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Network Working Group Keith McCloghrie
Internet Draft Cisco Systems
Obsoletes: 1573, 2233 Frank Kastenholz
Argon Networks
11 January 2000
The Interfaces Group MIB
draft-ietf-ifmib-ifmib2-02.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026 [RFC2026].
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Distribution of this document is unlimited. Please send comments
to the Interfaces MIB Working Group at if-mib@vnd.tek.com.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Internet Draft Interfaces Group MIB January 2000
1. Introduction
This memo defines a portion of the Management Information Base
(MIB) for use with network management protocols in the Internet
community. In particular, it describes managed objects used for
managing Network Interfaces. This memo discusses the 'interfaces'
group of MIB-II [17], especially the experience gained from the
definition of numerous media-specific MIB modules for use in
conjunction with the 'interfaces' group for managing various sub-
layers beneath the internetwork-layer. It specifies
clarifications to, and extensions of, the architectural issues
within the MIB-II model of the 'interfaces' group. This memo
obsoletes RFCs 1573 and 2233, the previous versions of the
Interfaces Group MIB.
The key words "MUST" and "MUST NOT" in this document are to be
interpreted as described in RFC 2119 [16].
2. The SNMP Network Management Framework
The SNMP Management Framework presently consists of five major
components:
o An overall architecture, described in RFC 2571 [1].
o Mechanisms for describing and naming objects and events for
the purpose of management. The first version of this
Structure of Management Information (SMI) is called SMIv1 and
described in STD 16/RFC 1155 [2], STD 16/RFC 1212 [3] and RFC
1215 [4]. The second version, called SMIv2, is described in
STD 58, which consists of RFC 2578 [5], RFC 2579 [6] and RFC
2580 [7].
o Message protocols for transferring management information.
The first version of the SNMP message protocol is called
SNMPv1 and described in STD 15/RFC 1157 [8]. A second
version of the SNMP message protocol, which is not an
Internet standards track protocol, is called SNMPv2c and
described in RFC 1901 [9] and RFC 1906 [10]. The third
version of the message protocol is called SNMPv3 and
described in RFC 1906 [10], RFC 2572 [11] and RFC 2574 [12].
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o Protocol operations for accessing management information.
The first set of protocol operations and associated PDU
formats is described in STD 15/RFC 1157 [8]. A second set of
protocol operations and associated PDU formats is described
in RFC 1905 [13].
o A set of fundamental applications described in RFC 2573 [14]
and the view-based access control mechanism described in RFC
2575 [15].
A more detailed introduction to the current SNMP Management
Framework can be found in RFC 2570 [22].
Managed objects are accessed via a virtual information store,
termed the Management Information Base or MIB. Objects in the MIB
are defined using the mechanisms defined in the SMI.
This memo specifies a MIB module that is compliant to the SMIv2.
A MIB conforming to the SMIv1 can be produced through the
appropriate translations. The resulting translated MIB must be
semantically equivalent, except where objects or events are
omitted because no translation is possible (e.g., use of
Counter64). Some machine readable information in SMIv2 will be
converted into textual descriptions in SMIv1 during the
translation process. However, this loss of machine readable
information is not considered to change the semantics of the MIB.
3. Experience with the Interfaces Group
One of the strengths of internetwork-layer protocols such as IP
[18] is that they are designed to run over any network interface.
In achieving this, IP considers any and all protocols it runs over
as a single "network interface" layer. A similar view is taken by
other internetwork-layer protocols. This concept is represented
in MIB-II by the 'interfaces' group which defines a generic set of
managed objects such that any network interface can be managed in
an interface-independent manner through these managed objects.
The 'interfaces' group provides the means for additional managed
objects specific to particular types of network interface (e.g., a
specific medium such as Ethernet) to be defined as extensions to
the 'interfaces' group for media-specific management. Since the
standardization of MIB-II, many such media-specific MIB modules
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have been defined.
Experience in defining these media-specific MIB modules has shown
that the model defined by MIB-II is too simplistic and/or static
for some types of media-specific management. As a result, some of
these media-specific MIB modules assume an evolution or loosening
of the model. This memo documents and standardizes that evolution
of the model and fills in the gaps caused by that evolution. This
memo also incorporates the interfaces group extensions documented
in RFC 1229 [19].
3.1. Clarifications/Revisions
There are several areas for which experience has indicated that
clarification, revision, or extension of the model would be
helpful. The following sections discuss the changes in the
interfaces group adopted by this memo in each of these areas.
In some sections, one or more paragraphs contain discussion of
rejected alternatives to the model adopted in this memo. Readers
not familiar with the MIB-II model and not interested in the
rationale behind the new model may want to skip these paragraphs.
3.1.1. Interface Sub-Layers
Experience in defining media-specific management information has
shown the need to distinguish between the multiple sub-layers
beneath the internetwork-layer. In addition, there is a need to
manage these sub-layers in devices (e.g., MAC-layer bridges) which
are unaware of which, if any, internetwork protocols run over
these sub-layers. As such, a model of having a single conceptual
row in the interfaces table (MIB-II's ifTable) represent a whole
interface underneath the internetwork-layer, and having a single
associated media-specific MIB module (referenced via the ifType
object) is too simplistic. A further problem arises with the
value of the ifType object which has enumerated values for each
type of interface.
Consider, for example, an interface with PPP running over an HDLC
link which uses a RS232-like connector. Each of these sub-layers
has its own media-specific MIB module. If all of this is
represented by a single conceptual row in the ifTable, then an
enumerated value for ifType is needed for that specific
combination which maps to the specific combination of media-
specific MIBs. Furthermore, such a model still lacks a method to
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describe the relationship of all the sub-layers of the MIB stack.
An associated problem is that of upward and downward multiplexing
of the sub-layers. An example of upward multiplexing is MLP
(Multi-Link-Procedure) which provides load-sharing over several
serial lines by appearing as a single point-to-point link to the
sub-layer(s) above. An example of downward multiplexing would be
several instances of PPP, each framed within a separate X.25
virtual circuit, all of which run over one fractional T1 channel,
concurrently with other uses of the T1 link. The MIB structure
must allow these sorts of relationships to be described.
Several solutions for representing multiple sub-layers were
rejected. One was to retain the concept of one conceptual row for
all the sub-layers of an interface and have each media-specific
MIB module identify its "superior" and "subordinate" sub-layers
through OBJECT IDENTIFIER "pointers". This scheme would have
several drawbacks: the superior/subordinate pointers would be
contained in the media-specific MIB modules; thus, a manager could
not learn the structure of an interface without inspecting
multiple pointers in different MIB modules; this would be overly
complex and only possible if the manager had knowledge of all the
relevant media-specific MIB modules; MIB modules would all need to
be retrofitted with these new "pointers"; this scheme would not
adequately address the problem of upward and downward
multiplexing; and finally, enumerated values of ifType would be
needed for each combination of sub-layers. Another rejected
solution also retained the concept of one conceptual row for all
the sub-layers of an interface but had a new separate MIB table to
identify the "superior" and "subordinate" sub-layers and to
contain OBJECT IDENTIFIER "pointers" to the media-specific MIB
module for each sub-layer. Effectively, one conceptual row in the
ifTable would represent each combination of sub-layers between the
internetwork-layer and the wire. While this scheme has fewer
drawbacks, it still would not support downward multiplexing, such
as PPP over MLP: observe that MLP makes two (or more) serial lines
appear to the layers above as a single physical interface, and
thus PPP over MLP should appear to the internetwork-layer as a
single interface; in contrast, this scheme would result in two (or
more) conceptual rows in the ifTable, both of which the
internetwork-layer would run over. This scheme would also require
enumerated values of ifType for each combination of sub-layers.
The solution adopted by this memo is to have an individual
conceptual row in the ifTable to represent each sub-layer, and
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have a new separate MIB table (the ifStackTable, see section 6
below) to identify the "superior" and "subordinate" sub-layers
through INTEGER "pointers" to the appropriate conceptual rows in
the ifTable. This solution supports both upward and downward
multiplexing, allows the IANAifType to Media-Specific MIB mapping
to identify the media-specific MIB module for that sub-layer, such
that the new table need only be referenced to obtain information
about layering, and it only requires enumerated values of ifType
for each sub-layer, not for combinations of them. However, it
does require that the descriptions of some objects in the ifTable
(specifically, ifType, ifPhysAddress, ifInUcastPkts, and
ifOutUcastPkts) be generalized so as to apply to any sub-layer
(rather than only to a sub-layer immediately beneath the network
layer as previously), plus some (specifically, ifSpeed) which need
to have appropriate values identified for use when a generalized
definition does not apply to a particular sub-layer.
In addition, this adopted solution makes no requirement that a
device, in which a sub-layer is instrumented by a conceptual row
of the ifTable, be aware of whether an internetwork protocol runs
on top of (i.e., at some layer above) that sub-layer. In fact,
the counters of packets received on an interface are defined as
counting the number "delivered to a higher-layer protocol". This
meaning of "higher-layer" includes:
(1) Delivery to a forwarding module which accepts
packets/frames/octets and forwards them on at the same
protocol layer. For example, for the purposes of this
definition, the forwarding module of a MAC-layer bridge is
considered as a "higher-layer" to the MAC-layer of each
port on the bridge.
(2) Delivery to a higher sub-layer within a interface stack.
For example, for the purposes of this definition, if a PPP
module operated directly over a serial interface, the PPP
module would be considered the higher sub-layer to the
serial interface.
(3) Delivery to a higher protocol layer which does not do
packet forwarding for sub-layers that are "at the top of"
the interface stack. For example, for the purposes of this
definition, the local IP module would be considered the
higher layer to a SLIP serial interface.
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Similarly, for output, the counters of packets transmitted out an
interface are defined as counting the number "that higher-level
protocols requested to be transmitted". This meaning of "higher-
layer" includes:
(1) A forwarding module, at the same protocol layer, which
transmits packets/frames/octets that were received on an
different interface. For example, for the purposes of this
definition, the forwarding module of a MAC-layer bridge is
considered as a "higher-layer" to the MAC-layer of each
port on the bridge.
(2) The next higher sub-layer within an interface stack. For
example, for the purposes of this definition, if a PPP
module operated directly over a serial interface, the PPP
module would be a "higher layer" to the serial interface.
(3) For sub-layers that are "at the top of" the interface
stack, a higher element in the network protocol stack. For
example, for the purposes of this definition, the local IP
module would be considered the higher layer to an Ethernet
interface.
3.1.2. Guidance on Defining Sub-layers
The designer of a media-specific MIB must decide whether to divide
the interface into sub-layers or not, and if so, how to make the
divisions. The following guidance is offered to assist the media-
specific MIB designer in these decisions.
In general, the number of entries in the ifTable should be kept to
the minimum required for network management. In particular, a
group of related interfaces should be treated as a single
interface with one entry in the ifTable providing that:
(1) None of the group of interfaces performs multiplexing for
any other interface in the agent,
(2) There is a meaningful and useful way for all of the
ifTable's information (e.g., the counters, and the status
variables), and all of the ifTable's capabilities (e.g.,
write access to ifAdminStatus), to apply to the group of
interfaces as a whole.
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Under these circumstances, there should be one entry in the
ifTable for such a group of interfaces, and any internal structure
which needs to be represented to network management should be
captured in a MIB module specific to the particular type of
interface.
Note that application of bullet 2 above to the ifTable's ifType
object requires that there is a meaningful media-specific MIB and
a meaningful ifType value which apply to the group of interfaces
as a whole. For example, it is not appropriate to treat an HDLC
sub-layer and an RS-232 sub-layer as a single ifTable entry when
the media-specific MIBs and the ifType values for HDLC and RS-232
are separate (rather than combined).
Subject to the above, it is appropriate to assign an ifIndex value
to any interface that can occur in an interface stack (in the
ifStackTable) where the bottom of the stack is a physical
interface (ifConnectorPresent has the value 'true') and there is a
layer-3 or other application that "points down" to the top of this
stack. An example of an application that points down to the top
of the stack is the Character MIB [21].
Note that the sub-layers of an interface on one device will
sometimes be different from the sub-layers of the interconnected
interface of another device; for example, for a frame-relay DTE
interface connected a frameRelayService interface, the inter-
connected DTE and DCE interfaces have different ifType values and
media-specific MIBs.
These guidelines are just that, guidelines. The designer of a
media-specific MIB is free to lay out the MIB in whatever SMI
conformant manner is desired. However, in doing so, the media-
specific MIB MUST completely specify the sub-layering model used
for the MIB, and provide the assumptions, reasoning, and rationale
used to develop that model.
