rfc1407.txt
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Trunk MIB Working Group [Page 6]
RFC 1407 DS3/E3 MIB January 1993
ifIndex (= dsx3IfIndex) dsx3LineIndex
1 Line#A Network Side 1
2 Line#A RouterSide 2
3 Line#B Network Side 3
4 Line#B RouterSide 4
5 Line#C Network Side 5
6 Line#C Router Side 6
7 Line#D Network Side 7
8 Line#D Router Side 8
3.2. 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.
3.3. 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
definitions from the ANSI T1M1.3/92-005R1 draft standard [12]. If
the definition in this document does not match the definition in the
ANSI T1M1.3/92-005R1 draft document, the implementer should follow
the definition described in this document.
3.3.1. 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.
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.
Line Coding Violation (LCV) Error Event
This parameter is a count of both BPVs and EXZs
occurring over the accumulation period. An EXZ
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RFC 1407 DS3/E3 MIB January 1993
increments the LCV by one regardless of the length
of the zero string.
P-bit Coding Violation (PCV) Error Event
For all DS3 applications, a coding violation error
event is a P-bit
Parity Error event. A P-bit Parity Error event is the
occurrence of a received P-bit code on the DS3 M-frame
that is not identical to the corresponding locally-
calculated code.
C-bit Coding Violation (CCV) Error Event
For C-bit Parity and SYNTRAN DS3 applications, this is
the count of coding violations reported via the C-bits.
For C-bit Parity, it is a count of CP-bit parity errors
occurring in the accumulation interval. For SYNTRAN, it
is a count of CRC-9 errors occurring in the accumulation
interval.
3.3.2. Performance Parameters
All performance parameters are accumulated in fifteen minute
intervals and up to 96 intervals (24 hours worth) are kept by an
agent. Fewer than 96 intervals of data will be available if the
agent has been restarted within the last 24 hours. In addition,
there is a rolling 24-hour total of each performance parameter.
There is no requirement for an agent to ensure fixed relationship
between the start of a fifteen minute interval and any wall clock;
however some agents may align the fifteen minute intervals with
quarter hours.
Line Errored Seconds (LES)
A Line Errored Second is a second in
which one or more CVs occurred OR one or more LOS defects.
P-bit Errored Seconds (PES)
An PES is a second with one or more PCVs OR
one or more Out of Frame defects OR a detected incoming AIS.
This gauge is not incremented when UASs are counted.
P-bit Severely Errored Seconds (PSES)
A PSES is a second with 44 or more PCVs OR
one or more Out of Frame defects OR a detected incoming AIS.
This gauge is not incremented when UASs are counted.
C-bit Errored Seconds (CES)
An CES is a second with one or more CCVs OR
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RFC 1407 DS3/E3 MIB January 1993
one or more Out of Frame defects OR a detected incoming AIS.
This count is only for the SYNTRAN and C-bit Parity DS3
applications. This gauge is not incremented when UASs are
counted.
C-bit Severely Errored Seconds (CSES)
A CSES is a second with 44 or more CCVs OR
one or more Out of Frame defects OR a detected incoming AIS.
This count is only for the SYNTRAN and C-bit Parity DS3
applications. This gauge is not incremented when UASs
are counted.
Severely Errored Framing Seconds (SEFS)
A SEFS is a second with one or more Out of Frame defects
OR a detected incoming AIS.
Unavailable Seconds (UAS)
UAS are calculated by counting the number of seconds that
the interface is unavailable. The DS3 interface is said
to be unavailable from the onset of 10 contiguous PSESs, or
the onset of the condition leading to a failure (see Failure
States). If the condition leading to the failure was
immediately preceded by one or more contiguous PSESs, then
the DS3 interface unavailability starts from the onset of
these PSESs. Once unavailable, and if no failure is
present, the DS3 interface becomes available at the onset
of 10 contiguous seconds with no PSESs. Once unavailable,
and if a failure is present, the DS3 interface becomes
available at the onset of 10 contiguous seconds with no
PSESs, if the failure clearing time is less than
or equal to 10 seconds. If the failure clearing time is
more than 10 seconds, the DS3 interface becomes available
at the onset of 10 contiguous seconds with no PSESs, or
the onset period leading to the successful clearing
condition, whichever occurs later. With respect to the
DS3 error counts, all counters are incremented
while the DS3 interface is deemed available. While the
interface is deemed unavailable, the only count that is
incremented is UASs.
A special case exists when the 10 or more second period
crosses the 900 second statistics window boundary, as the
foregoing description implies that the PSES and UAS
counters must be adjusted when the Unavailable Signal
State is entered. Clearly, successive GETs of the
affected dsx3IntervalPSESs and dsx3IntervalUASs objects
will return differing values if the first GET occurs
during the first few seconds of the window. This is
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RFC 1407 DS3/E3 MIB January 1993
viewed as an unavoidable side-effect of selecting the
presently defined managed objects as a basis for this
memo.
