- play_arrow Basic CoS Configuration
- play_arrow CoS Overview
- play_arrow CoS on Interfaces
- play_arrow CoS Code-Point Aliases
- play_arrow CoS Classifiers
- Understanding CoS Classifiers
- Defining CoS BA Classifiers (DSCP, DSCP IPv6, IEEE 802.1p)
- Example: Configuring Classifiers
- Example: Configuring Unicast Classifiers
- Example: Configuring Multidestination (Multicast, Broadcast, DLF) Classifiers
- Understanding Host Inbound Traffic Classification
- Configuring a Global MPLS EXP Classifier
- Monitoring CoS Classifiers
- play_arrow CoS Rewrite Rules
- Understanding CoS Rewrite Rules
- Defining CoS Rewrite Rules
- Understanding Applying CoS Classifiers and Rewrite Rules to Interfaces
- Troubleshooting an Unexpected Rewrite Value
- Understanding CoS MPLS EXP Classifiers and Rewrite Rules
- Configuring Rewrite Rules for MPLS EXP Classifiers
- Monitoring CoS Rewrite Rules
- play_arrow CoS Forwarding Classes and Forwarding Class Sets
- Understanding CoS Forwarding Classes
- Defining CoS Forwarding Classes
- Forwarding Policy Options Overview
- Configuring CoS-Based Forwarding
- Example: Configuring CoS-Based Forwarding
- Example: Configuring Forwarding Classes
- Understanding CoS Forwarding Class Sets (Priority Groups)
- Defining CoS Forwarding Class Sets
- Example: Configuring Forwarding Class Sets
- Monitoring CoS Forwarding Classes
- play_arrow Lossless Traffic Flows, Ethernet PAUSE Flow Control, and PFC
- Understanding CoS IEEE 802.1p Priorities for Lossless Traffic Flows
- Configuring CoS PFC (Congestion Notification Profiles)
- Understanding CoS Flow Control (Ethernet PAUSE and PFC)
- Enabling and Disabling CoS Symmetric Ethernet PAUSE Flow Control
- Configuring CoS Asymmetric Ethernet PAUSE Flow Control
- Understanding PFC Functionality Across Layer 3 Interfaces
- Example: Configuring PFC Across Layer 3 Interfaces
- Understanding PFC Using DSCP at Layer 3 for Untagged Traffic
- Configuring DSCP-based PFC for Layer 3 Untagged Traffic
- play_arrow CoS and Host Outbound Traffic
-
- play_arrow Weighted Random Early Detection (WRED) and Explicit Congestion Notification (ECN)
- play_arrow WRED and Drop Profiles
- play_arrow Explicit Congestion Notification (ECN)
-
- play_arrow Data Center Bridging and Lossless FCoE
- play_arrow Data Center Bridging
- Understanding DCB Features and Requirements
- Understanding DCBX
- Configuring the DCBX Mode
- Configuring DCBX Autonegotiation
- Understanding DCBX Application Protocol TLV Exchange
- Defining an Application for DCBX Application Protocol TLV Exchange
- Configuring an Application Map for DCBX Application Protocol TLV Exchange
- Applying an Application Map to an Interface for DCBX Application Protocol TLV Exchange
- Example: Configuring DCBX Application Protocol TLV Exchange
- play_arrow Lossless FCoE
- Example: Configuring CoS PFC for FCoE Traffic
- Example: Configuring CoS for FCoE Transit Switch Traffic Across an MC-LAG
- Example: Configuring CoS Using ELS for FCoE Transit Switch Traffic Across an MC-LAG
- Example: Configuring Lossless FCoE Traffic When the Converged Ethernet Network Does Not Use IEEE 802.1p Priority 3 for FCoE Traffic (FCoE Transit Switch)
- Example: Configuring Two or More Lossless FCoE Priorities on the Same FCoE Transit Switch Interface
- Example: Configuring Two or More Lossless FCoE IEEE 802.1p Priorities on Different FCoE Transit Switch Interfaces
- Example: Configuring Lossless IEEE 802.1p Priorities on Ethernet Interfaces for Multiple Applications (FCoE and iSCSI)
- Troubleshooting Dropped FCoE Traffic
-
- play_arrow CoS Buffers and the Shared Buffer Pool
- play_arrow CoS Buffers Overview
- play_arrow Shared Buffer Pool Examples
- Example: Recommended Configuration of the Shared Buffer Pool for Networks with Mostly Best-Effort Unicast Traffic
- Example: Recommended Configuration of the Shared Buffer Pool for Networks with Mostly Best-Effort Traffic on Links with Ethernet PAUSE Enabled
- Example: Recommended Configuration of the Shared Buffer Pool for Networks with Mostly Multicast Traffic
- Example: Recommended Configuration of the Shared Buffer Pool for Networks with Mostly Lossless Traffic
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- play_arrow CoS on EVPN VXLANs
- play_arrow Configuration Statements and Operational Commands
ON THIS PAGE
Example: Configuring Queue Scheduling Priority
You can configure the bandwidth scheduling priority of individual queues by specifying the priority in a scheduler, and then using a scheduler map to associate the scheduler with a queue.