3.1.3. Virtual Circuits
Several of the sub-layers for which media-specific MIB modules
have been defined are connection oriented (e.g., Frame Relay,
X.25). Experience has shown that each effort to define such a MIB
module revisits the question of whether separate conceptual rows
in the ifTable are needed for each virtual circuit. Most, if not
all, of these efforts to date have decided to have all virtual
circuits reference a single conceptual row in the ifTable.
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This memo strongly recommends that connection-oriented sub-layers
do not have a conceptual row in the ifTable for each virtual
circuit. This avoids the proliferation of conceptual rows,
especially those which have considerable redundant information.
(Note, as a comparison, that connection-less sub-layers do not
have conceptual rows for each remote address.) There may,
however, be circumstances under which it is appropriate for a
virtual circuit of a connection-oriented sub-layer to have its own
conceptual row in the ifTable; an example of this might be PPP
over an X.25 virtual circuit. The MIB in section 6 of this memo
supports such circumstances.
If a media-specific MIB wishes to assign an entry in the ifTable
to each virtual circuit, the MIB designer must present the
rationale for this decision in the media-specific MIB's
specification.
3.1.4. Bit, Character, and Fixed-Length Interfaces
RS-232 is an example of a character-oriented sub-layer over which
(e.g., through use of PPP) IP datagrams can be sent. Due to the
packet-based nature of many of the objects in the ifTable,
experience has shown that it is not appropriate to have a
character-oriented sub-layer represented by a whole conceptual row
in the ifTable.
Experience has also shown that it is sometimes desirable to have
some management information for bit-oriented interfaces, which are
similarly difficult to represent by a whole conceptual row in the
ifTable. For example, to manage the channels of a DS1 circuit,
where only some of the channels are carrying packet-based data.
A further complication is that some subnetwork technologies
transmit data in fixed length transmission units. One example of
such a technology is cell relay, and in particular Asynchronous
Transfer Mode (ATM), which transmits data in fixed-length cells.
Representing such a interface as a packet-based interface produces
redundant objects if the relationship between the number of
packets and the number of octets in either direction is fixed by
the size of the transmission unit (e.g., the size of a cell).
About half the objects in the ifTable are applicable to every type
of interface: packet-oriented, character-oriented, and bit-
oriented. Of the other half, two are applicable to both
character-oriented and packet-oriented interfaces, and the rest
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are applicable only to packet-oriented interfaces. Thus, while it
is desirable for consistency to be able to represent any/all types
of interfaces in the ifTable, it is not possible to implement the
full ifTable for bit- and character-oriented sub-layers.
A rejected solution to this problem would be to split the ifTable
into two (or more) new MIB tables, one of which would contain
objects that are relevant only to packet-oriented interfaces
(e.g., PPP), and another that may be used by all interfaces. This
is highly undesirable since it would require changes in every
agent implementing the ifTable (i.e., just about every existing
SNMP agent).
The solution adopted in this memo builds upon the fact that
compliance statements in SNMPv2 (in contrast to SNMPv1) refer to
object groups, where object groups are explicitly defined by
listing the objects they contain. Thus, in SNMPv2, multiple
compliance statements can be specified, one for all interfaces and
additional ones for specific types of interfaces. The separate
compliance statements can be based on separate object groups,
where the object group for all interfaces can contain only those
objects from the ifTable which are appropriate for every type of
interfaces. Using this solution, every sub-layer can have its own
conceptual row in the ifTable.
Thus, section 6 of this memo contains definitions of the objects
of the existing 'interfaces' group of MIB-II, in a manner which is
both SNMPv2-compliant and semantically-equivalent to the existing
MIB-II definitions. With equivalent semantics, and with the BER
("on the wire") encodings unchanged, these definitions retain the
same OBJECT IDENTIFIER values as assigned by MIB-II. Thus, in
general, no rewrite of existing agents which conform to MIB-II and
the ifExtensions MIB is required.
In addition, this memo defines several object groups for the
purposes of defining which objects apply to which types of
interface:
(1) the ifGeneralInformationGroup. This group contains those
objects applicable to all types of network interfaces,
including bit-oriented interfaces.
(2) the ifPacketGroup. This group contains those objects
applicable to packet-oriented network interfaces.
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(3) the ifFixedLengthGroup. This group contains the objects
applicable not only to character-oriented interfaces, such
as RS-232, but also to those subnetwork technologies, such
as cell-relay/ATM, which transmit data in fixed length
transmission units. As well as the octet counters, there
are also a few other counters (e.g., the error counters)
which are useful for this type of interface, but are
currently defined as being packet-oriented. To accommodate
this, the definitions of these counters are generalized to
apply to character-oriented interfaces and fixed-length-
transmission interfaces.
It should be noted that the octet counters in the ifTable
aggregate octet counts for unicast and non-unicast packets into a
single octet counter per direction (received/transmitted). Thus,
with the above definition of fixed-length-transmission interfaces,
where such interfaces which support non-unicast packets, separate
counts of unicast and multicast/broadcast transmissions can only
be maintained in a media-specific MIB module.
3.1.5. Interface Numbering
MIB-II defines an object, ifNumber, whose value represents:
"The number of network interfaces (regardless of their
current state) present on this system."
Each interface is identified by a unique value of the ifIndex
object, and the description of ifIndex constrains its value as
follows:
"Its value ranges between 1 and the value of ifNumber. The
value for each interface must remain constant at least from
one re-initialization of the entity's network management
system to the next re-initialization."
This constancy requirement on the value of ifIndex for a
particular interface is vital for efficient management. However,
an increasing number of devices allow for the dynamic
addition/removal of network interfaces. One example of this is a
dynamic ability to configure the use of SLIP/PPP over a character-
oriented port. For such dynamic additions/removals, the
combination of the constancy requirement and the restriction that
the value of ifIndex is less than ifNumber is problematic.
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Redefining ifNumber to be the largest value of ifIndex was
rejected since it would not help. Such a re-definition would
require ifNumber to be deprecated and the utility of the redefined
object would be questionable. Alternatively, ifNumber could be
deprecated and not replaced. However, the deprecation of ifNumber
would require a change to that portion of ifIndex's definition
which refers to ifNumber. So, since the definition of ifIndex
must be changed anyway in order to solve the problem, changes to
ifNumber do not benefit the solution.
The solution adopted in this memo is just to delete the
requirement that the value of ifIndex must be less than the value
of ifNumber, and to retain ifNumber with its current definition.
This is a minor change in the semantics of ifIndex; however, all
existing agent implementations conform to this new definition, and
in the interests of not requiring changes to existing agent
implementations and to the many existing media-specific MIBs, this
memo assumes that this change does not require ifIndex to be
deprecated. Experience indicates that this assumption does
"break" a few management applications, but this is considered
preferable to breaking all agent implementations.
This solution also results in the possibility of "holes" in the
ifTable, i.e., the ifIndex values of conceptual rows in the
ifTable are not necessarily contiguous, but SNMP's GetNext (and
SNMPv2's GetBulk) operation easily deals with such holes. The
value of ifNumber still represents the number of conceptual rows,
which increases/decreases as new interfaces are dynamically
added/removed.
The requirement for constancy (between re-initializations) of an
interface's ifIndex value is met by requiring that after an
interface is dynamically removed, its ifIndex value is not re-used
by a *different* dynamically added interface until after the
following re-initialization of the network management system.
This avoids the need for assignment (in advance) of ifIndex values
for all possible interfaces that might be added dynamically. The
exact meaning of a "different" interface is hard to define, and
there will be gray areas. Any firm definition in this document
would likely turn out to be inadequate. Instead, implementors
must choose what it means in their particular situation, subject
to the following rules:
(1) a previously-unused value of ifIndex must be assigned to a
dynamically added interface if an agent has no knowledge of
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whether the interface is the "same" or "different" to a
previously incarnated interface.
(2) a management station, not noticing that an interface has
gone away and another has come into existence, must not be
confused when calculating the difference between the
counter values retrieved on successive polls for a
particular ifIndex value.
When the new interface is the same as an old interface, but a
discontinuity in the value of the interface's counters cannot be
avoided, the ifTable has (until now) required that a new ifIndex
value be assigned to the returning interface. That is, either all
counter values have had to be retained during the absence of an
interface in order to use the same ifIndex value on that
interface's return, or else a new ifIndex value has had to be
assigned to the returning interface. Both alternatives have
proved to be burdensome to some implementations:
(1) maintaining the counter values may not be possible (e.g.,
if they are maintained on removable hardware),
(2) using a new ifIndex value presents extra work for
management applications. While the potential need for such
extra work is unavoidable on agent re-initializations, it
is desirable to avoid it between re-initializations.
To address this, a new object, ifCounterDiscontinuityTime, has
been defined to record the time of the last discontinuity in an
interface's counters. By monitoring the value of this new object,
a management application can now detect counter discontinuities
without the ifIndex value of the interface being changed. Thus,
an agent which implements this new object should, when a new
interface is the same as an old interface, retain that interface's
ifIndex value and update if necessary the interface's value of
ifCounterDiscontinuityTime. With this new object, a management
application must, when calculating differences between counter
values retrieved on successive polls, discard any calculated
difference for which the value of ifCounterDiscontinuityTime is
different for the two polls. (Note that this test must be
performed in addition to the normal checking of sysUpTime to
detect an agent re-initialization.) Since such discards are a
waste of network management processing and bandwidth, an agent
should not update the value of ifCounterDiscontinuityTime unless
absolutely necessary.
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While defining this new object is a change in the semantics of the
ifTable counter objects, it is impractical to deprecate and
redefine all these counters because of their wide deployment and
importance. Also, a survey of implementations indicates that many
agents and management applications do not correctly implement this
aspect of the current semantics (because of the burdensome issues
mentioned above), such that the practical implications of such a
change is small. Thus, this breach of the SMI's rules is
considered to be acceptable.
Note, however, that the addition of ifCounterDiscontinuityTime
does not change the fact that:
it is necessary at certain times for the assignment of
ifIndex values to change on a re-initialization of the agent
(such as a reboot).
The possibility of ifIndex value re-assignment must be accommodated by a
management application whenever the value of sysUpTime is reset to zero.
Note also that some agents support multiple "naming scopes", e.g., for
an SNMPv1 agent, multiple values of the SNMPv1 community string. For
such an agent (e.g., a CNM agent which supports a different subset of
interfaces for different customers), there is no required relationship
between the ifIndex values which identify interfaces in one naming scope
and those which identify interfaces in another naming scope. It is the
agent's choice as to whether the same or different ifIndex values
identify the same or different interfaces in different naming scopes.
Because of the restriction of the value of ifIndex to be less than
ifNumber, interfaces have been numbered with small integer values. This
has led to the ability by humans to use the ifIndex values as (somewhat)
user-friendly names for network interfaces (e.g., "interface number 3").
With the relaxation of the restriction on the value of ifIndex, there is
now the possibility that ifIndex values could be assigned as very large
numbers (e.g., memory addresses). Such numbers would be much less user-
friendly. Therefore, this memo recommends that ifIndex values still be
assigned as (relatively) small integer values starting at 1, even though
the values in use at any one time are not necessarily contiguous. (Note
that this makes remembering which values have been assigned easy for
agents which dynamically add new interfaces)
A new problem is introduced by representing each sub-layer as an ifTable
entry. Previously, there usually was a simple, direct, mapping of
interfaces to the physical ports on systems. This mapping would be
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based on the ifIndex value. However, by having an ifTable entry for
each interface sub-layer, mapping from interfaces to physical ports
becomes increasingly problematic.
To address this issue, a new object, ifName, is added to the MIB. This
object contains the device's local name (e.g., the name used at the
device's local console) for the interface of which the relevant entry in
the ifTable is a component. For example, consider a router having an
interface composed of PPP running over an RS-232 port. If the router
uses the name "wan1" for the (combined) interface, then the ifName
objects for the corresponding PPP and RS-232 entries in the ifTable
would both have the value "wan1". On the other hand, if the router uses
the name "wan1.1" for the PPP interface and "wan1.2" for the RS-232
port, then the ifName objects for the corresponding PPP and RS-232
entries in the ifTable would have the values "wan1.1" and "wan1.2",
respectively. As an another example, consider an agent which responds
to SNMP queries concerning an interface on some other (proxied) device:
if such a proxied device associates a particular identifier with an
interface, then it is appropriate to use this identifier as the value of
the interface's ifName, since the local console in this case is that of
the proxied device.
In contrast, the existing ifDescr object is intended to contain a
description of an interface, whereas another new object, ifAlias,
provides a location in which a network management application can store
a non-volatile interface-naming value of its own choice. The ifAlias
object allows a network manager to give one or more interfaces their own
unique names, irrespective of any interface-stack relationship.
Further, the ifAlias name is non-volatile, and thus an interface must
retain its assigned ifAlias value across reboots, even if an agent
chooses a new ifIndex value for the interface.
