IMS - SIP Performance Analysis

 

Introduction

There are several tools available for analyzing SIP data, but almost all of them only offer ordinary protocol decode along with some simple counters and statistics. Call Analyzer offers a lot more than this since it includes features such as latency measurements, call trace across different interfaces, user-defined performance indicators and much, much more.

 

Call trace

With Call Analyzer it is possible to define the rules and references for call trace, thus allowing the user to follow calls across different interfaces in order to find out which part of the network is causing problems or bottlenecks.

 

 

The above example of a display shows a call trace where the invite is captured on two different interfaces. This feature is fundamental for measuring latency in the server forwarding the messages or analyzing precisely which part of the network is replying with an error indication.

 

 

The user can also select and define what counters and latency measurements should be displayed in the different result windows. The previous example of a display shows the simplest performance and latency indications for the above example.

 

The ability to follow complete transactions makes it possible to see, for example, whether a message is repeated within a transaction and what the response is each time the message is sent. The display below shows an example of the response to first and second register, but the user can freely decide what sequences to analyze.

 

 

Load and response over time

Call Analyzer also allows the user to select any combination of counters to be viewed over time. This can be used to verify whether the response rate is dependent on the load on the server, whether a failure depends on the load on the server or to see whether a server can handle the expected number of transactions. For instance, the number of register messages can be compared to the number of accepts or the number of invites and OKs can be compared. This allows the user to see how many calls or registrations the server can handle per second.

  

 

Absolute latency

If enhanced latency measurements are needed, Call Analyzer can show the number of transactions performed along with their associated delays.

 

 

This display shows the number of transactions (Y-axis) that were completed with a given delay (X-axis), providing the user with the ability to see the latency distribution. Additionally, the graph intuitively depicts which transactions were suffering from long delays prior to being completed

 

Latency vs. load

Since latency may be dependent on network load, Call Analyzer can also provide a separate display showing both load and latency over time. This allows the user to see whether there is any relationship between the number of transactions and the latency for those same transactions.

 

 

Supported file formats

Call Analyzer is a post-processing tool that supports the following file types:

 

 

Other file formats can be implemented upon request.