Cisco Cisco IOS Software Release 12.2(27)SBC

The last line contains the information added by the NetFlow MPLS Label Information Export PAL table 
(VPN/10.0.0.9). This associates the VPN application and the 10.0.0.9 prefix with the top label in the 
MPLS stack.

You can configure the NetFlow MPLS Label Information Export feature on P or PE routers. That is, you 
can configure the feature on any router that has inbound MPLS traffic.

The NetFlow Collector can collect the information exported from the NetFlow cache of a P router and 
the PAL table information from a PE router. The Collector can then correlate the information from both 
based on the label value. For example, the PAL packet indicates that a label has the following mappings 
over a period of time, as each label is allocated and reallocated on the PE router:

label 5, prefix 10.0.0.0,  type LDP, 12:00:00

label 4, prefix 10.10.0.0, type LDP, 13:00:00

label 5, prefix 10.9.0.0,  type BGP, 14:00:00

Because the mapping may change over time as labels expire and are reused, each PAL record contains a 
time stamp indicating the system uptime at which the label was allocated. 

The NetFlow collector then receives a NetFlow packet from the adjacent P router indicating the 
following:

label 5, 123 packets, 9876 bytes, time 12:22:15.

The collector would match the time range known from the PAL packets, with the line card packet 
time stamp, resulting in the correct mapping for label 5 at time 12:22:15: 

label 5, application LDP, prefix 10.0.0.0. 

The correlation of the MPLS PAL record data exported from the PE router with NetFlow statistics 
exported from the P router on the collector is independent of the time at which the routers send the data. 
You can set up the exporting of the information and allow the collector to do the correlation of the data.

To successfully implement the offline label mapping checks in the NetFlow collector, the collector needs 
to maintain a history of label mappings obtained from the MPLS PAL packets sent by the RP. If a label 
is deallocated and reallocated, the NetFlow collector should track both the old and the new MPLS PAL 
information for the label. Cisco IOS 12.2S releases uses the MPLS Forwarding Infrastructure (MFI), 
which allows easy tracking of the allocation and deallocation of labels. This functionality does not exist 
in Cisco IOS 12.0S releases.

For more information on the NetFlow MPLS Label Export feature, see the 

 

feature module.

The NetFlow collector might not be able to accurately track how many packets flowed for a label that 
has been deallocated by one application and soon reallocated by another application. 

This section contains the following procedures for configuring MPLS-Aware NetFlow:

 (required)

 (optional)

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