3.1.6. Counter Size
As the speed of network media increase, the minimum time in which a 32
bit counter will wrap decreases. For example, a 10Mbs stream of back-
to-back, full-size packets causes ifInOctets to wrap in just over 57
minutes; at 100Mbs, the minimum wrap time is 5.7 minutes, and at 1Gbs,
the minimum is 34 seconds. Requiring that interfaces be polled
frequently enough not to miss a counter wrap is increasingly
problematic.
A rejected solution to this problem was to scale the counters; for
example, ifInOctets could be changed to count received octets in, say,
1024 byte blocks. While it would provide acceptable functionality at
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high rates of the counted-events, at low rates it suffers. If there is
little traffic on an interface, there might be a significant interval
before enough of the counted-events occur to cause the scaled counter to
be incremented. Traffic would then appear to be very bursty, leading to
incorrect conclusions of the network's performance.
Instead, this memo adopts expanded, 64 bit, counters. These counters
are provided in new "high capacity" groups. The old, 32-bit, counters
have not been deprecated. The 64-bit counters are to be used only when
the 32-bit counters do not provide enough capacity; that is, when the 32
bit counters could wrap too fast.
For interfaces that operate at 20,000,000 (20 million) bits per second
or less, 32-bit byte and packet counters MUST be supported. For
interfaces that operate faster than 20,000,000 bits/second, and slower
than 650,000,000 bits/second, 32-bit packet counters MUST be supported
and 64-bit octet counters MUST be supported. For interfaces that
operate at 650,000,000 bits/second or faster, 64-bit packet counters AND
64-bit octet counters MUST be supported.
These speed thresholds were chosen as reasonable compromises based on
the following:
(1) The cost of maintaining 64-bit counters is relatively high, so
minimizing the number of agents which must support them is
desirable. Common interfaces (such as 10Mbs Ethernet) should not
require them.
(2) 64-bit counters are a new feature, introduced in SNMPv2. It is
reasonable to expect that support for them will be spotty for the
immediate future. Thus, we wish to limit them to as few systems
as possible. This, in effect, means that 64-bit counters should
be limited to higher speed interfaces. Ethernet (10,000,000 bps)
and Token Ring (16,000,000 bps) are fairly wide-spread so it
seems reasonable to not require 64-bit counters for these
interfaces.
(3) The 32-bit octet counters will wrap in the following times, for
the following interfaces (when transmitting maximum-sized packets
back-to-back):
- 10Mbs Ethernet: 57 minutes,
- 16Mbs Token Ring: 36 minutes,
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- a US T3 line (45 megabits): 12 minutes,
- FDDI: 5.7 minutes
(4) The 32-bit packet counters wrap in about 57 minutes when 64-byte
packets are transmitted back-to-back on a 650,000,000 bit/second
link.
As an aside, a 1-terabit/second (1,000 Gbs) link will cause a 64 bit
octet counter to wrap in just under 5 years. Conversely, an 81,000,000
terabit/second link is required to cause a 64-bit counter to wrap in 30
minutes. We believe that, while technology rapidly marches forward,
this link speed will not be achieved for at least several years, leaving
sufficient time to evaluate the introduction of 96 bit counters.
When 64-bit counters are in use, the 32-bit counters MUST still be
available. They will report the low 32-bits of the associated 64-bit
count (e.g., ifInOctets will report the least significant 32 bits of
ifHCInOctets). This enhances inter-operability with existing
implementations at a very minimal cost to agents.
The new "high capacity" groups are:
(1) the ifHCFixedLengthGroup for character-oriented/fixed-length
interfaces, and the ifHCPacketGroup for packet-based interfaces;
both of these groups include 64 bit counters for octets, and
(2) the ifVHCPacketGroup for packet-based interfaces; this group
includes 64 bit counters for octets and packets.
3.1.7. Interface Speed
Network speeds are increasing. The range of ifSpeed is limited to
reporting a maximum speed of (2**31)-1 bits/second, or approximately
2.2Gbs. SONET defines an OC-48 interface, which is defined at operating
at 48 times 51 Mbs, which is a speed in excess of 2.4Gbs. Thus, ifSpeed
is insufficient for the future, and this memo defines an additional
object: ifHighSpeed.
The ifHighSpeed object reports the speed of the interface in 1,000,000
(1 million) bits/second units. Thus, the true speed of the interface
will be the value reported by this object, plus or minus 500,000
bits/second.
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Other alternatives considered (but rejected) were:
(1) Making the interface speed a 64-bit gauge. This was rejected
since the current SMI does not allow such a syntax.
Furthermore, even if 64-bit gauges were available, their use would
require additional complexity in agents due to an increased
requirement for 64-bit operations.
(2) We also considered making "high-32 bit" and "low-32-bit" objects
which, when combined, would be a 64-bit value. This simply
seemed overly complex for what we are trying to do.
Furthermore, a full 64-bits of precision does not seem necessary.
The value of ifHighSpeed will be the only report of interface speed
for interfaces that are faster than 4,294,967,295 bits per second.
At this speed, the granularity of ifHighSpeed will be 1,000,000
bits per second, thus the error will be 1/4294, or about 0.02%.
This seems reasonable.
(3) Adding a "scale" object, which would define the units which
ifSpeed's value is.
This would require two additional objects; one for the scaling
object, and one to replace the current ifSpeed. This later object
is required since the semantics of ifSpeed would be significantly
altered, and manager stations which do not understand the new
semantics would be confused.
3.1.8. Multicast/Broadcast Counters
In MIB-II, the ifTable counters for multicast and broadcast packets are
combined as counters of non-unicast packets. In contrast, the
ifExtensions MIB [19] defined one set of counters for multicast, and a
separate set for broadcast packets. With the separate counters, the
original combined counters become redundant. To avoid this redundancy,
the non-unicast counters are deprecated.
For the output broadcast and multicast counters defined in RFC 1229,
their definitions varied slightly from the packet counters in the
ifTable, in that they did not count errors/discarded packets. Thus,
this memo defines new objects with better aligned definitions. Counters
with 64 bits of range are also needed, as explained above.
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3.1.9. Trap Enable
In the multi-layer interface model, each sub-layer for which there is an
entry in the ifTable can generate linkUp/linkDown Traps. Since
interface state changes would tend to propagate through the interface
(from top to bottom, or bottom to top), it is likely that several traps
would be generated for each linkUp/linkDown occurrence.
It is desirable to provide a mechanism for manager stations to control
the generation of these traps. To this end, the ifLinkUpDownTrapEnable
object has been added. This object allows managers to limit generation
of traps to just the sub-layers of interest.
The default setting should limit the number of traps generated to one
per interface per linkUp/linkDown event. Furthermore, it seems that the
state changes of most interest to network managers occur at the lowest
level of an interface stack. Therefore we specify that by default, only
the lowest sub-layer of the interface generate traps.
3.1.10. Addition of New ifType values
Over time, there is the need to add new ifType enumerated values for new
interface types. If the syntax of ifType were defined in the MIB in
section 6, then a new version of this MIB would have to be re-issued in
order to define new values. In the past, re-issuing of a MIB has
occurred only after several years.
Therefore, the syntax of ifType is changed to be a textual convention,
such that the enumerated integer values are now defined in the textual
convention, IANAifType, defined in a different document. This allows
additional values to be documented without having to re-issue a new
version of this document. The Internet Assigned Number Authority (IANA)
is responsible for the assignment of all Internet numbers, including
various SNMP-related numbers, and specifically, new ifType values.
3.1.11. InterfaceIndex Textual Convention
A new textual convention, InterfaceIndex, has been defined. This
textual convention "contains" all of the semantics of the ifIndex
object. This allows other MIB modules to easily import the semantics of
ifIndex.
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3.1.12. New states for IfOperStatus
Three new states have been added to ifOperStatus: 'dormant',
'notPresent', and 'lowerLayerDown'.
The dormant state indicates that the relevant interface is not actually
in a condition to pass packets (i.e., it is not 'up') but is in a
"pending" state, waiting for some external event. For "on-demand"
interfaces, this new state identifies the situation where the interface
is waiting for events to place it in the up state. Examples of such
events might be:
(1) having packets to transmit before establishing a connection to a
remote system;
(2) having a remote system establish a connection to the interface
(e.g. dialing up to a slip-server).
The notPresent state is a refinement on the down state which indicates
that the relevant interface is down specifically because some component
(typically, a hardware component) is not present in the managed system.
Examples of use of the notPresent state are:
(1) to allow an interface's conceptual row including its counter
values to be retained across a "hot swap" of a card/module,
and/or
(2) to allow an interface's conceptual row to be created, and thereby
enable interfaces to be pre-configured prior to installation of
the hardware needed to make the interface operational.
Agents are not required to support interfaces in the notPresent state.
However, from a conceptual viewpoint, when a row in the ifTable is
created, it first enters the notPresent state and then subsequently
transitions into the down state; similarly, when a row in the ifTable is
deleted, it first enters the notPresent state and then subsequently the
object instances are deleted. For an agent with no support for
notPresent, both of these transitions (from the notPresent state to the
down state, and from the notPresent state to the instances being
removed) are immediate, i.e., the transition does not last long enough
to be recorded by ifOperStatus. Even for those agents which do support
interfaces in the notPresent state, the length of time and conditions
under which an interface stays in the notPresent state is
implementation-specific.
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The lowerLayerDown state is also a refinement on the down state. This
new state indicates that this interface runs "on top of" one or more
other interfaces (see ifStackTable) and that this interface is down
specifically because one or more of these lower-layer interfaces are
down.
3.1.13. IfAdminStatus and IfOperStatus
The down state of ifOperStatus now has two meanings, depending on the
value of ifAdminStatus.
(1) if ifAdminStatus is not down and ifOperStatus is down then a
fault condition is presumed to exist on the interface.
(2) if ifAdminStatus is down, then ifOperStatus will normally also be
down (or notPresent) i.e., there is not (necessarily) a fault
condition on the interface.
Note that when ifAdminStatus transitions to down, ifOperStatus will
normally also transition to down. In this situation, it is possible
that ifOperStatus's transition will not occur immediately, but rather
after a small time lag to complete certain operations before going
"down"; for example, it might need to finish transmitting a packet. If
a manager station finds that ifAdminStatus is down and ifOperStatus is
not down for a particular interface, the manager station should wait a
short while and check again. If the condition still exists, only then
should it raise an error indication. Naturally, it should also ensure
that ifLastChange has not changed during this interval.
Whenever an interface table entry is created (usually as a result of
system initialization), the relevant instance of ifAdminStatus is set to
down, and ifOperStatus will be down or notPresent.
An interface may be enabled in two ways: either as a result of explicit
management action (e.g. setting ifAdminStatus to up) or as a result of
the managed system's initialization process. When ifAdminStatus changes
to the up state, the related ifOperStatus should do one of the
following:
(1) Change to the up state if and only if the interface is able to
send and receive packets.
(2) Change to the lowerLayerDown state if and only if the interface
is prevented from entering the up state because of the state of
one or more of the interfaces beneath it in the interface stack.
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(3) Change to the dormant state if and only if the interface is found
to be operable, but the interface is waiting for other, external,
events to occur before it can transmit or receive packets.
Presumably when the expected events occur, the interface will
then change to the up state.
(4) Remain in the down state if an error or other fault condition is
detected on the interface.
(5) Change to the unknown state if, for some reason, the state of the
interface can not be ascertained.
(6) Change to the testing state if some test(s) must be performed on
the interface. Presumably after completion of the test, the
interface's state will change to up, dormant, or down, as
appropriate.
(7) Remain in the notPresent state if interface components are
missing.
3.1.14. IfOperStatus in an Interface Stack
When an interface is a part of an interface-stack, but is not the lowest
interface in the stack, then:
(1) ifOperStatus has the value 'up' if it is able to pass packets due
to one or more interfaces below it in the stack being 'up',
irrespective of whether other interfaces below it are 'down',
'dormant', 'notPresent', 'lowerLayerDown', 'unknown' or
'testing'.
(2) ifOperStatus may have the value 'up' or 'dormant' if one or more
interfaces below it in the stack are 'dormant', and all others
below it are either 'down', 'dormant', 'notPresent',
'lowerLayerDown', 'unknown' or 'testing'.
(3) ifOperStatus has the value 'lowerLayerDown' while all interfaces
below it in the stack are either 'down', 'notPresent',
'lowerLayerDown', or 'testing'.
3.1.15. Traps
The exact definition of when linkUp and linkDown traps are generated has
been changed to reflect the changes to ifAdminStatus and ifOperStatus.
