For communications service providers delivering IP-based triple-play services – voice, video, and data – to residential and enterprise customers, competition is intensifying and price is no longer the major differentiator. To add new customers, maintain their subscriber base, and reduce churn, it is now imperative that service providers ensure last-mile service quality and service performance to ensure a competitive advantage.

Most providers will agree that the highest percentages of problems occur through the access network to the customer’s premise. As a result, service providers not only need visibility into the user experience when there is a quality issue, but also ongoing fault testing to continuously monitor and ensure quality at the user’s endpoint.

However, until recently, the service provider’s options have been limited to:

• Simple ping and trace-route tests to the edge of the network;
• Deploying intrusive software agents at the endpoint;
• Installing expensive test probes with the customer premise equipment (CPE).

All of these options require new equipment or don’t offer the proper information to correctly diagnose and fix problems.

An Alternative – Loopback Testing

Now, there are alternatives. By leveraging existing and emerging standards – such as Session Initiation Protocol (SIP), Network Call Signaling (NCS), and RTP Control Protocol Extended Reports (RTCP-XR) – loopback testing provides a standards-based means for monitoring endpoint quality and IP service performance. Loopback testing – both SIP Media Loopback and NCS Loopback – allows continuous measurement of media and signaling quality all the way to the customer premise, to proactively identify faults and quickly repair problems before customers are impacted.

And, as equipment manufacturers roll out more endpoint devices capable of supporting loopback testing, service providers have the ability to select and install products that enable them to monitor service quality all the way to the customer premise. By extending visibility into the quality of experience (QoE) out to the customer premise, service providers can significantly increase customer satisfaction and reduce churn and operational costs.

Loopback testing provides statistical reporting on service availability, network and device availability, network quality, signaling quality, and audio quality, which service providers can use to address the following:

• Proactive QoE monitoring and problem isolation
• Segmented visibility of the customer experience
• Reducing repair times and truck-rolls
• Scheduled testing and verification of endpoint device quality
• Trending and capacity management.

How Loopback Testing Works

Regardless of the signaling protocols involved, the concept of loopback testing is very simple: a test is initiated by a loopback server to an endpoint device, which then “loops back” every packet it receives to the loopback server that initiated the test. Service providers initiate test packets from a loopback server to an end-user device (i.e., CPE, SIP phones, MTA, and ATA devices).

Performance metrics are shared between the loopback server and the endpoint device using RTCP-XR, and the data is available for correlation and analysis from a centralized management engine – providing visibility into the customer’s user experience, as well as last-mile troubleshooting, fault testing, and effective customer care.

Loopback tests are non-intrusive to the end-user device as policies can be set so as not to test the endpoint if it is busy, or terminate the loopback test if a new call either comes in or is initiated by the user. Service providers can automate this process through “smart scheduling” for proactive, periodic (scheduled) monitoring, or run on-demand tests as needed.

The Importance of Metrics and Reporting

By implementing loopback testing, service providers can continually test network performance, availability, and service quality of remote endpoint devices. By correlating and analyzing the collected signaling and service quality metrics, providers can generate a host of actionable-information reports for all levels of their organization, or seamlessly integrate the information into other operational support systems (OSS) or network management systems (NMS).

Additionally, the integration of this data with inventory management systems and customer billing information provides the ability to isolate problems to regions, neighborhoods, network devices, specific modems, ATAs, MTAs, and other areas based on correlation of the topology and customer database.

Ensuring Endpoint Quality and Performance

By testing and monitoring endpoints capable of supporting either NCS Loopback or SIP Media Loopback, communications service providers can proactively monitor end-to-end service performance and quality for their triple-play services, while also allowing active testing of problem devices to help solve problems at a specific customer premise device.

With loopback testing, service providers can integrate standards-based quality assurance into their IP services network, gaining a competitive advantage and reducing the cost of maintaining and troubleshooting their network while increasing customer satisfaction.

Kaynam Hedayat is the CTO and vice president of engineering at Chelmsford, Mass.-based Brix Networks.