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RFC2233 - The Interfaces Group MIB using SMIv2

王朝other·作者佚名  2008-05-31
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Network Working Group K. McCloghrie

Request for Comments: 2233 Cisco Systems

Obsoletes: 1573 F. Kastenholz

Category: Standards Track FTP Software

November 1997

The Interfaces Group MIB using SMIv2

Status of this Memo

This document specifies an Internet standards track protocol for the

Internet community, and requests discussion and suggestions for

improvements. Please refer to the current edition of the "Internet

Official Protocol Standards" (STD 1) for the standardization state

and status of this protocol. Distribution of this memo is unlimited.

Copyright Notice

Copyright (C) The Internet Society (1997). All Rights Reserved.

Table of Contents

1 IntrodUCtion .............................................. 2

2 The SNMP Network Management Framework ..................... 2

2.1 Object Definitions ...................................... 3

3 EXPerience with the Interfaces Group ...................... 3

3.1 Clarifications/Revisions ................................ 3

3.1.1 Interface Sub-Layers .................................. 4

3.1.2 Guidance on Defining Sub-layers ....................... 6

3.1.3 Virtual Circuits ...................................... 8

3.1.4 Bit, Character, and Fixed-Length Interfaces ........... 8

3.1.5 Interface Numbering ................................... 10

3.1.6 Counter Size .......................................... 14

3.1.7 Interface Speed ....................................... 16

3.1.8 Multicast/Broadcast Counters .......................... 17

3.1.9 Trap Enable ........................................... 18

3.1.10 Addition of New ifType values ........................ 18

3.1.11 InterfaceIndex Textual Convention .................... 18

3.1.12 New states for IfOperStatus .......................... 19

3.1.13 IfAdminStatus and IfOperStatus ....................... 20

3.1.14 IfOperStatus in an Interface Stack ................... 21

3.1.15 Traps ................................................ 21

3.1.16 ifSpecific ........................................... 23

3.1.17 Creation/Deletion of Interfaces ...................... 24

3.1.18 All Values Must be Known ............................. 24

4 Media-Specific MIB Applicability .......................... 25

5 Overview .................................................. 26

6 Interfaces Group Definitions .............................. 26

7 Acknowledgements .......................................... 64

8 References ................................................ 64

9 Security Considerations ................................... 65

10 Authors' Addresses ....................................... 65

11 Full Copyright Statement ................................. 66

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, 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 previous model used for the 'interfaces' group.

This memo also includes a MIB module. As well as including new

MIB definitions to support the architectural extensions, this MIB

module also re-specifies the 'interfaces' group of MIB-II in a

manner that is both compliant to the SNMPv2 SMI and semantically-

identical to the existing SNMPv1-based definitions.

The key Words "MUST" and "MUST NOT" in this document are to be

interpreted as described in RFC2119 [10].

2. The SNMP Network Management Framework

The SNMP Network Management Framework presently consists of three

major components. They are:

o RFC1902 which defines the SMI, the mechanisms used for

describing and naming objects for the purpose of management.

o STD 17, RFC1213 defines MIB-II, the core set of managed

objects for the Internet suite of protocols.

o STD 15, RFC1157 and RFC1905 which define two versions of

the protocol used for network Access to managed objects.

The Framework permits new objects to be defined for the purpose of

experimentation and evaluation.

2.1. Object Definitions

Managed objects are accessed via a virtual information store,

termed the Management Information Base or MIB. Objects in the MIB

are defined using the subset of Abstract Syntax Notation One

(ASN.1) defined in the SMI. In particular, each object object

type is named by an OBJECT IDENTIFIER, an administratively

assigned name. The object type together with an object instance

serves to uniquely identify a specific instantiation of the

object. For human convenience, we often use a textual string,

termed the descriptor, to refer to the object type.

3. Experience with the Interfaces Group

One of the strengths of internetwork-layer protocols such as IP

[6] 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

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 RFC1229 [7].

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

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

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.

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.

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 [9].

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.

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

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.

(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.

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 to 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

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.

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 reinitialization 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 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 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 used. 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 used and 64-bit octet counters MUST be used. For interfaces

that operate at 650,000,000 bits/second or faster, 64-bit packet

counters AND 64-bit octet counters MUST be used.

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,

- 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.

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 [7] 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 RFC1229,

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.

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/Down 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/Down 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/Down 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.

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.

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 presumably 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.

(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.

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 on just after ifOperStatus leaves, or just before it

enters, the down state, respectively; except that LinkUp and linkDown

traps never generated on transitions to/from the notPresent state.

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 rate- limit its

generation of 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.

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 [2] 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 [8] 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

[8]). 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).

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.

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.

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.

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.

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 FROM SNMPv2-CONF

snmpTraps FROM SNMPv2-MIB

IANAifType FROM IANAifType-MIB;

ifMIB MODULE-IDENTITY

LAST-UPDATED "9611031355Z"

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 RFC1229."

