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Network Working Group K. McCloghrie, Editor
Request for Comments: 1229 Hughes LAN Systems, Inc.
May 1991
Extensions to the Generic-Interface MIB
Status of this Memo
This RFC contains definitions of managed objects used as experimental
extensions to the generic interfaces structure of MIB-II. This memo
is a product of the SNMP Working Group of the Internet Engineering
Task Force (IETF). This RFC specifies 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. Abstract .............................................. 1
2. The Network Management Framework....................... 1
3. Objects ............................................... 2
4. Overview .............................................. 3
4.1 Generic Interface Extension Table .................... 3
4.2 Generic Interface Test Table ......................... 3
4.3 Generic Receive Address Table ........................ 4
5. Definitions ........................................... 5
6. Acknowledgements ...................................... 14
7. References ............................................ 15
8. Security Considerations................................ 15
9. Author's Address....................................... 16
1. Abstract
This memo defines an experimental portion of the Management
Information Base (MIB) for use with network management protocols in
TCP/IP-based internets. In particular, it defines managed object
types as experimental extensions to the generic interfaces structure
of MIB-II.
2. The Network Management Framework
The Internet-standard Network Management Framework consists of three
components. They are:
RFC 1155 which defines the SMI, the mechanisms used for describing
and naming objects for the purpose of management. RFC 1212
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RFC 1229 Interface MIB Extensions May 1991
defines a more concise description mechanism, which is wholly
consistent with the SMI.
RFC 1156 which defines MIB-I, the core set of managed objects for
the Internet suite of protocols. RFC 1213, defines MIB-II, an
evolution of MIB-I based on implementation experience and new
operational requirements.
RFC 1157 which defines the SNMP, the protocol used for network
access to managed objects.
The Framework permits new objects to be defined for the purpose of
experimentation and evaluation.
3. Objects
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. Objects in the MIB are
defined using the subset of Abstract Syntax Notation One (ASN.1) [7]
defined in the SMI. In particular, each object has a name, a syntax,
and an encoding. The name is an object identifier, an
administratively assigned name, which specifies an object type. The
object type together with an object instance serves to uniquely
identify a specific instantiation of the object. For human
convenience, we often use a textual string, termed the OBJECT
DESCRIPTOR, to also refer to the object type.
The syntax of an object type defines the abstract data structure
corresponding to that object type. The ASN.1 language is used for
this purpose. However, the SMI [3] purposely restricts the ASN.1
constructs which may be used. These restrictions are explicitly made
for simplicity.
The encoding of an object type is simply how that object type is
represented using the object type's syntax. Implicitly tied to the
notion of an object type's syntax and encoding is how the object type
is represented when being transmitted on the network.
The SMI specifies the use of the basic encoding rules of ASN.1 [8],
subject to the additional requirements imposed by the SNMP.
Section 5 contains the specification of all object types in this
section of the MIB. The object types are defined using the
conventions specified in the SMI, as amended by the extensions
specified in [9].
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RFC 1229 Interface MIB Extensions May 1991
4. Overview
The Internet Standard MIB [4,6] contains a group of management
objects pertaining to a network device's generic network
interface(s). These objects are generic in the sense that they apply
to all network interfaces, irrespective of the type of communication
media and protocols used on such interfaces. This has proved to be
necessary but not sufficient; there are efforts underway to define
additional MIB objects which are specific to particular media and
lower-level (subnetwork-layer and below) protocol stacks.
However, some of these efforts have identified objects which are
required (or at least useful), but are not specific to the
interface-type on which the effort is focusing. In order to avoid
redundancy, it is better that such objects be defined as extensions
to the generic interface group, rather than defined in multiple
specific-interface-type MIBs.
This memo defines the resultant extensions to the generic interface
group. These extensions are spread over three tables: the generic
Interface Extension table, the generic Interface Test table, and the
generic Receive Address table.
4.1. Generic Interface Extension Table
This table consists of new objects applicable to all types of
subnetwork interface.
4.2. Generic Interface Test Table
This section defines objects which allow a network manager to
instruct an agent to test an interface for various faults. A few
common types of tests are defined in this document but most will be
defined elsewhere, dependent on the particular type of interface.
