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Figure 70 NetStream system
Flow aging
NetStream uses flow aging to enable the NDE to export NetStream data to NetStream servers.
NetStream creates a NetStream entry for each flow for storing the flow statistics in the cache.
When a flow is aged out, the NDE performs the following operations:
•
Exports the summarized data to NetStream servers in a NetStream export format.
•
Clears NetStream entry information in the cache.
For more information about flow aging types and configurations, see "
."
NetStream data export
Traditional data export
Traditional NetStream collects the statistics of each flow and exports the statistics to NetStream
servers.
This method consumes more bandwidth and CPU than the aggregation method, and it requires a
large cache size.
Aggregation data export
NetStream aggregation merges the flow statistics according to the aggregation criteria of an
aggregation mode, and it sends the summarized data to NetStream servers. The NetStream
aggregation data export uses less bandwidth than the traditional data export.
lists the available aggregation modes. In each mode, the system merges statistics for
multiple flows into statistics for one aggregate flow if each aggregation criterion is of the same value.
The system records the statistics for the aggregate flow. These aggregation modes work
independently and can take effect concurrently.
For example, when the aggregation mode configured on the NDE is protocol-port, NetStream
aggregates the statistics of flow entries by protocol number, source port, and destination port. Four
NetStream entries record four TCP flows with the same destination address, source port, and
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