05-OAM Overview of MSTP+ Products

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Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved.

OAM Overview of MSTP+ Products MSTP Product Team, Network

Product Service Dept.

Copyright © 2006 Huawei Technologies Co., Ltd. All rights reserved. Page 3

Preface

This course is developed based on the

promotion and application of the MSTP+

product.With the development of the packet-oriented transport network, the carrier places more attention to the maintainability of the equipment and thus the operations, administration, and maintenance (OAM) of the packet services should be solved.

This course is intended to make the field engineers know the OAM function of packet services of the MSTP+ product and to master the principles and usage of the OAM function of packet services.


Guidelines

This course mainly provides the overview

of the OAM function of packet services of

the MSTP+ product.

Before taking this course, you should

have the following knowledge:

Basics on Ethernet and MPLS

Basics on packet services of the

MSTP+ product


Objectives

After taking this course, you are supposed to

reach the following objectives:

Master the basics and usage of the ETH_OAM

Master the basics and usage of the MPLS_OAM


Contents

ETH_OAM

MPLS_OAM


Preface The Ethernet technology is simple and low-cost, and can increase

the bandwidth. Therefore, either as a service type or a network str

ucture, Ethernet technology is applied on the enterprise networks,

MAN, and WAN in a large scale. The maintainability and operabilit

y of the traditional Ethernet, however, is poor. With the promotion

of the Ethernet, the more requirements are placed on the OAM fu

nction of the Ethernet.

Currently, OAM of the Ethernet can be classified into the end-to-e

nd OAM (802.1AG) and point-to-point OAM (802.3AH).


Application of the 802.3AH and 802.1AG in the Network

The IEEE 802.1AG OAM focuses on the maintenance of end-to-end Ethernet links. The application of the IEEE 802.1AG OAM is based on services.

The IEEE 802.3AH OAM focuses on the maintenance of end-to-end Ethernet links between two directly-connected devices on the Ethernet in the first mile (EFM). The application of the IEEE 802.3AH OAM is not based on specific services.


Position of the ETH_OAM in the Transmission Network Module


Contents

ETH_OAM End-to-end OAM, 802.1AG

End-to-end OAM, 802.3AH


Contents

End-to-end OAM, 802.1AG

Overview of the 802.1AG

Basic Concepts of the 802.1AG

Basic Functions of the 802.1AG

Continuity Check (CC)

Loopback (LB)

Link Trace (LT)

OAM Ping



Solves the end-to-end Ethernet OAM (over multiple bridge nodes).

The application is based on services and the end-to-end check is

implemented in the unit of “maintenance domain”.

VLAN-based OAM.

Main functions:


Loopback (LB)

Link Trace (LT)

OAM Ping


Data Unit of the 802.1AG

OAM Mac Destination Address: Indicates the MAC address of the sink MP. OAM Mac Source Address: Indicates the MAC address of the source MP. Ether Type (VLAN): Indicates the Ethernet data type, such as 0x8100. VLAN Tag: Indicates the VLAN value of the service traffic. Ether Type (OAM): Indicates the packet type of the ETH-OAM protocol. The packet type

of the IEEE 802.1AG OAM is 0x8809. OAM Type: Indicates that the MP differs and responds to various OAM operations

according to the types of OAM packets.


Basic Concepts of the 802.1AG-MD Maintenance domain (MD)

An MD supports multiple MAs. The MD name is the only identifier for an MD;

therefore, on the network, an MD name must be unique.

Level indicates the MD level. The MD of a lower level can be embedded in the

MD of a higher level.

An MD has the following attributes:

MD Name

Level (optional; it is defaulted as 0; larger the value, higher the level)


Basic Concepts of the 802.1AG-MA Maintenance association (MA)

An MD is divided into multiple MAs for checking the continuity of the MD. In an M

D, an MA name must be unique. The MA names in different MDs, however, can

be the same. The 802.1AG is used to check the continuity of certain links in a sp

ecific VLAN. Therefore, MA should be associated with VLAN. One MA can be as

sociated with only one VLAN, but multiple MAs can be associated with the same

VLAN.

In an MA, the CCM (continuity check message) interval can be configured to indic

ate the interval at which all MEPs in the MA transmit CCM. In an MA, all MEPs tr

ansmit CCM at the same interval.

An MA has the following attributes:

MA Name

VLAN

CCM Interval

The MA inherits all attributes of the MD


Basic Concepts of the 802.1AG-MP Maintenance point (MP) is the functional entity of the IEEE 802.1AG

OAM, including the maintenance end point (MEP) and maintenance

intermediate point (MIP).

