5-ptn trouble shooting

PTN Troubleshooting

Address: No.5, Dongxin Road, Guandong Science Park, Wuhan/ postal code: 430073

E-mail: [email protected]

www.fiberhome.com.cn

Agenda

1.OAM and Its Application

2.Typical Troubleshooting

3. Instrument Detection

4. PTN Engineering Cases

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OAM

OAM (Operation, Administration and Maintenance) refers to the production, organization and management activities to ensure the normal, safe and effective operation of networks and services, called as Operation, Administration and Maintenance or OAM for short.

According to the actual needs of network operators, OAM can be usually classified into 3 types:

Operation

Operation mainly analyzes daily network state, monitors alarms and controls performance.

Management

Management is to analyze, forecast, plan and configure daily network and service.

Maintenance

Maintenance is to conduct such daily operation activities as test and trouble management etc. of the network and its service.

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OAM Classification

According to functions, OAM can be classified into:

Trouble management: trouble testing, trouble classification,

trouble positioning and trouble notification etc.

Performance management: performance monitoring, performance

analysis and performance management and control etc.

Protection and recovery: protection system and recovery system

etc.

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OAM Terms

Management Entity (ME)

An entity in need of management indicates the relation between two MEPs. In T-MPLS , the basic ME is a T-MPLS path. Nest is allowed between MEs, but no overlapping is allowed among more than 2 MEs.

ME Group (MEG)

A group of MEs should meet the following conditions:

Belong to the same management domain;

Belong to the same MEG layer;

Belong to the same point-to-point or point-to-multipoint T-MPLS connection.

For point-to-point T-MPLS connection, a MEG includes a ME. For point-to-N (N>1)-point connection, a MEG includes N MEs.

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OAM Terms

MEG End Point (MEP)

It's used for marking the beginning and ending of a MEG and it can generate and terminate OAM grouping.

MEG Intermediate Point (MIP)

MEG Intermediate Point can not generate OAM group, but it can select special actions for some OAM groups and transmit passing-by T-MPLS frames transparently. MEP and MIP are designated by the management plane or control plane.

MEG Level (MEL)

When many MEGs nest, it is used for distinguishing various MEG OAM groups, and OAM groups in tunnels are processed by adding MELs in source direction and reducing MELs in destination direction.

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7

OAM of PTN in Different Network Areas

Client equipment Client equipment

PTN network

UNI access link LSP layer LSP layer LSP layer LSP layer UNI access link

LSP (tunnel) LSP (tunnel)

PW (pseudo-wire) / LSP (tunnel)

Client service

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8

OAM of PTN on Different Network Layers

T-MPLS channel layer presents PW information and indicates a VC channel; T-MPLS path expresses a T-MPLS tunnel, i.e. LSP; T-MPLS section indicates the sub-layer network of a T-MPLS, protecting the detection on the link layer; in T-MPLS OAM, it respectively correspond to the OAM detection on three layers: TMC, TMP and TMS.

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OAM Frame Structure of PTN

1 2 3 4

1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

1 Label(13) MEL S TTL

5 Function Type Res Version Flags TLV Offset

OAM PDU payload area

last End TLV

OAM information is contained in specific OAM frames and is transmitted in frames.

OAM frame: composed of OAM PDU and external forward label stack items.

Like other data groups, contents of forward label stack items are used for ensuring the correct forward of OAM frames on the path.

Every MEP or MIP just identifies and processes OAM groups on their own layers.

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OAM Frame Format of PTN

Label (14): 20-bit tag value of 14, indicating the OAM tag; MEL: 3-bit MEL with the range of 0-7 S:1-bit S with the value of 1, indicating the label stack bottom; TTL: 8-bit TTL with the value of 1 or the hop +1 from MEP to the designated MIP. The 5th bit is the OAM function type with 8 bits, indicating the function type of OAM. In addition, some of OAM PDUs require to be designated with target MEP or MIP, i.e. MEP or MIP ID. According to different function types, it can be in any of the three formats below: 48-bit MAC address; 13-bit MEG ID and 13-bit MEP/MIP ID; 128-bit IPV6 address.

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OAM Mechanism in T-MPLS Network

OAM functions in T-MPLS network can be classified into alarm OAM function, performance OAM function and other OAM functions.