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Operational experience indicates that management stations are most
concerned with an interface being in the down state and the fact that
this state may indicate a failure. Thus, it is most useful to
instrument transitions into/out of either the up state or the down
state.
Instrumenting transitions into or out of the up state was rejected since
it would have the drawback that a demand interface might have many
transitions between up and dormant, leading to many linkUp traps and no
linkDown traps. Furthermore, if a node's only interface is the demand
interface, then a transition to dormant would entail generation of a
linkDown trap, necessitating bringing the link to the up state (and a
linkUp trap)!!
On the other hand, instrumenting transitions into or out of the down
state (to/from all other states except notPresent) has the advantages:
(1) A transition into the down state (from a state other than
notPresent) will occur when an error is detected on an interface.
Error conditions are presumably of great interest to network
managers.
(2) Departing the down state (to a state other than the notPresent
state) generally indicates that the interface is going to either
up or dormant, both of which are considered "healthy" states.
Furthermore, it is believed that generating traps on transitions into or
out of the down state (except to/from the notPresent state) is generally
consistent with current usage and interpretation of these traps by
manager stations.
Transitions to/from the notPresent state are concerned with the
insertion and removal of hardware, and are outside the scope of these
traps.
Therefore, this memo defines that LinkUp and linkDown traps are
generated just after ifOperStatus leaves, or just before it enters, the
down state, respectively; except that LinkUp and linkDown traps are
never generated on transitions to/from the notPresent state. For the
purpose of deciding when these traps occur, the lowerLayerDown state and
the down state are considered to be equivalent, i.e., there is no trap
on transition from lowerLayerDown into down, and there is a trap on
transition from any other state except down (and notPresent) into
lowerLayerDown.
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Note that this definition allows a node with only one interface to
transmit a linkDown trap before that interface goes down. (Of course,
when the interface is going down because of a failure condition, the
linkDown trap probably cannot be successfully transmitted anyway.)
Some interfaces perform a link "training" function when trying to bring
the interface up. In the event that such an interface were defective,
then the training function would fail and the interface would remain
down, and the training function might be repeated at appropriate
intervals. If the interface, while performing this training function,
were considered to the in the testing state, then linkUp and linkDown
traps would be generated for each start and end of the training
function. This is not the intent of the linkUp and linkDown traps, and
therefore, while performing such a training function, the interface's
state should be represented as down.
An exception to the above generation of linkUp/linkDown traps on changes
in ifOperStatus, occurs when an interface is "flapping", i.e., when it
is rapidly oscillating between the up and down states. If traps were
generated for each such oscillation, the network and the network
management system would be flooded with unnecessary traps. In such a
situation, the agent should limit the rate at which it generates traps.
3.1.16. ifSpecific
The original definition of the OBJECT IDENTIFIER value of ifSpecific was
not sufficiently clear. As a result, different implementors used it
differently, and confusion resulted. Some implementations set the value
of ifSpecific to the OBJECT IDENTIFIER that defines the media-specific
MIB, i.e., the "foo" of:
foo OBJECT IDENTIFIER ::= { transmission xxx }
while others set it to be OBJECT IDENTIFIER of the specific table or
entry in the appropriate media-specific MIB (i.e., fooTable or
fooEntry), while still others set it be the OBJECT IDENTIFIER of the
index object of the table's row, including instance identifier, (i.e.,
fooIfIndex.ifIndex). A definition based on the latter would not be
sufficient unless it also allowed for media-specific MIBs which include
several tables, where each table has its own (different) indexing.
The only definition that can both be made explicit and can cover all the
useful situations is to have ifSpecific be the most general value for
the media-specific MIB module (the first example given above). This
effectively makes it redundant because it contains no more information
than is provided by ifType. Thus, ifSpecific has been deprecated.
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3.1.17. Creation/Deletion of Interfaces
While some interfaces, for example, most physical interfaces, cannot be
created via network management, other interfaces such as logical
interfaces sometimes can be. The ifTable contains only generic
information about an interface. Almost all 'create-able' interfaces
have other, media-specific, information through which configuration
parameters may be supplied prior to creating such an interface. Thus,
the ifTable does not itself support the creation or deletion of an
interface (specifically, it has no RowStatus [6] column). Rather, if a
particular interface type supports the dynamic creation and/or deletion
of an interface of that type, then that media-specific MIB should
include an appropriate RowStatus object (see the ATM LAN-Emulation
Client MIB [20] for an example of a MIB which does this). Typically,
when such a RowStatus object is created/deleted, then the conceptual row
in the ifTable appears/disappears as a by-product, and an ifIndex value
(chosen by the agent) is stored in an appropriate object in the media-
specific MIB.
3.1.18. All Values Must be Known
There are a number of situations where an agent does not know the value
of one or more objects for a particular interface. In all such
circumstances, an agent MUST NOT instantiate an object with an incorrect
value; rather, it MUST respond with the appropriate error/exception
condition (e.g., noSuchInstance for SNMPv2).
One example is where an agent is unable to count the occurrences defined
by one (or more) of the ifTable counters. In this circumstance, the
agent MUST NOT instantiate the particular counter with a value of, say,
zero. To do so would be to provide mis-information to a network
management application reading the zero value, and thereby assuming that
there have been no occurrences of the event (e.g., no input errors
because ifInErrors is always zero).
Sometimes the lack of knowledge of an object's value is temporary. For
example, when the MTU of an interface is a configured value and a device
dynamically learns the configured value through (after) exchanging
messages over the interface (e.g., ATM LAN-Emulation [20]). In such a
case, the value is not known until after the ifTable entry has already
been created. In such a case, the ifTable entry should be created
without an instance of the object whose value is unknown; later, when
the value becomes known, the missing object can then be instantiated
(e.g., the instance of ifMtu is only instantiated once the interface's
MTU becomes known).
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As a result of this "known values" rule, management applications MUST be
able to cope with the responses to retrieving the object instances
within a conceptual row of the ifTable revealing that some of the row's
columnar objects are missing/not available.
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4. Media-Specific MIB Applicability
The exact use and semantics of many objects in this MIB are open to some
interpretation. This is a result of the generic nature of this MIB. It
is not always possible to come up with specific, unambiguous, text that
covers all cases and yet preserves the generic nature of the MIB.
Therefore, it is incumbent upon a media-specific MIB designer to,
wherever necessary, clarify the use of the objects in this MIB with
respect to the media-specific MIB.
Specific areas of clarification include
Layering Model
The media-specific MIB designer MUST completely and unambiguously
specify the layering model used. Each individual sub-layer must be
identified, as must the ifStackTable's portrayal of the
relationship(s) between the sub-layers.
Virtual Circuits
The media-specific MIB designer MUST specify whether virtual
circuits are assigned entries in the ifTable or not. If they are,
compelling rationale must be presented.
ifRcvAddressTable
The media-specific MIB designer MUST specify the applicability of
the ifRcvAddressTable.
ifType
For each of the ifType values to which the media-specific MIB
applies, it must specify the mapping of ifType values to media-
specific MIB module(s) and instances of MIB objects within those
modules.
ifXxxOctets
The definitions of ifInOctets and ifOutOctets (and similarly,
ifHCInOctets and ifHCOutOctets) specify that their values include
framing characters. The media-specific MIB designer MUST specify
any special conditions of the media concerning the inclusion of
framing characters, especially with respect to frames with errors.
However, wherever this interface MIB is specific in the semantics,
DESCRIPTION, or applicability of objects, the media-specific MIB
designer MUST NOT change said semantics, DESCRIPTION, or applicability.
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5. Overview
This MIB consists of 4 tables:
ifTable
This table is the ifTable from MIB-II.
ifXTable
This table contains objects that have been added to the Interface
MIB as a result of the Interface Evolution effort, or replacements
for objects of the original (MIB-II) ifTable that were deprecated
because the semantics of said objects have significantly changed.
This table also contains objects that were previously in the
ifExtnsTable.
ifStackTable
This table contains objects that define the relationships among the
sub-layers of an interface.
ifRcvAddressTable
This table contains objects that are used to define the media-level
addresses which this interface will receive. This table is a
generic table. The designers of media-specific MIBs must define
exactly how this table applies to their specific MIB.
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6. Interfaces Group Definitions
IF-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY, OBJECT-TYPE, Counter32, Gauge32, Counter64,
Integer32, TimeTicks, mib-2,
NOTIFICATION-TYPE FROM SNMPv2-SMI
TEXTUAL-CONVENTION, DisplayString,
PhysAddress, TruthValue, RowStatus,
TimeStamp, AutonomousType, TestAndIncr FROM SNMPv2-TC
MODULE-COMPLIANCE, OBJECT-GROUP,
NOTIFICATION-GROUP FROM SNMPv2-CONF
snmpTraps FROM SNMPv2-MIB
IANAifType FROM IANAifType-MIB;
ifMIB MODULE-IDENTITY
LAST-UPDATED "9910110000Z"
ORGANIZATION "IETF Interfaces MIB Working Group"
CONTACT-INFO
" Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
US
408-526-5260
kzm@cisco.com"
DESCRIPTION
"The MIB module to describe generic objects for network
interface sub-layers. This MIB is an updated version of
MIB-II's ifTable, and incorporates the extensions defined in
RFC 1229."
REVISION "9910110000Z"
DESCRIPTION -- xxxx to be filled in by RFC-EDITOR
"Clarifications agreed upon by the Interfaces MIB WG, and
published as RFC xxxx."
REVISION "9602282155Z"
DESCRIPTION
"Revisions made by the Interfaces MIB WG, and published in
RFC 2233."
REVISION "9311082155Z"
DESCRIPTION
"Initial revision, published as part of RFC 1573."
McCloghrie & Kastenholz [Page 29]
Internet Draft Interfaces Group MIB January 2000
::= { mib-2 31 }
ifMIBObjects OBJECT IDENTIFIER ::= { ifMIB 1 }
interfaces OBJECT IDENTIFIER ::= { mib-2 2 }
--
-- Textual Conventions
--
-- OwnerString has the same semantics as used in RFC 1271
OwnerString ::= TEXTUAL-CONVENTION
DISPLAY-HINT "255a"
STATUS deprecated
DESCRIPTION
"This data type is used to model an administratively
assigned name of the owner of a resource. This information
is taken from the NVT ASCII character set. It is suggested
that this name contain one or more of the following: ASCII
form of the manager station's transport address, management
station name (e.g., domain name), network management
personnel's name, location, or phone number. In some cases
the agent itself will be the owner of an entry. In these
cases, this string shall be set to a string starting with
'agent'."
SYNTAX OCTET STRING (SIZE(0..255))
-- InterfaceIndex contains the semantics of ifIndex and should be used
-- for any objects defined in other MIB modules that need these semantics.
InterfaceIndex ::= TEXTUAL-CONVENTION
DISPLAY-HINT "d"
STATUS current
DESCRIPTION
"A unique value, greater than zero, for each interface or
interface sub-layer in the managed system. It is
recommended that values are assigned contiguously starting
from 1. The value for each interface sub-layer must remain
constant at least from one re-initialization of the entity's
network management system to the next re-initialization."
SYNTAX Integer32 (1..2147483647)
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InterfaceIndexOrZero ::= TEXTUAL-CONVENTION
DISPLAY-HINT "d"
STATUS current
DESCRIPTION
"This textual convention is an extension of the
InterfaceIndex convention. The latter defines a greater
than zero value used to identify an interface or interface
sub-layer in the managed system. This extension permits the
additional value of zero. the value zero is object-specific
and must therefore be defined as part of the description of
any object which uses this syntax. Examples of the usage of
zero might include situations where interface was unknown,
or when none or all interfaces need to be referenced."
SYNTAX Integer32 (0..2147483647)
McCloghrie & Kastenholz [Page 31]
Internet Draft Interfaces Group MIB January 2000
ifNumber OBJECT-TYPE
SYNTAX Integer32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of network interfaces (regardless of their
current state) present on this system."
::= { interfaces 1 }
ifTableLastChange OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time of the last creation or
deletion of an entry in the ifTable. If the number of
entries has been unchanged since the last re-initialization
of the local network management subsystem, then this object
contains a zero value."
::= { ifMIBObjects 5 }
-- the Interfaces table
-- The Interfaces table contains information on the entity's
-- interfaces. Each sub-layer below the internetwork-layer
-- of a network interface is considered to be an interface.
ifTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of interface entries. The number of entries is
given by the value of ifNumber."
::= { interfaces 2 }
ifEntry OBJECT-TYPE
SYNTAX IfEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry containing management information applicable to a
particular interface."
