Netflow On The Pisa; Netflow On The Pfc3B - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

Understanding NetFlow
Collecting and exporting a large volume of statistics can significantly impact supervisor engine and
PISA processor usage, so NetFlow provides configuration options to control the volume of statistics.
These options include the following:
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NetFlow defines three configurable timers to identify stale flows that can be deleted from the table.
NetFlow deletes the stale entries to free up table space for new entries.

NetFlow on the PISA

The NetFlow table on the PISA captures statistics for flows routed in software. NetFlow on the PISA
supports NetFlow aggregation. For information about the NetFlow aggregation schemes, refer to the
following document:
Cisco IOS NetFlow Configuration Guide.
For information about configuring NetFlow aggregation on the PISA, refer to the following document:
Cisco IOS NetFlow Configuration Guide.
NetFlow on the PISA supports ToS-based router aggregation, described in this document:
Cisco IOS NetFlow Configuration Guide.
For information about NetFlow for multicast IP, refer to the NetFlow Multicast Support documentation,
available in the following document:
Cisco IOS NetFlow Configuration Guide.
The NetFlow Multicast Support document contains a prerequisite specifying that you need to configure
multicast fast switching or multicast distributed fast switching (MDFS). However, this prerequisite does
not apply when configuring NetFlow multicast support on the Supervisor Engine 32 PISA.

NetFlow on the PFC3B

The NetFlow table on the PFC3B captures statistics for flows routed in hardware. The PFC3B supports
sampled NetFlow and NetFlow aggregation. The PFC3B does not support NetFlow ToS-based router
aggregation.
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
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NetFlow flow masks determine the granularity of the flows to be measured. Very specific flow
masks generate a large number of NetFlow table entries and a large volume of statistics to export.
Less specific flow masks aggregate the traffic statistics into fewer NetFlow table entries and
generate a lower volume of statistics.
Sampled NetFlow exports data for a subset of traffic in a flow, which can greatly reduce the volume
of statistics exported. Sampled NetFlow does not reduce the volume of statistics collected.
NetFlow aggregation merges the collected statistics prior to export. Aggregation reduces the volume
of records exported, but does not reduce the volume of statistics collected. Note that NetFlow
aggregation increases switch CPU utilization and reduces the data available at the collector.
NetFlow aggregation uses NetFlow version 8.
Chapter 47 Configuring NetFlow
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