Transport Network OAM Availability performance parameters Error performance parameters Bringingintos

1
Transport Network OAM- Availability performance
parameters - Error performance parameters -
Bringing-into-service and maintenance- Tandem
connection monitoring - Fault and Performance
Management Architectures within the Network
Element

• Maarten Vissers
• February 2008

To be Added OAM to support DCN (G.7712), OAM to
support synchronization (G.803, G.826x series)
2
Transport Network OAM Functions
3
T-MPLS layer networks
Customer/Client layer
mp2mp rmp
p2p p2mp
T-MPLS Channel layer
ETH Channel layer
T-MPLS Path layer
T-MPLS Section layer
T-MPLS layer networks
GFP
Physical Media (802.3)
Circuit Switching Technology (OTN, SDH, PDH)
Transmission Media
Physical Media (OTM-n, STM-N, DSn/En, xDSL)
T-MPLS Transport Module (TTM-n)
4
Availability ratio and unavailability ratio
(G.827)

• availability ratio (AR)
• is the proportion of time that a path is in the
  available state during an observation period. AR
  is calculated by dividing the total available
  time during the observation period by the
  duration of the observation period.
• unavailability ratio (UR)
• is the proportion of time that an end-to-end path
  is in the unavailable state during an observation
  period. UR is calculated by dividing the total
  unavailable time during the observation period by
  the duration of the observation period.
• observation period
• recommended to be one year
• outage intensity (OI)
• The number of outages (i.e. periods of
  unavailability ) per measurement period

5
Criteria for entry and exit for the unavailable
state (G.826, M.2100)

• A period of unavailable time begins at the onset
  of ten consecutive SES events. These ten seconds
  are considered to be part of unavailable time.
• A new period of available time begins at the
  onset of ten consecutive non-SES events. These
  ten seconds are considered to be part of
  available time.
• A bidirectional path or connection is in the
  unavailable state if either one or both
  directions are in the unavailable state.

6
Error performance parameters (G.826)

• errored second ratio (ESR)
• The ratio of ES to total seconds in available
  time during a fixed measurement interval.
• severely errored second ratio (SESR)
• The ratio of SES to total seconds in available
  time during a fixed measurement interval.
• background block error ratio (BBER)
• The ratio of Background Block Errors (BBE) to
  total blocks in available time during a fixed
  measurement interval. The count of total blocks
  excludes all blocks during SESs.
• G.7710 Severely Errored Period Intensity (SEPI)
• The number of SEP events in available time,
  divided by the total available time in seconds
  during a fixed measurement interval.

7
Error performance events (G.826, G.829)

• errored block (EB)
• A block in which one or more bits are in error.
• errored second (ES)
• A one-second period with one or more errored
  blocks or at least one defect.
• severely errored second (SES)
• A one-second period which contains  X errored
  blocks or at least one defect. SES is a subset of
  ES.
• background block error (BBE)
• An errored block not occurring as part of an SES.
• consecutive severely errored second (CSES) period
• A sequence of between three to nine consecutive
  SES. The sequence is terminated by a second,
  which is not a SES.

8
QoS performance parameters and NE measurements
(G.7710)
9
Bringing into service (M.2110)

• For bringing transmission entities into service,
  several tests are necessary according to the
  concerned transmission entity.
• These tests consist of recording the number of
  occurrences of performance events over a certain
  duration and comparing the result with a limit
  value.
• Limit values are different according to the type
  of tests and the tested transmission entity.
  These limits are defined for each performance
  event and for each test in the specific
  technology Recommendations.
• Tests 15 m, 2 h and 24 h should be applied to
  each direction of transmission.
• Wherever possible, the per-direction measurement
  configuration should be used.
• For a bidirectional path or section, the test is
  considered passed if both directions meet the
  limits, or failed if either direction fails the
  limit.

