MPLS Netflow Egress 12.2(25)S

Question

Hi,
Anybody knows how to configure mpls netflow egress for a cisco router running 12.2(25)S service provider image ?
The following link says there is a restriction for it:
http://www.cisco.com/en/US/partner/products/ps6350/products_configuration_guide_chapter09186a00805e1253.html#wp1043334
The MPLS Egress NetFlow Accounting feature is not supported in Cisco IOS Release 12.2(25)S and later. Use the Egress NetFlow Accounting feature, which captures either IP or MPLS packets as they leave the router.
I haven't found out how to exactly configure this feature because the ip flow egress work is not working.
Anybody care to shed some light ?
Thanks in advance,
Luis Rueda

Answer 1

Netflow was in ingress technology, in which the flows that were captured were flows that entered the interface. Flows leaving the interface were not captured. Also, it was an IP technology, hence non IP traffic were not captured.
With the introduction of MPLS VPN, traffic from remote PEs were recieved on the egress PE as labelled traffic. Hence, they were not captured by Netflow (Without MPLS, enabling netflow on the WAN interface of the egress PE would have allowed the traffic be captured).
MPLS Egress Netflow Accounting patched the situation above by allowing Netflow to capture the flow, when the mpls packet was untagged. This feature was introduced in 12.0(20)S. see
http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_white_paper09186a00800b3d18.shtml
It is configured with the command mpls netflow egress
To make things better, they bettered the netflow technology and allowed it to captured egress traffic. With it capturing outgoing traffic, the mpls egress netflow feature was not needed again. Or to put it in another way, Egress Netflow Accounting, replaced MPLS Egress Netflow. See
http://www.cisco.com/en/US/products/sw/iosswrel/ps5207/products_feature_guide09186a00802d41ea.html
This is configured with the command
ip flow egress
For using these features, check your IOS properly and see which one it supports. I have succesfully used the MPLS Netflow Egress.