How to monitor packet loss and jitter


How does IsItUp measure Packet Loss and Jitter?


IsItUp uses the Ping Sensor to measure packet loss and jitter. It is recommended that a large number of packets be sent per test to get a reasonable measure of packet loss and jitter. We suggest at least a 100 packets be sent per test for data only links and for Real Time Protocols at least 1000. You may also want to increase the size of each packet to be similar to the normal load on your network. IsItUp keeps complete statistics both on packet loss, jitter, and round trip time. It is also worthwhile to mention that ping packets (ICMP) usually have the lowest routing priority and are the first packets to be dropped when a router or a server gets overloaded. Consequently, using ping gives only an estimate of the packet loss experienced by network users. Still, for normal practices, ping is an excellent tool for determining connectivity, packet loss and jitter.


Get Started Protecting your Network


To quickly get started protecting your network, Download your free trial of our Ping Monitor and follow the simple steps below.


How to setup a Ping Monitor to monitor packet loss and jitter


1. On the home tab, select the Add Monitor button and then Ping Monitor. This will launch the Ping Monitor wizard.


2. Enter a device name and select the desired group. Next select whether you want to specify the device by an IP address or Fully Qualified Domain Name. It is generally recommended that an IP address be used since if the domain name server is down, no testing can be done. However, sometimes it is necessary to use a FQDN especially when the IP addresses are being assigned dynamically. IsItUp also has a handy feature to lookup a FQDN. Just enter the name in the “FQDN to Look Up” field and click the lookup button.


3. To configure the packet loss threshold, click on the Setup button. The following dialog will be displayed :


Decide on what percent packet loss is acceptable to you before being alerted. An acceptable packet loss depends on your situation and your tolerance for errors. However, packet losses greater than 1 to 2 per cent can cause problems for Real time protocols. This level of packet loss might make VOIP, streaming, and gaming appear choppy, sluggish, and jerky. Other protocols that are used primarily for data just slow down as the protocols retransmit to recover loss packets. For these protocols, packet losses of 3 to 5 percent begin to show effects.

Then decide on how many pings per test. It is recommend that at least 100 pings be sent for testing packet loss on a data link and up to 1000 packets for VOIP testing.

Finally, specify the number of successful pings required for the test to be considered up. This allows you to set the packet loss tolerance that meets your needs. For example, if the number of packets sent is 100 and the number required for a successful test is 90, then that would required a 90 percent success rate or conversely up to a 10 percent loss.

4. At this point, you can simply click on the finish button. The monitor will be created with a default frequency of once every 30 minutes. The state of the device being monitored will be displayed on the screen as a green arrow pointing up if the device is responding and meeting your packet loss thresholds and a red arrow pointing down if it is not. However, you can continue configuring the monitor to add frequency, dependency maintenance schedule, alerts, and actions.

Once the monitor runs, the results of the test will be displayed on the Details View (right top window). Here is a sample in part below :



5. IsItUp support three types of Alerts and two types of actions. The alert types are Email and SMS messages, Paging, and playing a sound. The actions are restarting a service and executing a program with optional parameters. In order to configure alerts, either click on the Next button until you come to the alert you want to configure or select from the Navigation links on the left side of the dialog. For information on how to setup alerts and actions see the table below :


How to create an Email alert
How to send a SMS alert
How to customize an Email or a SMS alert
How to Execute an External Program as an alert