

A network 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 both authentication and
authorization policies.

Network management stations execute management applications
which monitor and control network elements. Network elements
are devices such as hosts, routers, terminal servers, etc.,
which are monitored and controlled through 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 new define
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. All names used for the textual
conventions defined in all "standard" information modules

RFC1443 Textual Conventions for SNMPv2 April 1993

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, 1157,
and 1212, is termed the SNMP version 1 framework (SNMPv1).
The current framework is termed the SNMP version 2 framework
(SNMPv2).

RFC1443 Textual Conventions for SNMPv2 April 1993

2. Definitions

SNMPv2-TC DEFINITIONS ::= BEGIN

IMPORTS
ObjectSyntax, Integer32, TimeTicks
FROM SNMPv2-SMI;

-- definition of textual conventions

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

RFC1443 Textual Conventions for SNMPv2 April 1993

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 RFC854. 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:"
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) }

RFC1443 Textual Conventions for SNMPv2 April 1993

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."
SYNTAX INTEGER (0..2147483647)

RFC1443 Textual Conventions for SNMPv2 April 1993

AutonomousType ::= TEXTUAL-CONVENTION
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 current
DESCRIPTION
"A pointer to a specific instance of a conceptual
row of a MIB table in the managed device. By
convention, it is the name of the particular
instance of the first columnar object in the
conceptual row."
SYNTAX OBJECT IDENTIFIER

RFC1443 Textual Conventions for SNMPv2 April 1993

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

RFC1443 Textual Conventions for SNMPv2 April 1993

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,
because the agent lacks sufficient information
(the status column has value 'notReady').

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 be 'notInService' in order
for the value of some other column of the
same conceptual row to be modified.

RFC1443 Textual Conventions for SNMPv2 April 1993

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 |noError
column to some| | | |
value | ->A| see 1| ->C| ->D
--------------+--------------+-----------+-------------+-------------

RFC1443 Textual Conventions for SNMPv2 April 1993

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

(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, 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.

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

RFC1443 Textual Conventions for SNMPv2 April 1993

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.

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.

RFC1443 Textual Conventions for SNMPv2 April 1993

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

RFC1443 Textual Conventions for SNMPv2 April 1993

issued. This operation also sets the new instance
of the status column to 'createAndGo'.

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.

RFC1443 Textual Conventions for SNMPv2 April 1993

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 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.

RFC1443 Textual Conventions for SNMPv2 April 1993

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, 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.

- 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

RFC1443 Textual Conventions for SNMPv2 April 1993

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

RFC1443 Textual Conventions for SNMPv2 April 1993

indefinitely. The agent must detect conceptual
rows that have been in either state for an
abnormally long period of time and remove them.
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'. It is
suggested that this period be approximately 5
minutes in length.

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 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."

RFC1443 Textual Conventions for SNMPv2 April 1993

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

-- 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)
}

RFC1443 Textual Conventions for SNMPv2 April 1993

TimeStamp ::= TEXTUAL-CONVENTION
STATUS current
DESCRIPTION
"The value of MIB-II's 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)

RFC1443 Textual Conventions for SNMPv2 April 1993

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
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))

END

RFC1443 Textual Conventions for SNMPv2 April 1993

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. 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 only be present when
the syntax has an underlying primitive type of INTEGER or
OCTET STRING.

When the syntax has an underlying primitive type of INTEGER,
the hint consists of a single character suggesting a display
format, either: 'x' for hexadecimal, 'd' for decimal, or 'o'
for octal, or 'b' for binary.

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.

RFC1443 Textual Conventions for SNMPv2 April 1993

(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 '*'.

(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.

RFC1443 Textual Conventions for SNMPv2 April 1993

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 textual convention
is obsolete, but that an implementor may wish to support that
object 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.

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 [2].

Full ASN.1 sub-typing is allowed, as appropriate to the
underingly ASN.1 type, primarily as an aid to implementors in
understanding the meaning of the textual convention. Of
course, sub-typing is not allowed for textual conventions
derived from either the Counter32 or Counter64 types, but is

RFC1443 Textual Conventions for SNMPv2 April 1993

allowed for textual conventions derived from the Gauge32 type.

