IP-SLA Monitoring

IP-SLA monitoring is mostly used by VoIP monitoring tools to determine sound quality for VoIP traffic. VoIP related network traffic is especially sensitive to even slight problems in connectivity. Sound quality drops dramatically when UDP packets are not received in a timely fashion, if packets are lost or reordered.

PRTG Network Monitor offers an IP-SLA sensor, which monitors parameters such as

• ICPIF (Calculated Planning Impairment Factor), which represents predefined combinations of packet loss and packet delay in a VOIP network call and is a standard for measuring quality of service

• MOS (Mean Opinion Score), a numerical indication of the perceived quality of received media after compression and/or transmission.
• Average VoIP Jitter (Packet Delay Variation)
• Packets Lost
• Packets Out Of Sequence
• Packets Late
• Average Round Trip Time (network latency)
• DNS RTT
• TCP RTT
• Transaction RTT

How to set up IP SLA Monitoring With PRTG

In order to configure the PRTG IP SLA monitor, you need to create a device for the IP-SLA enabled Cisco device that you want to monitor. Remember to enter SNMP credentials because PRTG uses SNMP to get the data from the switch. The second step is to create a new sensor on that device, choose "IP SLA" from the "VoIP and Infrastructure" section and follow the instructions on the screen. A few moments later you will see the current measurements in PRTG's user interface - your IP SLA monitoring solution is ready to use.

VoIP Monitoring Without IP-SLA

Unfortunately, IP-SLA monitoring is only available in the more expensive boxes from Cisco. But even if you don't have IP SLA capable routers/switches you can still get similar information (jitter, packet delay variation, duplicate and reordered packets as well as packet loss monitoring) with PRTG's QoS sensor, which does not require any special hardware - just two PCs running Windows.

PRTG - a Free IP SLA Monitor

If you do own hardware which supports IP SLA then PRTG brings you probably the least-cost monitoring solution for IP SLA. Most vendors charge extra for IP SLA support. Following Paessler's long term policy we simply include this as one of our sensor types. With PRTG you can even use the Freeware Edition for IP SLA monitoring!

But PRTG is not only an advanced VoIP monitoring manager. The network and server monitoring software from Paessler ensures the availability of network components while also monitoring network traffic and usage. It saves costs by avoiding outages, optimizing connections, saving time and controlling service level agreements.

PRTG Network Monitor is available in two editions. For basic, free bandwidth and availability monitoring functionality (including IP SLA monitoring), the Freeware Edition may be downloaded and used for personal and commercial use completely free of charge. For more advanced needs, licenses for the Commercial Editions start at $400 / €300.