Cisco NetFlow-Lite on the Cisco Catalyst 2960-X, 2960-XR, 2960-CX, and 3560-CX Series Switches
We discussed the Cisco Catalyst 4948E NetFlow-lite/NFLite before. What’s the difference between the NetFlow and Netflow-Lite? We knew that NetFlow-lite was first introduced with Catalyst 4948E, and it bridges the gap by providing a lightweight solution that allows capturing of important flow information through packet sampling mechanisms combined with the extensibility of NetFlow version 9 and IPFIX. NetFlow-Lite introduces traffic visibility on the Cisco Catalyst 2960-X, 2960-XR, 2960-CX, and 3560-CX Series Switches for the first time.
NetFlow-Lite collects packets randomly, classifies them into flows, and measures flow statistics as they pass through the switch. It is a true flow-based traffic-monitoring mechanism that conserves valuable forwarding bandwidth when exporting flow-based data for analysis and reporting.
Firstly we can read what NetFlow-Lite is used for again
NetFlow-Lite offers network administrators and engineers the following capabilities:
● Unprecedented visibility: NetFlow-Lite provides real-time information about traffic flows from endpoints such as PCs, phones, IP cameras, etc. You can use this information for traffic monitoring of Layer 2 and Layer 3 traffic as well as capacity planning.
● Network planning: You can use NetFlow-Lite to capture data over a long period of time so that customers can understand traffic patterns, top talkers, top applications, etc. This feature provides accurate data to track and anticipate network growth and plan upgrades.
● Simplified troubleshooting: You can use NetFlow-Lite flow-based analysis techniques to understand traffic patterns, which can help in proactively detecting problems, troubleshooting efficiently, and resolving problems quickly.
NetFlow-Lite provides a granular packet-sampling mechanism that is adjustable up to 1:32 and available for all interfaces. The implication is that a subset of all packets passing through the switch is selected for reporting.
NetFlow-Lite on the Cisco Catalyst 2960-X, 2960-XR, 2960-CX, and 3560-CX Series Switches have the following capabilities:
- NetFlow-Lite is supported on all downlink and uplink ports.
- NetFlow-Lite is natively available with no additional hardware required.
- The sampling range is from 1:32 to 1:1022.
- The application measures 16,000 flows per switch.
- Physical ports and VLAN Interfaces (switched virtual interfaces [SVI]) are supported.
- NetFlow-Lite supports ingress flows only.
- Export using standards-based IP Information export (IPFIX) or Version 9 record format.
NetFlow-Lite Sampling Techniques
The sampling method of the traffic can be random or deterministic. Random sampling chooses one packet randomly out of a configured sample size, whereas deterministic sampling chooses the first packet out of a configured sample size. For example, for 1:32 sampling, deterministic mode would choose the 1st, 33rd, 65th, 97th, and so on packet coming into an interface, and random mode can choose the 5th, 39th, 72nd, 103rd, and so on packet coming into an interface. Random packet sampling is statistically more accurate than deterministic packet sampling.
NetFlow-Lite Solution-NetFlow-Lite configuration on the Cisco Catalyst 2960-X, 2960-XR, 2960-CX, and 3560-CX Series Switches
Steps-Only 5 Steps
Step1. Configure a Flow Record, which defines the data collection. You can customize it for specific requirements. You can use the following example with most NetFlow collectors:
flow record v4 match ipv4 tos match ipv4 protocol match ipv4 source address match ipv4 destination address match transport source-port match transport destination-port collect transport tcp flags collect interface input collect flow sampler collect counter bytes long collect counter packets long collect timestamp sys-uptime first collect timestamp sys-uptime last
Step2. Configure a Flow Exporter, which defines where the collected data needs to be sent. Please refer to the NetFlow collector application user guides and manual for specific details such as port number, differentiated services code point (DSCP), and other options. The configuration follows:
flow exporter Replicator description Exporter to Cisco Prime 2.0 destination 10.2.44.12 source GigabitEthernet1/0/1 dscp 16 template data timeout 60 option interface-table
Step3. Configure a Flow Monitor, which binds the flow record and exporter along with options to configure the flow cache:
flow monitor v4 record v4 exporter Replicator cache timeout active 30
Step4. Configure a Flow Sampler. Define the sampling technique and sample size. The configuration follows:
sampler v4 mode random 1 out-of 32
Step5. Attach the Flow Monitor and Sampler to the interface:
interface GigabitEthernet1/0/1 ip flow monitor v4 sampler v4 input
Reference from http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-2960-x-series-switches/solution_overview_c22-728776.html