RFC1443 Textual Conventions for SNMPv2 April 1993

4. Acknowledgements

PhysAddress (and textual conventions) originated in RFC1213.

MacAddress originated in RFCs 1230 and 1231.

TruthValue originated in RFC1253.

AutonomousType and InstancePointer originated in RFC1316.

RowStatus originated in RFC1271.

A special thanks to Bancroft Scott of Open Systems Solutions,
Inc., for helping in the definition of the TEXTUAL-CONVENTIONS
macro.

Finally, the comments of the SNMP version 2 working group are
gratefully acknowledged:

Beth Adams, Network Management Forum
Steve Alexander, INTERACTIVE Systems Corporation
David Arneson, Cabletron Systems
Toshiya Asaba
Fred Baker, ACC
Jim Barnes, Xylogics, Inc.
Brian Bataille
Andy Bierman, SynOptics Communications, Inc.
Uri Blumenthal, IBM Corporation
Fred Bohle, Interlink
Jack Brown
Theodore Brunner, Bellcore
Stephen F. Bush, GE Information Services
Jeffrey D. Case, University of Tennessee, Knoxville
John Chang, IBM Corporation
Szusin Chen, Sun Microsystems
Robert Ching
Chris Chiotasso, Ungermann-Bass
Bobby A. Clay, NASA/Boeing
John Cooke, Chipcom
Tracy Cox, Bellcore
Juan Cruz, Datability, Inc.
David Cullerot, Cabletron Systems
Cathy Cunningham, Microcom
James R. (Chuck) Davin, Bellcore
Michael Davis, Clearpoint

RFC1443 Textual Conventions for SNMPv2 April 1993

Mike Davison, FiberCom
Cynthia DellaTorre, MITRE
Taso N. Devetzis, Bellcore
Manual Diaz, DAVID Systems, Inc.
Jon Dreyer, Sun Microsystems
David Engel, Optical Data Systems
Mike Erlinger, Lexcel
Roger Fajman, NIH
Daniel Fauvarque, Sun Microsystems
Karen Frisa, CMU
Shari Galitzer, MITRE
Shawn Gallagher, Digital Equipment Corporation
Richard Graveman, Bellcore
Maria Greene, Xyplex, Inc.
Michel Guittet, Apple
Robert Gutierrez, NASA
Bill Hagerty, Cabletron Systems
Gary W. Haney, Martin Marietta Energy Systems
Patrick Hanil, Nokia Telecommunications
Matt Hecht, SNMP Research, Inc.
Edward A. Heiner, Jr., Synernetics Inc.
Susan E. Hicks, Martin Marietta Energy Systems
Geral Holzhauer, Apple
John Hopprich, DAVID Systems, Inc.
Jeff Hughes, Hewlett-Packard
Robin Iddon, Axon Networks, Inc.
David Itusak
Kevin M. Jackson, Concord Communications, Inc.
Ole J. Jacobsen, Interop Company
Ronald Jacoby, Silicon Graphics, Inc.
Satish Joshi, SynOptics Communications, Inc.
Frank Kastenholz, FTP Software
Mark Kepke, Hewlett-Packard
Ken Key, SNMP Research, Inc.
Zbiginew Kielczewski, Eicon
Jongyeoi Kim
Andrew Knutsen, The Santa Cruz Operation
Michael L. Kornegay, VisiSoft
Deirdre C. Kostik, Bellcore
Cheryl Krupczak, Georgia Tech
Mark S. Lewis, Telebit
David Lin
David Lindemulder, AT&T/NCR
Ben Lisowski, Sprint
David Liu, Bell-Northern Research

