Platform Support for Priority Scheduling

Hardware platforms support queue priorities in different ways:

• On all platforms, you can configure one queue per interface to have strict-high priority.

• Strict-high priority works differently on Multiservices and Services PIC link services IQ (lsq-) interfaces. For link services IQ interfaces, a queue with strict-high priority might starve all the other queues. For more information, see the Junos OS Services Interfaces Library for Routing Devices.

• The priority levels you configure map to hardware priority levels. These priority mappings depend on the FPC type in which the PIC is installed.

Table 1 shows the priority mappings by FPC type. Note, for example, that on Juniper Networks M320 Multiservice Edge Routers FPCs, T Series Core Routers FPCs and T Series Enhanced FPCs, the software priorities medium-low and medium-high behave similarly because they map to the same hardware priority level.