The Quality Puzzle

Video is a complex, performance-sensitive service. Those offering it to customers or subscribers require a network to provide excellent quality of experience (QoE). A comprehensive network-based approach to video assurance can help service providers of all stripes hit that ambitious goal.

Cable operators, in particular, are looking to reduce the number of truck rolls, service calls, and customer churn, while increasing their customer loyalty and delivering an assured video experience. These are no small challenges.

At the same time, the world of entertainment is changing to support alternative methods for viewing and additional devices for displaying video programs.

Accordingly, MSOs have been migrating video services onto IP transport networks. Yet they are concerned that identifying and correcting problems with video services will be more difficult due to perceived complexity of troubleshooting IP networks supporting multiple services. Isolating video anomalies to a specific problem domain and allocating proper operational resources is critical in supporting high-quality video over IP.

In response to the challenges of IP video assurance, video monitoring and assurance systems need to evolve from their current state of separate video and IP monitoring into an overall architecture for managing video services from the headend all the way to home.

What does a comprehensive architecture look like? At a high level, a desirable solution would be:

• Modular and extensible to support video services over multi-vendor IP networks.

• Standards-based to enable real-time, centralized monitoring and management of headend, backbone, regional, and aggregation networks for delivery of multi-vendor, multi-technology video services.

• Modular and integrated to help to promote flexibility and growth to accommodate future needs.

Better communication

Today’s cable networks are sophisticated, to say the least. That complexity calls for a topology-based capability for rapid and extensive fault detection, isolation, and root-cause correlation.

The goal is to enable communication among disparate organizations. Video operations, network operations and customer services all speak separate languages. (See Figure 1.) But they need to be in the same loop for efficient problem detection, isolation, troubleshooting and repair.

One downside to commercial-off-the-shelf (COTS) solutions, however, is their lack of integration between fault management for video services and the corresponding IP network. Absent such mapping, if a network event impacts the customers’ experience, a cable operator may not know which specific programs or streams were affected.

Point or partial solutions do have their appeal and benefits, but they address only a sub-section of the overall experience delivery. Another — and arguably preferable — approach is a delivery assurance architecture that tracks video services from the head-end through the IP transport and out to the subscriber’s home.

A comprehensive video assurance management system would also provide the ability to perform measurements of the video flow as it transfers between operational domains. The upshot is productivity savings. That occurs when a given anomaly is isolated to a specific domain in the end-to-end video path and therefore assigned to the right operational group for repair.

By providing both video and IP intelligence, the right tool could directly correlate between video and IP network identifiers for each program/channel. Resulting alarms would identify both the service channel and the network flow ID.

This kind of approach allows members of otherwise divergent groups and different disciplines to understand the common event and initiate appropriate corrective action.

Real solutions, tests

Here are a few examples of how this approach has helped solve problems in real video networks.

First, this platform was able to detect and report the loss of service at encoders and associated this with the affected transport flows at both the headend and downstream flows throughout the network. This allowed operators quickly to isolate errors in the video flows that may otherwise have gone undetected and resulted in unnecessary troubleshooting within the IP transport.

A second example comes from a large video distribution network, where a loss of service was detected, but no errors were being reported and no counters were available indicating any fault.

A recent hardware upgrade had been performed. Network engineers even rolled back the upgrade, thinking that might be the cause, but no luck. What the comprehensive video assurance platform did was isolate the loss to the specific interface where the flow was lost. The culprit? A bent pin in a line card on a completely different chassis.

"The culprit? A bent pin in a line card on a completely different chassis."

The integration of monitoring and routing holds additional promise.

Inline monitoring capabilities built into line cards offers efficient MPEG-level monitoring for video quality, allowing the usage of all slots for forwarding.

This capability would also help to reduce the number of external probes necessary in the network. Recently the European Advanced Networking Test Center (EANTC) tested this inline capability at data rates up to 40Gbps per slot. The upshot was successful in-depth monitoring at the backbone and regional network speeds. (For more details about and results from the EANTC test, visit http://blogs.cisco.com/sp/comments/experience_provider_mega_test_meets_the_zettabyte_challenge/.)

Wish list

As the previous examples suggest, a system that integrates video and IP intelligence offers multiple benefits.

The advantages of the approach outlined here would include enhanced video QoE, proactive video transport monitoring, increased operational efficiency, ease of integration, investment protection, reduced costs and reduced mean time to isolate (MTTI) and mean time to repair (MTTR)

Perhaps the key technical requirements for an integrated video assurance system is the coupling of events in the transport control plane with related events in the video control plane, thus providing operators with a common reference across the headend and IP video transport.

Additional requirements would include the following:

• dynamic visualization of video metrics

• custom service views

• service visibility and service tracking to any location

• problem domain reduction (isolation to video or network systems)

• redundancy monitoring

• fault correlation

• integration with other OSS/BSS solutions

• real-time alarm generation with configurable thresholds

• integration with video probes

• single-pane view of alarms/probes/system status

One last thing: To provide the scalability needed in a large cable network, the video assurance system must also include a manager of managers (MOM) allowing operations personnel to view a single screen for current status on the health of all network services.

The MOM is also used as a centralized alarming platform and integrates an intelligent rules engine to assist with determining event priority and number of customers affected. The MOM helps to simplify the operators’ responsibilities by limiting the number of management systems they must interact with and centralizing a number of the management functions.

A MOM could be used to initiate further troubleshooting by cross-launching applications on remote systems to gather additional details and support detailed diagnostics and repair. This functionality significantly simplifies operations and allows organizations to consolidate different operations centers.

A new era?

Cable providers are constantly looking at new service models and quality metrics that directly relate to customers’ video experiences.

There are myriad variables to measure and control in order to deliver an uninterrupted stream of broadcasts with a rich, clear signal and crisp sound. One factor determining continued success is likely to be a comprehensive video assurance management solution.

A unified approach, integrating IP and video, could maximize the quality of the consumer experience while reducing operations costs. It could spell a new era in video service assurance management.

Asha Kalyur is senior marketing manager at Cisco responsible for the Cisco Video Assurance Management Solution (VAMS).