Configuring Real-Time Performance Monitoring Probes

For both IP monitoring with route failover and IP monitoring with interface failover, the probes that are used to test the target device are real-time performance monitoring (RPM) probes that not only test the reachability of the IP address but also perform service-level monitoring on parameters such as jitter and latency.

Real-time performance monitoring allows you to perform service-level monitoring. When RPM is configured on a device, the device calculates network performance based on packet response time, jitter, and packet loss. These values are gathered by HTTP GET requests, Internet Control Message Protocol (ICMP) requests, TCP requests, and UDP requests, depending on the configuration.

You can gather RPM statistics by sending out probes to a specified probe target, identified by an IP address or URL. When the target receives the probe, it generates responses, which are received by the SRX Series device. By analyzing the transit times to and from the remote server, the device can determine network performance.

SRX Series gateways send out the following probe types:

• HTTP GET request to a target URL

• HTTP GET request for metadata from a target URL

• ICMP echo request to a target IP address (the default)

• ICMP timestamp request to a target address

• UDP ping packets to a target device

• UDP timestamp requests to a target IP address

• TCP ping packets to a target device

Each probed target is monitored over the course of a test. A test represents a collection of probes, sent out at regular intervals as defined in the configuration. Statistics are then returned for each test. Because a test is a collection of probes that have been monitored over some amount of time, test statistics such as standard deviation and jitter can be calculated and included with the average probe statistics.

Within a test, RPM probes are sent at regular intervals and configured in seconds. When the total number of probes has been sent and the corresponding responses received, the test is complete. You can manually set the probe interval for each test to control how the RPM test is conducted.

After all probes for a particular test have been sent, the test begins again. The time between tests is the test interval. You can manually set the test interval to tune RPM performance.

To monitor multiple IP addresses, multiple tests can be defined for each probe, and the probe fails only if all tests fail. The system can perform a logical AND operation of all test results to determine the outcome of a probe.

Figure 1 shows the topology used in the following configuration example.

Figure 1: Real-Time Performance Monitoring Topology

The following is an example configuration of an RPM probe that monitors three IP addresses:

After the RPM probe configuration is committed, results of the probe can be displayed using the following command:

With the RPM probes, you can detect the reachability of the monitored IP address, and you can also measure network parameters and take an action if round-trip time (RTT) or jitter is greater than a configured value. The following command displays the parameters that can be measured: