Faster Data Plane Convergence - Cisco ASR 5000 Series Administration Manual

System Settings
In the above configuration, there is a single, primary LAG. All ports work as a single bundle of ports that
distribute the traffic.
Important
Important
To achieve redundancy you must configure a second non-redundant LAG. You can use a higher layer load
balancing mechanism such as ECMP (Equal Cost Multiple Path) routing to uniformly distribute the traffic
across two LAG groups.
When one MIO/UMIO/MIO2 fails, half the ports from both the LAG groups will be available for distribution
of the traffic from the other MIO/UMIO/MIO2.
Figure 12: Non-Redundant LAG Configuration with ECMP
Configuring a second LAG group is not mandatory, but is the usual approach for achieving redundancy with
this mode of LAG.
However, if the aggregating ports are loaded with more than 50% of their capacity and an MIO/UMIO/MIO2
failure/switchover occurs, the ASR 5500 configured port capacity is oversubscribed and an indeterminate
amount of sessions are dropped and traffic lost.

Faster Data Plane Convergence

The Global Configuration mode fast-data-plane-convergence command enables faster recovery of existing
sessions in an Active-Active LAG configuration with aggressive MicroBFD timers. This feature can be enabled
with an Active-Standby LAG configuration, however, reduced switchover time cannot be guaranteed.
This feature eliminates false positive detection of failure with an external switch and false positive ICSR
failover with another ASR 5500.
configure
fast-data-plane-convergence
If you use the Ethernet Port Configuration mode shutdown command to shut down one of the ports on
an MIO/UMIO/MIO2 card in this LAG configuration, by default the paired port on the other
MIO/UMIO/MIO2 card will also be shut down. You can selectively disable an MIO/UMIO/MIO2 port
in this LAG configuration using the Exec mode port { disable | enable } ethernet slot/port command.
With this mode of operation, automatic ASR 5500 port redundancy is lost.
ASR 5500 System Administration Guide, StarOS Release 21.4
Faster Data Plane Convergence
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