Request for Comments: 3896 RAD Data Communications, Ltd.
Obsoletes: 2496 September 2004
Category: Standards Track
Definitions of Managed Objects for the DS3/E3 Interface Type
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 (2004).
Abstract
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 objects used for managing DS3 and E3
interfaces. This document is a companion to the documents that
define Managed Objects for the DS0, DS1/E1/DS2/E2 and Synchronous
Optical Network/Synchronous Digital Hierarchy (SONET/SDH) Interface
Types. This document obsoletes RFC 2496.
Table of Contents
1. The Internet Standard Management Framework. . . . . . . . . . 2
1.1. Changes from RFC 2496 . . . . . . . . . . . . . . . . . 2
1.2. Changes from RFC 1407 . . . . . . . . . . . . . . . . . 3
1.3. Companion Documents . . . . . . . . . . . . . . . . . . 4
2. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Use of ifTable for DS3 Layer . . . . . . . . . . . . . 4
2.2. Usage Guidelines. . . . . . . . . . . . . . . . . . . . 5
2.2.1. Usage of ifStackTable . . . . . . . . . . . . . 5
2.2.2. Usage of Channelization for DS3, DS1, DS0 . . . 7
2.2.3. Usage of Channelization for DS3, DS2, DS1 . . . 8
2.2.4. Usage of Loopbacks . . . . . . . . . . . . . . 9
2.3. Objectives of this MIB Module . . . . . . . . . . . . . 10
2.4. DS3/E3 Terminology . . . . . . . . . . . . . . . . . . 10
2.4.1. Error Events. . . . . . . . . . . . . . . . . . 10
2.4.2. Performance Parameters. . . . . . . . . . . . . 11
2.4.3. Performance Defects . . . . . . . . . . . . . . 14
2.4.4. Other Terms . . . . . . . . . . . . . . . . . . 16
3. Object Definitions . . . . . . . . . . . . . . . . . . . . . . 16
4. Appendix A - Use of the dsx3IfIndex and dsx3LineIndex. . . . . 54
5. Appendix B - The delay approach to Unavailable Seconds . . . . 56
6. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 58
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 58
7.1. Normative References . . . . . . . . . . . . . . . . . . 58
7.2. Informative References . . . . . . . . . . . . . . . . . 59
8. Security Considerations. . . . . . . . . . . . . . . . . . . . 60
9. Author’s Address . . . . . . . . . . . . . . . . . . . . . . . 62
10. Full Copyright Statement . . . . . . . . . . . . . . . . . . . 63
1. The Internet Standard Management Framework
For a detailed overview of the documents that describe the current
Internet-Standard Management Framework, please refer to section 7 of
RFC 3410 [RFC3410].
Managed objects are accessed via a virtual information store, termed
the Management Information Base or MIB. MIB objects are generally
accessed through the Simple Network Management Protocol (SNMP).
Objects in the MIB are defined using the mechanisms defined in the
Structure of Management Information (SMI). This memo specifies a MIB
module that is compliant to the SMIv2, which is described in STD 58,
RFC 2578 [RFC2578], STD 58, RFC 2579 [RFC2579] and STD 58, RFC 2580
[RFC2580].
1.1. Changes from RFC 2496
The changes from [RFC2496] are the following:
(1) The dsx3FracIfIndex SYNTAX matches the description range.
(2) Reference was added to Circuit Identifier object.
(3) Usage of ifStackTable section was updated.
(4) Align the DESCRIPTION clauses of few statistic objects with
the near end definition, the far end definition and with
[RFC3593].
(5) Add new value, dsx3M13, to dsx3LineType.
1.2. Changes from RFC 1407
The changes from RFC 1407 are the following:
(1) The Fractional Table has been deprecated.
(2) This document uses SMIv2.
(3) Values are given for ifTable and ifXTable.
(4) Example usage of ifStackTable is included.
(5) dsx3IfIndex has been deprecated.
(6) The definition of valid intervals has been clarified for the
case where the agent proxied for other devices. In
particular, the treatment of missing intervals has been
clarified.
