Adva - Training - FSP 150CC-GE20x R4.x Course - 8 - CFM and Y.1731

FSP 150CC-GE20x Product Training Course 8 - CFM & Y.1731

FSP 150CC-GE206 R4.4.x FSP 150CC-GE201 R4.3.x

October 2010 V1.3

© 2010 ADVA Optical Networking. All rights reserved. Confidential. 2

Module Contents

Connectivity Fault Management (CFM)

Y.1731


Connectivity Fault Management

Connectivity Fault Management is an emerging standard aimed at enhancing Ethernet service OAM capability CFM is defined by IEEE 802.1ag and ITU-T Y.1731 (with extended

functionality)

The main features provided by CFM include the ability to detect, verify, isolate and report connectivity faults on a service instance

The FSP 150CC-GE206 supports the following features Configure Maintenance Domain

Configure Maintenance Associations

Configure and manage Maintenance Points (MEP and MIP)

Transmit and receive Continuity Check Messages

Initiate and respond to Link Trace and Loopback Messages

Detect and raise CFM related alarms

Y.1731 Ethernet AIS

Y.1731 Performance Monitoring (Loss and Delay Measurement)

CFM based Link Loss Forwarding


Connectivity Fault Management (CFM) Overview

A Maintenance Domain (MD) is a bridged network maintained by an operator

Each MD is assigned a Maintenance Domain Level (0-7)

Multiple domains at different levels create a hierarchy of MDs

A Maintenance Association (MA) represents the service instance being monitored

It consists of two or more MEPs which define the boundary of the MA

Maintenance Points

can be created at port and VLAN level

Maintenance End Point (MEP)

At the boundary of a Maintenance Association

initiate and respond to CFM messages

Maintenance Intermediate Point (MIP)

MIPs receive and respond to messages.


Customer Domain

Service Provider Domain

Operator Domain

Operator A Provider Bridges Operator B Provider Bridges CPE CPE

MD Level=5

MD Level=3

MD Level=2

Operator Domain

MEP MIP MA

Connectivity Fault Management (CFM) Overview

Up MEP – CFM traffic is sent towards the bridge (e.g. from LAN towards WAN through the device)

Down MEP – CFM traffic is sent away from the bridge (e.g. from WAN towards the network)


Connectivity Fault Management (CFM) Maintenance Domain Hierarchy

MIPs at a higher level are MEPs at a lower level

Higher domain subscribes to service of lower domain

Maintenance level restricts visibility upward and downward in hierarchy

Network topology of Provider is not visible to customer.

Similarly, Provider cannot see Operator’s network topology.

Higher level can only see what lower level allows to be seen


Feature Overview CFM – MEP Directionality

“Up” means CFM traffic sent towards the bridge

“Down” means CFM traffic sent away from the bridge

On the FSP 150CC, the bridge functionality is implemented in the FPGA

GE206 Supports:

Client ports:

VLAN-based up and down-MEPs on client ports

Port-based down-MEPs on client ports

Network ports:

Port-based down-MEPs on network ports

VLAN-based down-MEPs on network ports

LAN WAN

Down MEP

CFM Traffic

Up MEP

CFM Traffic


Connectivity Fault Management (CFM) CFM Messages

The standard defines a set of CFM messages along with supporting protocols and procedures

CFM messages are used for monitoring and managing the connectivity between the maintenance points in a MA

CFM messages include:

Continuity Check messages (CCM)

Link Trace messages (LTM)

Loopback messages (LBM)

Y.1731

Alarm Indication Signal (AIS)

Delay Measurement Messages (DMM)

Loss Measurement Message (LMM)


Periodic multicast message toward other MEPs in the same MA Provides heartbeat for connectivity check

Also used for MEP MAC discovery

CCM contains: Source MAC Address, Maintenance Level, MA ID, MEP ID, Sequence #

RDI bit indicates CCM from a MEP has not been received

CCM MEP receiver: Checks for valid CCM data (maintenance level, MAID, MEPID, etc)

