Specifications

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Cisco MWR 2941 Mobile Wireless Edge Router Software Configuration Guide, Release 12.2(33)MRB
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Chapter 4 Configuring the Cisco MWR 2941 Router Using the CLI
Configuration Sequence
CFM over Bridge Domains
The Ethernet OAM 3.0—CFM over BD, Untagged feature allows untagged CFM packets to be
associated with a MEP. An incoming untagged customer CFM packet has an EtherType of CFM and is
mapped to an EVC or bridge domain (BD) based on the encapsulation configured on the EFP. The EFP
is configured specifically to recognize these untagged packets.
An EFP is a logical demarcation point of an EVC on an interface and can be associated with a bridge
domain. The VLAN ID is used to match and map traffic to the EFP. VLAN IDs have local significance
per port similar to ATM/FrameRelay virtual circuits. CFM is supported on a bridge domain associated
with an EFP. The association between the bridge domain and the EFP allows CFM to use the
encapsulation on the EFP. All EFPs in the same bridge domain form a broadcast domain. The bridge
domain ID determines the broadcast domain.
The distinction between a VLAN port and the EFP is the encapsulation. VLAN ports use a default dot1q
encapsulation. For EFPs, untagged, single tagged, and double tagged encapsulation exists with dot1q
and IEEE dot1ad EtherTypes. Different EFPs belonging to the same bridge domain can use different
encapsulations.
Note The Ethernet OAM 3.0—CFM over BD, Untagged feature is supported only on ES20 and ES40 line
cards.
NSF/SSO Support in CFM 802.1ag/1.0d
The redundancy configurations SSO and NSF are both supported in Ethernet CFM and are automatically
enabled. A switchover from an active to a standby RP occurs when the active RP fails, is removed from
the networking device, or is manually taken down for maintenance. NSF interoperates with the SSO
feature to minimize network downtime following a switchover. The primary function of Cisco NSF is
to continue forwarding IP packets following an RP switchover.
For detailed information about SSO, see the “Stateful Switchover” chapter of the Cisco IOS High
Availability Configuration Guide. For detailed information about the NSF feature, see the “Cisco
Nonstop Forwarding” chapter of the Cisco IOS High Availability Configuration Guide.
ISSU Support in CFM 802.1ag/1.0d
ISSU allows you to perform a Cisco IOS software upgrade or downgrade without disrupting packet flow.
CFM performs a bulk update and a runtime update of the continuity check database to the standby RP,
including adding, deleting, or updating a row. This checkpoint data requires ISSU capability to
transform messages from one release to another. All the components that perform active RP to standby
RP updates using messages require ISSU support.
ISSU is automatically enabled in CFM and lowers the impact that planned maintenance activities have
on network availability by allowing software changes while the system is in service. For detailed
information about ISSU, see the “Cisco IOS In Service Software Upgrade Process” chapter of the
Cisco IOS High Availability Configuration Guide.