Each MP has a maintenance point identification (MPID). This ID is unique

on the entire network. The information about the MP is recorded in the

MAC address table, MP table , and route table. The service type, service

ID, and VLAN tag are key contents in the MP configuration information.

Once the MP is created successfully, the protocol packet carrying the

information about this MP is broadcast to the entire network periodically.

Then, the other MPs receive the protocol packet and record the

information for spare use.

All the OAM operations must be started by the MEP. The MIP cannot

start any OAM operation or send any OAM packet.


Basic Concepts of the 802.1AG-MEP Maintenance association end point (MEP)

The MEP is configured based on the port. All OAM operations and

OAM packets are started by the MEP. The MEP ID is the only

identifier of an MEP in an MA. In one VLAN, the MEP ID must be

unique. The MEP is direction-based. Generally, an arrowhead is used

to identify an MEP and the direction of the arrowhead is the direction

of the MEP.

An MEP has the following attributes:

MEPID

Port

Direction

All attributes of the MA


Basic Concepts of the 802.1AG-MIPMaintenance domain intermediate point (MIP)

MIP does not initiate the OAM operation but only processes the OAM packets.

An MIP can function as the node of LB or LT.

An MIP supports the following functions:

Lets all service packets pass through.

Checks all OAM packets that pass through the MIP.

Lets the OAM packets at higher layers than the MIP to pass through.

Selects one of the following processing methods according to certain specific o

peration codes or destination MAC address:

Transparent transmission

Transparent transmission and processing

Obtaining and processing all OAM packets at the layer of the MIP

Discards all OAM packets at lower layers than that of the MIP according to cert

ain specific operation codes.


Logic Relationship Between Different Layers in an MD

Layer level: User ME level > Vendor ME level > Carrier ME level The dashed lines in the diagram show the logic channels where IEEE 802.1AG OAM packets pass through. For MPs at different layers,

the processing methods for the OAM packets are as follows: In the case of the OAM protocol packets whose level is higher than the MP, the MP transparently transmits the packets. In the case of the OAM protocol packets whose level is lower than the MP, the MP discards the packets directly. In the case of the OAM protocol packets whose level is the same as the MP, the MP responds to or terminates the packets according to the

types of the OAM packets.


Contents

End-to-End OAM, 802.1AG


Basic Concepts of the 802.1AG

Basic Functions of the 802.1AG


Loopback (LB)

Link Trace (LT)

OAM Ping


Basic Functions of the 802.1AG-CC

The source MEP constructs the CCM packets and transmits the packets periodically. After receiving the CCM packets, the sink MEP starts the CC. If the sink MEP fails to receive the CCM

packets from the source MEP within the check period (that is, 3.5 times of the transmit period), it

reports the CC_LOS alarm automatically till the link restores normality. As shown in the previous figure, after the CC of MEP1 is started, MEP1 transmits CCM packets.

MEP2, MEP3, and MEP4 that are in the same MD of MEP1 receive CCM packets from MEP1

periodically. Once the link fails, the sink MEP cannot receive the CCM packets in 3.5 times of the

transmit period, and then the sink MEP reports the EX_ETHOAM_CC_LOS alarm, which lasts till the

link restores normality.


Basic Functions of the 802.1AG-LB

LB test is based on bi-directional services. The source MEP constructs the loopback message (LBM)

packets and fills the MP (MIP or MEP) ID in the packets. Then the source MEP transmits the packets

and starts the timer at the same time. After receiving the LBM packets, the sink MP constructs the loopback return (LBR) packets and trans

mits them back to the source MEP. In this case, the loopback test is successful. If the source MEP timer times out and fails to receive the LBR packets from the sink MP, the loopback

test fails. As shown in the previous figure, MEP1 transmits LBM packets to sink MEP4; after MIP2 and MIP3 rec

eive the packets and find that the MPID of these packets is different from the MPID of themselves, MI

P2 and MIP3 transparently transmit these packets. After receiving these packets, the sink MEP4 trans

mits the LBR packets to the source MEP1. At this moment, the loopback test is complete. Only MEPs can initiate the LB test, but both the MEP and MIP can work as the receive end in the test.


Basic Functions of the 802.1AG-LT

The source MEP constructs the link trace message (LTM) packets and fills the sink MEP ID in the packets. Then the source MEP transmits the packets and starts the timer at the same time.

All MIPs that belong to this MD in the link transmit the received LTM packets to the sink MEP. At the same time, a link trace reply (LTR) packet is returned to the source MEP.

After the sink MEP receives the LTM packets, the packet transmission is complete. Then, the sink MEP transmits LTR packets to the source MEP. In this case, the link trace test is successful. If the source MEP timer times out and fails to receive the LTR packets from the sink MEP, the loopback test fails.

As shown in the previous figure1. The source MEP1 transmits the LTM packet to the sink MEP4.2. After receiving the LTM packet, MIP2 transmits the LTR packet to the source MEP1 and forwards the LTM packet at the

same time.3. After receiving the LTM packet, MIP3 transmits the LTR packet to the source MEP1 and forwards the LTM packet at the

same time.4. After receiving the LTM packet, the sink MEP4 terminates the LTM packet and transmits the LTR packet to the source M

EP1. Only an MEP can initiate or terminate an LT test.


Basic Functions of the 802.1AG-OAM Ping The OAM_ping test includes the following:

MPID-ping: In the case that the Ethernet service boards on the

Huawei equipment at both ends support the IEEE 802.1AG OA

M, the MP of the Ethernet service board at one end can initiate

the ping test.

IP-ping: In the case that the equipment at both ends supports the ARP

and ICMP protocols, the ping test can be initiated on the Huawei equip

ment, which does not respond to the ping test initiated by the peer equ

ipment.


Contents

ETH_OAM End-to-End OAM, 802.1AG

End-to-End OAM, 802.3AH


Contents

End-to-End OAM, 802.3AH

Overview of the 802.3AH

Basic Concepts of the 802.3AH

Basic Functions of the 802.3AH

OAM Capability Discovering

OAM Link Monitoring

Remote Fault Detecting

OAM Remote Loopback

Self-Loop Test


Overview of the 802.3AH--I

It mainly solves the Ethernet OAM of the "first mile". It also applicable to t

he Ethernet physical link between two equipment.

Main Functions

OAM Capability Discovering

OAM Link Monitoring

Remote Fault Detecting

OAM Remote Loopback

Self-Loop Test

It does not support the functions, such as node position management, pro

tection switching, and bandwidth reservation and allocation, irrelated to a

single link.


Overview of the 802.3AH--II

The protocol defines that the 802.3AH packets are multicast

packets.

For the 802.3AH, the interval for transmitting packets is 1s.

The 802.3AH packets cannot be forwarded by the bridge.

No matter whether the 802.3AH function is supported or is

activated, the 802.3AH packets cannot be forwarded over

multiple hops.

The 802.3AH requires the equipment at both ends transmits

3AH handshake packets to keep the handshake.


Application Scenarios of the 802.3AH OAM

As shown in the previous figure, the IEEE 802.3AH OAM is mainly applicable to CE NEs and data communication equipment that are directly connected.

The IEEE 802.3AH OAM is only applicable to external physical ports and the OAM PDU cannot be forwarded on the system side.


Data Unit of the 802.3AH (OAMPDU)

It is fixed as 0x01-80-C2-00-00-02, the multicast address of the low-speed protocol.

Indicates the MAC address of the port.

It is the data part of the OAMPDU.

It is fixed as 0x8809, indicating the low-speed protocol type.

It is fixed as 0x03, indicates the IEEE 802.3AH OAM type.

Indicates the status information, such as the link fault, critical fault, and emergent event.

Identifies the IEEE 802.3AH OAM protocol packets of different types.

Indicates the frame check.


Basic Concepts of the 802.3AH-OAM Mode

OAM Mode

Active: Be able to initiate the link discovering and remote

loopback.

Passive: Different from the active mode, in the passive

mode, the link discovering and remote loopback cannot be

initiated actively. The other processing in the passive mode

is the same as that in the active mode.


Basic Functions of the 802. 3AH-Automatic OAM Discovering

Active Passive

NE1 NE2

NE1 initiates the discovering actively and transmits the

packets that carry information about NE1.

After receiving the packets from NE1, NE2 compares the packets

with the local end and judges whether the setting meets the

requirements. Then, NE2 transmits the OAM packets that carry the

information about NE1 and NE2.

After receiving the OAM packets from NE2, NE1 updates the local information about NE2 and judges

whether the setting meets the requirements. Then, NE1 transmits

the OAM packets that carry the information about NE1 and NE2.

802.3AH packets transmitted by NE1802.3AH packets transmitted by NE2

By exchanging the "information OAMPDU" periodically, the local equipment is informed whether the peer equipment supports the IEEE 802.3AH OAM. OAM automatic discovering is a prerequisite to realizing the link performance monitoring and remote loopback.

Only the active end can initiate the discovering. The equipment at both ends can work as the active one, or one works as the active and the other works as the passive, but the two cannot work as the passive at the same time.

In the discovering phase, the interval for transmitting packet is 1s. In the discovering phase, the contents that need be negotiated are as

follows: whether the remote loopback is supported, whether the detection of error frame and error code is supported, and whether the fast detection (not protocol standard) is supported. The discovering phase is complete when the negotiation is successful.