After testing, the object ifExtnsTestResult can be read to determine
the outcome. If an agent cannot perform the test, ifExtnsTestResult
is set to so indicate. The object ifExtnsTestCode can be used to
provide further test-specific or interface-specific (or even
enterprise-specific) information concerning the outcome of the test.
Only one test can be in progress on each interface at any one time.
If one test is in progress when another test is invoked, the second
test is rejected. Some agents may reject a test when a prior test is
active on another interface.
When a test is invoked, the identity of the originator of the request
and the request-id are saved by the agent in the objects
ifExtnsTestRequestId and ifExtnsTestCommunity. These values remain
set until the next test is invoked. In the (rare) event that the
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RFC 1229 Interface MIB Extensions May 1991
invocation of tests by two network managers were to overlap, then
there would be a possibility that the first test's results might be
overwritten by the second test's results prior to the first results
being read. This unlikely circumstance can be detected by a network
manager retrieving ifExtnsTestCommunity, and ifExtnsTestRequestId at
the same time as the test results are retrieved, and ensuring that
the results are for the desired request.
In general, a Management station must not retransmit a request to
invoke a test for which it does not receive a response; instead, it
properly inspects an agent's MIB to determine if the invocation was
successful. The invocation request is retransmitted only if the
invocation was unsuccessful.
Some tests may require the interface to be taken off-line or may even
require the agent to be rebooted after completion of the test. In
these circumstances, communication with the management station
invoking the test may be lost until after completion of the test.
The agent should make every effort to transmit a response to the
request that invoked the test prior to losing communication. When
the agent is restored to normal service, the results of the test are
properly made available in the appropriate objects. Note that this
requires that the ifIndex value assigned to an interface must be
unchanged even if the test causes a reboot. An agent must reject any
test for which it cannot, perhaps due to resource constraints, make
available at least the minimum amount of information after that test
completes.
4.3. Generic Receive Address Table
This table contains objects relating to an interface's support for
receiving packets/frames at more than one address on the same
interface.
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5. Definitions
RFC1229-MIB DEFINITIONS ::= BEGIN
-- Extensions to MIB-II's Generic Interface Table
IMPORTS
experimental, Counter FROM RFC1155-SMI
DisplayString, PhysAddress FROM RFC1213-MIB
OBJECT-TYPE FROM RFC-1212;
ifExtensions OBJECT IDENTIFIER ::= { experimental 6 }
-- Generic Interface Extension Table
--
-- This group of objects is mandatory for all types of
-- subnetwork interface.
ifExtnsTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfExtnsEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"A list of interfaces extension entries.
The number of entries is given by the value
of ifNumber, defined in [4,6]."
::= { ifExtensions 1 }
ifExtnsEntry OBJECT-TYPE
SYNTAX IfExtnsEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"An extension to the interfaces entry,
defined in [4,6], containing additional
objects at the subnetwork layer and below
for a particular interface."
INDEX { ifExtnsIfIndex }
::= { ifExtnsTable 1 }
IfExtnsEntry ::=
SEQUENCE {
ifExtnsIfIndex
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RFC 1229 Interface MIB Extensions May 1991
INTEGER,
ifExtnsChipSet
OBJECT IDENTIFIER,
ifExtnsRevWare
DisplayString,
ifExtnsMulticastsTransmittedOks
Counter,
ifExtnsBroadcastsTransmittedOks
Counter,
ifExtnsMulticastsReceivedOks
Counter,
ifExtnsBroadcastsReceivedOks
Counter,
ifExtnsPromiscuous
INTEGER
}
ifExtnsIfIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of this object identifies the
interface for which this entry contains
extended management information. The value
of this object for a particular interface
has the same value as the ifIndex object,
defined in [4,6], for the same interface."
::= { ifExtnsEntry 1 }
ifExtnsChipSet OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This object identifies the hardware chip
set being used in the interface. The
assignment of OBJECT IDENTIFIERs to various
types of hardware chip sets is managed
by the IANA. If the hardware chip set is
unknown, the object identifier
unknownChipSet OBJECT IDENTIFIER ::= { 0 0 }
is returned. Note that unknownChipSet is a
syntactically valid object identifier, and
any conformant implementation of ASN.1 and
the BER must be able to generate and
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RFC 1229 Interface MIB Extensions May 1991
recognize this value."