(7) An inward loopback has been added.
(8) Additional lineStatus bits have been added for Near End in
Unavailable Signal State, Carrier Equipment Out of Service.
(9) A read-write line Length object has been added.
(10) Added a lineStatus last change, trap and enabler.
(11) Textual Conventions for statistics objects have been used.
(12) A new object, dsx3LoopbackStatus, has been introduced to
reflect the loopbacks established on a DS3/E3 interface and
the source to the requests. dsx3LoopbackConfig continues to
be the desired loopback state while dsx3LoopbackStatus
reflects the actual state.
(13) A dual loopback has been added to allow the setting of an
inward loopback and a line loopback at the same time.
(14) An object has been added to indicated whether or not this is
a channelized DS3/E3.
(15) A new object has been added to indicate which DS1 is to set
for remote loopback.
1.3. Companion Documents
This document is a companion to the documents that define
Managed Objects for the DS0 [RFC2494], DS1/E1/DS2/E2
[RFC3895], and Synchronous Optical Network/Synchronous
Digital Hierarchy (SONET/SDH) [RFC3592] Interface Types.
2. Overview
These objects are used when the particular media being used to
realize an interface is a DS3/E3 interface. At present, this applies
to these values of the ifType variable in the Internet-standard MIB:
ds3 (30)
The DS3 definitions contained herein are based on the DS3
specifications in ANSI T1.102-1987 [ANSI-T1.102], ANSI T1.107-1988
[ANSI-T1.107], ANSI T1.107a-1990 [ANSI-T1.107a], and ANSI T1.404-1989
[ANSI-T1.404]. The E3 definitions contained herein are based on the
E3 specifications in CCITT G.751 [CCITT-G.751] and ETSI T/NA(91)18
[ETSI-T/NA(91)18].
2.1. Use of ifTable for DS3 Layer
Only the ifGeneralInformationGroup needs to be supported.
ifTable Object Use for DS3 Layer
===================================================================
ifIndex Interface index.
ifDescr See interfaces MIB [RFC2863]
ifType ds3(30)
ifSpeed Speed of line rate
DS3 - 44736000
E3 - 34368000
ifPhysAddress The value of the Circuit Identifier.
If no Circuit Identifier has been assigned
this object should have an octet string
with zero length.
ifAdminStatus See interfaces MIB [RFC2863]
ifOperStatus See interfaces MIB [RFC2863]
ifLastChange See interfaces MIB [RFC2863]
ifName See interfaces MIB [RFC2863]
ifLinkUpDownTrapEnable Set to enabled(1).
ifHighSpeed Speed of line in Mega-bits per second
(either 45 or 34)
ifConnectorPresent Set to true(1) normally, except for
cases such as DS3/E3 over AAL1/ATM where
false(2) is appropriate
2.2. Usage Guidelines
2.2.1. Usage of ifStackTable
The object dsx3IfIndex has been deprecated. This object previously
allowed a very special proxy situation to exist for Routers and CSUs.
This section now describes how to use ifStackTable to represent this
relationship.
The paragraphs discussing dsx3IfIndex and dsx3LineIndex have been
preserved in Appendix A for informational purposes.
The ifStackTable is used in the proxy case to represent the
association between pairs of interfaces, e.g., this DS3 is attached
to that DS3. This use is consistent with the use of the ifStackTable
to show the association between various sub-layers of an interface.
In both cases entire PDUs are exchanged between the interface pairs -
in the case of a DS3, entire DS3 frames are exchanged; in the case of
PPP and HDLC, entire HDLC frames are exchanged. This usage is not
meant to suggest the use of the ifStackTable to represent Time
Division Multiplexing (TDM) connections in general.
External&Internal interface scenario: the SNMP Agent resides on a
host external from the device supporting DS3/E3 interfaces (e.g., a
router). The Agent represents both the host and the DS3/E3 device.