The handshake phase starts upon the complete of the discovering phase.


802.3AH OAM Handshake Phase

After the handshake phase starts, the handshake packets are

transmitted continuously at the interval of 1s.

All 802.3AH packets, including the handshake packets, fault

report packets, and loopback packets, can keep the normal

handshake state.

If no 802.3AH packet is received in 5s, the link is considered as

faulty and the discovering phase begins.

In the handshake phase, if the negotiation fails because of the

configuration change at either end, discovering phase begins.


Basic Functions of the 802.3AH OAM-Link Monitoring Link performance monitoring is used to monitor the bit error performance (error

frames or error signals). When the local end detects that the bit errors exceed the

threshold, the bit error event is transmitted to the opposite end over the specified

OAMPDU. In this case, the opposite end reports the alarm accordingly. The standard fault report event is as follows:

Error frame: Indicates that the number of error frames exceeds the threshold in a period.

Count of error frame seconds: Indicates the count of seconds when error frames occur

within the specified seconds.

Error code: Indicates that the number of error codes exceeds the threshold in a period.

When the IEEE 802.3AH OAM protocol is enabled at a port, the protocol queries

the RMON statistic of the hardware chip periodically to obtain the information such

as the number of correct packets and the number of error packets. After related

processing of the information, it can be judged whether the previous three

performance events occur. If a performance event is generated, the peer end is

notified with this event through the OAMPDU. After receiving the notification, the

peer end reports the ETHOAM_RMT_SD alarm.


Basic Functions of the 802.3AH OAM-Remote Fault Detecting

Fault or unavailability of the equipment causes interruption of the

traffic. Then, the information is transmitted to the peer end through

the flag domain in the OAMPDU.

Fault type:

Link fault: This type of fault is transmitted when the local port is

shut down.

Dying gasp: This type of fault is transmitted in the case of reboot

and reset.

Critical event: This type of fault is transmitted when a fault

transmitted by the OAM manager is received.


Basic Functions of the 802.3AH OAM-Remote Loopback

Active Passive

NE1 NE2

NE1 initiates the remote loopback request

actively.

After receiving the loopback request packets from NE1, NEs starts loopback and transmits loopback reply packets to NE1.

After receiving the loopback response packets from NE2, NE1 initiates the loopback.

Loopback request packets transmitted by NE1Loopback response packets transmitted by NE2

Only the active end can initiate the remote loopback request. If the equipment at both ends initiate the remote loopback request, the end with larger MAC address enters the passive loopback state.

After entering the loopback state, NE2 returns the packets (excluding the OAM packets) that are received on the loopback port to NE1.

NE1 transmits the test packets to detect the link. The MAC address, length, and number of the test packets can be specified. After receiving the test packets, NE2 returns the packets to NE1, and then NE1 performs the packet loss statistics.

The loopback cancelling process is similar the loopback requesting process.


Basic Functions of the 802.3AH OAM-Self-Loop Test

The self-loop test can detect the self-loop of a port with a fiber connecting the Rx a

nd Tx and the self-loop on a board with a fiber connecting two ports on the board.

With the self-loop detecting function enabled on all ports of the equipment, once a s

elf-loop (described previously) occur in the networking process, the self-loop is dete

cted and the ETHOAM_SELF_LOOP or ETHOAM_VCG_SELF_LOOP alarm is rep

orted to prompt the user.

The self-loop detecting function is developed by Huawei based on the IEEE 802.3A

H. Self-looped port is detected and blocked, and thus the loopback of the port is rec

tified.


Contents

ETH_OAM

MPLS_OAM


MPLS OAM Overview

The MPLS OAM can effectively detect, confirm, and locate the internal

defects of the MPLS-layer network, and thus can monitor the network

performance. By providing an OAM mechanism independent of any upper

layer or lower layer, the MPLS OAM supports the following features:

Providing the query based on requirements and the consecutive detection so that at

any moment you can learn whether the monitored LSP has defects.

Detecting, analyzing, and locating the defects in the network, and reporting the

defect information to the T2000.

Fast triggering protection switching when the link has a defect or becomes faulty.

Monitoring and reporting the packet loss ratio, delay, and delay variation in real

time.

The MPLS OAM complies with the ITU-T Y.1711 and ITU-T Y.1731.


Basic Functions of the MPLS OAM-CV/FFD

You can check the connectivity of a label switch path (LSP) by performing

a connectivity verification (CV) or fast failure detection (FFD).

