- play_arrow Overview
- play_arrow Understanding How Class of Service Manages Congestion and Defines Traffic Forwarding Behavior
- Understanding How Class of Service Manages Congestion and Controls Service Levels in the Network
- How CoS Applies to Packet Flow Across a Network
- The Junos OS CoS Components Used to Manage Congestion and Control Service Levels
- Mapping CoS Component Inputs to Outputs
- Default Junos OS CoS Settings
- Packet Flow Through the Junos OS CoS Process Overview
- Configuring Basic Packet Flow Through the Junos OS CoS Process
- Example: Classifying All Traffic from a Remote Device by Configuring Fixed Interface-Based Classification
- Interface Types That Do Not Support Junos OS CoS
-
- play_arrow Configuring Platform-Specific Functionality
- play_arrow Configuring Class of Service on ACX Series Universal Metro Routers
- CoS on ACX Series Routers Features Overview
- Understanding CoS CLI Configuration Statements on ACX Series Routers
- DSCP Propagation and Default CoS on ACX Series Routers
- Configuring CoS on ACX Series Routers
- Classifiers and Rewrite Rules at the Global, Physical, and Logical Interface Levels Overview
- Configuring Classifiers and Rewrite Rules at the Global and Physical Interface Levels
- Applying DSCP and DSCP IPv6 Classifiers on ACX Series Routers
- Schedulers Overview for ACX Series Routers
- Shared and Dedicated Buffer Memory Pools on ACX Series Routers
- CoS for PPP and MLPPP Interfaces on ACX Series Routers
- CoS for NAT Services on ACX Series Routers
- Hierarchical Class of Service in ACX Series Routers
- Storm Control on ACX Series Routers Overview
- play_arrow Configuring Class of Service on MX Series 5G Universal Routing Platforms
- Junos CoS on MX Series 5G Universal Routing Platforms Overview
- CoS Features and Limitations on MX Series Routers
- Configuring and Applying IEEE 802.1ad Classifiers
- Scheduling and Shaping in Hierarchical CoS Queues for Traffic Routed to GRE Tunnels
- Example: Performing Output Scheduling and Shaping in Hierarchical CoS Queues for Traffic Routed to GRE Tunnels
- CoS-Based Interface Counters for IPv4 or IPv6 Aggregate on Layer 2
- Enabling a Timestamp for Ingress and Egress Queue Packets
- play_arrow Configuring Class of Service on PTX Series Packet Transport Routers
- CoS Features and Limitations on PTX Series Routers
- CoS Feature Differences Between PTX Series Packet Transport Routers and T Series Routers
- Understanding Scheduling on PTX Series Routers
- Virtual Output Queues on PTX Series Packet Transport Routers
- Example: Configuring Excess Rate for PTX Series Packet Transport Routers
- Identifying the Source of RED Dropped Packets on PTX Series Routers
- Configuring Queuing and Shaping on Logical Interfaces on PTX Series Routers
- Example: Configuring Queuing and Shaping on Logical Interfaces in PTX Series Packet Transport Routers
- Example: Configuring Strict-Priority Scheduling on a PTX Series Router
- CoS Support on EVPN VXLANs
- Understanding CoS CLI Configuration Statements on PTX Series Routers
- Classification Based on Outer Header of Decapsulation Tunnel
-
- play_arrow Configuring Line Card-Specific and Interface-Specific Functionality
- play_arrow Feature Support of Line Cards and Interfaces
- play_arrow Configuring Class of Service for Tunnels
- play_arrow Configuring Class of Service on Services PICs
- CoS on Services PICs Overview
- Configuring CoS Rules on Services PICs
- Configuring CoS Rule Sets on Services PICs
- Example: Configuring CoS Rules on Services PICs
- Packet Rewriting on Services Interfaces
