RED Drop Profiles and Congestion Control

If the device must support assured forwarding, you can control congestion by configuring random early detection (RED) drop profiles. RED drop profiles use drop probabilities for different levels of buffer fullness to determine which scheduling queue on the device is likely to drop assured forwarding packets under congested conditions. The device can drop packets when the queue buffer becomes filled to the configured percentage.

Assured forwarding traffic with the PLP (packet loss priority) bit set is more likely to be discarded than traffic without the PLP bit set. This example shows how to configure a drop probability and a queue fill level for both PLP and non-PLP assured forwarding traffic. It is only one example of how to use RED drop profiles.

The example shows how to configure the RED drop profiles listed in Table 1.

To configure RED drop profiles for assured forwarding congestion control on the device:

1. Navigate to the top of the configuration hierarchy in either the J-Web or CLI configuration editor.

2. Perform the configuration tasks described in Table 2.

3. If you are finished configuring the device, commit the configuration.

4. Go on to one of the following tasks:

   • To assign resources, priorities, and profiles to output queues, see Example: Configuring Class-of-Service Schedulers on a Security Device.

   • To apply rules to logical interfaces, see Example: Configuring Virtual Channels.

   • To use adaptive shapers to limit bandwidth for Frame Relay, see Example: Configuring and Applying an Adaptive Shaper.