Download Throttling

On the Quality of Service (QoS) > Download Throttling tab you can define and manage rules to throttle incoming traffic. If packets are coming in faster than the configured threshold, excess packets will be dropped immediately without being listed in the firewall rules log file. As a result of TCP congestion avoidance mechanisms, affected senders should reduce their sending rates in response to the dropped packets.

To create a download throttling rule, proceed as follows:

  1. On the Download Throttling tab, select an interface.

    From the Bound to interface drop-down list, select the interface for which you want to create a download throttling rule.

  2. Click New Download Throttling Rule.

    The Add Throttling Rule dialog box opens.

  3. Make the following settings:

    Name: Enter a descriptive name for this download throttling rule.

    Position: The position that defines the priority of the rule. Lower numbers have higher priority. Rules are matched in ascending order. Once a rule has matched, rules with a higher number will not be evaluated anymore. Place the more specific rules at the top of the list to make sure that more vague rules match last.

    Limit (kbit/s): The upper limit (in Kbit) for the specified traffic. For example, if you want to limit the rate to 1 Mbit/s for a particular type of traffic, enter 1024.

    Limit: Combination of traffic source and destination where the above defined limit should apply:

    • shared: The limit is equally distributed between all existing connections. I.e., the overall download rate of the traffic defined by this rule is limited to the specified value.
    • each source address: The limit applies to each particular source address.
    • each destination address: The limit applies to each particular destination address.
    • each source/destination: The limit applies to each particular pair of source or destination address.

    Traffic selectors: Select the traffic selectors for which you want to throttle the download rates. The defined limit will be divided between the selected traffic selectors.

    Comment (optional): Add a description or other information.

  4. Click Save.

    The new download throttling rule appears on the Download Throttling list.

  5. Enable the rule.

    The new rule is disabled by default (toggle switch is gray). Click the toggle switch to enable the rule.The rule is now enabled (toggle switch is green).

To either edit or delete a rule, click the corresponding buttons.