- Multiservices PIC ToS Translation
- Fragmentation by Forwarding Class Overview
- Configuring Fragmentation by Forwarding Class
- Configuring Drop Timeout Interval for Fragmentation by Forwarding Class
- Example: Configuring Fragmentation by Forwarding Class
- Allocating Excess Bandwidth Among Frame Relay DLCIs on Multiservices PICs
- Configuring Rate Limiting and Sharing of Excess Bandwidth on Multiservices PICs
- play_arrow Configuring Class of Service on IQ and Enhanced IQ (IQE) PICs
- CoS on Enhanced IQ PICs Overview
- Calculation of Expected Traffic on IQE PIC Queues
- Configuring the Junos OS to Support Eight Queues on IQ Interfaces for T Series and M320 Routers
- BA Classifiers and ToS Translation Tables
- Configuring ToS Translation Tables
- Configuring Hierarchical Layer 2 Policers on IQE PICs
- Configuring Excess Bandwidth Sharing on IQE PICs
- Configuring Rate-Limiting Policers for High Priority Low-Latency Queues on IQE PICs
- Applying Scheduler Maps and Shaping Rate to Physical Interfaces on IQ PICs
- Applying Scheduler Maps to Chassis-Level Queues
- play_arrow Configuring Class of Service on Ethernet IQ2 and Enhanced IQ2 PICs
- CoS on Enhanced IQ2 PICs Overview
- CoS Features and Limitations on IQ2 and IQ2E PICs (M Series and T Series)
- Differences Between Gigabit Ethernet IQ and Gigabit Ethernet IQ2 PICs
- Shaping Granularity Values for Enhanced Queuing Hardware
- Ethernet IQ2 PIC RTT Delay Buffer Values
- Configuring BA Classifiers for Bridged Ethernet
- Setting the Number of Egress Queues on IQ2 and Enhanced IQ2 PICs
- Configuring the Number of Schedulers per Port for Ethernet IQ2 PICs
- Applying Scheduler Maps to Chassis-Level Queues
- CoS for L2TP Tunnels on Ethernet Interface Overview
- Configuring CoS for L2TP Tunnels on Ethernet Interfaces
- Configuring LNS CoS for Link Redundancy
- Example: Configuring L2TP LNS CoS Support for Link Redundancy
- Configuring Shaping on 10-Gigabit Ethernet IQ2 PICs
- Configuring Per-Unit Scheduling for GRE Tunnels Using IQ2 and IQ2E PICs
- Understanding Burst Size Configuration on IQ2 and IQ2E Interfaces
- Configuring Burst Size for Shapers on IQ2 and IQ2E Interfaces
- Configuring a CIR and a PIR on Ethernet IQ2 Interfaces
- Example: Configuring Shared Resources on Ethernet IQ2 Interfaces
- Configuring and Applying IEEE 802.1ad Classifiers
- Configuring Rate Limits to Protect Lower Queues on IQ2 and Enhanced IQ2 PICs
- Simple Filters Overview
- Configuring a Simple Filter
- play_arrow Configuring Class of Service on 10-Gigabit Ethernet LAN/WAN PICs with SFP+
- CoS on 10-Gigabit Ethernet LAN/WAN PIC with SFP+ Overview
- BA and Fixed Classification on 10-Gigabit Ethernet LAN/WAN PIC with SFP+ Overview
- DSCP Rewrite for the 10-Gigabit Ethernet LAN/WAN PIC with SFP+
- Configuring DSCP Rewrite for the 10-Gigabit Ethernet LAN/WAN PIC
- Queuing on 10-Gigabit Ethernet LAN/WAN PICs Properties
- Mapping Forwarding Classes to CoS Queues on 10-Gigabit Ethernet LAN/WAN PICs
- Scheduling and Shaping on 10-Gigabit Ethernet LAN/WAN PICs Overview
- Example: Configuring Shaping Overhead on 10-Gigabit Ethernet LAN/WAN PICs
- play_arrow Configuring Class of Service on Enhanced Queuing DPCs
- Enhanced Queuing DPC CoS Properties
- Configuring Rate Limits on Enhanced Queuing DPCs
- Configuring WRED on Enhanced Queuing DPCs
- Configuring MDRR on Enhanced Queuing DPCs
- Configuring Excess Bandwidth Sharing
- Configuring Customer VLAN (Level 3) Shaping on Enhanced Queuing DPCs
- Simple Filters Overview
- Configuring Simple Filters on Enhanced Queuing DPCs
- Configuring a Simple Filter