Configuring Queue Scheduling Priority
CLI Quick Configuration
To quickly configure queue scheduling priority, copy the following commands, paste them in a text file, remove line breaks, change variables and details to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level:
[edit class-of-service] set schedulers fcoe-sched priority low set schedulers nl-sched priority low set scheduler-maps schedmap1 forwarding-class fcoe scheduler fcoe-sched set scheduler-maps schedmap1 forwarding-class no-loss scheduler nl-sched
Step-by-Step Procedure
To configure queue priority using the CLI:
Create the FCoE scheduler with
lowpriority:content_copy zoom_out_map[edit class-of-service] user@switch# set schedulers fcoe-sched priority low
Create the no-loss scheduler with
lowpriority:content_copy zoom_out_map[edit class-of-service] user@switch# set schedulers nl-sched priority low
Associate the schedulers with the desired queues in the scheduler map:
content_copy zoom_out_map[edit class-of-service] user@switch# set scheduler-maps schedmap1 forwarding-class fcoe scheduler fcoe-sched user@switch# set scheduler-maps schedmap1 forwarding-class no-loss scheduler nl-sched
Requirements
This example uses the following hardware and software components:
One switch.
Junos OS Release 11.1 or later for the QFX Series or Junos OS Release 14.1X53-D20 or later for the OCX Series.
Overview
Queues can have one of several bandwidth priorities:
strict-high—Strict-high priority allocates bandwidth to the queue before any other queue receives bandwidth. Other queues receive the bandwidth that remains after the strict-high queue has been serviced. On QFX10000 switches, you can configure as many queues as you want as strict-high priority queues. On QFX5200, QFX3500, and QFX3600 switches and on QFabric systems, you can configure only one queue as a strict-high queue. On QFX5100 and EX4600 switches, you can configure only one forwarding-class-set (priority group) as strict-high priority. All queues which are part of that strict-high forwarding class set then act as strict-high queues.Note:On QFX5200 switches, it is not possible to support multiple queues with strict-high priority because QFX5200 doesn’t support flexible hierarchical scheduling. When multiple strict-high priority queues are configured, all of those queues are treated as strict-high priority but the higher number queue among them is given highest priority.
On QFX10000 switches, if you configure strict-high priority queues on a port, we strongly recommend that you configure a transmit rate on those queues. The transmit rate sets the amount of traffic that the switch forwards as strict-high priority; traffic in excess of the transmit rate is treated as best-effort traffic that receives the queue excess rate. Even if you configure only one strict-high priority queue, we strongly recommend that you configure a transmit rate the queue to prevent it from starving other queues. If you do not configure a transmit 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.
On QFX5200, QFX5100, QFX3500, QFX3600, and EX4600 switches and on QFabric systems, we recommend that you always apply a shaping rate to strict-high priority queues to prevent them from starving other queues. 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.
Note:On switches that support enhanced transmission selection (ETS) hierarchical scheduling, if you use ETS and you configure a
strict-highpriority queue, you must create a forwarding class set that is dedicated only tostrict-highpriority traffic. Only one forwarding class set can contain a strict-high priority queue. Queues that are not strict-high priority cannot belong to the same forwarding class set as strict-high priority queues.On switches that use different output queues for unicast and multidestination traffic, the multidestination forwarding class set cannot contain strict-high priority queues.
high(QFX10000 Series switches only)—High priority. Traffic with high priority is serviced after any queue that has astrict-highpriority, and before queues with low priority.low—Low priority. Traffic with low priority is serviced after any queue that has astrict-highpriority.
By default, all queues are low priority queues.
Table 1 shows the configuration components for this example.
This example describes how to set the queue priority for two forwarding classes (queues) named fcoe and no-loss. Both queues have a priority of low. The scheduler for the fcoe queue is named fcoe-sched and the scheduler for the no-loss queue is named nl-sched. One scheduler map, schedmap1, associates the schedulers to the queues.
Component | Settings |
|---|---|
Hardware | One switch |
Schedulers |
|
Priority |
|
Scheduler map |
FCoE mapping: scheduler No-loss mapping: scheduler |
OCX Series switches do not support lossless transport. On OCX Series switches, the default DSCP classifier does not map traffic to the default fcoe and no-loss forwarding classes. On an OCX Series switch, you could use this example by substituting other forwarding classes (for example, best-effort or network-control) for the fcoe and no-loss forwarding classes, and naming the schedulers appropriately. The active forwarding classes (best-effort, network-control, and mcast) share the unused bandwidth assigned to the fcoe and no-loss forwarding classes.
Verification
To verify that you configured the queue scheduling priority for bandwidth and mapped the schedulers to the correct forwarding classes, perform these tasks:
Verifying the Queue Scheduling Priority
Purpose
Verify that you configured the queue schedulers fcoe-sched and nl-sched with low queue scheduling priority.
Action
Display the fcoe-sched scheduler priority configuration using the operational mode command show configuration class-of-service schedulers fcoe-sched priority:
user@switch> show configuration class-of-service schedulers fcoe-sched priority priority low;
Display the nl-sched scheduler priority configuration using the operational mode command show configuration class-of-service schedulers nl-sched priority:
user@switch> show configuration class-of-service schedulers nl-sched priority priority low;
Verifying the Scheduler-to-Forwarding-Class Mapping
Purpose
Verify that you configured the scheduler map schedmap1 to map scheduler fcoe-sched to forwarding class fcoe and schedule nl-sched to forwarding class no-loss.
Action
Display the scheduler map schedmap1 using the operational mode command show configuration class-of-service scheduler-maps schedmap1:
user@switch> show configuration class-of-service scheduler-maps schedmap1 forwarding-class fcoe scheduler fcoe-sched; forwarding-class no-loss scheduler nl-sched;