10
Bringing into service (M.2110)

• Continuity test
• This test consists of verifying the continuity of
  the link, during a short period of time (15
  minutes maximum). For a per-direction
  measurement, the continuity test consists of
  sending bit errors with a test set at both
  termination points.
• Test15m
• This test consists of recording the number of
  occurrences of each performance event for a time
  period of 15 minutes and comparing the result
  with a single limit value, named S15.
• Test2h
• This test consists of recording the number of
  occurrences of each performance event for a time
  period of 2 hours and comparing the result with a
  single limit value, named S2.
• Test24h
• This test consists of recording the number of
  occurrences for each performance event for a time
  period of 24 hours and comparing the result with
  a single limit value, named S24.

11
Maintenance limits and System restoration limit
(M.2100)

• Once entities have been placed into service,
  supervision of the network requires additional
  limits, as described in ITU-T M.20.
• This supervision is done on an in-service basis
  using performance monitoring equipment.
• The supervision process involves analyzing
  anomalies and defects detected by maintenance
  entities to determine if the performance level is
  normal, degraded, or unacceptable.
• A limit on performance after intervention
  (repair) is required it is equal to the BIS
  limit.

12
Performance limits for maintenance (M.2100)

• Unacceptable performance level
• An unacceptable performance level is defined in
  ITU-T M.20. The unacceptable performance limit
  for a given entity is derived from an objective
  of at least 10 times the APO during a 15-minute
  period.
• Degraded performance level
• A degraded performance level is defined in ITU-T
  M.20. The degraded performance limit for a given
  entity is derived from an objective on the order
  of 0.5 times the APO for transmission systems and
  0.75 times the APO for paths. The monitoring
  duration is a fixed duration of 24 hours.
• Performance limit after intervention (repair)
• This performance limit is derived from an
  objective in the order of 0.125 times the APO for
  transmission systems and the same as the BIS
  limit for paths (see ITU-T M.35 and ITU-T
  M.2110).

13
Performance thresholds (M.2100)

• Performance limits are defined for ES and SES.
  Each performance level will have its own
  threshold to detect crossing of the limit and
  will require its own measurement duration.
• Use of thresholds
• The general strategy for the use of performance
  monitoring information and thresholds is
  described in ITU-T M.20 and ITU-T M.34. These
  thresholds and information will be reported to
  operations systems via the TMN for both real time
  and longer term analysis. When thresholds of
  unacceptable or degraded performance levels are
  exceeded, maintenance action should be initiated
  independently of the performance measurement.
  Other thresholds may be used for longer term
  quality analysis. The operations systems will use
  real-time processing to assign maintenance
  priorities to these thresholds and information,
  using the performance supervision process
  described in ITU-T M.20.
• Thresholds based on a T1 evaluation period
• The monitoring duration T1 is 15-minutes and ES
  and SES are counted over this period. The T1
  period is to assist in detection of transition to
  or from the unacceptable performance.
• A threshold report occurs when an ES or SES
  threshold is met or exceeded. The reset threshold
  report, which is an optional feature, occurs when
  the number of ES and SES is lower than or equal
  to the reset threshold. Those principles are
  explained in ITU-T M.2120.
• Thresholds based on a T2 evaluation period
• The monitoring duration T2 is fixed to a 24-hour
  value. The T2 period is to assist in detection of
  transition to the degraded performance.
• A threshold report occurs when an ES or SES
  threshold is met or exceeded over the period of
  time T2 as explained in ITU-T M.2120.