Example:
A shelf full of CSUs connected to a Router. An SNMP Agent residing
on the router proxies for itself and the CSU. The router has also an
Ethernet interface:
+-----+
| | |
| | | +---------------------+
|E | | 44.736 MBPS | ds3 M13 Line#A | ds3 C-bit Parity
|t | R |---------------+ - - - - - - - - - +------>
|h | | | |
|e | O | 44.736 MBPS | ds3 M13 Line#B | ds3 C-bit Parity
|r | |---------------+ - - - - - - - - - - +------>
|n | U | | |
|e | | 44.736 MBPS | ds3 M13 Line#C | ds3 C-bit Parity
|t | T |---------------+ - - - -- -- - - - - +------>
| | | | |
|-----| E | 44.736 MBPS | ds3 M13 Line#D | ds3 C-bit Parity
| | |---------------+ - - - - -- - - - - +------>
| | R | |_____________________|
| | |
| +-----+
The assignment of the index values could for example be:
ifIndex Description
1 Ethernet
2 Line#A Router
3 Line#B Router
4 Line#C Router
5 Line#D Router
6 Line#A CSU Router
7 Line#B CSU Router
8 Line#C CSU Router
9 Line#D CSU Router
10 Line#A CSU Network
11 Line#B CSU Network
12 Line#C CSU Network
13 Line#D CSU Network
The ifStackTable is then used to show the relationships between the
various DS3 interfaces.
ifStackTable Entries
HigherLayer LowerLayer
2 6
3 7
4 8
5 9
6 10
7 11
8 12
9 13
If the CSU shelf is managed by itself by a local SNMP Agent, the
situation would be identical, except the Ethernet and the 4 router
interfaces are deleted. Interfaces would also be numbered from 1 to
8.
ifIndex Description
1 Line#A CSU Router
2 Line#B CSU Router
3 Line#C CSU Router
4 Line#D CSU Router
5 Line#A CSU Network
6 Line#B CSU Network
7 Line#C CSU Network
8 Line#D CSU Network
ifStackTable Entries
HigherLayer LowerLayer
1 5
2 6
3 7
4 8
2.2.2. Usage of Channelization for DS3, DS1, DS0
An example is given here to explain the channelization objects in the
DS3, DS1, and DS0 MIBs to help the implementor use the objects
correctly. Treatment of E3 and E1 would be similar, with the number
of DS0s being different depending on the framing of the E1.
Assume that a DS3 (with ifIndex 1) is Channelized into DS1s (without
DS2s). The object dsx3Channelization is set to enabledDs1. When
this object is set to enabledDS1, 28 ifEntries of type DS1 will be
created by the agent. If dsx3Channelization is set to disabled, then
the DS1s are destroyed.
Assume the entries in the ifTable for the DS1s are created in channel
order and the ifIndex values are 2 through 29. In the DS1 MIB, there
will be an entry in the dsx1ChanMappingTable for each ds1. The
entries will be as follows:
dsx1ChanMappingTable Entries
ifIndex dsx1Ds1ChannelNumber dsx1ChanMappedIfIndex
1 1 2
1 2 3
......
1 28 29
In addition, the DS1s are channelized into DS0s. The object
dsx1Channelization is set to enabledDS0 for each DS1. There will be
24 DS0s in the ifTable for each DS1. Assume the entries in the
ifTable are created in channel order and the ifIndex values for the
DS0s in the first DS1 are 30 through 53. In the DS0 MIB [RFC2494],
there will be an entry in the dsx0ChanMappingTable for each DS0. The
entries will be as follows:
dsx0ChanMappingTable Entries
ifIndex dsx0Ds0ChannelNumber dsx0ChanMappedIfIndex
2 1 30
2 2 31
......
2 24 53
2.2.3. Usage of Channelization for DS3, DS2, DS1
An example is given here to explain the channelization objects in the
DS3 and DS1 MIBs to help the implementor use the objects correctly.
