Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Release 3.5 Software Configuration Guide, Cisco IOS Release 15.1(3)MR
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Chapter 15 Configuring Ethernet OAM, CFM, and E-LMI
Understanding Ethernet CFM
Configuration Error List
CFM configuration errors in CFM 802.1ag can be misconfigurations or extra configuration commands
detected during MEP configuration. They can be caused by overlapping maintenance associations. For
example, if you create a maintenance association with a VLAN list and a MEP on an interface, a
potential leak error could occur if other maintenance associations associated with the same VLAN exist
at a higher level without any MEPs configured. You can display the configuration error list, which is
informational only, by entering the show ethernet cfm errors configuration privileged EXEC
command.
CFM Version Interoperability
When customers upgrade their network from the Cisco CFM draft 1 to IEEE standardized 802.1ag CFM,
they might not upgrade all equipment at the same time, which could result in a mix of Cisco CFM draft 1
and IEEE standardized CFM devices in the network. CFM areas are regions in a network running Cisco
CFM draft 1 software. Internal area bridges are all Cisco devices running CFM draft 1, and external area
bridges are devices (Cisco or third-party devices) running IEEE standardized 802.1ag CFM.
Devices at the edge of these areas perform message translation. Translation is not needed for
maintenance domains that do not span different areas (that is, where CFM messages end on a port on the
device) since the port can respond in the same message format as was received. However, for
maintenance domains that span across two areas, the device must translate the CFM message
appropriately before sending it on to the other area.
Note The Cisco MWR 2941 does not support translation between CFM draft 1.0 and IEEE standardized
802.1ag CFM.
When designing a network with CFM areas, follow these guidelines:
• Whenever possible, group devices with the same CFM version together.
• Minimize the number of boundaries between CFM clusters, minimizing the number of devices that
must perform translation.
• Never mix CFM versions on a single segment.
IP SLAs Support for CFM
The router supports CFM with IP Service Level Agreements (SLAs), which provides the ability to gather
Ethernet layer network performance metrics. Available statistical measurements for the IP SLAs CFM
operation include round-trip time, jitter (interpacket delay variance), and packet loss. You can schedule
multiple IP SLAs operations and use Simple Network Management Protocol (SNMP) trap notifications
and syslog messages for proactive threshold violation monitoring.
For more information about IP SLAs, see Chapter 41, “Configuring Cisco IOS IP SLAs Operations“, of
the Cisco Catalyst Blade Switch 3020 for HP Software Configuration Guide, 12.2(55)SE.
IP SLAs integration with CFM gathers Ethernet layer statistical measurements by sending and receiving
Ethernet data frames between CFM MEPs. Performance is measured between the source MEP and the
destination MEP. Unlike other IP SLAs operations that provide performance metrics for only the IP
layer, IP SLAs with CFM provides performance metrics for Layer 2.