14
Tandem connection monitoring (G.805)

• A tandem connection represents the part of a
  trail that requires monitoring independently from
  the monitoring of the complete trail. In this
  role, the following functions may be required by
  the tandem connection
• tandem connection near end fault management and
  performance monitoring (error performance and
  failure/alarm conditions)
• tandem connection far end fault management and
  performance monitoring (error performance and
  failure/alarm conditions)
• tandem connection monitoring independent of
  incoming server signal fail indication (AIS,
  FDI)
• tandem connection incoming signal fail indication
  (signal fail before the tandem connection)
• tandem connection connectivity verification (i.e.
  trace) (between the ends of the tandem
  connection)
• tandem connection continuity verification (i.e.
  loss of signal, unequipped, loss of continuity)
  (between the ends of the tandem connection)
• tandem connection near end outgoing signal
  monitoring in order to allow localization of
  faults and errors in white spot areas between two
  successive tandem connection domains
• tandem connection far end outgoing signal
  monitoring in order to allow localization of
  faults and errors in white spot areas between two
  successive tandem connection domains
• tandem connection idle signal (including idle
  signal identity).

15
Three applications of tandem connections (G.805)

• serving operator administrative domain (e.g.
  public network domain, network operator domain,
  network operator subnetwork domain)
• A tandem connection that measures the quality of
  the service delivered to the customer. A serving
  operator administrative domain supporting tandem
  connection has its source as close as possible
  behind the NNI/UNI and its sink as close as
  possible in front of the NNI/UNI
• protected domain (e.g. sublayer monitored SNC
  protection)
• A tandem connection that measures the defect
  status of the working and protection connections.
  A protected domain supporting tandem connection
  has its source behind the protection switch
  bridge and its sink in front of the protection
  switch selector functions
• service requesting administrative domain (e.g.
  user domain)
• A tandem connection that measures the quality of
  the service received from the operator. A service
  requesting administrative domain supporting
  tandem connection has its source as close as
  possible in front of the UNI/NNI and its sink as
  close as possible behind the NNI/UNI.

16
Performance data collection (G.7710)
17
Near-end and Far-end concepts
18
Fault Management and Performance Monitoring
Architecture

• anomaly (nXXX)
• defect (dXXX)
• fault cause (cXXX)
• failure (fXXX)

• alarm
• consequent action (aXXX)
• performance primitives (pXXX)

19
Equipment Management Function process block
diagram (G.7710)
20
Supervision process within adaptation functions
(G.806)
21
Supervision process within termination functions
(G.806)
22
Fault Management inside the EMF (G.7710)
23
Performance Monitoring inside the EMF (G.7710)
24
Performance Monitoring inside the EMF (G.7710)
25
Access to OAM PDUs in T-MPLS networks
ETH Customer frame
label ?16
label ?16, S1
VID
MSDU
TYPE
TPID
ETH Customer OAM
8902
MEL
label ?16, S1
VID
label ?16
TPID
ETH CustomerOAM
8902
MEL
label ?16, S1
VID
label ?16
TPID
8902
MEL
label ?16, S1
label ?16
ETH Channel OAM
14
MEL
label ?16, S0
label ?16
T-MPLS Channel OAM
label ?16
8902
MEL
label ?16, S1
ETH Channel OAM
label ?16
14
MEL
label ?16, S0
T-MPLS Channel OAM
label ?16
14
MEL
T-MPLS Path OAM
label ?16
14
MEL
T-MPLS Path OAM
14
MEL
T-MPLS Section OAM
MATRIX
MATRIX
MATRIX
PHY
NCMEP
ILM
TCMEPMIP
NCMEP
NCMEPTCMEP
ILM
TCMEPMIP
EN-CAP
MIP
MIP
PHY
SuppEISS
NCMEP
TMS
TMP
TMP
TMCorETH
TMCorETH
ETH
ETH
0-15
0-15
unknownlabels
unknownlabels

unreqist.VLAN IDs
26
OAM MEG level and label/VLAN ID based filtering
label based filtering
label based filtering
VLAN ID based filtering
OAM MEG Level based filtering inside MEPs
SW
SW
SW
PHY
NCMEP
ILM
TCMEPMIP
NCMEP
NCMEPTCMEP
ILM
TCMEPMIP
EN-CAP
MIP
MIP
PHY
SuppEISS
TMS
TMP
TMP
TMCorETH
TMCorETH
ETH
ETH
0-15
0-15
unknownlabels
unknownlabels

unreqist.VLAN IDs
27
T-MPLS Basic functions and processes
one or more client signals(ETHn, TDM, MPLS, IP,
T-MPLS, )

