MICROCHIP Connectivity Fault Management Configuration User Guide
- June 10, 2024
- MICROCHIP
Table of Contents
MICROCHIP Connectivity Fault Management Configuration
Product Information
The CFM Configuration Guide is a document that explains how to setup Connectivity Fault Management (CFM) features for networks. CFM is defined by the IEEE 802.1ag standard and provides protocols and practices for OAM (Operations, Administration, and Maintenance) for paths through 802.1 bridges and LANs. The guide provides definitions and explanations of maintenance domains, associations, end points, and intermediate points. It also describes the three CFM protocols: Continuity Check Protocol, Link Trace, and Loopback.
Product Usage Instructions
- Read the CFM Configuration Guide carefully to understand how to setup CFM features.
- Configure maintenance domains with names and levels according to recommended values. Customer domains should be the largest (e.g., 7), provider domains should be in between (e.g., 3), and operator domains should be the smallest (e.g., 1).
- Define maintenance associations as sets of MEPs configured with the same MAID (Maintenance Association Identifier) and MD level. Each MEP should be configured with a MEPID unique within that MAID and MD level, and all MEPs should be configured with the complete list of MEPIDs.
- Set up maintenance association end points (MEPs) at the edge of the domain to define the boundary for the domain. MEPs should send and receive CFM frames through the relay function and drop all CFM frames of its level or lower that come from the wire side.
- Configure maintenance domain intermediate points (MIPs) internal to the domain but not at the boundary. CFM frames received from MEPs and other MIPs should be catalogued and forwarded, while all CFM frames at a lower level should be stopped and dropped. MIPs are passive points and respond only when triggered by CFM trace route and loop-back messages.
- Set up Continuity Check Protocol (CCP) by transmitting periodic multicast Continuity Check Messages (CCMs) inward towards other MEPs to detect connectivity failures in an MA.
- Configure Link Trace (LT) messages, also known as Mac Trace Route, which are multicast frames that a MEP transmits to track the path (hop-by-hop) to a destination MEP. Each receiving MEP should send a Trace Route Reply directly to the Originating MEP and regenerate the Trace Route Message.
- Make sure to follow all other instructions and protocols provided in the CFM Configuration Guide for successful setup of CFM features.
Introduction
This document explains how to setup Connectivity Fault Management (CFM) features. Connectivity Fault Management is defined by the IEEE 802.1ag standard. It defines protocols and practices for OAM (Operations, Administration, and Maintenance) for paths through 802.1 bridges and local area networks (LANs). IEEE 802.1ag is largely identical with ITU-T Recommendation Y.1731, which additionally addresses performance monitoring.
IEEE 802.1ag
Defines maintenance domains, their constituent maintenance points, and the
managed objects required to create and administer them Defines the
relationship between maintenance domains and the services offered by VLAN-
aware bridges and provider bridges Describes the protocols and procedures used
by maintenance points to maintain and diagnose connectivity faults within a
maintenance domain;
Definitions
-
Maintenance Domain (MD)
Maintenance Domains are management space on a network. MDs are configured with Names and Levels, where the eight levels range from 0 to 7. A hierarchical relationship exists between domains based on levels. The larger the domain, the higher the level value. Recommended values of levels are as follows: Customer Domain: Largest (e.g., 7) Provider Domain: In between (e.g., 3) Operator Domain: Smallest (e.g., 1) -
Maintenance Association (MA)
Defined as a “set of MEPs, all of which are configured with the same MAID (Maintenance Association Identifier) and MD Level, each of which is configured with a MEPID unique within that MAID and MD Level, and all of which are configured with the complete list of MEPIDs.” -
Maintenance association End Point (MEP)
Points at the edge of the domain, define the boundary for the domain. A MEP sends and receives CFM frames through the relay function, drops all CFM frames of its level or lower that come from the wire side. -
Maintenance domain Intermediate Point (MIP)
Points internal to a domain, not at the boundary. CFM frames received from MEPs and other MIPs are cataloged and forwarded, all CFM frames at a lower level are stopped and dropped. MIPs are passive points, respond only when triggered by CFM trace route and loop-back messages.
CFM Protocols
IEEE 802.1ag Ethernet CFM (Connectivity Fault Management) protocols comprise
three protocols. They are:
-
Continuity Check Protocol (CCP)
The Continuity Check Message (CCM) provides a means to detect connectivity failures in an MA. CCMs are multicast messages. CCMs are confined to a domain (MD). These messages are unidirectional and do not solicit a response. Each MEP transmits a periodic multicast Continuity Check Message inward towards the other MEPs. -
Link Trace (LT)
Link Trace messages otherwise known as Mac Trace Route are Multicast frames that a MEP transmits to track the path (hop-by-hop) to a destination MEP which is similar in concept to User Datagram Protocol (UDP) Trace Route. Each receiving MEP sends a Trace Route Reply directly to the Originating MEP, and regenerates the Trace Route Message. -
Loop-back (LB)
Loop-back messages otherwise known as MAC ping are Unicast frames that a MEP transmits, they are similar in concept to an Internet Control Message Protocol (ICMP) Echo (Ping) messages, sending Loopback to successive MIPs can determine the location of a fault. Sending a high volume of Loopback Messages can test bandwidth, reliability, or jitter of a service, which is similar to flood ping. A MEP can send a Loopback to any MEP or MIP in the service. Unlike CCMs, Loop back messages are administratively initiated and stopped.
Implementation limitations
The current implementation does not support Maintenance domain Intermediate
Point (MIP), Up-MEP, Link Trace (LT), and Loop-back (LB).
Configuration
An example of a full stack CFM configuration is shown below:
Configuration of global parameters
The syntax for cfm global level cli command is:
Where:
An example is shown below:
Configuration of Domain parameters
The syntax for cfm domain CLI command is:
Where:
Example:
Configuration of Service parameters
The syntax for cfm service level cli command is:
Where:
Example:
Configuration of MEP parameters
The syntax for cfm mep level cli command is as follows:
Where:
Example:
Show Status
The format of the ‘show cfm’ CLI command is as shown below:
Where:
Example:
