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Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter38 Configuring NetFlow
Configuring NetFlow Statistics Collection

Configuring the Minimum Mask of a Source-Prefix Aggregation Scheme

To configure the minimum mask of a source-prefix aggregation scheme, perform this task :

Monitoring and Maintaining Minimum Masks for Aggregation Schemes

To view the configured value of the minimum mask, use the following commands for each aggregation
scheme, as needed:
Configuring NetFlow Aging Parameters
You can control when flows are purged from the software flow cache (and, if configured, reported
through NDE) with the configuration aging parameters, Active and Inactive, of the ip flow-cache
timeout command.
Active Aging specifies the period of time in which a flow should be removed from the software flow
cache after the flow is created. Generally, this parameter is used to periodically notify external collection
devices about active flows. This parameter operates independently of existing traffic on the flow. Active
timeout settings tend to be on the order of minutes (default is 30min).
Inactive Aging specifies how long to wait before removing a flow after the last packet is seen. The
Inactive parameter clears the flow cache of “stale” flows thereby preventing new flows from starving
(due to lack of resources). Inactive timeout settings tend to be on the order of seconds (default is 15sec).
Command Purpose
Step1 Router(config)# ip flow-aggregation cache source-prefix Configures the source-prefix aggregation
cache.
Step2 Router(config-flow-cache)# mask source minimum
value
Specifies the minimum value for the source
mask.
Command Purpose
Router# show ip cache flow aggregation prefix Displays the configured value of the
minimum mask in the prefix aggregation
scheme.
Router# show ip cache flow aggregation
destination-prefix
Displays the configured value of the
minimum mask in the destination-prefix
aggregation scheme.
Router# show ip cache flow aggregation
source-prefix
Displays the configured value of the
minimum mask in the source-prefix
aggregation scheme.