- play_arrow Configuring Class of Service on MICs, MPCs, and MLCs
- CoS Features and Limitations on MIC and MPC Interfaces
- Dedicated Queue Scaling for CoS Configurations on MIC and MPC Interfaces Overview
- Verifying the Number of Dedicated Queues Configured on MIC and MPC Interfaces
- Scaling of Per-VLAN Queuing on Non-Queuing MPCs
- Increasing Available Bandwidth on Rich-Queuing MPCs by Bypassing the Queuing Chip
- Flexible Queuing Mode
- Multifield Classifier for Ingress Queuing on MX Series Routers with MPC
- Example: Configuring a Filter for Use as an Ingress Queuing Filter
- Ingress Queuing Filter with Policing Functionality
- Ingress Rate Limiting on MX Series Routers with MPCs
- Rate Shaping on MIC and MPC Interfaces
- Per-Priority Shaping on MIC and MPC Interfaces Overview
- Example: Configuring Per-Priority Shaping on MIC and MPC Interfaces
- Configuring Static Shaping Parameters to Account for Overhead in Downstream Traffic Rates
- Example: Configuring Static Shaping Parameters to Account for Overhead in Downstream Traffic Rates
- Traffic Burst Management on MIC and MPC Interfaces Overview
- Understanding Hierarchical Scheduling for MIC and MPC Interfaces
- Configuring Ingress Hierarchical CoS on MIC and MPC Interfaces
- Configuring a CoS Scheduling Policy on Logical Tunnel Interfaces
- Per-Unit Scheduling and Hierarchical Scheduling for MPC Interfaces
- Managing Dedicated and Remaining Queues for Static CoS Configurations on MIC and MPC Interfaces
- Excess Bandwidth Distribution on MIC and MPC Interfaces Overview
- Bandwidth Management for Downstream Traffic in Edge Networks Overview
- Scheduler Delay Buffering on MIC and MPC Interfaces
- Managing Excess Bandwidth Distribution on Static Interfaces on MICs and MPCs
- Drop Profiles on MIC and MPC Interfaces
- Intelligent Oversubscription on MIC and MPC Interfaces Overview
- Jitter Reduction in Hierarchical CoS Queues
- Example: Reducing Jitter in Hierarchical CoS Queues
- CoS on Ethernet Pseudowires in Universal Edge Networks Overview
- CoS Scheduling Policy on Logical Tunnel Interfaces Overview
- Configuring CoS on an Ethernet Pseudowire for Multiservice Edge Networks
- CoS for L2TP LNS Inline Services Overview
- Configuring Static CoS for an L2TP LNS Inline Service
- CoS on Circuit Emulation ATM MICs Overview
- Configuring CoS on Circuit Emulation ATM MICs
- Understanding IEEE 802.1p Inheritance push and swap from a Transparent Tag
- Configuring IEEE 802.1p Inheritance push and swap from the Transparent Tag
- CoS on Application Services Modular Line Card Overview
- play_arrow Configuring Class of Service on Aggregated, Channelized, and Gigabit Ethernet Interfaces
- Limitations on CoS for Aggregated Interfaces
- Policer Support for Aggregated Ethernet Interfaces Overview
- Understanding Schedulers on Aggregated Interfaces
- Examples: Configuring CoS on Aggregated Interfaces
- Hierarchical Schedulers on Aggregated Ethernet Interfaces Overview
- Configuring Hierarchical Schedulers on Aggregated Ethernet Interfaces
- Example: Configuring Scheduling Modes on Aggregated Interfaces
- Enabling VLAN Shaping and Scheduling on Aggregated Interfaces
- Class of Service on demux Interfaces
- Example: Configuring Per-Unit Schedulers for Channelized Interfaces
- Applying Layer 2 Policers to Gigabit Ethernet Interfaces
-
- play_arrow Configuration Statements and Operational Commands
Oversubscribing Interface Bandwidth
The term oversubscribing interface bandwidth means configuring shaping rates (peak information rates [PIRs]) so that their sum exceeds the interface bandwidth.
