Customizing Classes

The Citrix SD-WAN configuration provides a default set of application-classification, rule-filtering, and class-assignment settings that can be applied to any virtual path service in the SD-WAN environment. You can also customize these settings.

Using classes, you can classify a specific type of traffic on the virtual path, and then you can apply rules to handle this traffic. Traffic is assigned to a specific class, as defined in the rule.

For more information about creating rules, see Rules by IP Address and Port Number.

The SD-WAN system provides 17 classes (0-16). Classes 0–3 are predefined for Citrix HDX QoS prioritization. To use QoS for HDX traffic, you must enable the following options either in Global > applications > DPI setting or Connnections > applications >DPI setting at site level:

  • Enable Deep Packet Inspection (DPI) for Citrix ICA Applications
  • Select Enable Multi-Stream ICA

These classes (0–3) are used to classify HDX traffic with different ICA priority tags. You can edit the class types and their assigned bandwidth sharing to obtain the optimal Quality of Service, but you cannot edit the names of the classes.

Classes 10–16 are predefined and are associated with Real-time, Interactive, and Bulk class types. Each type can be configured further to optimize Quality of Service for its type of traffic. Classes 4–9 can be used to specify user defined classes. Classes are of one of the following three types:

  • Realtime: Used for low latency, low bandwidth, time-sensitive traffic. Real-time applications are time sensitive but don’t really need high bandwidth (for example voice over IP). Real-time applications are very sensitive to latency and jitter, but can tolerate some loss.
  • Interactive: Used for interactive traffic with low to medium latency requirements and low to medium bandwidth requirements. Interactive applications involve human input in the form of mouse clicks or cursor moves. The interaction is typically between a client and a server. The communication might not need high bandwidth but is sensitive to loss and latency. However, server to client does need high bandwidth to transfer graphical information, which might not be sensitive to loss.
  • Bulk: Used for high bandwidth traffic that can tolerate high latency. Applications that handle file transfer and need high bandwidth are categorized as bulk class. These applications involve very little human interference and are mostly handled by the systems themselves.

To customize classes:

  1. In the SD-WAN Configuration Editor, navigate to Global > Virtual Path Default Sets.

  2. Click Add Default Set, enter a name for the default set and click Add. In the Section field select Classes.

    Virtual path default sets

  3. In the Name field, either leave the default name or enter a name of your choice.

  4. In the Type field, select the class type (Real-time, Interactive, or Bulk).

  5. For real-time classes, you can specify the following attributes:

    • Initial Period: The time period in milliseconds to apply an initial rate before switching to a sustained rate.

    • Initial Rate: Maximum rate at which packets leave the queue during the initial period.

    • Sustained Rate: Maximum rate at which the packets leave the queue after the initial period.

    When in contention, the scheduler ensures that the real-time class receives the Initial Rate and the Sustained Rate that you specify, plus a small percentage of the available bandwidth that is shared with interactive and bulk classes.

  6. For interactive classes, you can specify the following attributes:

    • Initial Period: The time period, in milliseconds, during which to apply initial percentage of the available bandwidth before switching to the sustained percentage. Typically, 20 ms.

    • Initial Share %: The maximum share of virtual-path bandwidth during the initial period.

    • Sustained Share %: The maximum share of virtual-path bandwidth after the initial period.

    Interactive classes use the remaining bandwidth after the real-time traffic has been serviced.

  7. For bulk classes, you can specify only the Sustained Share%, which determines the remaining virtual path bandwidth to be used for a bulk class.

    Bulk traffic is serviced after real-time and interactive traffic are serviced. Typically, a bulk class gets a lower sustained share % than an interactive class.

  8. Click Apply.


Save the configuration, export it to the change management inbox, and initiate the change management process.

Customizing Classes