NBAR
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Network Based Application Recognition (NBAR) is the mechanism used to recognize a dataflow by the first packet sent.
The networking equipment which uses NBAR does a deep packet inspection on the first packet in a dataflow, to determine which traffic category the flow belongs to. It then programmes the internal ASICs to handle this flow appropriately. The categorisation is usually done with OSI-layer4 info, but new applications have made it difficult to cling to this kind of tagging.
The NBAR approach is useful in dealing with malicious software using known ports to fake being "priority traffic", as well as non-standard apps using non-determinaly ports.
External links
- Cisco's website (http://www.cisco.com)