On Channelized IQ PICs, Gigabit Ethernet IQ PICs, and FRF.15 and FRF.16 link services IQ (LSQ) interfaces on Services PICs, Multiservices PICs, and Multiservices DPCs, you can oversubscribe interface bandwidth. This means that the logical interfaces (and DLCIs within an FRF.15 or FRF.16 bundle) can be oversubscribed when there is leftover bandwidth. In the case of FRF.16 bundle interfaces, the physical interface can be oversubscribed. The oversubscription is capped to the configured PIR. Any unused bandwidth is distributed equally among oversubscribed logical interfaces or data-link connection identifiers (DLCIs), or physical interfaces.
For networks that are not likely to experience congestion, oversubscribing interface bandwidth improves network utilization, thereby allowing more customers to be provisioned on a single interface. If the actual data traffic does not exceed the interface bandwidth, oversubscription allows you to sell more bandwidth than the interface can support.
We recommend avoiding oversubscription in networks that are likely to experience congestion. Be cautious not to oversubscribe a service by too much, because this can cause degradation in the performance of the routing platform during congestion. When you configure oversubscription, starvation of some output queues can occur if the actual data traffic exceeds the physical interface bandwidth. You can prevent degradation by using statistical multiplexing to ensure that the actual data traffic does not exceed the interface bandwidth.
You cannot oversubscribe interface bandwidth when you configure traffic shaping using the method described in Applying Scheduler Maps and Shaping Rate to DLCIs and VLANs.
When configuring oversubscription for FRF.16 bundle interfaces, you can assign traffic control profiles that apply on a physical interface basis. When you apply traffic control profiles to FRF.16 bundles at the logical interface level, member link interface bandwidth is underutilized when there is a small proportion of traffic or no traffic at all on an individual DLCI. Support for traffic control features on the FRF.16 bundle physical interface level addresses this limitation.
To configure oversubscription of the interface, perform the following steps:
Include the
shaping-rate
statement at the[edit class-of-service traffic-control-profiles profile-name]
hierarchy level:content_copy zoom_out_map[edit class-of-service traffic-control-profiles profile-name] shaping-rate (percent percentage | rate);
Note:When configuring oversubscription for FRF.16 bundle interfaces on a physical interface basis, you must specify
shaping-rate
as a percentage.On LSQ interfaces, you can configure the shaping rate as a percentage from 1 through 100.
On IQ and IQ2 interfaces, you can configure the shaping rate as an absolute rate from 1000 through 6,400,000,000,000 bps.
For all MX Series router and EX Series switch interfaces, the shaping rate can be from 65,535 through 6,400,000,000,000 bps.
Alternatively, you can configure a shaping rate for a logical interface and oversubscribe the physical interface by including the
shaping-rate
statement at the[edit class-of-service interfaces interface-name unit logical-unit-number]
hierarchy level. However, with this configuration approach, you cannot independently control the delay-buffer rate, as described in Step 2.Note:For channelized and Gigabit Ethernet IQ interfaces, the
shaping-rate
andguaranteed-rate
statements are mutually exclusive. You cannot configure some logical interfaces to use a shaping rate and others to use a guaranteed rate. This means there are no service guarantees when you configure a PIR. For these interfaces, you can configure either a PIR or a committed information rate (CIR), but not both.This restriction does not apply to Gigabit Ethernet IQ2 PICs or LSQ interfaces on Multiservices and Services PICs. For LSQ and Gigabit Ethernet IQ2 interfaces, you can configure both a PIR and a CIR on an interface. For more information about CIRs, see Providing a Guaranteed Minimum Rate.
For more information about Gigabit Ethernet IQ2 PICs, see CoS on Enhanced IQ2 PICs Overview.
Optionally, you can base the delay-buffer calculation on a delay-buffer rate. To do this, include the
delay-buffer-rate
statement at the[edit class-of-service traffic-control-profiles profile-name]
hierarchy level:Note:When configuring oversubscription for FRF.16 bundle interfaces on a physical interface basis, you must specify
delay-buffer-rate
as a percentage.content_copy zoom_out_map[edit class-of-service traffic-control-profiles profile-name] delay-buffer-rate (percent percentage | rate);
The delay-buffer rate overrides the shaping rate as the basis for the delay-buffer calculation. In other words, the shaping rate or scaled shaping rate is used for delay-buffer calculations only when the delay-buffer rate is not configured.
