Healthy VoIP Nets�Part XXV�Network Management Architectures: Empirix

Empirix, a privately-held company headquartered in Bedford, Mass., develops testing and monitoring products designed to assist organizations with a successful transition from legacy to emerging voice and web technologies, including VoIP, computer-telephony integration (CTI), and IP Multimedia Subsystem (IMS) networking infrastructures.

Empirix was formed in 2001 from the combination of Hammer Technologies and RSW Software; the company’s name is derived from the word empirical—that which is dependent upon observable evidence or consequences.

The company prides itself in having the ability to span the evolution of these advanced technologies across multiple applications—from testing requirements in R&D laboratories to the monitoring of the end user experience—and claims to have released the world’s first VoIP testing platform in 1998.

Empirix also claims a blue ribbon list of customers, including 70 of the Fortune 100, and 9 of the top 10 service providers, including Alcatel-Lucent, AT&T, Barclay’s Bank, Cisco, France Telecom, Sprint, T-Mobile, and Wachovia.

Empirix has a staff of over 350, located in offices worldwide, including London and Tokyo.

Empirix’ Hammer line of test and monitoring products span the realm of TDM, VoIP, and IMS networks, and include solutions for four critical management applications: feature testing, load testing, installation, and service monitoring.

Feature testing is a quality assurance process that verifies the proper implementation and key functions of VoIP and IMS products, networks, and applications. This testing is used in product development, interoperability testing, and field trials.

Load testing verifies proper network function under stress conditions, and is used in lab and trial networks to simulate peak calling periods, malicious attacks, and other situations in which the network is placed under moderate to extreme conditions.

Installation testing ensures that the network components and applications were installed correctly, and that the network is equipped and ready to handle live traffic. This process would include end-user simulation, service feature testing, service quality benchmarking, and problem diagnostics.

Service monitoring provides a view of the real-time service quality, and can be used by network operations, network engineering, and customer support organizations as a proactive step to avoid service quality problems before the customer’s quality of experience (QoE) is impacted. This function allows these organizations to respond quickly to customer-affecting network or service issues.

Three of the Empirix products are focused specifically on supporting VoIP and IMS networks:

The Hammer XMS integrates diagnostics with analytic and monitoring capabilities for signaling and media quality, and is designed to scale to support network configurations that range up to large VoIP/IMS service deployments.

The system consists of several elements. The XMS Probes are configured with either Ethernet or TDM interfaces and capture the VoIP or Signaling System 7 (SS7) or ISDN signaling and media packets on the wire. Carrier-class scalability is achieved because a significant amount of processing is accomplished at the probes, thus concentrating the processing where the traffic is being monitored.

Once captured, the compressed, real-time call and media data records are forwarded to a Centralized Data Management System for processing and storage.

A Network Management System Interface allows the signaling and media stream metrics to be forwarded to an SNMP (Simple Network Management Protocol)-based network management system for post processing, such as network optimization analysis.

This same design enables XMS Packet Analysis, an on-demand, session-based capture and analysis process for both call- and non–call-related signaling and media packets.

The Hammer XMS Active sends a known test signal through a live network, and compares the output signal with the original signal to provide active test and monitoring functions. This system consists of two elements: Active Probes that emulate IP and TDM voice and fax endpoints, and an Operations Serverthat handles the applications, such as probe management, test scheduling, diagnostics, reporting, and system administration. This system is designed to support pre-deployment testing, post-deployment troubleshooting, and service level agreement (SLA) verification.

The XMS Active can simulate calls between endpoints, measure voice quality for both TDM and IP calls using the Perceptual Evaluation of Speech Quality (PESQ) algorithm (defined in ITU-T Recommendation P.862), perform loopback, inbound and outbound tests, test for complex features, such as call forwarding and three-way calling, and also test fax quality in both TDM and IP network environments.

The Hammer Call Analyzer provides packet-level protocol analysis supporting the SIP, H.323, MGCP, and MEGACO/H.248 systems, plus a large number of underlying protocols. The system has a very interesting multi-stage call flow display that can walk the user through the various legs of a call, even when that call traverses multiple signaling domains. The portable PC-based tool also includes advanced media analysis to simplify the diagnosis of voice quality problems.

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

Copyright Acknowledgement: © 2008 DigiNet Corporation ®, All Rights Reserved

Author’s Biography
Mark A. Miller, P.E., is President of DigiNet Corporation®, a Denver-based consulting engineering firm. He is the author of many books on networking technologies, including Voice over IP Technologies, and Internet Technologies Handbook, both published by John Wiley & Sons.

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