Networks Unlimited

NetFlow Technical Info

NetFlow is an embedded feature within Cisco IOS Software that records network traffic into the device cache to provide extremely granular and accurate traffic measurements. Because network traffic has a flow nature to it, the NetFlow accounting data that is built in the cache, characterizes the IP traffic being forwarded.

Exported NetFlow statistics can be used for a variety of purposes including, network traffic accounting, usage-based network billing, network monitoring, and data warehousing for marketing purposes.

NetFlow data records exported by routers and switches consist of expired traffic flows with detailed traffic statistics. These flows contain information about Layer 3 sources and destinations, along with the protocols and ports used in the end-to-end conversation.

This information assists IT in monitoring and fine-tuning network traffic by identifying additional bandwidth requirements, and allocating available bandwidth efficiently across the network.

NetFlow traffic statistics include

1. Time stamp of the flow
2. Source and destination IP address
3. Source and destination port number
4. Input and output interface number
5. Next hop IP address
6. Total bytes in the flow
7. Number of packets in the flow
8. First and last time stamps of packets switched as part of this flow
9. Source and destination AS, and prefix masks
10. Sequence number (version 5 only)

For more information on Cisco NetFlow go to

The specifications and the performance of NetFlow Analyzer depends on the number of routers sending NetFlow data to the system, as well as how busy each router is.

O/S | Processor | Speed | Memory | Storage | Database
Windows | Pentium III | 1 GHz | 512 MB | 150 MB | 10 GB
Linux | Pentium III | 1 GHz | 512 MB | 150 MB | 10 GB
Solaris | Pentium III | 1 GHz | 512 MB | 150 MB | 10 GB

For the Cisco router:

The router and its IOS version must support NetFlow. For more information consult the NetFlow IOS support specs.

Note: NetFlow Analyzer 4 supports NetFlow version 5 exports only.

Supported Operating Systems

NetFlow Analyzer has been tested to support the following operating systems and versions:

* Windows 2000 Server / Professional with SP 4, Windows XP with SP 1
* RedHat Linux 8.0 and 9.0
* Sun Solaris 5.8

Supported Browsers

* Internet Explorer 5.5 and above
* Netscape 7.0 and above
* Mozilla 1.5 and above

Note: NetFlow Analyzer is optimized for 1024 x 768 resolution and above. The product should be started in an X-windows environment in Linux and Solaris operating systems for generating graphs.