OAM

Technology Trouble management Performance management

Function

Trouble DetectionTrouble VerificationTrouble Location and Trouble announcement

Performance monitoringAnalysis of performancePerformance management controlStart the trouble management system when the performance fall.

Purpose

Cooperate with network

management system to improve the

reliability and usabilility of network

Maintain the quality of service and the

operation efficiency of network.

Main tools

and method

Check the connection (CC) Alarm indication signal (AIS) Remote defect indication (RDI) Link tracking (LT) Loopback detection (LB) Lock (LCK)Test (TST) Customer signaling failure (CSF)

Loss measurement of Frames Delay measurement of Frames Delay jitter measurement

Page11

Introduction to OAM Type - CC

CC - Continuity and Connectivity Check

It can be used for trouble management, performance monitoring,

protection switching and signal continuity detection between any pair of

MEPs in MEG area.

Frames used for transferring CC information are CV ones and their

main parameters include:

MEG ID

Their own MEP IDs

All target MEP IDs

Transmission period: 3.3ms/10ms/100ms/1s

In case no CV frames can be received within 3.5 times of transmission

period, LOC (loss of continuity) alarms will generate.

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Introduction to OAM Types - AIS, LB and LCK

AIS: Alarm Indication Signal When troubles are detected on the service layer, the client layer shall be

informed.

FDI frames are used for transferring.

Transferring period: 1s

If no more AIS message is received within 3.5 times of receiving period again, AIS alarm shall be cleared.

LB: Loopback Loopback function. MEP is the starting point for Loopback to request for

grouping and the execution point of Loopback can be MEP or MIP.

It's used for verifying the connection in between MEPs or between MEP and MIP.

It is used for bi-directional on-line or off-line diagnosis between MEPs and for testing bandwidth throughout and bit error rate etc.

LBM and LBR

LCK: Lock It's used for informing MEP at the opposite end that MEP at the home end has

interrupted the normal service as required by management.

MEP at the opposite end can judge whether the service interruption is foreseen or caused by troubles.

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Introduction to OAM-TST, CSF, LM and DM

TST: Test Test request signal that is sent to another MEP by one MEP

Unidirectional on-line or off-line diagnostic test

Differences from LB

CSF: Client Signal Fail Notice the far end that client signal fails at the entrance of the home end.

LM: Frame Loss Measurement It's used for testing the unidirectional or bidirectional loss rate from one MEP to another

MEP.

CV frames are used for testing. SD: Performance degradation with an accuracy to one thousandth at most.

DM: Packet Delay and Packet Delay Variation Measurement It's used for testing the packet transfer delay and delay variation from one MEP to another

MEP .

Unidirectional: Clocks at the transmitting and receiving ends are synchronous, source end transmits DM frame and unidirectional time delay is calculated when the destination end receives the DM frame. 1DM frames are used for testing.

Bidirectional: Source end transmits the DM request frames and the destination end shall loopback DM response frames to the source end when receiving the DM . Then when the source end receives the responded DM frames, bidirectional time delay shall be calculated with DMM and DMR.

Page14

Introduction to OAM-APS, MCC, SCC and SSM

APS : Automatic Protection Switching

It's defined by G..8131/G.8132 and used for transmitting APS .

MCC: Management Communication Channel

It's used for transmitting MCC management channel information, TMS layer

SCC : Signaling Communication Channel

Its used by a MEP for transmitting control plane information to its counterpart

MEP.

SSM: Synchronization Status Message

It's defined by G.8261 and used for transmitting SSM frames.

Page15

OAM Operation Corresponding to MEP and MIP

Customer

Equipment

Customer

Equipment PTN Equipment

MEG ID

MEG Layer

Local MEP ID

MEP ID of opposite end

Sending cycle of CC message

CC active

MEP Configuration MIP Configuration

MEG ID

MEG Layer

Local MIP ID

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Positions of Corresponding Layers in PTN Equipment

Page17

OAM Alarm

MMG: Used for receiving mismatching MEG-ID.

UNM: When MEG-ID matches, source MEP-ID of received CV frames mismatch local expectation values.

UNP: When MEG-ID matches the expected MEP-ID, time interval to receive CV frames mismatch s the local transmitting time interval.

LOC: No correct CV frames are received within 3.5 transmitting cycles in a row.

