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Cisco ME 3400 Ethernet Access Switch Software Configuration Guide
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Chapter 39 Configuring Ethernet OAM, CFM, and E-LMI Understanding E-LMI
OAM manager, which streamlines interaction between any two OAM protocols, handles the interaction
between CFM and E-LMI. This interaction is unidirectional, running only from OAM manager to E-LMI
on the UPE side of the switch. Information is exchanged either as a result of a request from E-LMI or
triggered by OAM when it received notification of a change from the OAM protocol. This type of
information is relayed:
• EVC name and availability status
• Remote UNI name and status
• Remote UNI counts
You can configure Ethernet virtual connections (EVCs), service VLANs, UNI ids (for each CE-to-PE
link), and UNI count and attributes. You need to configure CFM to notify the OAM manager of any
change to the number of active UNIs and or the remote UNI ID for a given S-VLAN domain.
You can configure the switch as either the customer-edge device or the provider-edge device.
E-LMI Interaction with OAM Manager
No interactions are required between E-LMI and OAM manager on the CE side. On the UPE side, OAM
manager defines an abstraction layer that relays data collected from OAM protocols (in this case CFM)
running within the metro network to the E-LMI switch. The information flow is unidirectional (from
OAM manager to the E-LMI) but is triggered in one of two ways:
• Synchronous data flow triggered by a request from the E-LMI
• Asynchronous data flow triggered by OAM manager when it receives notification from CFM that
the number of remote UNIs has changed
This data includes:
• EVC name and availability status (active, not active, partially active, or not defined)
• Remote UNI name and status (up, disconnected, administratively down, excessive FCS failures, or
not reachable)
• Remote UNI counts (the total number of expected UNIs and the actual number of active UNIs)
The asynchronous update is triggered only when the number of active UNIs has changed.
CFM Interaction with OAM Manager
When there is a change in the number of active UNIs or remote UNI ID for a given S-VLAN or domain,
CFM asynchronously notifies the OAM manager. A change in the number of UNIs might (or might not)
cause a change in EVC status. OAM manager calculates EVC status given the number of active UNIs
and the total number of associated UNIs.
Note If crosscheck is disabled, no SNMP traps are sent when there is a change in the number of UNIs.