For LSQ interfaces, if you do not configure a delay-buffer rate, the guaranteed rate (CIR) is used to assign buffers. If you do not configure a guaranteed rate, the shaping rate (PIR) is used in the undersubscribed case, and the scaled shaping rate is used in the oversubscribed case.
On LSQ interfaces, you can configure the delay-buffer rate as a percentage from 1 through 100.
On IQ and IQ2 interfaces, you can configure the delay-buffer rate as an absolute rate from 1000 through 6,400,000,000,000 bps.
The actual delay buffer is based on the calculations described in Managing Congestion on the Egress Interface by Configuring the Scheduler Buffer Size. For an example showing how the delay-buffer rates are applied, see Examples: Oversubscribing Interface Bandwidth.
Configuring large buffers on relatively slow-speed links can cause packet aging. To help prevent this problem, the software requires that the sum of the delay-buffer rates be less than or equal to the port speed.
This restriction does not eliminate the possibility of packet aging, so you should be cautious when using the
delay-buffer-rate
statement. Though some amount of extra buffering might be desirable for burst absorption, delay-buffer rates should not far exceed the service rate of the logical interface.If you configure delay-buffer rates so that the sum exceeds the port speed, the configured delay-buffer rate is not implemented for the last logical interface that you configure. Instead, that logical interface receives a delay-buffer rate of zero, and a warning message is displayed in the CLI. If bandwidth becomes available (because another logical interface is deleted or deactivated, or the port speed is increased), the configured delay-buffer-rate is reevaluated and implemented if possible.
If you do not configure a delay-buffer rate or a guaranteed rate, the logical interface receives a delay-buffer rate in proportion to the shaping rate and the remaining delay-buffer rate available. In other words, the delay-buffer rate for each logical interface with no configured delay-buffer rate is equal to:
content_copy zoom_out_map(remaining delay-buffer rate * shaping rate) / (sum of shaping rates)
where the remaining delay-buffer rate is equal to:
content_copy zoom_out_map(interface speed) - (sum of configured delay-buffer rates)
To assign a scheduler map to the logical interface, include the
scheduler-map
statement at the[edit class-of-service traffic-control-profiles profile-name]
hierarchy level:content_copy zoom_out_map[edit class-of-service traffic-control-profiles profile-name] scheduler-map map-name;
For information about configuring schedulers and scheduler maps, see Configuring Schedulers and Configuring Scheduler Maps.
Optionally, you can enable large buffer sizes to be configured. To do this, include the
q-pic-large-buffer
statement at the[edit chassis fpc slot-number pic pic-number]
hierarchy level:content_copy zoom_out_map[edit chassis fpc slot-number pic pic-number] q-pic-large-buffer;
If you do not include this statement, the delay-buffer size is more restricted. We recommend restricted buffers for delay-sensitive traffic, such as voice traffic. For more information, see Managing Congestion on the Egress Interface by Configuring the Scheduler Buffer Size.
To enable scheduling on logical interfaces, include the
per-unit-scheduler
statement at the[edit interfaces interface-name]
hierarchy level:content_copy zoom_out_map[edit interfaces interface-name] per-unit-scheduler;
When you include this statement, the maximum number of VLANs supported is 768 on a single-port Gigabit Ethernet IQ PIC. On a dual-port Gigabit Ethernet IQ PIC, the maximum number is 384.
To enable scheduling for FRF.16 bundles physical interfaces, include the
no-per-unit-scheduler
statement at the[edit interfaces interface-name]
hierarchy level:content_copy zoom_out_map[edit interfaces interface-name] no-per-unit-scheduler;
To apply the traffic-scheduling profile , include the output-traffic-control-profile statement at the
[edit class-of-service interfaces interface-name unit logical-unit-number]
hierarchy level:content_copy zoom_out_map[edit class-of-service interfaces interface-name unit logical-unit-number] output-traffic-control-profile profile-name;
You cannot include the
output-traffic-control-profile
statement in the configuration if either thescheduler-map
orshaping-rate
statement is included in the logical interface configuration.
Table 1 shows how the bandwidth and delay buffer are allocated in various configurations.
