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also see that in the last 2 hours only the two lowest bandwidth profiles are without errors (no red bars). The sequence numbers on live streams are also checked up against a user definable maximum allowed sequence age. If the sequence numbers are older than the threshold setting then this usually indicates a problem with the Origin segmentation server having frozen up. If so an alarm is generated. This is a common issue in real deployments. Currently up to 18 different alarms can be generated split into 3 main groups depending: • Transport Errors (e.g insufficient bandwidth for profile) • HTTP errors (e.g HTTP 404 - not found) • XML structure errors (e.g static manifest file for longer than threshold) Tying it together The method described above of actively testing at one point in the OTT delivery chain can be expanded to a whole system by deploying multiple monitoring points. The OTT monitoring devices report upwards to an overlying system that registers alarms and counts Errored Seconds at each monitoring point. Errored Second is well known from the telecommunications sector and is defined as an interval of one second during which any error whatsoever occurred. By comparing counted Errored Seconds at each monitoring point in the OTT distribution architecture it is possible to quickly identify problem areas in the distribution chain. Using this technique it is possible to easily identify whether issues arise at the Origin server, inside the CDN, at a particular local ISP or at the customer premises. Quickly identifying this translates directly into expenses saved in the form of less reported trouble tickets, less truck rolls, less churn and more customers.