::= { ifExtnsEntry 2 }
ifExtnsRevWare OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
ACCESS read-only
STATUS mandatory
DESCRIPTION
"An arbitrary octet string that describes
the firmware version of this interface.
It is intended that this should be human
readable. It must only contain ASCII
printable characters. Typically this
will be the firmware version of the main
interface software."
::= { ifExtnsEntry 3 }
ifExtnsMulticastsTransmittedOks OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The count of frames successfully
transmitted to a subnetwork or link-layer
multicast destination address other than a
broadcast address. For a MAC layer protocol,
this includes both Group and Functional
addresses."
::= { ifExtnsEntry 4 }
ifExtnsBroadcastsTransmittedOks OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The count of frames successfully
transmitted to a subnetwork or link-layer
broadcast addresses. It does not include
frames sent to a multicast address."
::= { ifExtnsEntry 5 }
ifExtnsMulticastsReceivedOks OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The count of frames successfully received
that are directed to an active subnetwork
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RFC 1229 Interface MIB Extensions May 1991
or link-layer multicast address (for a MAC
layer protocol, this includes both Group and
Functional addresses). This does not include
frames directed to a broadcast address, nor
frames received with errors."
::= { ifExtnsEntry 6 }
ifExtnsBroadcastsReceivedOks OBJECT-TYPE
SYNTAX Counter
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The count of frames successfully received
that are directed to a subnetwork or
link-layer broadcast address. This does not
include frames received with errors."
::= { ifExtnsEntry 7 }
ifExtnsPromiscuous OBJECT-TYPE
SYNTAX INTEGER {
true(1),
false(2)
}
ACCESS read-only -- Note: agent implementors are
-- encouraged to extend this
-- access to read-write if that
-- makes sense in their agent.
STATUS mandatory
DESCRIPTION
"This object has a value of false(2) if
this interface only accepts packets/frames
that are addressed to this station. This
object has a value of true(1) when the
station accepts all packets/frames
transmitted on the media. The value
true(1) is only legal on certain types of
media. If legal, setting this object to a
value of true(1) may require the interface
to be reset before becoming effective."
::= { ifExtnsEntry 8 }
--
-- Generic Interface Test Table
--
-- This group of objects is optional, but if the table is
-- implemented, all objects in the table must be implemented.
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RFC 1229 Interface MIB Extensions May 1991
ifExtnsTestTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfExtnsTestEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"This table contains one entry per interface."
::= { ifExtensions 2 }
ifExtnsTestEntry OBJECT-TYPE
SYNTAX IfExtnsTestEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"An entry containing objects for invoking
tests on an interface."
INDEX { ifExtnsTestIfIndex }
::= { ifExtnsTestTable 1 }
IfExtnsTestEntry ::=
SEQUENCE {
ifExtnsTestIfIndex
INTEGER,
ifExtnsTestCommunity
OCTET STRING,
ifExtnsTestRequestId
INTEGER,
ifExtnsTestType
OBJECT IDENTIFIER,
ifExtnsTestResult
INTEGER,
ifExtnsTestCode
OBJECT IDENTIFIER
}
ifExtnsTestIfIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of this object identifies the
interface for which this entry contains
information on interface tests. The value
of this object for a particular interface
has the same value as the ifIndex object,
defined in [4,6], for the same interface."
::= { ifExtnsTestEntry 1 }
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ifExtnsTestCommunity OBJECT-TYPE
SYNTAX OCTET STRING
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This object contains the name of the SNMP
authentication community [5] which was used
to authenticate the SNMP Message which invoked
the current or most recent test on this
interface. If the authentication community
is unknown or undefined, this value contains
the zero-length string."
::= { ifExtnsTestEntry 2 }
ifExtnsTestRequestId OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This object contains the value of the
request-id field in the SNMP PDU [5] which
invoked the current or most recent test on
this interface. If the request-id is
unknown or undefined, this value contains
the value zero."
