IMS Latency Analysis

 

Introduction

Key challenges faced by IMS (IP Multimedia Subsystems) servers involve their ability to achieve high performance and fast response times. Because of complex procedures and interworking between different servers, latency analysis is a key area of investigation for both troubleshooting and performance verification.

 

Call Analyzer is the ideal tool for latency analysis because it includes features for simple average latency measurements as well as for more detailed verification of latency over time and latency compared with network load.  Latency can be measured as response times on a single interface or as delays across different interfaces.

 

Average latency

In Call Analyzer, a wide range of counters for performance or latency analysis can be selected and displayed, either as a summary or in detail if required.

In order to find the bottlenecks, for example in creating new subscribers in IMS servers, a powerful overview can be provided for each of the different functions related to subscriber creation.

 

 

The above figure shows how a simple table can show the response rate and average delay for the different procedures with the different protocols.

 

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

 

Average latency over time

Another key issue in latency measurement is to either look at the trend in latency for a unique procedure or to compare the trend in latency over time for several different procedures in order to see whether the performance is identical for the different servers

 

With Call Analyzer, the user can select any combination of latency counters and display them over time. An overview showing the latency over the entire recording is given with the option to zoom in to a specific timeframe

 

The display below shows an example of how the trend in latency for different procedures can be compared.

 

 

Latency vs. load

Since latency may be dependent on network load, Call Analyzer can also provide a single 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.

 

Supported protocols

For latency measurement within the IMS/IMT environment, the following protocols are supported:

 

 

Call Analyzer supports a wide range of other protocols for other applications. Contact Netcare International Ltd. or your local distributor for further information.