{{indexmenu_n>1}}
====== Detecting degradation in internet access quality ======
<note important>[[dpi:dpi_options:opt_statistics:statistics_ipfix|DPI exports information about all client sessions in IPFIX (NetFlow v10) format.]]</note>

The DPI exports [[dpi:qoe_analytics:qoe_gui:reports:paramdescript|information about delays]] between the client and the DPI, and between the DPI and the host during TCP session establishment — [[https://ru.wikipedia.org/wiki/%D0%9A%D1%80%D1%83%D0%B3%D0%BE%D0%B2%D0%B0%D1%8F_%D0%B7%D0%B0%D0%B4%D0%B5%D1%80%D0%B6%D0%BA%D0%B0|RTT]].
The statistics record latency for each protocol, linked to the UserAgent (taken from ClickStream), which allows tracking the performance of a specific device.\\
Required steps to investigate:
  - Go to QoE Analytics → Subscribers → Netflow
  - Create a filter where:
  * It is recommended to limit the search to http/https protocols to exclude the behavior of other protocols during TCP session setup.
  * Specify average speed to select subscribers who actively use the internet.
  * Specify the lower RTT threshold from the client side. 
{{ dpi:qoe:use_cases:фильтр_rtt.png?direct&600 |}}
Interpreting the resulting statistics: {{ dpi:qoe:use_cases:результат_rtt.png?direct&600 |}}
  * The filter identified 25 potential clients who may have access quality issues.
  * Detailed latency information for these clients can be viewed in the **"Details"** window.
  * Using the megaphone icon, they can be added to a __[[dpi:dpi_components:dpiui:user_guide:ssg_control_section:ad_campaign_management|marketing campaign]] and notified or surveyed through the browser regarding service satisfaction__.
  * The report can be exported in a convenient format.