priority (Schedulers)
Syntax
priority priority-level;
Hierarchy Level
[edit class-of-service schedulers scheduler-name]
Description
Specify the packet-scheduling priority value.
Options
Available options can vary by platform and software release.
priority-level can be one of the following:
-
low—Scheduler has low priority. -
medium-low—Scheduler has medium-low priority. -
medium-high—Scheduler has medium-high priority. -
high—Scheduler has high priority. Assigning high priority to a queue prevents the queue from being underserved. -
strict-high—Scheduler has strictly high priority. Configure ahighpriority queue with unlimited transmission bandwidth available to it. As long as it has traffic to send, thestrict-highpriority queue receives precedence overlow,medium-low, andmedium-highpriority queues, but nothighpriority queues. You can configurestrict-highpriority on only one queue per interface. -
low-latency—Scheduler has low latency queuing (LLQ) priority. LLQ enables delay-sensitive data to have preferential treatment over other traffic. A queue configured as a low latency queue has the highest priority over any other priority queues, includingstrict-highqueues.
Required Privilege Level
interface—To view this statement in the configuration.
interface-control—To add this statement to the configuration.
Platform Information
-
ACX7000 Series routers running Junos OS Evolved support all six levels of priority, including
low-latency. -
On EX4400 switches, applying strict-high priority schedulers to queues 0 through 3 also applies strict-high priority to queues 8 through 11. Therefore, Juniper recommends applying strict-high priority schedulers only to queues 4 through 7.
-
On QFX10000 switches, you can configure as many strict-high priority queues as you want. On QFX10000 switches, we strongly recommend that you apply a transmit rate to strict-high priority queues to prevent them from starving other queues. A transmit rate configured on a strict-high priority queue limits the amount of traffic that receives strict-high priority treatment to the amount or percentage set by the transmit rate.
-
On QFX5100 and EX4600 switches, you can configure only one queue as a strict-high priority queue. We recommend that you always apply a shaping rate to strict-high priority queues to prevent them from starving other queues. A shaping rate (shaper) sets the maximum amount of bandwidth a queue can consume. (Unlike using the transmit rate on a QFX10000 switch to limit traffic that receives strict-high priority treatment, traffic that exceeds the shaping rate is dropped, and is not treated as best-effort traffic that shares in excess bandwidth.) If you do not apply a shaping rate to limit the amount of bandwidth a strict-high priority queue can use, then the strict-high priority queue can use all of the available port bandwidth and starve other queues on the port.
Release Information
Statement introduced before Junos OS Release 7.4.
low-latency support introduced for Junos OS Evolved Release
23.4R1.