Mep And Cfm Processing Overview - Cisco NCS 5500 Series Configuration Manual

Configuring Ethernet OAM
• The level of the highest-level MEP on the interface is found. From among the services considered above,
the service in the domain with the lowest level that is higher than the highest MEP level is selected. If
there are no MEPs on the interface, the service in the domain with the lowest level is selected.
• The MIP auto-creation configuration (mip auto-create command) for the selected service is examined
to determine whether a MIP should be created.
Note

MEP and CFM Processing Overview

The boundary of a domain is an interface, rather than a bridge or host. Therefore, MEPs can be sub-divided
into two categories:
• Down MEPs—Send CFM frames from the interface where they are configured, and process CFM frames
received on that interface. Down MEPs transmit AIS messages upward (toward the cross-connect).
• Up MEPs—Send frames into the bridge relay function, as if they had been received on the interface
where the MEP is configured. They process CFM frames that have been received on other interfaces,
and have been switched through the bridge relay function as if they are going to be sent out of the
interface where the MEP is configured. Up MEPs transmit AIS messages downward (toward the wire).
However, AIS packets are only sent when there is a MIP configured on the same interface as the MEP
and at the level of the MIP.
The terms Down MEP and Up MEP are defined in the IEEE 802.1ag and ITU-T Y.1731 standards, and
Note
refer to the direction that CFM frames are sent from the MEP. The terms should not be confused with the
operational status of the MEP.
Configuring a MIP auto-creation policy for a service does not guarantee that a MIP will
automatically be created for that service. The policy is only considered if that service
is selected by the algorithm first.
Interface and Hardware Component Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.1.x
Ethernet CFM
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