RDI: Used by MEP for informing its counterpart MEP that it has some defects and only used for bidirectional T-MPLS connection. Its

information shall be initiated by the defective MEP and the information

shall be sent to its counterpart MEP periodically until defects are

cleared.

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Summary

Since OAMs of PTN network path can be classified into three OAM layers:

TMS, TMP and TMC, where:

OAM at TMS layer is mainly used for WRAPPING protection and MCC

communication;

OAM at TMP layer is mainly used for LSP1:1/1+1 protection;

OAM at TMC layer is closest to the service layer, therefore OAM frames at

TMC layer can be used for simulation test of service continuity.

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Agenda

Common Troubles of PTN

Trouble I: Unavailable service

Processing steps:

1. Since service package will be multiplexed into PW first when service is transmitted in PTN network, the continuity of wires can be

judged from the continuity of PW layer;

2. If channels on PW layer is of discontinuity, performance method is required to judge which section of the line side the service

interruption occurs on;

3. If channels of PW layer are in continuity, troubles are positioned to add/drop voice service sites of source and destination. At this time,

alarms, status, performance and configuration of card relevant to

source and destination shall be checked emphatically.

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Trouble Example

Trouble description:

FE1 of card ESJ1 at Slot

Position 1F in Office 1

has developed an FE

service to Port FE3 in

Office 9, which is

reflected to be

unavailable.

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Trouble Example

According to the first processing step, it shall detect the continuity of PW

layer first.

Detection means: CV frames in PW configuration

CV frames on PW layer are defaulted to be disabled, therefore, they are

necessary to be opened at both the source end and destination end in the

PW configuration.

Position of PW configuration in single board configuration:

1. 660 low-level service is configured on XCU;

2. 660 high-level service is configured on the corresponding UNI card;

3. All 640 services are configured on XCU;

4. All 620 services are configured on PSSB.

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Trouble Example

According to the service shown in the example, we need to open CV frames

both in ESJ1 in Office 1 and in 620 PW configuration. Corresponding

configurations are as follows:

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Trouble Example

At this time, the 2 conditions below may appear:

1. No TMC_LOC alarms are on service cards of the source and destination sites;

2. TMC_LOC alarms are on all service cards of the source and destination sites, or

TMC_LOC alarms are on the service card of either site.

Description:

Condition 1 indicates that the line channel is continuous, therefore, trouble

causes can be positioned to add/drop voice service sites of the source and

destination. At this time, single card configuration mapping shall be

checked emphatically and performance method is needed to position

trouble points under the condition of correct card configuration mapping;

Condition 2 indicates that the line channel is in discontinuity and trouble

causes may be in the intermediate straight-through sites or the source or

destination of add/drop voice service.

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Condition 1

1. Check whether there are abnormal alarms on the service signal disc first and

alarms about configuration mismatch and unit disc troubles must be handled.

These two kinds of alarms are caused by wrong configurations, therefore

inspection shall be mainly conducted on whether the labels, PW labels, VLAN

ID, simulation serial numbers, LSP-ID and PW-ID being used are repeated.

2. If no obvious alarms for wrong configuration are found, card configuration

mapping shall be inspected, mainly including items such as interface mode,

correlation configuration, VPWS configuration, PW configuration and TUNNEL

instrument configuration.

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Condition 1

Mapping rules are:

Operating mode of interfaces (determining whether interfaces can operate

normally)

Interface correlation mode (determining whether services can be accepted at

interfaces)

Flow classification value in VPWS configuration (determining whether its accessible to PW according to VLAN values or simulation serial numbers)

NNI in VPWS configuration (assigned PW-ID for the service is found in NNI

interface)

PW configuration block (ingress/egress PW labels and TUNNEL/LSP index can be

known by searching out the corresponding items according to PW-ID)

TUNNEL table (corresponding LABEL value can be got)

Reference data configuration in XCU

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Condition 2

When CV frames at TMC layer are opened for equipments at both the source end

and destination end, if TMC_LOC alarm still exists, it indicates that the channel is

in discontinuity and now it's necessary to conduct troubleshooting one by one from

the source site according to the following steps (mainly depending on the

performance method):

1. Inspect whether packets are received at the UNI interface and whether there are

lost packet, damaged packet, wrong packet or broken packet therein?