INDEX { ifIndex }
McCloghrie & Kastenholz [Page 32]
Internet Draft Interfaces Group MIB January 2000
::= { ifTable 1 }
IfEntry ::=
SEQUENCE {
ifIndex InterfaceIndex,
ifDescr DisplayString,
ifType IANAifType,
ifMtu Integer32,
ifSpeed Gauge32,
ifPhysAddress PhysAddress,
ifAdminStatus INTEGER,
ifOperStatus INTEGER,
ifLastChange TimeTicks,
ifInOctets Counter32,
ifInUcastPkts Counter32,
ifInNUcastPkts Counter32, -- deprecated
ifInDiscards Counter32,
ifInErrors Counter32,
ifInUnknownProtos Counter32,
ifOutOctets Counter32,
ifOutUcastPkts Counter32,
ifOutNUcastPkts Counter32, -- deprecated
ifOutDiscards Counter32,
ifOutErrors Counter32,
ifOutQLen Gauge32, -- deprecated
ifSpecific OBJECT IDENTIFIER -- deprecated
}
ifIndex OBJECT-TYPE
SYNTAX InterfaceIndex
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"A unique value, greater than zero, for each interface. It
is recommended that values are assigned contiguously
starting from 1. The value for each interface sub-layer
must remain constant at least from one re-initialization of
the entity's network management system to the next re-
initialization."
::= { ifEntry 1 }
ifDescr OBJECT-TYPE
SYNTAX DisplayString (SIZE (0..255))
MAX-ACCESS read-only
McCloghrie & Kastenholz [Page 33]
Internet Draft Interfaces Group MIB January 2000
STATUS current
DESCRIPTION
"A textual string containing information about the
interface. This string should include the name of the
manufacturer, the product name and the version of the
interface hardware/software."
::= { ifEntry 2 }
ifType OBJECT-TYPE
SYNTAX IANAifType
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The type of interface. Additional values for ifType are
assigned by the Internet Assigned Numbers Authority (IANA),
through updating the syntax of the IANAifType textual
convention."
::= { ifEntry 3 }
ifMtu OBJECT-TYPE
SYNTAX Integer32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The size of the largest packet which can be sent/received
on the interface, specified in octets. For interfaces that
are used for transmitting network datagrams, this is the
size of the largest network datagram that can be sent on the
interface."
::= { ifEntry 4 }
ifSpeed OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An estimate of the interface's current bandwidth in bits
per second. For interfaces which do not vary in bandwidth
or for those where no accurate estimation can be made, this
object should contain the nominal bandwidth. If the
bandwidth of the interface is greater than the maximum value
reportable by this object then this object should report its
maximum value (4,294,967,295) and ifHighSpeed must be used
to report the interace's speed. For a sub-layer which has
no concept of bandwidth, this object should be zero."
McCloghrie & Kastenholz [Page 34]
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::= { ifEntry 5 }
ifPhysAddress OBJECT-TYPE
SYNTAX PhysAddress
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The interface's address at its protocol sub-layer. For
example, for an 802.x interface, this object normally
contains a MAC address. The interface's media-specific MIB
must define the bit and byte ordering and the format of the
value of this object. For interfaces which do not have such
an address (e.g., a serial line), this object should contain
an octet string of zero length."
::= { ifEntry 6 }
ifAdminStatus OBJECT-TYPE
SYNTAX INTEGER {
up(1), -- ready to pass packets
down(2),
testing(3) -- in some test mode
}
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"The desired state of the interface. The testing(3) state
indicates that no operational packets can be passed. When a
managed system initializes, all interfaces start with
ifAdminStatus in the down(2) state. As a result of either
explicit management action or per configuration information
retained by the managed system, ifAdminStatus is then
changed to either the up(1) or testing(3) states (or remains
in the down(2) state)."
::= { ifEntry 7 }
ifOperStatus OBJECT-TYPE
SYNTAX INTEGER {
up(1), -- ready to pass packets
down(2),
testing(3), -- in some test mode
unknown(4), -- status can not be determined
-- for some reason.
dormant(5),
notPresent(6), -- some component is missing
lowerLayerDown(7) -- down due to state of
McCloghrie & Kastenholz [Page 35]
Internet Draft Interfaces Group MIB January 2000
-- lower-layer interface(s)
}
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The current operational state of the interface. The
testing(3) state indicates that no operational packets can
be passed. If ifAdminStatus is down(2) then ifOperStatus
should be down(2). If ifAdminStatus is changed to up(1)
then ifOperStatus should change to up(1) if the interface is
ready to transmit and receive network traffic; it should
change to dormant(5) if the interface is waiting for
external actions (such as a serial line waiting for an
incoming connection); it should remain in the down(2) state
if and only if there is a fault that prevents it from going
to the up(1) state; it should remain in the notPresent(6)
state if the interface has missing (typically, hardware)
components."
::= { ifEntry 8 }
ifLastChange OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time the interface entered
its current operational state. If the current state was
entered prior to the last re-initialization of the local
network management subsystem, then this object contains a
zero value."
::= { ifEntry 9 }
ifInOctets OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets received on the interface,
including framing characters.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 10 }
McCloghrie & Kastenholz [Page 36]
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ifInUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were not addressed to a multicast
or broadcast address at this sub-layer.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 11 }
ifInNUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a multicast or
broadcast address at this sub-layer.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime.
This object is deprecated in favour of ifInMulticastPkts and
ifInBroadcastPkts."
::= { ifEntry 12 }
ifInDiscards OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of inbound packets which were chosen to be
discarded even though no errors had been detected to prevent
their being deliverable to a higher-layer protocol. One
possible reason for discarding such a packet could be to
free up buffer space.
Discontinuities in the value of this counter can occur at
McCloghrie & Kastenholz [Page 37]
Internet Draft Interfaces Group MIB January 2000
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 13 }
ifInErrors OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For packet-oriented interfaces, the number of inbound
packets that contained errors preventing them from being
deliverable to a higher-layer protocol. For character-
oriented or fixed-length interfaces, the number of inbound
transmission units that contained errors preventing them
from being deliverable to a higher-layer protocol.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 14 }
ifInUnknownProtos OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For packet-oriented interfaces, the number of packets
received via the interface which were discarded because of
an unknown or unsupported protocol. For character-oriented
or fixed-length interfaces that support protocol
multiplexing the number of transmission units received via
the interface which were discarded because of an unknown or
unsupported protocol. For any interface that does not
support protocol multiplexing, this counter will always be
0.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 15 }
ifOutOctets OBJECT-TYPE
McCloghrie & Kastenholz [Page 38]
Internet Draft Interfaces Group MIB January 2000
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets transmitted out of the
interface, including framing characters.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 16 }
ifOutUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were not addressed to a
multicast or broadcast address at this sub-layer, including
those that were discarded or not sent.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 17 }
ifOutNUcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
multicast or broadcast address at this sub-layer, including
those that were discarded or not sent.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime.
This object is deprecated in favour of ifOutMulticastPkts
McCloghrie & Kastenholz [Page 39]
Internet Draft Interfaces Group MIB January 2000
and ifOutBroadcastPkts."
::= { ifEntry 18 }
ifOutDiscards OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of outbound packets which were chosen to be
discarded even though no errors had been detected to prevent
their being transmitted. One possible reason for discarding
such a packet could be to free up buffer space.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 19 }
ifOutErrors OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"For packet-oriented interfaces, the number of outbound
packets that could not be transmitted because of errors.
For character-oriented or fixed-length interfaces, the
number of outbound transmission units that could not be
transmitted because of errors.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifEntry 20 }
ifOutQLen OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"The length of the output packet queue (in packets)."
::= { ifEntry 21 }
ifSpecific OBJECT-TYPE
McCloghrie & Kastenholz [Page 40]
Internet Draft Interfaces Group MIB January 2000
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"A reference to MIB definitions specific to the particular
media being used to realize the interface. It is
recommended that this value point to an instance of a MIB
object in the media-specific MIB, i.e., that this object
have the semantics associated with the InstancePointer
textual convention defined in RFC 2579. In fact, it is
recommended that the media-specific MIB specify what value
ifSpecific should/can take for values of ifType. If no MIB
definitions specific to the particular media are available,
the value should be set to the OBJECT IDENTIFIER { 0 0 }."
::= { ifEntry 22 }
--
-- Extension to the interface table
--
-- This table replaces the ifExtnsTable table.
--
ifXTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfXEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of interface entries. The number of entries is
given by the value of ifNumber. This table contains
additional objects for the interface table."
::= { ifMIBObjects 1 }
ifXEntry OBJECT-TYPE
SYNTAX IfXEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry containing additional management information
applicable to a particular interface."
AUGMENTS { ifEntry }
::= { ifXTable 1 }
IfXEntry ::=
McCloghrie & Kastenholz [Page 41]
Internet Draft Interfaces Group MIB January 2000
SEQUENCE {
ifName DisplayString,
ifInMulticastPkts Counter32,
ifInBroadcastPkts Counter32,
ifOutMulticastPkts Counter32,
ifOutBroadcastPkts Counter32,
ifHCInOctets Counter64,
ifHCInUcastPkts Counter64,
ifHCInMulticastPkts Counter64,
ifHCInBroadcastPkts Counter64,
ifHCOutOctets Counter64,
ifHCOutUcastPkts Counter64,
ifHCOutMulticastPkts Counter64,
ifHCOutBroadcastPkts Counter64,
ifLinkUpDownTrapEnable INTEGER,
ifHighSpeed Gauge32,
ifPromiscuousMode TruthValue,
ifConnectorPresent TruthValue,
ifAlias DisplayString,
ifCounterDiscontinuityTime TimeStamp
}
ifName OBJECT-TYPE
SYNTAX DisplayString
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The textual name of the interface. The value of this
object should be the name of the interface as assigned by
the local device and should be suitable for use in commands
entered at the device's `console'. This might be a text
name, such as `le0' or a simple port number, such as `1',
depending on the interface naming syntax of the device. If
several entries in the ifTable together represent a single
interface as named by the device, then each will have the
same value of ifName. Note that for an agent which responds
to SNMP queries concerning an interface on some other
(proxied) device, then the value of ifName for such an
interface is the proxied device's local name for it.
If there is no local name, or this object is otherwise not
applicable, then this object contains a zero-length string."
::= { ifXEntry 1 }
McCloghrie & Kastenholz [Page 42]
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ifInMulticastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a multicast
address at this sub-layer. For a MAC layer protocol, this
includes both Group and Functional addresses.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 2 }
ifInBroadcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a broadcast
address at this sub-layer.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 3 }
ifOutMulticastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
multicast address at this sub-layer, including those that
were discarded or not sent. For a MAC layer protocol, this
includes both Group and Functional addresses.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
McCloghrie & Kastenholz [Page 43]
Internet Draft Interfaces Group MIB January 2000
ifCounterDiscontinuityTime."
::= { ifXEntry 4 }
ifOutBroadcastPkts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
broadcast address at this sub-layer, including those that
were discarded or not sent.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 5 }
--
-- High Capacity Counter objects. These objects are all
-- 64 bit versions of the "basic" ifTable counters. These
-- objects all have the same basic semantics as their 32-bit
-- counterparts, however, their syntax has been extended
-- to 64 bits.
--
ifHCInOctets OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets received on the interface,
including framing characters. This object is a 64-bit
version of ifInOctets.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 6 }
ifHCInUcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
McCloghrie & Kastenholz [Page 44]
Internet Draft Interfaces Group MIB January 2000
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were not addressed to a multicast
or broadcast address at this sub-layer. This object is a
64-bit version of ifInUcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 7 }
ifHCInMulticastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a multicast
address at this sub-layer. For a MAC layer protocol, this
includes both Group and Functional addresses. This object
is a 64-bit version of ifInMulticastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 8 }
ifHCInBroadcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The number of packets, delivered by this sub-layer to a
higher (sub-)layer, which were addressed to a broadcast
address at this sub-layer. This object is a 64-bit version
of ifInBroadcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 9 }
McCloghrie & Kastenholz [Page 45]
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ifHCOutOctets OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of octets transmitted out of the
interface, including framing characters. This object is a
64-bit version of ifOutOctets.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 10 }
ifHCOutUcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were not addressed to a
multicast or broadcast address at this sub-layer, including
those that were discarded or not sent. This object is a
64-bit version of ifOutUcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 11 }
ifHCOutMulticastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
multicast address at this sub-layer, including those that
were discarded or not sent. For a MAC layer protocol, this
includes both Group and Functional addresses. This object
is a 64-bit version of ifOutMulticastPkts.
Discontinuities in the value of this counter can occur at
McCloghrie & Kastenholz [Page 46]
Internet Draft Interfaces Group MIB January 2000
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 12 }
ifHCOutBroadcastPkts OBJECT-TYPE
SYNTAX Counter64
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets that higher-level protocols
requested be transmitted, and which were addressed to a
broadcast address at this sub-layer, including those that
were discarded or not sent. This object is a 64-bit version
of ifOutBroadcastPkts.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
ifCounterDiscontinuityTime."