In Junos OS Release 13.3, IP packets with DLCI 0 or 1023 are identified as part of control traffic and routed to the high-priority queue. This oversubscribes the high-priority queue, which is reserved for frame relay control traffic. Oversubscribing the high-priority queue causes the frame relay Local Management Interface (LMI) packets to be dropped.
Verifying Configuration of Bandwidth Oversubscription
To verify your configuration, you can issue this following operational mode commands:
show class-of-service interfaces
show class-of-service traffic-control-profile profile-name
Examples: Oversubscribing Interface Bandwidth
This section provides two examples: oversubscription of a channelized interface and oversubscription of an LSQ interface.
Oversubscribing a Channelized Interface
Two logical interface units, 0
and 1
,
are shaped to rates 2 Mbps and 3 Mbps, respectively. The
delay-buffer rates are 750 Kbps and 500 Kbps, respectively.
The actual delay buffers allocated to each logical interface
are 1 second of 750 Kbps and 2 seconds of 500 Kbps,
respectively. The 1-second and 2-second values are based on the following
calculations:
delay-buffer-rate < [16 x 64 Kbps]): 1 second of delay-buffer-rate delay-buffer-rate < [8 x 64 Kbps]): 2 seconds of delay-buffer-rate
For more information about these calculations, see Managing Congestion on the Egress Interface by Configuring the Scheduler Buffer Size.
chassis { fpc 3 { pic 0 { q-pic-large-buffer; } } } interfaces { t1-3/0/0 { per-unit-scheduler; } } class-of-service { traffic-control-profiles { tc-profile1 { shaping-rate 2m; delay-buffer-rate 750k; # 750 Kbps is less than 16 x 64 Kbps scheduler-map sched-map1; } tc-profile2 { shaping-rate 3m; delay-buffer-rate 500k; # 500 Kbps is less than 8 x 64 Kbps scheduler-map sched-map2; } } interfaces { t1-3/0/0 { unit 0 { output-traffic-control-profile tc-profile1; } unit 1 { output-traffic-control-profile tc-profile2; } } } }
Oversubscribing an LSQ Interface with Scheduling Based on the Logical Interface
Apply a traffic-control profile to a logical interface representing a DLCI on an FRF.16 bundle:
interfaces { lsq-1/3/0:0 { per-unit-scheduler; unit 0 { dlci 100; } unit 1 { dlci 200; } } } class-of-service { traffic-control-profiles { tc_0 { shaping-rate percent 100; guaranteed-rate percent 60; delay-buffer-rate percent 80; } tc_1 { shaping-rate percent 80; guaranteed-rate percent 40; } } interfaces { lsq-1/3/0 { unit 0 { output-traffic-control-profile tc_0; } unit 1 { output-traffic-control-profile tc_1; } } } }
Oversubscribing an LSQ Interface with Scheduling Based on the Physical Interface
Apply a traffic-control profile to the physical interface representing an FRF.16 bundle:
interfaces { lsq-0/2/0:0 { no-per-unit-scheduler; encapsulation multilink-frame-relay-uni-nni; unit 0 { dlci 100; family inet { address 10.18.18.2/24; } } } class-of-service { traffic-control-profiles { rlsq_tc { scheduler-map rlsq; shaping-rate percent 60; delay-buffer-rate percent 10; } } interfaces { lsq-0/2/0:0 { output-traffic-control-profile rlsq_tc; } } } scheduler-maps { rlsq { forwarding-class best-effort scheduler rlsq_scheduler; forwarding-class expedited-forwarding scheduler rlsq_scheduler1; } } schedulers { rlsq_scheduler { transmit-rate percent 20; priority low; } rlsq_scheduler1 { transmit-rate percent 40; priority high; } }
On an FRF.15 bundle, apply the following configuration:
class-of-service { traffic-control-profiles { rlsq { scheduler-map sched_0; shaping-rate percent 40; delay-buffer-rate percent 50; } } interfaces lsq-2/0/0 { unit 0 { output-traffic-control-profile rlsq; } } } interfaces lsq-2/0/0 { per-unit-scheduler; unit 0 { encapsulation multilink-frame-relay-end-to-end; family inet { address 10.1.1.2/32; } } }