2. If packets are received at corresponding UNI interface, whether the TMC

concerned has corresponding packets?

3. Whether corresponding TMP of TMC has corresponding packets?

4. Whether corresponding TMP of the straight-through site has corresponding

packets to be forwarded?

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Condition 2: 620-source Site

Normally, if interface LAN3 has received packets, its

corresponding TMC shall also have packets. If its

corresponding TMC has no corresponding packets, it indicates

that the service has not completed the add voice service.

As shown in the figure above: corresponding service of TMC1

corresponds to the service with a label value of 400.

Current performance in the figure above indicates that the

service can complete add voice service.

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Condition 2: 640- straight-through Site

Total packets received by TMP1 are equal to those received by S15.1,

Total packets sent out by TMP1 are equal to those sent out by S15.2,

As shown in the figure above, hexadecimal label value of TMP1 is 0x190,

which corresponds to decimal 400

Performance in the figure above indicates that service with label value of

400 can complete the straight-through from 14.1 to 15.1

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Condition 2: 660-Straight-through Site

The service through Office 2 is straight-through, the pass-by cards are

XSJ2 and ESJ1 and its performances are as follows:

As shown in the figure, TMP1 channel of XSJ2 has total packet

numbers received, and TMP1 of ESJ1 has total packet number

sent out, so if the corresponding label values of TMP1 of the two

cards are the same, the service can complete the straight-through

from XSJ2 to ESJ1.

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Page32

Agenda

Topology Description

As shown in the figure below, Office 1, 2 and 3 are of 660

equipment, Office 4, 5 and 6 are of 640 equipment and Office 7,

8 and 9 are of 620 equipment. Develop a 100 M service from

Office 1 to Office 8.

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Topology Description

Use Smartbits table to transmit unicast packet 6000.

Page34

660-ESJ1 Disc (Source Site)

Performance on 100M disc at 660 (source site) is as

follows:

Therefore, the service on ESJ1 card is to:

Page35

660-XCUJ1 Disc (Source Site)

Performance on XCUJ1 card is as follows:

The service on XCUJ1 card is as shown in

the right figure:

Page36

660-XSJ2 Disc (Source Site)

Performance on XSJ2 card

is as follows:

The service on XSJ2 card is to:

Page37

660 (Straight-through Site)

The service through Office 2 is straight-through, the passed cards

are XSJ2, XCUJ1 and GSJ2and its performances are as follows:

Page38


Therefore, the service flow in Office 2 is as follows:

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The service on 640 in Office 4 is straight-through and its

performance is as follows:

Page40


The service flow in Office 4 is as follows:

Page41

620 (Destination Site)

620 in Office 8 is the drop voice site of service and its

performance is as follows:

Its service direction is:

Page42





Page43

Agenda

Case 1 Connection between S1J1 of Equipment 660 and

0155-8 of Equipment ASON - 1

[Phenomenon description] As shown in the figure, the 2G service of a certain project is transmitted

with PTN network and MSTP network. of which, card S1J1 of PTN

Equipment 660 is connected with card 0155-8 of ASON. It is found that card

S1J1 connected to PTN equipment reports LP-RDI that the channel used for

alarm service at BSC side is unavailable.

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[Processing procedure]

When equipment loopback at the line interface is made on the card S1J1 of the connected PTN, the LP-RDI alarm on card S1J1 disappears and the service from base site to PTN

equipment is normal, so the problem of equipment troubles at the PTN side is excluded.

When equipment loopback is made on card 0155-8 of connected Equipment MSTP, similarly, the LP-RDI alarm on the card disappears and the service channel at the BSC side

is normal, so the problem of equipment troubles at the MSTP side is excluded.

It's found to be normal by checking the connecting time slot of Equipment PTN and Equipment ASON, so the problem of configuration is excluded.

When line loopback is made on card S1J1 of connected PTN, the channel used for alarm service at the BSC side is unavailable.

When a hard loop is made on Equipment PTN by being downloaded to site, the LP-RDI alarm on card S1J1 disappears and the service from base site to Equipment PTN is normal;

when a hard loop is made on card 0155-8 of Equipment MSTP, the channel used for alarm

service at the BSC side is unavailable. Therefore, the problems is positioned on the Optical

Port of 0155-8.