::= { ifXEntry 13 }
ifLinkUpDownTrapEnable OBJECT-TYPE
SYNTAX INTEGER { enabled(1), disabled(2) }
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"Indicates whether linkUp/linkDown traps should be generated
for this interface.
By default, this object should have the value enabled(1) for
interfaces which do not operate on 'top' of any other
interface (as defined in the ifStackTable), and disabled(2)
otherwise."
::= { ifXEntry 14 }
ifHighSpeed OBJECT-TYPE
SYNTAX Gauge32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"An estimate of the interface's current bandwidth in units
of 1,000,000 bits per second. If this object reports a
value of `n' then the speed of the interface is somewhere in
the range of `n-500,000' to `n+499,999'. For interfaces
McCloghrie & Kastenholz [Page 47]
Internet Draft Interfaces Group MIB January 2000
which do not vary in bandwidth or for those where no
accurate estimation can be made, this object should contain
the nominal bandwidth. For a sub-layer which has no concept
of bandwidth, this object should be zero."
::= { ifXEntry 15 }
ifPromiscuousMode OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-write
STATUS current
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.
The value of ifPromiscuousMode does not affect the reception
of broadcast and multicast packets/frames by the interface."
::= { ifXEntry 16 }
ifConnectorPresent OBJECT-TYPE
SYNTAX TruthValue
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"This object has the value 'true(1)' if the interface
sublayer has a physical connector and the value 'false(2)'
otherwise."
::= { ifXEntry 17 }
ifAlias OBJECT-TYPE
SYNTAX DisplayString (SIZE(0..64))
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object is an 'alias' name for the interface as
specified by a network manager, and provides a non-volatile
'handle' for the interface.
On the first instantiation of an interface, the value of
ifAlias associated with that interface is the zero-length
string. As and when a value is written into an instance of
McCloghrie & Kastenholz [Page 48]
Internet Draft Interfaces Group MIB January 2000
ifAlias through a network management set operation, then the
agent must retain the supplied value in the ifAlias instance
associated with the same interface for as long as that
interface remains instantiated, including across all re-
initializations/reboots of the network management system,
including those which result in a change of the interface's
ifIndex value.
An example of the value which a network manager might store
in this object for a WAN interface is the (Telco's) circuit
number/identifier of the interface.
Some agents may support write-access only for interfaces
having particular values of ifType. An agent which supports
write access to this object is required to keep the value in
non-volatile storage, but it may limit the length of new
values depending on how much storage is already occupied by
the current values for other interfaces."
::= { ifXEntry 18 }
ifCounterDiscontinuityTime OBJECT-TYPE
SYNTAX TimeStamp
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime on the most recent occasion at which
any one or more of this interface's counters suffered a
discontinuity. The relevant counters are the specific
instances associated with this interface of any Counter32 or
Counter64 object contained in the ifTable or ifXTable. If
no such discontinuities have occurred since the last re-
initialization of the local management subsystem, then this
object contains a zero value."
::= { ifXEntry 19 }
McCloghrie & Kastenholz [Page 49]
Internet Draft Interfaces Group MIB January 2000
-- The Interface Stack Group
--
-- Implementation of this group is optional, but strongly recommended
-- for all systems
--
ifStackTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfStackEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table containing information on the relationships
between the multiple sub-layers of network interfaces. In
particular, it contains information on which sub-layers run
'on top of' which other sub-layers, where each sub-layer
corresponds to a conceptual row in the ifTable. For
example, when the sub-layer with ifIndex value x runs over
the sub-layer with ifIndex value y, then this table
contains:
ifStackStatus.x.y=active
For each ifIndex value, I, which identifies an active
interface, there are always at least two instantiated rows
in this table associated with I. For one of these rows, I
is the value of ifStackHigherLayer; for the other, I is the
value of ifStackLowerLayer. (If I is not involved in
multiplexing, then these are the only two rows associated
with I.)
For example, two rows exist even for an interface which has
no others stacked on top or below it:
ifStackStatus.0.x=active
ifStackStatus.x.0=active "
::= { ifMIBObjects 2 }
ifStackEntry OBJECT-TYPE
SYNTAX IfStackEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"Information on a particular relationship between two sub-
layers, specifying that one sub-layer runs on 'top' of the
McCloghrie & Kastenholz [Page 50]
Internet Draft Interfaces Group MIB January 2000
other sub-layer. Each sub-layer corresponds to a conceptual
row in the ifTable."
INDEX { ifStackHigherLayer, ifStackLowerLayer }
::= { ifStackTable 1 }
IfStackEntry ::=
SEQUENCE {
ifStackHigherLayer InterfaceIndexOrZero,
ifStackLowerLayer InterfaceIndexOrZero,
ifStackStatus RowStatus
}
ifStackHigherLayer OBJECT-TYPE
SYNTAX InterfaceIndexOrZero
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The value of ifIndex corresponding to the higher sub-layer
of the relationship, i.e., the sub-layer which runs on 'top'
of the sub-layer identified by the corresponding instance of
ifStackLowerLayer. If there is no higher sub-layer (below
the internetwork layer), then this object has the value 0."
::= { ifStackEntry 1 }
ifStackLowerLayer OBJECT-TYPE
SYNTAX InterfaceIndexOrZero
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The value of ifIndex corresponding to the lower sub-layer
of the relationship, i.e., the sub-layer which runs 'below'
the sub-layer identified by the corresponding instance of
ifStackHigherLayer. If there is no lower sub-layer, then
this object has the value 0."
::= { ifStackEntry 2 }
ifStackStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
McCloghrie & Kastenholz [Page 51]
Internet Draft Interfaces Group MIB January 2000
"The status of the relationship between two sub-layers.
Changing the value of this object from 'active' to
'notInService' or 'destroy' will likely have consequences up
and down the interface stack. Thus, write access to this
object is likely to be inappropriate for some types of
interfaces, and many implementations will choose not to
support write-access for any type of interface."
::= { ifStackEntry 3 }
ifStackLastChange OBJECT-TYPE
SYNTAX TimeTicks
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The value of sysUpTime at the time of the last change of
the (whole) interface stack. A change of the interface
stack is defined to be any creation, deletion, or change in
value of any instance of ifStackStatus. If the interface
stack has been unchanged since the last re-initialization of
the local network management subsystem, then this object
contains a zero value."
::= { ifMIBObjects 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.
--
-- This table replaces the ifExtnsRcvAddr table. The main
-- difference is that this table makes use of the RowStatus
-- textual convention, while ifExtnsRcvAddr did not.
ifRcvAddressTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfRcvAddressEntry
MAX-ACCESS not-accessible
STATUS current
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, except as follows:
- for an interface operating in promiscuous mode, entries
McCloghrie & Kastenholz [Page 52]
Internet Draft Interfaces Group MIB January 2000
are only required for those addresses for which the system
would receive frames were it not operating in promiscuous
mode.
- for 802.5 functional addresses, only one entry is
required, for the address which has the functional address
bit ANDed with the bit mask of all functional addresses for
which the interface will accept frames.
A system is normally able to use any unicast address which
corresponds to an entry in this table as a source address."
::= { ifMIBObjects 4 }
ifRcvAddressEntry OBJECT-TYPE
SYNTAX IfRcvAddressEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A list of objects identifying an address for which the
system will accept packets/frames on the particular
interface identified by the index value ifIndex."
INDEX { ifIndex, ifRcvAddressAddress }
::= { ifRcvAddressTable 1 }
IfRcvAddressEntry ::=
SEQUENCE {
ifRcvAddressAddress PhysAddress,
ifRcvAddressStatus RowStatus,
ifRcvAddressType INTEGER
}
ifRcvAddressAddress OBJECT-TYPE
SYNTAX PhysAddress
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An address for which the system will accept packets/frames
on this entry's interface."
::= { ifRcvAddressEntry 1 }
ifRcvAddressStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
McCloghrie & Kastenholz [Page 53]
Internet Draft Interfaces Group MIB January 2000
"This object is used to create and delete rows in the
ifRcvAddressTable."
::= { ifRcvAddressEntry 2 }
ifRcvAddressType OBJECT-TYPE
SYNTAX INTEGER {
other(1),
volatile(2),
nonVolatile(3)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object has the value nonVolatile(3) 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(2) are valid 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."
DEFVAL { volatile }
::= { ifRcvAddressEntry 3 }
McCloghrie & Kastenholz [Page 54]
Internet Draft Interfaces Group MIB January 2000
-- definition of interface-related traps.
linkDown NOTIFICATION-TYPE
OBJECTS { ifIndex, ifAdminStatus, ifOperStatus }
STATUS current
DESCRIPTION
"A linkDown trap signifies that the SNMP entity, acting in
an agent role, has detected that the ifOperStatus object for
one of its communication links is about to enter the down
state from some other state (but not from the notPresent
state). This other state is indicated by the included value
of ifOperStatus."
::= { snmpTraps 3 }
linkUp NOTIFICATION-TYPE
OBJECTS { ifIndex, ifAdminStatus, ifOperStatus }
STATUS current
DESCRIPTION
"A linkUp trap signifies that the SNMP entity, acting in an
agent role, has detected that the ifOperStatus object for
one of its communication links left the down state and
transitioned into some other state (but not into the
notPresent state). This other state is indicated by the
included value of ifOperStatus."
::= { snmpTraps 4 }
McCloghrie & Kastenholz [Page 55]
Internet Draft Interfaces Group MIB January 2000
-- conformance information
ifConformance OBJECT IDENTIFIER ::= { ifMIB 2 }
ifGroups OBJECT IDENTIFIER ::= { ifConformance 1 }
ifCompliances OBJECT IDENTIFIER ::= { ifConformance 2 }
-- compliance statements
ifCompliance3 MODULE-COMPLIANCE
STATUS current
DESCRIPTION
"The compliance statement for SNMP entities which have
network interfaces."
MODULE -- this module
MANDATORY-GROUPS { ifGeneralInformationGroup,
linkUpDownNotificationsGroup }
-- The groups:
-- ifFixedLengthGroup
-- ifHCFixedLengthGroup
-- ifPacketGroup
-- ifHCPacketGroup
-- ifVHCPacketGroup
-- are mutually exclusive; at most one of these groups is implemented
-- for a particular interface. When any of these groups is implemented
-- for a particular interface, then ifCounterDiscontinuityGroup must
-- also be implemented for that interface.
GROUP ifFixedLengthGroup
DESCRIPTION
"This group is mandatory for those network interfaces which
are character-oriented or transmit data in fixed-length
transmission units, and for which the value of the
corresponding instance of ifSpeed is less than or equal to
20,000,000 bits/second."
GROUP ifHCFixedLengthGroup
DESCRIPTION
"This group is mandatory for those network interfaces which
are character-oriented or transmit data in fixed-length
transmission units, and for which the value of the
McCloghrie & Kastenholz [Page 56]
Internet Draft Interfaces Group MIB January 2000
corresponding instance of ifSpeed is greater than 20,000,000
bits/second."
GROUP ifPacketGroup
DESCRIPTION
"This group is mandatory for those network interfaces which
are packet-oriented, and for which the value of the
corresponding instance of ifSpeed is less than or equal to
20,000,000 bits/second."
GROUP ifHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second but less than or equal to 650,000,000
bits/second."
GROUP ifVHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than
650,000,000 bits/second."
GROUP ifCounterDiscontinuityGroup
DESCRIPTION
"This group is mandatory for those network interfaces that
are required to maintain counters (i.e., those for which one
of the ifFixedLengthGroup, ifHCFixedLengthGroup,
ifPacketGroup, ifHCPacketGroup, or ifVHCPacketGroup is
mandatory)."
GROUP ifRcvAddressGroup
DESCRIPTION
"The applicability of this group MUST be defined by the
media-specific MIBs. Media-specific MIBs must define the
exact meaning, use, and semantics of the addresses in this
group."
OBJECT ifLinkUpDownTrapEnable
MIN-ACCESS read-only
DESCRIPTION
McCloghrie & Kastenholz [Page 57]
Internet Draft Interfaces Group MIB January 2000
"Write access is not required."
OBJECT ifPromiscuousMode
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."
OBJECT ifAlias
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
::= { ifCompliances 3 }
McCloghrie & Kastenholz [Page 58]
Internet Draft Interfaces Group MIB January 2000
-- units of conformance
ifGeneralInformationGroup OBJECT-GROUP
OBJECTS { ifIndex, ifDescr, ifType, ifSpeed, ifPhysAddress,
ifAdminStatus, ifOperStatus, ifLastChange,
ifLinkUpDownTrapEnable, ifConnectorPresent,
ifHighSpeed, ifName, ifNumber, ifAlias,
ifTableLastChange }
STATUS current
DESCRIPTION
"A collection of objects providing information applicable to
all network interfaces."