RFC1443 Textual Conventions for SNMPv2 April 1993

John Lunny, The Wollongong Group
Robert C. Lushbaugh Martin, Marietta Energy Systems
Michael Luufer, BBN
Carl Madison, Star-Tek, Inc.
Keith McCloghrie, Hughes LAN Systems
Evan McGinnis, 3Com Corporation
Bill McKenzie, IBM Corporation
Donna McMaster, SynOptics Communications, Inc.
John Medicke, IBM Corporation
Doug Miller, Telebit
Dave Minnich, FiberCom
Mohammad Mirhakkak, MITRE
Rohit Mital, Protools
George Mouradian, AT&T Bell Labs
Patrick Mullaney, Cabletron Systems
Dan Myers, 3Com Corporation
Rina Nathaniel, Rad Network Devices Ltd.
Hien V. Nguyen, Sprint
Mo Nikain
Tom Nisbet
William B. Norton, MERIT
Steve Onishi, Wellfleet Communications, Inc.
David T. Perkins, SynOptics Communications, Inc.
Carl Powell, BBN
Ilan Raab, SynOptics Communications, Inc.
Richard Ramons, AT&T
Venkat D. Rangan, Metric Network Systems, Inc.
Louise Reingold, Sprint
Sam Roberts, Farallon Computing, Inc.
Kary Robertson, Concord Communications, Inc.
Dan Romascanu, Lannet Data Communications Ltd.
Marshall T. Rose, Dover Beach Consulting, Inc.
Shawn A. Routhier, Epilogue Technology Corporation
Chris Rozman
Asaf Rubissa, Fibronics
Jon Saperia, Digital Equipment Corporation
Michael Sapich
Mike Scanlon, Interlan
Sam Schaen, MITRE
John Seligson, Ultra Network Technologies
Paul A. Serice, Corporation for Open Systems
Chris Shaw, Banyan Systems
Timon Sloane
Robert Snyder, Cisco Systems
Joo Young Song

RFC1443 Textual Conventions for SNMPv2 April 1993

Roy Spitier, Sprint
Einar Stefferud, Network Management Associates
John Stephens, Cayman Systems, Inc.
Robert L. Stewart, Xyplex, Inc. (chair)
Kaj Tesink, Bellcore
Dean Throop, Data General
Ahmet Tuncay, France Telecom-CNET
Maurice Turcotte, Racal Datacom
Warren Vik, INTERACTIVE Systems Corporation
Yannis Viniotis
Steven L. Waldbusser, Carnegie Mellon Universitty
Timothy M. Walden, ACC
Alice Wang, Sun Microsystems
James Watt, Newbridge
Luanne Waul, Timeplex
Donald E. Westlake III, Digital Equipment Corporation
Gerry White
Bert Wijnen, IBM Corporation
Peter Wilson, 3Com Corporation
Steven Wong, Digital Equipment Corporation
Randy Worzella, IBM Corporation
Daniel Woycke, MITRE
Honda Wu
Jeff Yarnell, Protools
Chris Young, Cabletron
Kiho Yum, 3Com Corporation

RFC1443 Textual Conventions for SNMPv2 April 1993

5. 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] Case, J., McCloghrie, K., Rose, M., and Waldbusser, S.,
"Structure of Management Information for version 2 of the
Simple Network Management Protocol (SNMPv2)", RFC1442,
SNMP Research, Inc., Hughes LAN Systems, Dover Beach
Consulting, Inc., Carnegie Mellon University, April 1993.

RFC1443 Textual Conventions for SNMPv2 April 1993

6. Security Considerations

Security issues are not discussed in this memo.

7. Authors' Addresses

Jeffrey D. Case
SNMP Research, Inc.
3001 Kimberlin Heights Rd.
Knoxville, TN 37920-9716
US

Phone: +1 615 573 1434
Email: case@snmp.com

Keith McCloghrie
Hughes LAN Systems
1225 Charleston Road
Mountain View, CA 94043
US

Phone: +1 415 966 7934
Email: kzm@hls.com

Marshall T. Rose
Dover Beach Consulting, Inc.
420 Whisman Court
Mountain View, CA 94043-2186
US

Phone: +1 415 968 1052
Email: mrose@dbc.mtview.ca.us

Steven Waldbusser
Carnegie Mellon University
4910 Forbes Ave
Pittsburgh, PA 15213
US

Phone: +1 412 268 6628
Email: waldbusser@cmu.edu

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