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Supported Platforms
Related Documentation
- ACX, EX, M, MX, PTX, T Series
- Configuring Schedulers for Priority Scheduling
- EX, M, MX, PTX, T Series
- Schedulers Overview
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. However, strict-high priority works differently on Juniper Networks J Series Services Routers than it does on M Series Multiservice Edge Routers and T Series Core Routers. For configuration instructions, see the J Series router documentation and Configuring Schedulers for Priority Scheduling.
- Strict-high priority works differently on AS 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.
- On Juniper Networks J Series Services Routers, high priority queues might starve low priority queues. For
example:Queue priority and transmission rate:Queue 0: priority low, transmit-rate 50 percentQueue 2: priority high, transmit-rate 30 percent Traffic profile:Queue 0: 100 percent of the interface speedQueue 2: 100 percent of the interface speed Results:Queue 0: 0 percent of traffic is delivered.Queue 2: 100 percent of traffic is delivered.
- On J Series routers, you can include the transmit-rate statement at the [edit class-of-service schedulers scheduler-name] hierarchy level to assign the WRR weights within a given priority level and not between priorities.
- On J Series routers, adding the exact option with the transmit-rate statement is useful within a given priority and not between the priorities.
- 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.
Table 1: Scheduling Priority Mappings by FPC Type
Priority Levels | Mappings for FPCs | Mappings for M320 FPCs and T Series Enhanced FPCs | Mappings for M120 FEBs |
|---|---|---|---|
low | 0 | 0 | 0 |
medium-low | 0 | 1 | 1 |
medium-high | 1 | 1 | 2 |
high | 1 | 2 | 3 |
strict-high (full interface bandwidth) | 1 | 2 | 3 |
Related Documentation
- ACX, EX, M, MX, PTX, T Series
- Configuring Schedulers for Priority Scheduling
- EX, M, MX, PTX, T Series
- Schedulers Overview
Published: 2013-07-31
Supported Platforms
Related Documentation
- ACX, EX, M, MX, PTX, T Series
- Configuring Schedulers for Priority Scheduling
- EX, M, MX, PTX, T Series
- Schedulers Overview
