Realtime Protocol Monitoring of MPEG traffic

IPTV is a live broadcast and any disturbance in the network is immediately visible to the viewer. Network problems therefore have a greater impact on IPTV than on other  services. A fact that your Customer Service and Support teams are certainly aware of!

Our network processor (NPU) switches are able to inspect and analyse TV traffic on the fly. This allows your network team to have access to historic and current data so that they can react immediately if there is a deterioration in the quality of TV services. At a glance, it is possible to determine which part of the network that is affected and where to begin the troubleshooting, a feature that greatly shortens the time it takes to restore the service.

The challenge

IPTV services are commonly provided as MPEG-2 transport streams that are carried as mulitcast throughout the network to the viewers.

Packet loss of MPEG-2 frames is seen directly by the end-user on the TV screen. End-users demand high quality TV broadcasts and therefore picture problems will immediately result in calls to customer service teams. When problems are intermittent, they are very difficult to track down.

There are two basic types of tools available to the network operator:

1 - The appliance

A network appliance or software to run on a standard laptop PC that performs analysis of MPEG-2 is a common tool for network engineers that work with TV problems. These tools often have the ability to monitor several streams and to provide detailed information about the MPEG-2 transport stream. Due to their advanced functionality they often are quite expensive. They also have the drawback of being stationary – able to monitor multicast traffic at a single location in the network. To track down a problem, such appliances have to be moved about in the network.

This means, that to track down a particular problem reported by an end-user, the appliance have to be physically moved to that point in the network. If the problem is intermittent it has to be left there for some time in order to capture enough information about the problem. Often it is not sufficient to monitor the traffic in a single location. The appliance has to be moved to multiple locations to narrow down and isolate the area where problems are introduced. Again, if the problem is intermittent - not happening all the time - it can take days of valuable engineering time to resolve a single issue.

2 - Central monitoring

A central monitoring server is set up to collect MPEG-2 statistics from set top boxes. Each set top box in the network download a software that provides analysis and statistics about the channel that the set top box is currently displaying to the end-user.

In a large network every end-user becomes a monitoring point feeding information back to the central monitoring server. The advantage is that statistics is continuously generated and whenever a problem is reported it is possible to track down the problem by comparing the statistics from multiple end-users that have watched the same channel at the time of the problem. This helps the network engineer to determine if the problem was local to a single end-user or if multiple users experienced the problem. It also allows the network engineer to get a rough indication in which area of the network that the problem was introduced.

But there are also problems with this approach. The solution is commonly quite expensive. In an open access network the provider of the TV service, not the network operator, will be the recipient of the information. It also relies on multiple users watching the channel at the same time. If this is not the case, there will be insufficient data to draw the conclusions necessary for a fast recovery.

The solution

The NPU based platforms from Waystream are able to monitor several TV channels at the same time, looking for packet loss, delay and other issues that affect the end-user viewing experience. With this feature, every switch in the network suddenly becomes a probe that monitors and measures quality. Using standards based protocol, the quality data can be collected and displayed as graphs. The network equipment can even generate alarms when key thresholds are exceeded to trigger proactive activities by the operations team.

Simultaneous monitoring of the same set of channels on many locations provides valuable data about the performance in different parts of the network. By comparing the data from mulitple probes fault types and affected areas can be immediately determined. A reference probe at the source provides quality control of the TV streams going into the network.

For example, referring to figure 2 above, if each ASR in the topology is running RPM MPEG-2, the network engineer can check the statistics reported for the TV-channel from each of the switches A to F and quickly determine that the problem is seen on all of them except A, thereby concluding that the problem occurs between A and B. This can be done from the engineers’ desk in a few minutes allowing further investigation to determine if onsite visit is required to correct the problem.

Compared to using a probe that has to be moved around, the RPM feature saves significant time in troubleshooting and allows proactive control of TV quality.

The RPM feature is included in the latest generation ASR6000 and is also available in earlier ASR5000 units and other NPU based platforms.