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Managing Congestion Using Drop Profiles and Packet Loss Priorities on vMX

When you are configuring CoS, you can manage congestion by configuring drop profiles to specify the thresholds for packet loss priority. You reference the drop profiles in the scheduler configuration to assign a drop profile to the loss priority setting.

To configure how packet loss priority is handled for queues, perform these tasks:

Configuring Drop Profiles

Drop profiles specify the threshold for a given loss priority.

Note:

The threshold for the loss priority assigned this drop profile is the fill-level value associated with the drop-probability of 100. If you do not specify a drop probability of 100 percent in the drop profile, the fill level defaults to 100 percent. All other fill levels are ignored.

To specify the drop profile, include the drop-profiles statement at the [edit class-of-service] hierarchy level.

To specify the threshold for the loss priority, include the fill-level and drop-probability statements at the [edit class-of-service drop-profiles profile-name] hierarchy level.

For example, the dpLow drop profile specifies a threshold of 100 percent, the dpMed drop profile specifies a threshold of 75 percent, and the dpHigh drop profile specifies a threshold of 50 percent.

Configuring Schedulers with Drop Profiles

The drop profile map contains the mapping of loss priority and protocol type to configured drop profiles. You can associate multiple drop profile maps with a scheduler.

Note:

If you do not apply drop profiles to the queue, then packets are tail dropped.

To specify the drop profile map, include the drop-profile-map statement at the [edit class-of-service schedulers scheduler-name] hierarchy level.

For example, the sched-be scheduler applies the dpLow drop profile to packets with low loss priority for any protocol type, applies the dpMed drop profile to packets with medium-high loss priority for any protocol type, and applies the dpHigh drop profile to packets with high loss priority for any protocol type.