::= { ifGroups 10 }
-- the following five groups are mutually exclusive; at most
-- one of these groups is implemented for any interface
ifFixedLengthGroup OBJECT-GROUP
OBJECTS { ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
non-high speed (non-high speed interfaces transmit and
receive at speeds less than or equal to 20,000,000
bits/second) character-oriented or fixed-length-transmission
network interfaces."
::= { ifGroups 2 }
ifHCFixedLengthGroup OBJECT-GROUP
OBJECTS { ifHCInOctets, ifHCOutOctets,
ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
high speed (greater than 20,000,000 bits/second) character-
oriented or fixed-length-transmission network interfaces."
::= { ifGroups 3 }
ifPacketGroup OBJECT-GROUP
OBJECTS { ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors,
ifMtu, ifInUcastPkts, ifInMulticastPkts,
ifInBroadcastPkts, ifInDiscards,
McCloghrie & Kastenholz [Page 59]
Internet Draft Interfaces Group MIB January 2000
ifOutUcastPkts, ifOutMulticastPkts,
ifOutBroadcastPkts, ifOutDiscards,
ifPromiscuousMode }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
non-high speed (non-high speed interfaces transmit and
receive at speeds less than or equal to 20,000,000
bits/second) packet-oriented network interfaces."
::= { ifGroups 4 }
ifHCPacketGroup OBJECT-GROUP
OBJECTS { ifHCInOctets, ifHCOutOctets,
ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors,
ifMtu, ifInUcastPkts, ifInMulticastPkts,
ifInBroadcastPkts, ifInDiscards,
ifOutUcastPkts, ifOutMulticastPkts,
ifOutBroadcastPkts, ifOutDiscards,
ifPromiscuousMode }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
high speed (greater than 20,000,000 bits/second but less
than or equal to 650,000,000 bits/second) packet-oriented
network interfaces."
::= { ifGroups 5 }
ifVHCPacketGroup OBJECT-GROUP
OBJECTS { ifHCInUcastPkts, ifHCInMulticastPkts,
ifHCInBroadcastPkts, ifHCOutUcastPkts,
ifHCOutMulticastPkts, ifHCOutBroadcastPkts,
ifHCInOctets, ifHCOutOctets,
ifInOctets, ifOutOctets, ifInUnknownProtos,
ifInErrors, ifOutErrors,
ifMtu, ifInUcastPkts, ifInMulticastPkts,
ifInBroadcastPkts, ifInDiscards,
ifOutUcastPkts, ifOutMulticastPkts,
ifOutBroadcastPkts, ifOutDiscards,
ifPromiscuousMode }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
higher speed (greater than 650,000,000 bits/second) packet-
oriented network interfaces."
McCloghrie & Kastenholz [Page 60]
Internet Draft Interfaces Group MIB January 2000
::= { ifGroups 6 }
ifRcvAddressGroup OBJECT-GROUP
OBJECTS { ifRcvAddressStatus, ifRcvAddressType }
STATUS current
DESCRIPTION
"A collection of objects providing information on the
multiple addresses which an interface receives."
::= { ifGroups 7 }
ifStackGroup2 OBJECT-GROUP
OBJECTS { ifStackStatus, ifStackLastChange }
STATUS current
DESCRIPTION
"A collection of objects providing information on the
layering of MIB-II interfaces."
::= { ifGroups 11 }
ifCounterDiscontinuityGroup OBJECT-GROUP
OBJECTS { ifCounterDiscontinuityTime }
STATUS current
DESCRIPTION
"A collection of objects providing information specific to
interface counter discontinuities."
::= { ifGroups 13 }
linkUpDownNotificationsGroup NOTIFICATION-GROUP
NOTIFICATIONS { linkUp, linkDown }
STATUS current
DESCRIPTION
"The notifications which indicate specific changes in the
value of ifOperStatus."
::= { ifGroups 14 }
McCloghrie & Kastenholz [Page 61]
Internet Draft Interfaces Group MIB January 2000
-- Deprecated Definitions - Objects
--
-- The Interface Test Table
--
-- This group of objects is optional. However, a media-specific
-- MIB may make implementation of this group mandatory.
--
-- This table replaces the ifExtnsTestTable
--
ifTestTable OBJECT-TYPE
SYNTAX SEQUENCE OF IfTestEntry
MAX-ACCESS not-accessible
STATUS deprecated
DESCRIPTION
"This table contains one entry per interface. It defines
objects which allow a network manager to instruct an agent
to test an interface for various faults. Tests for an
interface are defined in the media-specific MIB for that
interface. After invoking a test, the object ifTestResult
can be read to determine the outcome. If an agent can not
perform the test, ifTestResult is set to so indicate. The
object ifTestCode 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.
Before starting a test, a manager-station must first obtain
'ownership' of the entry in the ifTestTable for the
interface to be tested. This is accomplished with the
ifTestId and ifTestStatus objects as follows:
try_again:
get (ifTestId, ifTestStatus)
while (ifTestStatus != notInUse)
/*
* Loop while a test is running or some other
* manager is configuring a test.
*/
short delay
McCloghrie & Kastenholz [Page 62]
Internet Draft Interfaces Group MIB January 2000
get (ifTestId, ifTestStatus)
}
/*
* Is not being used right now -- let's compete
* to see who gets it.
*/
lock_value = ifTestId
if ( set(ifTestId = lock_value, ifTestStatus = inUse,
ifTestOwner = 'my-IP-address') == FAILURE)
/*
* Another manager got the ifTestEntry -- go
* try again
*/
goto try_again;
/*
* I have the lock
*/
set up any test parameters.
/*
* This starts the test
*/
set(ifTestType = test_to_run);
wait for test completion by polling ifTestResult
when test completes, agent sets ifTestResult
agent also sets ifTestStatus = 'notInUse'
retrieve any additional test results, and ifTestId
if (ifTestId == lock_value+1) results are valid
A manager station first retrieves the value of the
appropriate ifTestId and ifTestStatus objects, periodically
repeating the retrieval if necessary, until the value of
ifTestStatus is 'notInUse'. The manager station then tries
to set the same ifTestId object to the value it just
retrieved, the same ifTestStatus object to 'inUse', and the
corresponding ifTestOwner object to a value indicating
itself. If the set operation succeeds then the manager has
obtained ownership of the ifTestEntry, and the value of the
McCloghrie & Kastenholz [Page 63]
Internet Draft Interfaces Group MIB January 2000
ifTestId object is incremented by the agent (per the
semantics of TestAndIncr). Failure of the set operation
indicates that some other manager has obtained ownership of
the ifTestEntry.
Once ownership is obtained, any test parameters can be
setup, and then the test is initiated by setting ifTestType.
On completion of the test, the agent sets ifTestStatus to
'notInUse'. Once this occurs, the manager can retrieve the
results. In the (rare) event that the 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 ifTestId at the
same time as retrieving the test results, and ensuring that
the results are for the desired request.
If ifTestType is not set within an abnormally long period of
time after ownership is obtained, the agent should time-out
the manager, and reset the value of the ifTestStatus object
back to 'notInUse'. It is suggested that this time-out
period be 5 minutes.
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. Only if the
invocation was unsuccessful, is the invocation request
retransmitted.
Some tests may require the interface to be taken off-line in
order to execute them, or may even require the agent to
reboot 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. An agent is not required to support such tests.
However, if such tests are supported, then the agent should
make every effort to transmit a response to the request
which 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,
McCloghrie & Kastenholz [Page 64]
Internet Draft Interfaces Group MIB January 2000
perhaps due to resource constraints, make available at least
the minimum amount of information after that test
completes."
::= { ifMIBObjects 3 }
ifTestEntry OBJECT-TYPE
SYNTAX IfTestEntry
MAX-ACCESS not-accessible
STATUS deprecated
DESCRIPTION
"An entry containing objects for invoking tests on an
interface."
AUGMENTS { ifEntry }
::= { ifTestTable 1 }
IfTestEntry ::=
SEQUENCE {
ifTestId TestAndIncr,
ifTestStatus INTEGER,
ifTestType AutonomousType,
ifTestResult INTEGER,
ifTestCode OBJECT IDENTIFIER,
ifTestOwner OwnerString
}
ifTestId OBJECT-TYPE
SYNTAX TestAndIncr
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"This object identifies the current invocation of the
interface's test."
::= { ifTestEntry 1 }
ifTestStatus OBJECT-TYPE
SYNTAX INTEGER { notInUse(1), inUse(2) }
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"This object indicates whether or not some manager currently
has the necessary 'ownership' required to invoke a test on
this interface. A write to this object is only successful
when it changes its value from 'notInUse(1)' to 'inUse(2)'.
After completion of a test, the agent resets the value back
to 'notInUse(1)'."
McCloghrie & Kastenholz [Page 65]
Internet Draft Interfaces Group MIB January 2000
::= { ifTestEntry 2 }
ifTestType OBJECT-TYPE
SYNTAX AutonomousType
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"A control variable used to start and stop operator-
initiated interface tests. Most OBJECT IDENTIFIER values
assigned to tests are defined elsewhere, in association 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 currently in progress, in which
case the indicated test is initiated.
When read, this object always returns the most recent value
that ifTestType 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."
::= { ifTestEntry 3 }
ifTestResult 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)
}
MAX-ACCESS read-only
STATUS deprecated
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
McCloghrie & Kastenholz [Page 66]
Internet Draft Interfaces Group MIB January 2000
when starting another, as could be required if used by
multiple managers concurrently."
::= { ifTestEntry 4 }
ifTestCode OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS read-only
STATUS deprecated
DESCRIPTION
"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. The value may have the semantics of either the
AutonomousType or InstancePointer textual conventions as
defined in RFC 2579. The identifier:
testCodeUnknown OBJECT IDENTIFIER ::= { 0 0 }
is defined for use if no additional result code is
available."
::= { ifTestEntry 5 }
ifTestOwner OBJECT-TYPE
SYNTAX OwnerString
MAX-ACCESS read-write
STATUS deprecated
DESCRIPTION
"The entity which currently has the 'ownership' required to
invoke a test on this interface."
::= { ifTestEntry 6 }
McCloghrie & Kastenholz [Page 67]
Internet Draft Interfaces Group MIB January 2000
-- Deprecated Definitions - Groups
ifGeneralGroup OBJECT-GROUP
OBJECTS { ifDescr, ifType, ifSpeed, ifPhysAddress,
ifAdminStatus, ifOperStatus, ifLastChange,
ifLinkUpDownTrapEnable, ifConnectorPresent,
ifHighSpeed, ifName }
STATUS deprecated
DESCRIPTION
"A collection of objects deprecated in favour of
ifGeneralInformationGroup."
::= { ifGroups 1 }
ifTestGroup OBJECT-GROUP
OBJECTS { ifTestId, ifTestStatus, ifTestType,
ifTestResult, ifTestCode, ifTestOwner }
STATUS deprecated
DESCRIPTION
"A collection of objects providing the ability to invoke
tests on an interface."
::= { ifGroups 8 }
ifStackGroup OBJECT-GROUP
OBJECTS { ifStackStatus }
STATUS deprecated
DESCRIPTION
"The previous collection of objects providing information on
the layering of MIB-II interfaces."
::= { ifGroups 9 }
ifOldObjectsGroup OBJECT-GROUP
OBJECTS { ifInNUcastPkts, ifOutNUcastPkts,
ifOutQLen, ifSpecific }
STATUS deprecated
DESCRIPTION
"The collection of objects deprecated from the original MIB-
II interfaces group."
::= { ifGroups 12 }
McCloghrie & Kastenholz [Page 68]
Internet Draft Interfaces Group MIB January 2000
-- Deprecated Definitions - Compliance
ifCompliance MODULE-COMPLIANCE
STATUS deprecated
DESCRIPTION
"A compliance statement defined in a previous version of
this MIB module, for SNMP entities which have network
interfaces."
MODULE -- this module
MANDATORY-GROUPS { ifGeneralGroup, ifStackGroup }
GROUP ifFixedLengthGroup
DESCRIPTION
"This group is mandatory for all network interfaces which
are character-oriented or transmit data in fixed-length
transmission units."
GROUP ifHCFixedLengthGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are character-oriented or transmit data in fixed-
length transmission units, and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second."
GROUP ifPacketGroup
DESCRIPTION
"This group is mandatory for all network interfaces which
are packet-oriented."
GROUP ifHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than
650,000,000 bits/second."
