Subscriber quality of experience (QoE) can be difficult to quantify. A variety of factors both inside and outside the customer premises can affect a subscriber’s service — and unfortunately, not all of these can be controlled. For instance, within the home network, there may be signal blockage or range issues affecting the service of a WiFi connected device, while outside the network there may be channel interference caused by nearby cell towers or even neighboring networks.
How can network operators and administrators adequately understand the factors affecting a subscriber’s QoE if they are unable to see the external factors impacting service quality?
Why TR-069 is Only the Beginning
You probably have already heard of TR-069 — the Broadband Forum specification used for remote monitoring and management of CPEs with an auto-configuration server. The term “TR-069” is sometimes shorthand for a suite of Broadband Forum specifications that work with TR-069 to improve quality of experience.
TR-143 is one such specification — and an important one. The goal of TR-143 is to provide a means of baselining nominal service levels and validating quantitative QoS and/or qualitative QoS distinctions. TR-143 activates this by defining means of active monitoring of the broadband access network. Active monitoring in this context refers to actively transmitting or receiving data in a controlled test.
The key benefit of active monitoring is that it allows the network operator to characterize the performance of end-to-end paths and/or path segments, depending on the scope of the probing. In short, it gives insights into the network quality outside the subscriber network.
TR-143 consists, in essence, of two parts: A set of diagnostics to perform per-CPE network quality and throughput monitoring, and network initiated monitoring to give network-wide quality metrics.
Per-CPE Monitoring and Speed Tests
This suite of CPE diagnostics includes UDP Echo Tests and speed tests.
UDP Echo and UDP Echo Plus tests give insights into the quality of the network by probing a series of UDP Echo Servers strategically placed in various paths of the network. These tests give insight into different factors affecting service quality, such as packet loss and overall network path quality.
Upload and Download Speed tests give insights into the throughput of the network between the CPE and a well placed server hosting an FTP or HTTP service to upload/download files and measure the throughput speed. This is very similar to visiting sites like speedtest.com, but starts right at the CPE, as opposed to the subscriber’s computer.
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Note that these methods require additional hardware and software, such as an UDP echo server and a HTTP/FTP server, as well as consideration and planning as to their placement within the network path.
Network-initiated diagnostics represents an alternative approach to minimize the burden on the ACS for network service providers that want to support continual proactive monitoring of samplings of CPE. For example, dedicated network test servers distributed per serving area can perform network-initiated diagnostics to continually characterize the state of broadband access paths to samplings of subscribers and build performance trends on those paths.
In essence, the CPE is turned into an UDP Echo Server. For security reasons, the source IP of the network test can be specified and only requests from this IP will be answered. The network test server initiates the client request and sends the UDP Echo packets. The CPE UDP Echo server responds to the UDP Echo packets
Note: this method of testing requires a dedicated network test server.
Network throughput tests are only run by an individual CPE, and it is not recommended to run these network wide as the tests would interfere with each other. Network-initiated monitoring enables you to derive quality, yet statistical, data across the network for further analysis.