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Foundry NetIron M2404C and M2404F Metro Access Switches
Network Administration Tools (Rev. 03)
802.1ag Connectivity Fault Management (CFM)
© 2008 Foundry Networks, Inc.
Page 80 of 155
802.1ag Connectivity Fault Management (CFM)
Overview
IEEE 802.1ag Connectivity Fault Management (CFM) refers to the ability of a network to monitor
the health of a service delivered to customers as opposed to just links or individual bridges. A pre-
standard IEEE 802.1ag CFM feature called MAC ping/traceroute defines the end-to-end OAM
capabilities that are intrinsic to Ethernet technology, enabling service providers to monitor the
Ethernet service that the customer receives.
The 802.1ag CFM standard specifies protocols, procedures, and managed objects to support
transport fault management. These allow discovery and verification of the path, through bridges
and LANs, taken for frames addressed to and from specified network users, detection, and isolation
of a connectivity fault to a specific bridge or LAN.
Ethernet CFM defines proactive and diagnostic fault localization procedures for point-to-point and
multipoint Ethernet Virtual Connections (EVC) that span one or more links. It is end-to-end within
an Ethernet network.
Ethernet OAM Capabilities
Ethernet OAM is able to:
•
monitor the health of links (because providers and customers might not have access to the
management layer)
•
check connectivity of ports
•
detect fabric failures
•
provide the building blocks for error localization tools
•
give appropriate scope to customers, providers and operators (hierarchical layering of
OAM)
•
avoid security breaches (be “leak-proof”)
•
easy to configure (Plug-and-Play operation)
•
in some cases, it can perform basic performance monitoring (delay, jitter, frame loss) end
to end.
802.1ag Purpose
Bridges are increasingly used in networks operated by multiple independent organizations, each
with restricted management access to each other equipment. CFM provides capabilities for
detecting, verifying and isolating connectivity failures in such networks
There are multiple organizations involved in a Metro Ethernet Service: Customers, Service
Providers and Operators.
Customers purchase Ethernet Service from Service Providers. Service Providers may utilize their
own networks, or the networks of other Operators to provide connectivity for the requested service.
Customers themselves may be Service Providers, for example a Customer may be an Internet
Service Provider which sells Internet connectivity.