Monitors for missing MEP IDs

Populates CCM database

CCM Interval 3.3 msec

10 msec

100 msec

1 sec

10 sec

1 min

10 min

Connectivity Fault Management (CFM) Continuity Check Messages (CCM)

B

A D

Provider Domain

Operator B Operator A

MEP MIP MA

C


Some RDI Received a CCM from one or more MEPs with the RDI bit set

A MEP will set the RDI bit if it has detected one or more of the following defects

Some MAC Status One or more remote MEPs sent CCM with interface status TLV

(Type/Length/Value tuple) indicating its interface is not up

All remote MEPs sent CCM with port status TLV indicating its port is not up

Some Remote MEP CCM Defect is raised if no CCM received for one or more remote MEPs in the MA for 3

consecutive intervals. If the defect persists for 2.5 secs, the alarm is raised.

Erroneous CCM: CCM received from MEP not configured in the MA

A CCM is from a MEP with the same MEP ID as the receiving MEP

The CCM interval of a received CCM does not match the receiving MEP’s MA value.

Crossconnect CCM: The MA ID does not match the MAID of the receiving MEP

The MD is less than the level of the receiving MEP’s level

Connectivity Fault Management (CFM) CCM Alarms


Connectivity Fault Management (CFM) Loopback Messages (LBM)

Loopback Messages (LBM) are unicast messages used for fault isolation (similar to ping)

LBMs are used to verify the connectivity between two maintenance points - i.e. between two MEPs or between a MEP and MIP

At the destination, a Loopback Reply (LBR) is sent back to the sender

MEP MIP LBM LBR

Provider Domain Provider Domain


A

C

B

D


Connectivity Fault Management (CFM) Link Trace Message (LTM)

Link Trace Messages (LTM) are used for path discovery

Sent from the source MEP to the target MEP (or MIP)

At each intermediate MIP to the target, a Link Trace Response (LTR) message is sent back to the originating MEP

The LTM is forwarded to the next MIP until the target MEP is reached

Based on the information in the LTRs received, the originating MEP can determine the path to the target MEP

Up to 10 link trace operations can be active at one time.

Provider Domain

MEP MIP LTM LTR

D


A

C

B


Connectivity Fault Management (CFM) Maintenance Domain (MD) Creation

Up to 32 MD’s are supported

Format Types:

String

MAC – Integer

DNS Name

No Name

MD Level: 0-7

MIP Creation Control*:

None

Default

Explicit

* Discussed later


Connectivity Fault Management (CFM) Maintenance Association (MA) Creation - Network

Up to 32 MANET’s supported

Format Types:

Integer

Primary VID

String

VPN ID

ICC Format

CCM Interval:

3.3, 10, 100 msec; 1, 10 s; 1, 10 m

MEP List:

All MEPs that are part of this MA, one of which will be local


Connectivity Fault Management (CFM) MA Creation – Component

Associates the MA to a port on the device

Associated Port

Primary VID

MIP Creation Control*:

None

Default

Explicit

Defer

* Discussed later


Connectivity Fault Management (CFM) Maintenance End Point (MEP) Creation

Direction

State:

Expects to received CCMs

CCM Generation

Fault Alarm Priority:

Lowest priority fault that will result in an alarm

VLAN Priority:

P-bit value for this MEP

Primary VID:

VLAN ID for this MEP

At most 1 MEP per MA per device is supported


Not intended to be used to measure performance (e.g. roundtrip delay)

Only 1 loopback operation can be initiated at a time per MEP

Invoked by choosing the “Loopback” option when right-clicking on the MEP Destination Type:

MAC Address – MAC address of the port supporting the remote MEP

Remote MEP Id – ID of the remote MEP

Destination ID based on the “Destination Type”

Number of LBMs to be transmitted: 1 – 50

Number of padding bytes in the Data TLV: 0 – 1473

Data Pattern: All Zeroes

All Ones

Alternate

VLAN Priority: 0 – 7

Transmit LBM Sequence number: automatically incremented by the system and is the value used in the first LBM sent in the group of LBMs.

VLAN Drop Enable: If an S-Tag is applied, “true” results in the DE-bit (Drop Eligible bit) being set.

Connectivity Fault Management (CFM) Loopback Initiation


Only 1 link trace can be initiated at a time per MEP

A single multicast message is transmitted

Invoked by choosing the “Initiate LTM” option when right-clicking on the MEP

Destination Type:

MAC Address – MAC address of the port supporting the remote MEP

Remote MEP Id – MEP ID of the remote MEP

Destination ID

based on the “Destination Type”

TTL [1-255]

LTM Time To Live the max number of 802.1ag hops

Use FDB Only [Enabled/Disabled]

Next LTM Transaction ID (automatically incremented by the system)

Egress ID [8 octets]

Identifies the MEP Linktrace Initiator.

Connectivity Fault Management (CFM) Link Trace Initiation


As a response to the LTM a device receives LTR

Based on the received LTRs there is a Database generated consisting of all MEPs and MIPs that have responded with their statuses, MAC addresses etc.

Connectivity Fault Management (CFM) Link Trace Response


If a MIP is required, an MA or the default MD must exist.

MIPs are only created at the lowest MD level that is higher than the level where a MEP exists on that port.

MIP Creation Contol: None: MIPs are not created

Explicit: MIPs are created on the ports for the specified VIDs only if a MEP exists on that port at a lower MD level.

Default: MIPs are created when the MA is created.

Defer: Only applicable to the MA. The enclosing MD’s MIP Creation Control attribute is used to dictate MIP creation.

Two ways that a MIP can be created: As the result of the creation of an MA. If MA has MIP Creation Control:

Default: Created at same MD level as the MA and for all ports that do not support a MEP.

Explicit: Created at higher MD level as the MA if a MEP exists

As the result of creating an entry in the “CFM Vlan Table”

Connectivity Fault Management (CFM) MIPs


Connectivity Fault Management (CFM) Ethernet AIS

AIS – Alarm Indication Signal

AIS frames can be generated by a MEP based on Error conditions on the underlying Ethernet port

link level

Error conditions reported by CCMs Mismerge/ Crossconnect CCM

Loss of connectivity

Unexpected or Error CCM

AIS defect

AIS frames are sent to higher level MEPs to report problems on the lower level MEPs

Higher Level MEPs can be configured to react in different ways to the reception of an AIS, e.g. Generate AIS frame for higher level MEPs

Activate Link Loss Forwarding

Do nothing (Suppress AIS)


Connectivity Fault Management (CFM) Link Loss Forwarding

Link Loss Forwarding is an easy way to inform remote equipment about error conditions on the service.

If an error condition exists the Ethernet port is taken down causing the remote device to see a Link Loss

MEPs can be configured to switch off the underlying Ethernet port on reception of

AIS defect

CCM with Interface Status TLV “isDown”

RDI

Remote MEP CCM Failure


Connectivity Fault Management (CFM) Y.1731 Performance Monitoring

On-demand layer 2 test frames between MEPs in the same MA. Less processing overhead and more accuracy than layer 3 test frames as used in ESA tests

until now.

Loss Measurement Single-ended LM fully supported

MEP sends LM messages, the other MEP responds with LMR

LM messages carry data frame counts

Delay Measurement MEP sends DMM, the other MEP responds with DMR

DM messages carry time stamps

Offered via ESA Probe Do not need to create a Reflector

Select protocol Y.1731, associate with LAN up MEPs,

Parameters are

Destination MEP

DMM and LMM interval

DMM size

ESA statistics are collected, e.g. packet count, loss, one-way and round-trip delay, jitter, … Times are in microseconds!

Binned and retrievable like regular ESA results

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End of CFM & Y.1731

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Adva - Training - FSP 150CC-GE20x R4.x Course - 8 - CFM and Y.1731