Description

The sFlow monitoring system consists of an sFlow agent embedded in the EX Switch and has a centralized collector. The sFlow agent’s two main activities are random sampling and statistics gathering. It combines interface counters and flow samples and sends them across the network to the sFlow collector.  The sFlow collector uses the sFlow agent’s IP address to determine the source of the sFlow data. This KB article explains how the EX Switch assigns the IP address to the sFlow agent.

Symptoms


Solution

The IP address assigned to the sFlow agent is based on the following order of priority, of interfaces, configured on the EX switch:
  1. Virtual Management Ethernet (VME) interface
  2. Management Ethernet interface

If any of the above interfaces have not been configured the IP address of any Layer 3 interface or the Routed VLAN Interface (RVI) is used as the IP address for the agent. At least one interface must be configured for an IP address to be assigned to the agent.

Please note that this behavior is different prior to JUNOS 9.5 and it follows the order below for JUNOS 9.5 and above.  Please review JUNOS EX Switch Guide for releases prior to JUNOS 9.5.
  1. Loopback interface
  2. Virtual Management Ethernet (VME) interface
  3. Management Ethernet interface
  4. Any other Layer 3 interface