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.
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.
[edit] user@vmx# set class-of-service drop-profiles profile-name
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.
[edit class-of-service drop-profiles profile-name] user@vmx# set fill-level percentage drop-probability percentage
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.
[edit] user@vmx# set class-of-service drop-profiles dpLow fill-level 100 drop-probability 100 user@vmx# set class-of-service drop-profiles dpMed fill-level 75 drop-probability 100 user@vmx# set class-of-service drop-profiles dpHigh fill-level 50 drop-probability 100
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.
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.
[edit class-of-service schedulers scheduler-name] user@vmx# set drop-profile-map loss-priority (any | low | medium-low | medium-high | high) protocol any drop-profile profile-name
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.
[edit class-of-service schedulers sched-be] user@vmx# set drop-profile-map loss-priority low protocol any drop-profile dpLow user@vmx# set drop-profile-map loss-priority medium-high protocol any drop-profile dpMed user@vmx# set drop-profile-map loss-priority high protocol any drop-profile dpHigh