Assume that a DS3 (with ifIndex 1) is Channelized into DS2s. The
object dsx3Channelization is set to enabledDs2. There will be 7 DS2s
(ifType of DS1) in the ifTable. Assume the entries in the ifTable
for the DS2s are created in channel order and the ifIndex values are
2 through 8. In the DS1 MIB [RFC3895], there will be an entry in the
dsx1ChanMappingTable for each DS2. The entries will be as follows:
dsx1ChanMappingTable Entries
ifIndex dsx1Ds1ChannelNumber dsx1ChanMappedIfIndex
1 1 2
1 2 3
......
1 7 8
In addition, the DS2s are channelized into DS1s. The object
dsx1Channelization is set to enabledDS1 for each DS2. There will be
4 DS1s in the ifTable for each DS2. Assume the entries in the
ifTable are created in channel order and the ifIndex values for the
DS1s in the first DS2 are 9 through 12, then 13 through 16 for the
second DS2, and so on. In the DS1 MIB, there will be an entry in the
dsx1ChanMappingTable for each DS1. The entries will be as follows:
dsx1ChanMappingTable Entries
ifIndex dsx1Ds1ChannelNumber dsx1ChanMappedIfIndex
2 1 9
2 2 10
2 3 11
2 4 12
3 1 13
3 2 14
...
8 4 36
2.2.4. Usage of Loopbacks
This section discusses the behaviour of objects related to loopbacks.
The object dsx3LoopbackConfig represents the desired state of
loopbacks on this interface. Using this object a Manager can
request:
LineLoopback
PayloadLoopback (if ESF framing)
InwardLoopback
DualLoopback (Line + Inward)
NoLoopback
The remote end can also request lookbacks either through the FDL
channel if ESF or inband if D4. The loopbacks that can be requested
this way are:
LineLoopback
PayloadLoopback (if ESF framing)
NoLoopback
To model the current state of loopbacks on a DS3 interface, the
object dsx3LoopbackStatus defines which loopback is currently applied
to an interface. This object, which is a bitmap, will have bits
turned on which reflect the currently active loopbacks on the
interface as well as the source of those loopbacks.
The following restrictions/rules apply to loopbacks:
The far end cannot undo loopbacks set by a manager.
A manager can undo loopbacks set by the far end.
Both a line loopback and an inward loopback can be set at the same
time. Only these two loopbacks can co-exist and either one may be
set by the manager or the far end. A LineLoopback request from the
far end is incremental to an existing Inward loopback established by
a manager. When a NoLoopback is received from the far end in this
case, the InwardLoopback remains in place.
2.3. Objectives of this MIB Module
There are numerous things that could be included in a MIB for DS3/E3
signals: the management of multiplexors, CSUs, DSUs, and the like.
The intent of this document is to facilitate the common management of
all devices with DS3/E3 interfaces. As such, a design decision was
made up front to very closely align the MIB with the set of objects
that can generally be read from DS3/E3 devices that are currently
deployed.
2.4. DS3/E3 Terminology
The terminology used in this document to describe error conditions on
a DS3 interface as monitored by a DS3 device are based on the late
but not final draft of what became the ANSI T1.231 standard [ANSI-
T1.231]. If the definition in this document does not match the
definition in the ANSI T1.231 document, the implementer should follow
the definition described in this document.
2.4.1. Error Events
Bipolar Violation (BPV) Error Event
A bipolar violation error event, for B3ZS(HDB3)-coded signals,
is the occurrence of a pulse of the same polarity as the
previous pulse without being part of the zero substitution
code, B3ZS(HDB3). For B3ZS(HDB3)-coded signals, a bipolar
violation error event may also include other error patterns
such as: three(four) or more consecutive zeros and incorrect
polarity (See T1.231 section 7.1.1.1.1).
Excessive Zeros (EXZ) Error Event
An EXZ is the occurrence of any zero string length equal to or
greater than 3 for B3ZS, or greater than 4 for HDB3 (See T1.231
section 7.1.1.1.2).
Line Coding Violation (LCV) Error Event
This parameter is a count of both BPVs and EXZs occurring over