Cisco NetFlow is a network monitoring and traffic analysis technology developed by Cisco Systems, a leading provider of networking equipment and solutions. NetFlow allows network administrators to collect and analyze data about the traffic flowing through a Cisco router or switch. It provides valuable insights into network traffic patterns, helping organizations optimize network performance, troubleshoot issues, and enhance security.

Here are some key features and benefits of Cisco NetFlow:

Traffic Analysis: NetFlow collects data on network traffic, including details about the source and destination IP addresses, port numbers, protocol types, and data volume. This information is used to create detailed traffic reports and analyze network behaviour.

Bandwidth Monitoring: Network administrators can use NetFlow to monitor bandwidth usage by different applications, devices, or users. This helps in identifying bandwidth-hungry applications and optimizing network resources.

Security Analysis: NetFlow data can be used to detect and analyze suspicious or malicious network activity. Security professionals can use it to identify potential threats, such as DDoS attacks or unauthorized access attempts.

Troubleshooting: When network issues arise, NetFlow data can provide valuable insights into the root cause. It helps in diagnosing problems, locating bottlenecks, and optimizing network configurations.

Capacity Planning: By analyzing historical NetFlow data, organizations can make informed decisions about network capacity planning and resource allocation. This ensures that the network can meet current and future demands.

Billing and Accounting: Service providers and organizations with multiple departments or customers can use NetFlow data to create usage-based billing and accounting reports, helping them allocate costs accurately.

Flow-based Reporting: NetFlow operates on a "flow" basis, where a flow represents a unidirectional stream of packets between a specific source and destination. This flow-based approach allows for granular and efficient data collection.

Cisco NetFlow has evolved over the years, and there are several versions of NetFlow, including NetFlow v5, NetFlow v9, and Flexible NetFlow. Each version offers different capabilities and flexibility in terms of data export and customization.

In summary, Cisco NetFlow is a powerful tool for network administrators and security professionals to gain visibility into their network traffic, optimize performance, and enhance security by monitoring and analyzing traffic patterns.

Restrictions for NetFlow Monitoring:

• NetFlow ingress monitoring is not supported on MPLS core interface.
• Configuration of cache entries number is not supported.
• MPLS and BGP-based NetFlow is not supported.
• NetFlow monitoring can account for a maximum of 1Gbps traffic rate in the system.
• Flow monitoring of multicast traffic is not supported.