Cisco 7604 Configuration Manual page 854

Configuring NetFlow
To display the IP MLS flow mask configuration, perform this task:
Command
Router# show mls netflow flowmask
This example shows how to display the MLS flow mask configuration:
Router# show mls netflow flowmask
current ip flowmask for unicast: destination address
Router#
Configuring the MLS Aging Time
The MLS aging time (default 300 seconds) applies to all NetFlow table entries. You can configure the
normal aging time in the range of 32 to 4092 seconds. Flows can age as much as 4 seconds sooner or
later than the configured interval. On average, flows age within 2 seconds of the configured value.
Other events might cause MLS entries to be purged, such as routing changes or a change in link state.
If the number of MLS entries exceeds the recommended utilization (see the
Note
Guidelines and Restrictions" section on page
flows.
To keep the NetFlow table size below the recommended utilization, enable the following parameters
when using the mls aging command:
•
•
•
A typical table entry that is removed by fast aging is the entry for flows to and from a Domain Name
Server (DNS) or TFTP server.
If you need to enable MLS fast aging time, initially set the value to 128 seconds. If the size of the
NetFlow table continues to grow over the recommended utilization, decrease the setting until the table
size stays below the recommended utilization. If the table continues to grow over the recommended
utilization, decrease the normal MLS aging time.
To configure the MLS aging time, perform this task:
Command
Router(config)# mls aging {fast [threshold { 1-128 } |
time { 1-128 }] | long 64-1920 | normal 32-4092 }
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
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normal—Configures an inactivity timer. If no packets are received on a flow within the duration of
the timer, the flow entry is deleted from the table.
fast aging—Configures an efficient process to age out entries created for flows that only switch a
few packets, and then are never used again. The fast aging parameter uses the time keyword value
to check if at least the threshold keyword value of packets have been switched for each flow. If a
flow has not switched the threshold number of packets during the time interval, then the entry is aged
out.
long—Configures entries for deletion that have been active for the specified value even if the entry
is still in use. Long aging is used to prevent counter wraparound, which can cause inaccurate
statistics.
Purpose
Displays the flow mask configuration.
50-5), only adjacency statistics might be available for some
Purpose
Configures the MLS aging time for a NetFlow table entry.
Chapter 50 Configuring NetFlow
"NetFlow Configuration
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