Ready for VoIP: Network Management Architectures: Telchemy

Telchemy, Inc., headquartered in Duluth, Georgia, develops technology that enables
enterprises and service providers to deploy and manage voice and video over IP, streaming
audio and video, and networked gaming services over their networking infrastructures.

Telchemy’s products provide real-time visibility of service quality, estimates of
user-perceived Quality of Service (QoS), and detailed analysis of the root cause of
quality degradation. Their software technology can be integrated by equipment
manufacturers into a wide range of products, ranging from consumer electronics devices to
large telecom systems; it monitors every call and detects problems in real time.

The company was founded in 1999, and since that time has developed a number of
products that have been integrated into IP telephones, gateways, probes, analyzers, and
routers, and deployed by telephone companies, cable service providers, ISPs, and major
enterprises. Telchemy’s customers include AudioCodes, Brix Networks, Ditech
Communications, Empirix, Ixia, NexTone, and Nortel Networks.

Telchemy has two broad categories of products to manage the performance of voice and
video over IP environments: embedded software and turnkey system applications. All of
these products are based on a distributed architecture for performance management with a
goal of providing end-to-end monitoring of service quality in any size or type of

For passive monitoring, the architecture includes agents embedded into endpoints,
distributed probes, and other mid-stream devices.

For active testing, distributed software test agents generate voice, video, and
network diagnostic traffic to each other and report quality/performance metrics back to a
central reporting and configuration interface.

On the embedded side is Telchemy’s core technology, a passive monitoring performance
analysis agent called VQmon. This agent generates listening and conversational
quality Mean Opinion Scores (MOS) and R factors, plus a wide range of diagnostic data,
and then makes that information available through an API (application programming

VQmon is based on the ITU-T E Model, but with many extensions that improve the
accuracy. The product comes in three versions: VQmon/EP (End Point), which is integrated
into IP phones, gateways, and cellular handsets; VQmon/SA (Stream Analysis), which is
integrated into mid-stream devices like probes, analyzers, and routers; and VQmon/HD, for
video stream analysis, to be integrated into IP set-top boxes, videoconferencing
equipment, and so on. VQmon is in wide use by equipment providers, with over 36 million
units currently licensed.

Telchemy’s OEM system products are targeted for either passive or active monitoring,
with one additional product for report collection/mediation.

There are two products for passive monitoring. The SQprobe is a software probe
for the Linux operating system, incorporating VQmon/SA. SQprobe passively monitors a
100-BaseT/GigE link and detects VoIP/IP video calls/sessions, reporting MOS/R-factor
scores, burst/gap statistics, degradation factors such as packet loss and delay, plus
transport metrics, and provides them in a Web user interface or via SNMP, as shown in
Figure 1.

In addition to the metrics it collects by monitoring the stream directly, SQprobe
collects the Real Time Control Protocol Extended Reports (RTCP XR-see sent by
endpoints such as IP phones, if they are running VQmon/EP, and correlates the data

Voyager is also a probe incorporating VQmon/SA, but it is a self-contained
plug-and-play device designed for small workgroups and branch offices. It comes with a
built-in passive tap, and includes a DVQattest test agent that can be used to
generate active VoIP calls. Voyager has a GUI similar to SQprobe’s and also provides data
via SNMP (see Figure 2). For example, an enterprise with one main
location and several branch offices (like a bank) might want to deploy SQprobe in the
main office and put a Voyager unit in each branch, in order to monitor calls coming into
and going out of each location.

For active testing, Telchemy has developed DVQattest, a distributed active test
application for VoIP and IPTV/IP videoconferencing that incorporates VQmon. This product
is available in two versions. DVQattest/EN is designed for enterprise network
environments, installed on Linux/Windows/Mac PCs or servers, where it runs in the
background as a daemon or service. DVQattest/RE is designed for residential VoIP/IPTV or
hosted PBX service provider applications, with agents that are placed on a public Web
server on the service provider’s network, and then downloaded to subscriber desktops as
needed. Both versions of DVQattest includes expert analysis with a text diagnosis of
problem conditions detected, plus a list of specific degradation factors and the
percentage of quality degradation attributable to each (see Figures 3 and 4).

In addition, Telchemy offers SQmediator, a central report collection/mediation
application. SQmediator collects endpoint reports, analyzes them, and provides quality
scores, performance metrics, and expert analysis/diagnostic data for individual calls and
video sessions. Performance data can be viewed in a Web-based GUI or accessed via SNMP or
a custom API.

Further details on the Telchemy architecture and products can be found at Our next
tutorial will continue our examination of vendors’ network management architectures.

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