REVISION "9602282155Z"

DESCRIPTION

"Revisions made by the Interfaces MIB WG."

REVISION "9311082155Z"

DESCRIPTION

"Initial revision, published as part of RFC1573."

::= { mib-2 31 }

ifMIBObjects OBJECT IDENTIFIER ::= { ifMIB 1 }

interfaces OBJECT IDENTIFIER ::= { mib-2 2 }

OwnerString ::= TEXTUAL-CONVENTION

DISPLAY-HINT "255a"

STATUS current

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 on 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)

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)

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 }

::= { 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

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."

::= { 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

-- 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 }

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 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

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 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

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

1903. 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 ::=

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 }

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

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

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 }

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 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 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 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 }

-- The Interface Stack Group

--

-- Implementation of this group is mandatory 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 other sub-layer. Each sub-layer

corresponds to a conceptual row in the ifTable."

INDEX { ifStackHigherLayer, ifStackLowerLayer }

::= { ifStackTable 1 }

IfStackEntry ::=

SEQUENCE {

ifStackHigherLayer Integer32,

ifStackLowerLayer Integer32,

ifStackStatus RowStatus

}

ifStackHigherLayer OBJECT-TYPE

SYNTAX Integer32

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 Integer32

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

"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 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

"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 }

-- definition of interface-related traps.

linkDown NOTIFICATION-TYPE

OBJECTS { ifIndex, ifAdminStatus, ifOperStatus }

STATUS current

DESCRIPTION

"A linkDown trap signifies that the SNMPv2 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 linkDown trap signifies that the SNMPv2 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 }

-- conformance information

ifConformance OBJECT IDENTIFIER ::= { ifMIB 2 }

ifGroups OBJECT IDENTIFIER ::= { ifConformance 1 }

ifCompliances OBJECT IDENTIFIER ::= { ifConformance 2 }

-- compliance statements

ifCompliance2 MODULE-COMPLIANCE

STATUS current

DESCRIPTION

"The compliance statement for SNMPv2 entities which

have network interfaces."

MODULE -- this module

MANDATORY-GROUPS { ifGeneralInformationGroup, ifStackGroup2,

ifCounterDiscontinuityGroup }

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 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)."

OBJECT ifAlias

MIN-ACCESS read-only

DESCRIPTION

"Write access is not required."

::= { ifCompliances 2 }

-- 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,

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."

::= { 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 }

-- 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

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 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, 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)'."

::= { 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 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

1903. 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 }

-- 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 }

-- Deprecated Definitions - Compliance

ifCompliance MODULE-COMPLIANCE

STATUS deprecated

DESCRIPTION

"The previous compliance statement for SNMPv2 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."

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 }

END

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] Case, J., McCloghrie, K., Rose, M., and

S. Waldbusser, "Structure of Management Information for

version 2 of the Simple Network Management Protocol

(SNMPv2)", RFC1902, January 1996.

[2] Case, J., McCloghrie, K., Rose, M., and

S. Waldbusser, "Textual Conventions for version 2 of the

Simple Network Management Protocol (SNMPv2)", RFC1903,

January 1996.

[3] Case, J., McCloghrie, K., Rose, M., and

S. Waldbusser, "Protocol Operations for version 2 of the

Simple Network Management Protocol (SNMPv2)", RFC1905,

January 1996.

[4] McCloghrie, K., and M. Rose, "Management Information Base for

Network Management of TCP/IP-based internets - MIB-II", STD

17, RFC1213, March 1991.

[5] Case, J., Fedor, M., Schoffstall, M., and J. Davin, "Simple

Network Management Protocol", STD 15, RFC1157, May 1990.

[6] Postel, J., "Internet Protocol", STD 5, RFC791, September 1981.

[7] McCloghrie, K., "Extensions to the Generic-Interface MIB", RFC

1229, May 1991.

[8] ATM Forum Technical Committee, "LAN Emulation Client

Management: Version 1.0 Specification", af-lane-0044.000, ATM

Forum, September 1995.

[9] Stewart, B., "Definitions of Managed Objects for Character

Stream Devices using SMIv2", RFC1658, July 1994.

[10] Bradner, S., "Key words for use in RFCs to Indicate

Requirements Levels", RFC2119, March 1997.

9. Security Considerations

This MIB contains both readable objects whose values provide the

number and status of a device's network interfaces, and write-able

objects which allow an administrator to control the interfaces and to

perform tests on the interfaces. Unauthorized access to the readable

objects is relatively innocuous. Unauthorized access to the write-

able objects could cause a denial of service, or in combination with

other (e.g., physical) security breaches, could cause unauthorized

connectivity to a device.

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

FTP Software

2 High Street

North Andover, Mass. USA 01845

Phone: 508-685-4000

EMail: kasten@ftp.com

11. Full Copyright Statement

Copyright (C) The Internet Society (1997). 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 implementation 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 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.

 
 
 
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