sFlow and Agent Address

The sampled sFlow data sent to the collectors includes an agent_address field. This field identifies the IP address of the device that sent the data:

On a Layer 2 switch, agent_address is the Layer 2 switch management IP address. You must configure the management IP address in order to export sFlow data from the device. If the switch has both an IPv4 address and IPv6 address, the agent_address is the IPv4 address. If the switch has an IPv6 address only, the agent_address is the global IPv6 address.

On a Layer 3 switch with IPv6 interfaces only, sFlow looks for an IPv6 address in the following order, and uses the first address found:
- The first IPv6 address on the lowest-numbered loopback interface
- The first IPv6 address on the lowest-numbered virtual interface
- The first IPv6 address on any interface

On a Layer 3 switch with both IPv4 and IPv6 interfaces, or with IPv4 interfaces only, sFlow looks for an IP address in the following order, and uses the first address found:
- The IPv4 router ID configured by the ip router-id command
- The first IPv4 address on the lowest-numbered loopback interface
- The first IPv4 address on the lowest-numbered virtual interface
- The first IPv4 address on any interface

Note: A device uses the router ID only if the device also has an IP interface with the same address. The router ID is not supported on IPv6 devices.

Note: If an IP address is not already configured when you enable sFlow, the sFlow version 5 feature uses the source address 0.0.0.0. To display the agent_address, enable sFlow, and then enter the show sflow command. Refer to step 7 in Configuring sFlow and Displaying sFlow information.

Note: In sFlow version 5, you can set an arbitrary IPv4 or IPv6 address as the sFlow agent IP address. Refer to step 3 in Configuring sFlow Version 5.