Cisco Systems EA6500 Manual De Usuario

NDE captures statistics for Layer 3-switched flows in the MLS cache on the PFC. 

NDE maintains traffic statistics for each active flow in the MLS cache and increments the statistics when 
packets within each flow are switched. Periodically, NDE exports summarized traffic statistics for all 
expired flows, which the external data collector receives and processes.

Exported NetFlow data contains statistics for the flow entries in the MLS cache that have expired since 
the last export. Flow entries in the MLS cache expire and are flushed from the MLS cache when one of 
the following conditions occurs:

The transport protocol indicates that the connection is completed. 

Traffic inactivity exceeds 15 seconds. 

For flows that remain continuously active, flow entries in the MLS cache expire every 32 minutes to 
ensure periodic reporting of active flows. 

NetFlow data export packets go to the external data collector either when the number of recently expired 
flows reaches a predetermined maximum, or every second, whichever occurs first. 

By default, all expired flows are exported unless filtered. With a filter configured, NDE only exports 
expired and purged flows that match the filter criteria. NDE flow filters are stored in NVRAM and are 
not cleared when NDE is disabled. See the 

 for 

NDE filter configuration procedures.

Sampled NetFlow exports data for a subset of the Layer 3-switched IP packets instead of for all packets 
in a flow. Sampled NetFlow substantially decreases the Supervisor Engine 2 CPU utilization. Release 
12.1(13)E and later releases support sampled NetFlow on the Supervisor Engine 2. 

With the full-interface or destination-source-interface flow masks, you can enable or disable sampled 
NetFlow on each LAN port. With all other flow masks, sampled Netflow is enabled or disabled globally.

42–43 dst_as

Autonomous system number of the 
destination, either origin or peer

44

src_mask Source 

address prefix mask bits 

45

dst_mask  Destination address prefix mask bits 

46–47 pad2

Pad 2

48–51 MLS RP

IP address of MLS router

1.

Supported in Release 12.1(13)E and later releases.

2.

With the destination flowmask, the “Next hop router’s IP address” field and the “Output interface’s SNMP ifIndex” field might not contain information 
that is accurate for all flows.

Flow masks:
• X=Populated
• A=Additional field (see the 

“Populating Additional NDE 

Fields” section on page 33-10

)

 

 

 

 

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