• one or more ETHnclient signals

Multiplex (opt.), encapsulate client
signal(s)Insert CW fieldInsert TMC S-bit
(value 1)
Mux (opt.), encap. client signal(s)Insert TPID
field
EHC/ETH
TMC/CL
EHC
TMC
Insert TMC TTL field
Insert ETH OAM (Y.1731) frames
Insert T-MPLS OAM (G.8114) frames
Bridging(non)selectiveforwarding
EHC VLAN
Switchingnon-selective forwarding
TMC
Multiplex ETH signalsInsert CW/LSE fieldsInsert
TMP S-bit field
Multiplex TMC signalsInsert TMC label and EXP
fieldsInsert TMP S-bit field (value 0)
TMP/TMCEHC
TMP
Insert TMP TTL field
Insert T-MPLS OAM (G.8114) frames
TMP
Switchingnon-selective forwarding
Multiplex ETHInsert CW/LSE fieldInsert TMS S-bit
Multiplex TMP signalsInsert TMP label and EXP
fieldsInsert TMS S-bit field
Multiplex TMCTMC label/EXPTMS S-bit
TMS/TMCEHC
TMS/TMP
TMS
TMS
Insert TMS TTL field
Insert T-MPLS OAM (G.8114) frames
Remove TMS TTL/S fields (TMS case only)Insert
label and EXP fields (TMP and TMC cases)Insert
TYPE, SA, DA, PA, SFD, FCS, inter-frame gap
(802.3)Insert GFP-F Core/Payload Headers,
Payload FCS (other)
PHY/TMS
PHY/TMP
PHY/TMS
PHY/TMCEHC
PHY
PHY
PHY
PHY
Note PHY can be 802.3, SDH, OTH or PDH based
physical interface
TTM-n signal
TTM-n signal
TTM-n signal
TTM-n signal
28
T-MPLS Frame structures
mp2mp rmp
p2p p2mp
FCS
FCS
EncapsClientSignal
MSDU
FCS
C-SA
ETHOAMPDU
C-DA
EHC/ETH
TMC/CL
FCS
TMPLSOAMPDU
TMC
EHC
TYPE
0x8902
SA
CW (opt)
DA
TMP/TMCEHC
CW (opt)
FCS
FCS
TTL
TTL
TMPLSOAMPDU
TMPLSOAMPDU
TMP
S
S
QoS
QoS
Label
Label
TMS/TMCEHC
TMS/TMP
FCS
FCS
TTL
TTL
TMPLSOAMPDU
TMPLSOAMPDU
TMS
TMS
S
S
QoS
QoS
Label
Label
PHY/TMS
PHY/TMP
PHY/TMS
PHY/TMCEHC
TYPE
TYPE
GPH
GPH
0x8847
0x8847
PHY
PHY
PHY
PHY
SA
SA
GCH
GCH
DA
DA
GFPinOTNSDHPDH
GFPinOTNSDHPDH
SFD
SFD
PA
PA
TTM-n signal
TTM-n signal
TTM-n signal
TTM-n signal
802.3
802.3
29
References

• M.2100 Performance limits for bringing-into-servic
  e and maintenance of international multi-operator
  PDH paths and connections
• M.2110 Bringing into service international
  multi-operator paths, sections and transmission
  systems
• G.826 End-to-end error performance parameters and
  objectives for international, constant bit-rate
  digital paths and connections
• G.827 Availability performance parameters and
  objectives for end-to-end international constant
  bit-rate digital paths
• G.829 Error performance events for SDH multiplex
  and regenerator sections
• G.805 Generic functional architecture of
  transport networks
• G.806 Characteristics of transport equipment
  Description methodology and generic functionality
• G.7710 Common equipment management function
  requirements