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shaping-rate (Oversubscribing an Interface)


Hierarchy Level


For Gigabit Ethernet IQ, Channelized IQ PIC, FRF.15 and FRF.16 LSQ interfaces, and for EQ DPC, MIC, and MPC interfaces on MX Series routers, configure a shaping rate for a logical interface. You can also configure an optional burst size for a logical interface on EQ DPC interfaces and on IQ2 and IQ2E PIC interfaces. 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 Table 1.


percent percentage

For LSQ interfaces, shaping rate as a percentage of the available interface bandwidth.

  • Range: 1 through 100 percent


For IQ and IQ2 interfaces, and T4000 routers with Type 5 FPCs, 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).


  • IQ and IQ2 interfaces—1000 through 6,400,000,000,000 bps


    Through Junos OS Release 13.3, the upper limit is 160,000,000,000 bps. Beginning with Junos OS Release 14.1, the upper limit is 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 for Enhanced Queuing (EQ) DPC interfaces on MX Series routers in Junos OS Release 9.4.

Option burst-size option introduced for MIC and MPC interfaces on MX Series routers in Junos OS Release 11.4.


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

Option burst-size introduced for IQ2 and IQ2E interfaces in Junos OS Release 12.3.

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.