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shaping-rate (Oversubscribing an Interface)


Hierarchy Level


FConfigure a shaping rate for a logical interface. On some interfaces, you can also configure an optional burst size for a logical interface. This can help to ensure that higher-priority services do not starve lower-priority services.

For physical interfaces on T4000 router interfaces on Type 5 FPCs and on PTX Series routers, configure traffic shaping rate.

The sum of the shaping rates for all logical interfaces on the physical interface can exceed the physical interface bandwidth. This practice is known as oversubscription of the peak information rate (PIR).


The default behavior depends on various factors. For more information, see Bandwidth and Delay Buffer Allocations by Configuration Scenario.


percent percentage

Shaping rate as a percentage of the available interface bandwidth.

  • Range: 1 through 100 percent


Peak shaping rate, in bits per second (bps). You can specify a value in bits per second either as a complete decimal number or as a decimal number followed by the abbreviation k (1000), m (1,000,000), or g (1,000,000,000).


  • 1000 through 6,400,000,000,000 bps

  • T4000 routers with Type 5 FPCs—The shaping rate value for the physical interface must be a minimum of 292 Kbps. The maximum value of shaping-rate is limited by the maximum transmission rate of the interface.

burst-size bytes

(Optional) Maximum burst size, in bytes.

  • Range: 0 through 1,000,000,000

Required Privilege Level

interface—To view this statement in the configuration.

interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 7.6.

Option burst-size introduced in Junos OS Release 9.4.


Option burst-size is not supported on MPC5 interfaces. The burst-size configuration is allowed on these interfaces, but does not take effect.

Statement introduced for PTX Series Packet Transport Routers in Junos OS Release 16.1. PTX Series Packet Transport Routers do not support the burst-size option or defining the shaping-rate as a percentage.