::= { ifExtnsTestEntry 3 }
ifExtnsTestType OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
ACCESS read-write
STATUS mandatory
DESCRIPTION
"A control variable used to start and stop
operator-initiated interface tests.
Most OBJECT IDENTIFIER values assigned
to tests are defined elsewhere, in associ-
ation with specific types of interface.
However, this document assigns a value for
a full-duplex loopback test, and defines the
special meanings of the subject identifier:
noTest OBJECT IDENTIFIER ::= { 0 0 }
When the value noTest is written to this
object, no action is taken unless a test is
in progress, in which case the test is
aborted. Writing any other value to this
object is only valid when no test is
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RFC 1229 Interface MIB Extensions May 1991
currently in progress, in which case the
indicated test is initiated.
Note that noTest is a syntactically valid
object identifier, and any conformant
implementation of ASN.1 and BER must be able
to generate and recognize this value.
When read, this object always returns
the most recent value that ifExtnsTestType
was set to. If it has not been set since
the last initialization of the network
management subsystem on the agent, a value
of noTest is returned."
::= { ifExtnsTestEntry 4 }
wellKnownTests OBJECT IDENTIFIER ::= { ifExtensions 4 }
-- full-duplex loopback test
testFullDuplexLoopBack OBJECT IDENTIFIER ::=
{ wellKnownTests 1 }
ifExtnsTestResult OBJECT-TYPE
SYNTAX INTEGER {
none(1), -- no test yet requested
success(2),
inProgress(3),
notSupported(4),
unAbleToRun(5), -- due to state of system
aborted(6),
failed(7)
}
ACCESS read-only
STATUS mandatory
DESCRIPTION
"This object contains the result of the most
recently requested test, or the value
none(1) if no tests have been requested since
the last reset. Note that this facility
provides no provision for saving the results
of one test when starting another, as could
be required if used by multiple managers
concurrently."
::= { ifExtnsTestEntry 5 }
ifExtnsTestCode OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
ACCESS read-only
STATUS mandatory
DESCRIPTION
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"This object contains a code which contains
more specific information on the test result,
for example an error-code after a failed
test. Error codes and other values this
object may take are specific to the type of
interface and/or test. However, one subject
identifier:
testCodeUnknown OBJECT IDENTIFIER ::= { 0 0 }
for use if no additional result code is
available.
Note that testCodeUnknown is a
syntactically valid object identifier, and
any conformant implementation of ASN.1 and
the BER must be able to generate and
recognize this value."
::= { ifExtnsTestEntry 6 }
-- Generic Receive Address Table
--
-- This group of objects is mandatory for all types of
-- interfaces which can receive packets/frames addressed to
-- more than one address.
ifExtnsRcvAddrTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfExtnsRcvAddrEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"This table contains an entry for each
address (broadcast, multicast, or uni-cast)
for which the system will receive packets/
frames on a particular interface. When an
interface is operating in promiscuous mode,
entries are only required for those addresses
for which the system would receive frames
were it not operating in promiscuous mode."
::= { ifExtensions 3 }
ifExtnsRcvAddrEntry OBJECT-TYPE
SYNTAX IfExtnsRcvAddrEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"A list of objects identifying an address
for which the system will accept packets/
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RFC 1229 Interface MIB Extensions May 1991
frames on a particular interface."
INDEX { ifExtnsRcvAddrIfIndex, ifExtnsRcvAddress }
::= { ifExtnsRcvAddrTable 1 }
IfExtnsRcvAddrEntry ::=
SEQUENCE {
ifExtnsRcvAddrIfIndex
INTEGER,
ifExtnsRcvAddress
PhysAddress,
ifExtnsRcvAddrStatus
INTEGER
}
ifExtnsRcvAddrIfIndex OBJECT-TYPE
SYNTAX INTEGER
ACCESS read-only
STATUS mandatory
DESCRIPTION
"The value of ifIndex, defined in [4,6], of an
interface which recognizes this entry's
address."