Replace the optical module at the corresponding Optical Port of 0155-8 and the channel

used for alarm service at the BSC side is unavailable too. Then replace an Optical Port to

remake the service and the whole service becomes normal.

Case 1 Connection between S1J1 of Equipment 660

and 0155-8 of Equipment ASON - 2

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[Problem analysis]

1. The LP-RDI alarm is an optical disc alarm, so once the channel used for

connected service is unavailable, the LP-RDI alarm will appear on the card

S1J1 of Equipment PTN but no LP-RDI alarm will appear on the Optical Port

disc of 0155-8.

2. When software equipment loopbacks are made on card of PTN and

MSTP, the problems of Optical Port hardware cannot be positioned, so only

when hard loops are made on them, can problems be positioned to the

Optical Port and its module.

[Supplementary information]

1. In a certain project, when many times of connections of Interface 0155-8

of Equipment 780B with Interface RNC are found, the optical disc reports the

bit error alarm to the remote end and the alarm of high bit error ratio also

appears on RNC. When Optical Port of card 0155-8 is replaced, the trouble

alarm disappears.

Case 1 Connection between S1J1 of Equipment 660 and

0155-8 of Equipment ASON - 3

Page46

Case 2 Operating Mode for PTN Subnet to Eliminate Unnecessary

VLAN Configuration Items crossways - 1

[Phenomenon description]

Disc FE is inserted at Slot Position

12. Download 4 services for Port line1

in Office 4 from Port line 1 at Slot 12 in

Office 1 first and then there will be 4

VLAN configuration items on the

corresponding 100M discs. If we

delete the services with the VIDs of 3,

4 and 5, the corresponding VLAN

configuration items of the 3 services

are not eliminated and still stay at the

VLAN configuration of the card, which

will bring up with unnecessary troubles

to later inspection. Therefore, the

VLAN configuration items for

nonexistent services shall be deleted.

Page47


1. Open the cross interface of subnet and

right click on the corresponding NE.



Page48

2. Choose VLAN configurations. VLAN-ID values of corresponding slot positions

can be found here, so choose the unneeded VLAN-ID values and delete them.



Page49

3. Conduct the same operations to the VLAN configurations of

cards relevant with NEs at the opposite end, then close the dialog

boxes and it will be OK to re-download the configurations. Thus,

the relevant unused configurations will be eliminated.

[trouble detection and analysis]

When cross data in the NMS is deleted, NMS keeps the relevant LAN

configurations and considers that this VLAN is still in use so as not to delete it.

Thus it's necessary for us to delete it manually. We can create, modify and

delete the VLAN information of relevant cards through the VLAN management to

NEs.



Page50

Case 3 Repetition of VLAN Configuration Leading to Interruption

of Other 100M Data Transmission Services - 1

660-1 660-2 5

[Phenomenon description]

One day, when an issued subnet crossing configuration is added, the

users reflect that interruptions happened to another 100M service between

Site 1# and Site 2#. This service is from Interface line4 at Slot Position 17 of

Site 2 to Interface line12 at Slot Position 1B of Site 1.

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Case 3 Repetition of VLAN Configuration Leading to Interruption

of Other 100M Data Transmission Services - 2


1. Check alarms on corresponding cards and no abnormal alarms are found;

2. Check the cross configurations of subnets and the service is in transmitting mode, so the

cross configurations are correct;

3. Check single configurations of machine panels and it's found the operating mode of ports

is correct, ports are enabled, configurations of PVID are normal and VMAN of Interface LAN is

enabled;

4. Check the setting of VLAN and it's found that LAN Port 12 corresponds to 2 VLAN values

in the "VLAN configuration" of the 100M card;

5. Delete the excessive VLAN values in subnet cross VLAN settings and VLAN

configurations of card and save the downloaded cross, then the service recovers.

[trouble analysis]

1. The cause is as follows: when cross data is deleted in subnet cross, the database of

subnet saves relevant VLAN configuration. When services are added, the corresponding

VLANs of the deleted services aren't duly deleted, so once a new subnet cross is added and

downloaded configurations are saved, the VLAN in the subnet cross will recover the card

configuration, which then causes unavailable services.

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Thank you!

5-ptn trouble shooting

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