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When is a Flow Assigned QoS Priority 255?


When is a flow categorized with QoS priority 255, even though there is no network rule to assign this priority?


QoS priority 255 is referred to as the Default priority in the BW Management window (Networking > BW Management).

There are several reasons why a flow can be assigned the lowest QoS priority 255:

  • Blocked flows are assigned their designated QoS priority unless none are defined, in which case the flows are assigned QoS 255.
  • Traffic that is redirected from a block page is assigned QoS priority 255. For example, when someone tries to go to a compromised website that is blocked by IPS.

The flow will get the highest priority when:

  • Cato evaluates the network profile for each flow, and the QoS priority is assigned when the flow is identified with a specific application as follows:
    • The first packets (before the flow is identified) are assigned the highest QoS priority.
    • As long as the application for a flow isn't identified, the flow is assigned with the highest QoS priority and is shown in the Analytics windows with that priority.

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