Fluke Computer Accessories ip flow-cache timeout active, ip flow-cache timeout inactive, exit

User’s Guide – version 3.5 NetFlow Tracker

ip flow-cache timeout active 1

This breaks up long-lived flows into one-minute segments.

ip flow-cache timeout inactive 15

This ensures that flows that have finished are exported in a timely manner.

interface <interface>

ip route-cache flow or ip flow ingress or ip route-cache cef bandwidth <kbps>

exit

You need to enable NetFlow on each interface through which traffic you are interested in will flow. This will normally be the Ethernet and WAN interfaces. Note that there are several commands to enable NetFlow on an interface and you must use the same command for every interface. ip route-cache flow and ip flow ingress enable NetFlow for inbound traffic on the interface; the only difference between the two is that the latter can be applied to individual sub-interfaces whereas the former must be applied to the physical interface. Be careful not to enable NetFlow for both a physical interface and one or more of its sub-interfaces.

ip flow egress enables NetFlow for outbound traffic on the interface and is required if you are using input filters. You may enable NetFlow for both inbound and outbound traffic on a single interface if you are interested only in its traffic; in this case ensure that no other interface has NetFlow enabled.

Egress NetFlow is also useful if you are monitoring a router that is applying QoS to the traffic it routes – by using egress NetFlow you will see the QoS settings that the router applied rather than those that were on the traffic before it was routed.

You may also need to set the speed of the interface in kilobits per second. It is especially important to set the speed for frame relay or ATM virtual circuits. Note that a Catalyst 4000 series switch does not support any of the commands to enable NetFlow for an interface; instead NetFlow is enabled for all interfaces using a special command documented below.

show ip flow export

This will show the current NetFlow configuration. Issue this in normal (not configuration) mode.

show ip cache flow

show ip cache verbose flow

These commands issued in normal mode summarize the active flows and give an indication of how much NetFlow data the router is exporting.

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