The CV and FFD processes are the same except for that CV packets are

transmitted always at a rate (1 frame/s, not for setting) whereas FFD

packets are transmitted at a user-defined rate.


MPLS OAM-CC

MSTP+

MSTP+

MPLSMSTP+

RNC Core network

MSTP+ RNC

GE

MPLS_TUNNEL_LOCV

NB 1

NB2

MSTP+

MSTP+

ETH

SDH

or ETHGE/FE

ETH

GEGE/FE

CV packet: The ingress node transmits the CV packet at an interval of 1s. The egress

node checks the number and correctness of received CV packets in any 3s.

FFD packet: The function of the FFD packet is the same as the CV packet, which is used

to check the continuity. The ingress node transmits the FFD packet at an interval of 3.3

ms to 500 ms. The egress node checks the number and correctness of received FFD

packets in the period of any three transmit intervals. The transmit interval can be 3.3 ms,

10 ms, 20 ms, 50 ms, 100 ms, 200 ms, and 500 ms.


MPLS OAM-Mismatch

MPLS

MSTP+

MSTP+

MPLS

MSTP+

RNC Core network

MSTP+ RNC

GE

MPLS_TUNNEL_MISMATCH

MPLS_TUNNEL_LOCV

NB 1

NB2

MSTP+

MSTP+

ETH

GE/FE

ETH

GE/FEGE


MPLS OAM-Mismerge

NB 1

NB2

MSTP+

MSTP+

ETHNB3

MSTP+

MPLS

MSTP+

MSTP+

MPLSMSTP

+RNC Core

network

MSTP+

RNC

GE/FE

GE

MPLS_TUNNEL_MISMERGE

MPLS_TUNNEL_LOCV

ETH

GE/FE

ETH GE/FE

GE


MPLS OAM-BDI

NB 1

NB2

MSTP+

MSTP+

ETHNB3

MSTP+

MPLS

MSTP+

MSTP+

MPLSMSTP+

RNC Core network

MSTP+ RNC

GE/FE

GE

MPLS_TUNNEL_LOCVBind the reverse tunnel

Bind the reverse tunnel

MPLS_TUNNEL_BDI

GE/FE

GE/FE

ETH

ETH

GE

BDI packet: The BDI packet is used by the egress node to notify the i

ngress node of the LSP defect information.

A reverse LSP (dedicated or shared) or a outband channel can carry

the BDI packets.


MPLS OAM-FDI

NB 1

NB2

MSTP+

MSTP+

ETHNB3

MSTP+

MPLS

MSTP+

MSTP+

MPLSMSTP+

RNC Core network

MSTP+ RNC

GE/FE

GE

MPLS_TUNNEL_FDI

ETH

ETH

GE/FE

GE/FE

GE

FDI packet: The FDI packet is used by the LSP upstream node to notify the

LSP egress node of the bottom layer defect information. At the node that is

most close to the defect, the FDI packets are inserted to the LSP where the

defect occurs.


NB 1 ETH

ETHNB2

MSTP+

MSTP+

Basic Functions of the MPLS-LSP Ping

ETHNB3

MSTP+

MPLS

MSTP+

MSTP+

MPLSMSTP+

RNC Core network

MSTP+ RNC

GE/FE

GE

GE/FE

GE/FE

GE

The MPLS ping and MPLS echo request messages should arrive at

the egress node of the tunnel. Then, the control plane of the egress

node checks whether the node is the egress for the FEC. The MPLS

ping packets help check whether the LSP is successfully set up.


NB 1 ETH

ETHNB2

MSTP+

MSTP+

Basic Functions of the MPLS-LSP Trace Route

ETHNB3

MSTP+

MPLS

MSTP+

MSTP+

MPLSMSTP+

RNC Core network

MSTP+ RNC

STM-X

GE/FE

STM-X

GE

GE/FE

The MPLS trace route and MPLS Echo Request packets should be transmitted

to each transit node. Then, the control plane of each transmit node checks

whether the node is an intermediate node on the LSP. You can locate the place

where a network fault occurs by using the trace route function.


Application Scenarios of the MPLS OAM Detection

OAM Type Function Application Scenario

CV/FFD Unidirectional continuity check Real-time status detection of the

tunnel

Ping Bidirectional continuity check Dual-ended location or dual-ended

detection

Trace route Fault locating Tunnel route detecting

Note: For the MPLS APS 1+1/1:1 protection, the corresponding MPLS OAM must be enabled.

On the MPLS network, the MPLS OAM mechanism enables end-to-end detection.

The MPLS OAM is mainly applied to the LSP on the packet switching network (PSN), as shown in the figure.

Thank You

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05-OAM Overview of MSTP+ Products