3.3.3. Performance Defects
Failure States:
The Remote Alarm Indication (RAI) failure, in SYNTRAN
applications, is declared after detecting
the Yellow Alarm Signal on the alarm channel. See ANSI
T1.107a-1990 [10]. The Remote Alarm Indication failure,
in C-bit Parity DS3 applications, is declared
as soon as the preqsence of either one or two alarm signals
are detected on then Far End Alarm Channel. See [10].
The Remote Alarm Indication failure may also be declared
after detecting the far-end SEF/AIS defect (aka yellow).
The Remote Alarm Indication failure is cleared as soon as
the presence of the any of the above alarms are removed.
Also, the incoming failure state is declared when a defect
persists for at least 2-10 seconds. The defects are
the following: Loss of Signal (LOS), an Out of Frame (OOF)
or an incoming Alarm Indication Signal (AIS).
The Failure State is cleared when the defect is absent
for less than or equal to 20 seconds.
Far End SEF/AIS defect (aka yellow)
A Far End SEF/AIS defect is the occurrence of the two X-bits
in a M-frame set to zero. The Far End SEF/AIS defect is
terminated when the two X-bits in a M-frame are set to
one.
Out of Frame (OOF) defect
A DS3 OOF defect is detected when any three or more errors
in sixteen or fewer consecutive F-bits occur within a DS3
M-frame. An OOF defect may also be called a Severely
Errored Frame (SEF) defect. An OOF defect is cleared when
reframe occurs. A DS3 Loss of Frame (LOF) failure is
declared when the DS3 OOF defect is consistent for 2 to 10
seconds. The DS3 OOF defect ends when reframe occurs.
The DS3 LOF failure is cleared when the DS3 OOF
defect is absent for 10 to 20 seconds.
An E3 OOF defect is detected when four consecutive frame
alignment signals have been incorrectly received in there
predicted positions in an E3 signal. E3 frame alignment
occurs when the presence of three consecutive frame
alignment signals have been detected.
Trunk MIB Working Group [Page 10]
RFC 1407 DS3/E3 MIB January 1993
Loss of Signal (LOS) defect
The DS3 LOS defect is declared upon observing 175 +/- 75
contiguous pulse positions with no pulses of either
positive or negative polarity.
The DS3 LOS defect is terminated upon observing an average
pulse density of at least 33% over a period of 175 +/- 75
contiguous pulse positions starting with the receipt of a
pulse.
Alarm Indication Signal (AIS) defect
The DS3 AIS is framed with "stuck stuffing." This implies
that it has a valid M-subframe alignments bits, M-frame
alignment bits, and P bits. The information bits are set
to a 1010... sequence, starting with a one (1) after each
M-subframe alignment bit, M-frame alignment bit, X bit, P
bit, and C bit. The C bits are all set to zero giving
what is called "stuck stuffing." The X bits are set to
one. The DS3 AIS defect is declared after DS3 AIS is
present in contiguous M-frames for a time equal to or
greater than T, where 0.2 ms <= T <= 100 ms.
The DS3 AIS defect is terminated after AIS is absent in
contiguous M-frames for a time equal to or greater than T.
The E3 binary content of the AIS is nominally a continuous
stream of ones. AIS detection and the application of
consequent actions, should be completed within a time
limit of 1 ms.
3.3.4. Other Terms
Circuit Identifier
This is a character string specified by the circuit
vendor, and is useful when communicating with the vendor
during the troubleshooting process.
Trunk MIB Working Group [Page 11]
RFC 1407 DS3/E3 MIB January 1993
4. Object Definitions
RFC1407-MIB DEFINITIONS ::= BEGIN
IMPORTS
Gauge
FROM RFC1155-SMI
DisplayString, transmission
FROM RFC1213-MIB
OBJECT-TYPE
FROM RFC-1212;
-- This MIB module uses the extended OBJECT-TYPE macro
-- as defined in RFC 1212.
ds3 OBJECT IDENTIFIER ::= { transmission 30 }
-- The DS3/E3 Near End Group
-- Implementation of this group is mandatory for all
-- systems that attach to a DS3/E3 Interface.
-- The DS3/E3 Near End Group consists of four tables:
-- DS3/E3 Configuration
-- DS3/E3 Current
-- DS3/E3 Interval
-- DS3/E3 Total
-- the DS3/E3 Configuration
dsx3ConfigTable OBJECT-TYPE
SYNTAX SEQUENCE OF Dsx3ConfigEntry
ACCESS not-accessible
STATUS mandatory
DESCRIPTION
"The DS3/E3 Configuration table."
::= { ds3 5 }
dsx3ConfigEntry OBJECT-TYPE
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