::= { ifExtnsRcvAddrEntry 1 }
ifExtnsRcvAddress OBJECT-TYPE
SYNTAX PhysAddress
ACCESS read-only
STATUS mandatory
DESCRIPTION
"An address for which the system will accept
packets/frames on this entry's interface."
::= { ifExtnsRcvAddrEntry 2 }
ifExtnsRcvAddrStatus OBJECT-TYPE
SYNTAX INTEGER {
other(1),
invalid(2),
volatile(3),
nonVolatile(4)
}
ACCESS read-write
STATUS mandatory
DESCRIPTION
"This object has the value nonVolatile(4)
for those entries in the table which are
valid and will not be deleted by the next
restart of the managed system. Entries
having the value volatile(3) are valid
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and exist, but have not been saved, so
that will not exist after the next
restart of the managed system. Entries
having the value other(1) are valid and
exist but are not classified as to whether
they will continue to exist after the next
restart. Entries having the value invalid(2)
are invalid and do not represent an address
for which an interface accepts frames.
Setting an object instance to one of
the values other(1), volatile(3), or
nonVolatile(4) causes the corresponding
entry to exist or continue to exist, and
to take on the respective status as regards
the next restart of the managed system.
Setting an object instance to the value
invalid(2) causes the corresponding entry
to become invalid or cease to exist.
It is an implementation-specific matter
as to whether the agent removes an
invalidated entry from the table.
Accordingly, management stations must be
prepared to receive tabular information
from agents that corresponds to entries not
currently in use. Proper interpretation of
such entries requires examination of the
relevant ifExtnsRcvAddrStatus object
instance."
DEFVAL { volatile }
::= { ifExtnsRcvAddrEntry 3 }
END
6. Acknowledgements
Most of the MIB objects defined in this document were originally
proposed as a part of a MIB for management of IEEE 802.5 Token Ring
networks, as prepared by:
Eric B. Decker, cisco Systems, Inc., and
Richard Fox, Synoptics Inc.
In addition, the comments of the following individuals are
acknowledged:
James R. Davin, MIT-LCS
Stan Froyd, ACC
Frank Kastenholz, Racal Interlan
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RFC 1229 Interface MIB Extensions May 1991
Dave Perkins, 3Com
Marshall T. Rose, PSI
Bob Stewart, Xyplex
David Waitzman, BBN
Wengyik Yeong, PSI
7. References
[1] Cerf, V., "IAB Recommendations for the Development of Internet
Network Management Standards", RFC 1052, NRI, April 1988.
[2] Cerf, V., "Report of the Second Ad Hoc Network Management Review
Group", RFC 1109, NRI, August 1989.
[3] Rose M., and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based internets", RFC 1155,
Performance Systems International, Hughes LAN Systems, May 1990.
[4] McCloghrie K., and M. Rose, "Management Information Base for
Network Management of TCP/IP-based internets", RFC 1156, Hughes
LAN Systems, Performance Systems International, May 1990.
[5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple
Network Management Protocol", RFC 1157, SNMP Research,
Performance Systems International, Performance Systems
International, MIT Laboratory for Computer Science, May 1990.
[6] Rose M., Editor, "Management Information Base for Network
Management of TCP/IP-based internets: MIB-II", RFC 1213,
Performance Systems International, March 1991.
[7] Information processing systems - Open Systems Interconnection -
Specification of Abstract Syntax Notation One (ASN.1),
International Organization for Standardization, International
Standard 8824, December 1987.
[8] Information processing systems - Open Systems Interconnection -
Specification of Basic Encoding Rules for Abstract Notation One
(ASN.1), International Organization for Standardization,
International Standard 8825, December 1987.
[9] Rose, M., and K. McCloghrie, Editors, "Concise MIB Definitions",
RFC 1212, Performance Systems International, Hughes LAN Systems,
March 1991.
8. Security Considerations
Security issues are not discussed in this memo.
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RFC 1229 Interface MIB Extensions May 1991
9. Author's Address
Keith McCloghrie
Hughes LAN Systems, Inc.
1225 Charleston Road
Mountain View, CA 94043
Phone: (415) 966-7934
EMail: kzm@hls.com
SNMP Working Group [Page 16]