GROUP ifTestGroup
DESCRIPTION
"This group is optional. Media-specific MIBs which require
interface tests are strongly encouraged to use this group
for invoking tests and reporting results. A medium specific
MIB which has mandatory tests may make implementation of
this group mandatory."
McCloghrie & Kastenholz [Page 69]
Internet Draft Interfaces Group MIB January 2000
GROUP ifRcvAddressGroup
DESCRIPTION
"The applicability of this group MUST be defined by the
media-specific MIBs. Media-specific MIBs must define the
exact meaning, use, and semantics of the addresses in this
group."
OBJECT ifLinkUpDownTrapEnable
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifPromiscuousMode
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifStackStatus
SYNTAX INTEGER { active(1) } -- subset of RowStatus
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, and only one of the six
enumerated values for the RowStatus textual convention need
be supported, specifically: active(1)."
OBJECT ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."
::= { ifCompliances 1 }
ifCompliance2 MODULE-COMPLIANCE
STATUS deprecated
DESCRIPTION
"A compliance statement defined in a previous version of
this MIB module, for SNMP entities which have network
interfaces."
MODULE -- this module
MANDATORY-GROUPS { ifGeneralInformationGroup, ifStackGroup2,
ifCounterDiscontinuityGroup }
GROUP ifFixedLengthGroup
McCloghrie & Kastenholz [Page 70]
Internet Draft Interfaces Group MIB January 2000
DESCRIPTION
"This group is mandatory for all network interfaces which
are character-oriented or transmit data in fixed-length
transmission units."
GROUP ifHCFixedLengthGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are character-oriented or transmit data in fixed-
length transmission units, and for which the value of the
corresponding instance of ifSpeed is greater than 20,000,000
bits/second."
GROUP ifPacketGroup
DESCRIPTION
"This group is mandatory for all network interfaces which
are packet-oriented."
GROUP ifHCPacketGroup
DESCRIPTION
"This group is mandatory only for those network interfaces
which are packet-oriented and for which the value of the
corresponding instance of ifSpeed is greater than
650,000,000 bits/second."
GROUP ifRcvAddressGroup
DESCRIPTION
"The applicability of this group MUST be defined by the
media-specific MIBs. Media-specific MIBs must define the
exact meaning, use, and semantics of the addresses in this
group."
OBJECT ifLinkUpDownTrapEnable
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifPromiscuousMode
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
OBJECT ifStackStatus
SYNTAX INTEGER { active(1) } -- subset of RowStatus
MIN-ACCESS read-only
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Internet Draft Interfaces Group MIB January 2000
DESCRIPTION
"Write access is not required, and only one of the six
enumerated values for the RowStatus textual convention need
be supported, specifically: active(1)."
OBJECT ifAdminStatus
SYNTAX INTEGER { up(1), down(2) }
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required, nor is support for the value
testing(3)."
OBJECT ifAlias
MIN-ACCESS read-only
DESCRIPTION
"Write access is not required."
::= { ifCompliances 2 }
END
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7. Acknowledgements
This memo has been produced by the IETF's Interfaces MIB working-group.
The original proposal evolved from conversations and discussions with
many people, including at least the following: Fred Baker, Ted Brunner,
Chuck Davin, Jeremy Greene, Marshall Rose, Kaj Tesink, and Dean Throop.
8. References
[1] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for
Describing SNMP Management Frameworks", RFC 2571, Cabletron
Systems, Inc., BMC Software, Inc., IBM T. J. Watson Research, April
1999.
[2] Rose, M., and K. McCloghrie, "Structure and Identification of
Management Information for TCP/IP-based Internets", STD 16, RFC
1155, Performance Systems International, Hughes LAN Systems, May
1990.
[3] Rose, M., and K. McCloghrie, "Concise MIB Definitions", STD 16, RFC
1212, Performance Systems International, Hughes LAN Systems, March
1991.
[4] M. Rose, "A Convention for Defining Traps for use with the SNMP",
RFC 1215, Performance Systems International, March 1991.
[5] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.
and S. Waldbusser, "Structure of Management Information Version 2
(SMIv2)", STD 58, RFC 2578, April 1999.
[6] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.
and S. Waldbusser, "Textual Conventions for SMIv2", STD 58, RFC
2579, April 1999.
[7] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J., Rose, M.
and S. Waldbusser, "Conformance Statements for SMIv2", STD 58, RFC
2580, April 1999.
[8] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple Network
Management Protocol", STD 15, RFC 1157, SNMP Research, Performance
Systems International, Performance Systems International, MIT
Laboratory for Computer Science, May 1990.
McCloghrie & Kastenholz [Page 73]
Internet Draft Interfaces Group MIB January 2000
[9] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Introduction to Community-based SNMPv2", RFC 1901,
SNMP Research, Inc., Cisco Systems, Inc., Dover Beach Consulting,
Inc., International Network Services, January 1996.
[10] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Transport Mappings for Version 2 of the Simple Network
Management Protocol (SNMPv2)", RFC 1906, SNMP Research, Inc., Cisco
Systems, Inc., Dover Beach Consulting, Inc., International Network
Services, January 1996.
[11] Case, J., Harrington D., Presuhn R., and B. Wijnen, "Message
Processing and Dispatching for the Simple Network Management
Protocol (SNMP)", RFC 2572, SNMP Research, Inc., Cabletron Systems,
Inc., BMC Software, Inc., IBM T. J. Watson Research, January 1998.
[12] Blumenthal, U., and B. Wijnen, "User-based Security Model (USM) for
version 3 of the Simple Network Management Protocol (SNMPv3)", RFC
2574, IBM T. J. Watson Research, January 1998.
[13] SNMPv2 Working Group, Case, J., McCloghrie, K., Rose, M., and S.
Waldbusser, "Protocol Operations for Version 2 of the Simple
Network Management Protocol (SNMPv2)", RFC 1905, SNMP Research,
Inc., Cisco Systems, Inc., Dover Beach Consulting, Inc.,
International Network Services, January 1996.
[14] Levi, D., Meyer, P., and B. Stewart, "SMPv3 Applications", RFC
2573, SNMP Research, Inc., Secure Computing Corporation, Cisco
Systems, January 1998.
[15] Wijnen, B., Presuhn, R., and K. McCloghrie, "View-based Access
Control Model (VACM) for the Simple Network Management Protocol
(SNMP)", RFC 2575, IBM T. J. Watson Research, BMC Software, Inc.,
Cisco Systems, Inc., January 1998.
[16] S. Bradner, "Key words for use in RFCs to Indicate Requirements
Levels", RFC 2119, Harvard University, March 1997.
[17] McCloghrie, K., and M. Rose, "Management Information Base for
Network Management of TCP/IP-based internets - MIB-II", RFC 1213,
Hughes LAN Systems, Performance Systems International, March 1991.
[18] J. Postel, "Internet Protocol", RFC 791, Information Sciences
Institute, USC, September 1981.
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[19] K. McCloghrie, "Extensions to the Generic-Interface MIB", RFC 1229,
Hughes LAN Systems, May 1991.
[20] ATM Forum Technical Committee, "LAN Emulation Client Management:
Version 1.0 Specification", af-lane-0044.000, ATM Forum, September
1995.
[21] B. Stewart, "Definitions of Managed Objects for Character Stream
Devices using SMIv2", RFC 1658, Xyplex Inc., July 1994.
[22] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction to
Version 3 of the Internet-standard Network Management Framework",
RFC 2570, April 1999.
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9. Security Considerations
There are a number of management objects defined in this MIB that have a
MAX-ACCESS clause of read-write and/or read-create. Such objects may be
considered sensitive or vulnerable in some network environments. The
support for SET operations in a non-secure environment without proper
protection can have a negative effect on network operations.
In particular, write-able objects allow an administrator to control the
interfaces and to perform tests on the interfaces, and unauthorized
access to these could cause a denial of service, or in combination with
other (e.g., physical) security breaches, could cause unauthorized
connectivity to a device.
SNMPv1 by itself is not a secure environment. Even if the network
itself is secure (for example by using IPSec), even then, there is no
control as to who on the secure network is allowed to access and GET/SET
(read/change/create/delete) the objects in this MIB.
It is recommended that the implementers consider the security features
as provided by the SNMPv3 framework. Specifically, the use of the User-
based Security Model RFC 2574 [12] and the View- based Access Control
Model RFC 2575 [15] is recommended.
It is then a customer/user responsibility to ensure that the SNMP entity
giving access to an instance of this MIB, is properly configured to give
access to the objects only to those principals (users) that have
legitimate rights to indeed GET or SET (change/create/delete) them.
10. Authors' Addresses
Keith McCloghrie
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, CA 95134-1706
Phone: 408-526-5260
Email: kzm@cisco.com"
Frank Kastenholz
Argon Networks
25 Porter Rd
Littleton Ma 01460
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Internet Draft Interfaces Group MIB January 2000
Phone: (508)685-4000
Email: kasten@argon.com
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11. Changes from RFC 2233
Added linkUpDownNotificationsGroup.
Changed the status of the definition of OwnerString in this MIB to
be deprecated, because it is only used by ifTestOwner, which is now
deprecated, and because other MIBs should import OwnerString from
RFC 1757 or its successors.
Added ifCompliance3 as a replacement for ifCompliance2 to omit the
ifStackGroup2 group, and add linkUpDownNotificationsGroup. Also,
corrected the omission of ifVHCPacketGroup, and typos in the
DESCRIPTIONs of ifHCPacketGroup and ifFixedLengthGroup. Obsoleted
ifCompliance2.
Modified syntax of ifStackHigherLayer and ifStackLowerLayer to be
InterfaceIndexOrZero.
Added requirement that media-specific MIB designers specify any
special conditions concerning the counting of framing characters in
ifInOctets and ifOutOctets.
Corrected a typo in the DESCRIPTION of the linkUp notification.
Modified the introductory SNMP Network Management Framework
boilerplate text.
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12. Notice on Intellectual Property
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to pertain
to the implementation or use of the technology described in this
document or the extent to which any license under such rights might or
might not be available; neither does it represent that it has made any
effort to identify any such rights. Information on the IETF's
procedures with respect to rights in standards-track and standards-
related documentation can be found in BCP-11. Copies of claims of
rights made available for publication and any assurances of licenses to
be made available, or the result of an attempt made to obtain a general
license or permission for the use of such proprietary rights by
implementors or users of this specification can be obtained from the
IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary rights
which may cover technology that may be required to practice this
standard. Please address the information to the IETF Executive
Director.
13. Full Copyright Statement
Copyright (C) The Internet Society (2000). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it or
assist in its implmentation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
provided that the above copyright notice and this paragraph are included
on all such copies and derivative works. However, this document itself
may not be modified in any way, such as by removing the copyright notice
or references to the Internet Society or other Internet organizations,
except as needed for the purpose of developing Internet standards in
which case the procedures for copyrights defined in the Internet
Standards process must be followed, or as required to translate it into
languages other than English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
McCloghrie & Kastenholz [Page 79]
Internet Draft Interfaces Group MIB January 2000
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE."
McCloghrie & Kastenholz [Page 80]
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Table of Contents
1 Introduction .................................................... 2
2 The SNMP Network Management Framework ........................... 2
3 Experience with the Interfaces Group ............................ 3
3.1 Clarifications/Revisions ...................................... 4
3.1.1 Interface Sub-Layers ........................................ 4
3.1.2 Guidance on Defining Sub-layers ............................. 7
3.1.3 Virtual Circuits ............................................ 8
3.1.4 Bit, Character, and Fixed-Length Interfaces ................. 9
3.1.5 Interface Numbering ......................................... 11
3.1.6 Counter Size ................................................ 15
3.1.7 Interface Speed ............................................. 17
3.1.8 Multicast/Broadcast Counters ................................ 18
3.1.9 Trap Enable ................................................. 19
3.1.10 Addition of New ifType values .............................. 19
3.1.11 InterfaceIndex Textual Convention .......................... 19
3.1.12 New states for IfOperStatus ................................ 20
3.1.13 IfAdminStatus and IfOperStatus ............................. 21
3.1.14 IfOperStatus in an Interface Stack ......................... 22
3.1.15 Traps ...................................................... 22
3.1.16 ifSpecific ................................................. 24
3.1.17 Creation/Deletion of Interfaces ............................ 25
3.1.18 All Values Must be Known ................................... 25
4 Media-Specific MIB Applicability ................................ 27
5 Overview ........................................................ 28
6 Interfaces Group Definitions .................................... 29
7 Acknowledgements ................................................ 73
8 References ...................................................... 73
9 Security Considerations ......................................... 76
10 Authors' Addresses ............................................. 76
11 Changes from RFC 2233 .......................................... 78
12 Notice on Intellectual Property ................................ 79
13 Full Copyright Statement ....................................... 79
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