Cisco Systems WSC4500X16SFP Manual De Usuario
38-7
Software Configuration Guide—Release 12.2(25)SG
OL-7659-03
Chapter 38 Configuring NetFlow
Configuring NetFlow Statistics Collection
M MAC addresses Hw Fw Sw Status
--+--------------------------------+---+------------+----------------+---------
1 0001.6442.2c00 to 0001.6442.2c01 0.4 12.1(14r)EW( 12.1(20030513:00 Ok
2 0001.6442.2c02 to 0001.6442.2c03 0.4 12.1(14r)EW( 12.1(20030513:00 Ok
6 0050.3ed8.6780 to 0050.3ed8.67af 1.6 12.1(14r)EW( 12.1(20030513:00 Ok
Mod Submodule Model Serial No. Hw Status
----+-----------------------+-----------------+------------+----+---------
1 Netflow Services Card WS-F4531 JAB062209CG 0.2 Ok
2 Netflow Services Card WS-F4531 JAB062209AG 0.2 Ok
Switch#
Note
Enabling this feature does not impact the hardware-forwarding performance of the switch.
The effective size of the hardware flow cache table is 65,000 flows. (The hardware flow cache for the
Supervisor Engine V-10GE is 85,000 flows.) If more than 85,000 flows are active simultaneously,
statistics may be lost for some of the flows.
Supervisor Engine V-10GE is 85,000 flows.) If more than 85,000 flows are active simultaneously,
statistics may be lost for some of the flows.
The effective size of the software flow table is 256, 000 flows. The NetFlow software manages the
consistency between the hardware and software tables, keeping the hardware table open by purging
inactive hardware flows to the software table.
consistency between the hardware and software tables, keeping the hardware table open by purging
inactive hardware flows to the software table.
User-configured timeout settings dictate when the flows are purged and exported through NDE from the
software cache. Hardware flow management ensures consistency between hardware flow purging and the
user-configured timeout settings.
software cache. Hardware flow management ensures consistency between hardware flow purging and the
user-configured timeout settings.
Software-forwarded flows are also monitored. Moreover, statistics will overflow if any flow receives
traffic at a sustained rate exceeding 2 gigabits per second. Generally, this situation should not occur
because a port cannot transmit at a rate higher than 1 gigabit per second.
traffic at a sustained rate exceeding 2 gigabits per second. Generally, this situation should not occur
because a port cannot transmit at a rate higher than 1 gigabit per second.
Note
By design, even if the timeout settings are high, flows will automatically “age out” as they approach their
statistics limit.
statistics limit.
Enabling NetFlow Statistics Collection
Note
NetFlow Flow Statistics are disabled by default.
To enable NetFlow switching, first configure the switch for IP routing as described in the IP
configuration chapters in the Cisco IOS IP and IP Routing Configuration Guide. After you configure IP
routing, perform one of these tasks:
configuration chapters in the Cisco IOS IP and IP Routing Configuration Guide. After you configure IP
routing, perform one of these tasks:
Command
Purpose
Switch(config)# ip flow ingress
Enables NetFlow for IP routing.
Switch(config)# ip flow ingress
infer-fields
Enables NetFlow with inferred input/output
interfaces and source/destination BGP as
information.
interfaces and source/destination BGP as
information.
The inter-fields option must be configured for AS
information to be determined.
information to be determined.