Help us improve your experience.

Let us know what you think.

Do you have time for a two-minute survey?

TechLibrary
Navigation

Example: Configuring Transmission Rate with Intelligent Oversubscription on SONET/SDH OC48/STM16 IQE PICs

This example shows how to configure transmission rates on a sonet interface for eight forwarding classes with transmission rate values that exceed 100 percent, causing the interface to be in an oversubscribed state.

Requirements

This example requires the following hardware and software components:

  • Networking devices using a SONET/SDH OC48/STM16 IQE PIC.
  • Junos OS Release 12.2 or later running on the devices.

Before you begin:

  1. Configure the device interfaces.
  2. Enable class-of-service (CoS) queuing, scheduling, and shaping on the device interfaces.

Overview and Topology

Junos OS Release 12.2 and later support oversubscribing the available bandwidth on a SONET/SDH OC48/STM16 IQE PIC up to 300 percent. This optimization is achieved by creating an additional priority group for all queues specified for low priority, and the sum of transmission rates for all the low priority queues adding up to 100 percent, independent of the transmission rate configured for all other queues.

Previously, the SONET/SDH OC48/STM16 IQE PIC supported a maximum bandwidth optimization by oversubscribing the available bandwidth up to 200 percent, by excluding the transmission rate percentage specified for the Strict-High queue from the total 100 percent transmission rate. Therefore, the transmission rate percentage for all the non-Strict-High queues added up to 100 percent. This computation was done after the internal mapping of the excess priority or the excess rate.

As an enhancement to the intelligent oversubscription feature on SONET/SDH OC48/STM16 IQE PICs, support for maximum bandwidth optimization is increased to 300 percent.

When the sum of transmission rates for all queues exceeds 100 percent, the interface is in an oversubscribed state. At the time of oversubscription, the queues are split into three priority groups with the intelligent oversubscription feature enhancement:

  • Strict-High
  • High, Medium-High, and Medium-Low
  • Low

Each of the above priority groups can be configured to have a transmission rate oversubscription up to 100 percent. The transmission rate oversubscription value can be expressed as a percentage of the CIR or PIR value or as an absolute value.

Note: The remainder option is not supported on an oversubscribed SONET/SDH OC48/STM16 IQE PIC. When the sum of the transmission rates for all queues exceeds 100 percent, and if one or more queues are configured with the remainder option, a syslog error message is generated and the configuration is ignored.

In this example, Router R0 is the route on which the CoS options are configured. Routers R1 and R2 are directly connected to R0 and send traffic to R0.

Configuration

CLI Quick Configuration

To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.

R0

set class-of-service classifiers inet-precedence inet_classy forwarding-class fc0 loss-priority low code-points 000set class-of-service classifiers inet-precedence inet_classy forwarding-class fc1 loss-priority low code-points 001set class-of-service classifiers inet-precedence inet_classy forwarding-class fc2 loss-priority low code-points 010set class-of-service classifiers inet-precedence inet_classy forwarding-class fc3 loss-priority low code-points 011set class-of-service classifiers inet-precedence inet_classy forwarding-class fc4 loss-priority low code-points 100set class-of-service classifiers inet-precedence inet_classy forwarding-class fc5 loss-priority low code-points 101set class-of-service classifiers inet-precedence inet_classy forwarding-class fc6 loss-priority low code-points 110set class-of-service classifiers inet-precedence inet_classy forwarding-class fc7 loss-priority low code-points 111set class-of-service forwarding-classes class fc0 queue-num 0set class-of-service forwarding-classes class fc1 queue-num 1set class-of-service forwarding-classes class fc2 queue-num 2set class-of-service forwarding-classes class fc3 queue-num 3set class-of-service forwarding-classes class fc4 queue-num 4set class-of-service forwarding-classes class fc5 queue-num 5set class-of-service forwarding-classes class fc6 queue-num 6set class-of-service forwarding-classes class fc7 queue-num 7set class-of-service traffic-control-profiles TCP scheduler-map map_iflsset class-of-service traffic-control-profiles TCP shaping-rate 1gset class-of-service interfaces so-4/1/0 unit 0 classifiers inet-precedence inet_classyset class-of-service interfaces so-4/1/1 unit 0 output-traffic-control-profile TCPset class-of-service schedulers s0 transmit-rate percent 25set class-of-service schedulers s0 priority strict-highset class-of-service schedulers s1 transmit-rate percent 20set class-of-service schedulers s1 priority highset class-of-service schedulers s2 transmit-rate percent 15set class-of-service schedulers s2 priority highset class-of-service schedulers s3 transmit-rate percent 35set class-of-service schedulers s3 priority medium-highset class-of-service schedulers s4 transmit-rate percent 10set class-of-service schedulers s4 priority medium-lowset class-of-service schedulers s5 transmit-rate percent 15set class-of-service schedulers s5 priority lowset class-of-service schedulers s6 transmit-rate percent 15set class-of-service schedulers s6 priority lowset class-of-service schedulers s7 transmit-rate percent 15set class-of-service schedulers s7 priority lowset class-of-service scheduler-maps map_ifls forwarding-class fc0 scheduler s0set class-of-service scheduler-maps map_ifls forwarding-class fc1 scheduler s1set class-of-service scheduler-maps map_ifls forwarding-class fc2 scheduler s2set class-of-service scheduler-maps map_ifls forwarding-class fc3 scheduler s3set class-of-service scheduler-maps map_ifls forwarding-class fc4 scheduler s4set class-of-service scheduler-maps map_ifls forwarding-class fc5 scheduler s5set class-of-service scheduler-maps map_ifls forwarding-class fc6 scheduler s6set class-of-service scheduler-maps map_ifls forwarding-class fc7 scheduler s7

Step-by-Step Procedure

The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode. To configure the R0 router:

  1. Configure an IP Precedence classifier to classify incoming packets based on the code point values.
    [edit class-of-service classifiers]user@R0# set inet-precedence inet_classy
  2. Define the classification of code point values to a forwarding class, and configure code point values to classify to loss priority Low.
    [edit class-of-service classifiers inet-precedence inet_classy]user@R0# set fc0 loss-priority low code-points 000user@R0# set fc1 loss-priority low code-points 001user@R0# set fc2 loss-priority low code-points 010user@R0# set fc3 loss-priority low code-points 011user@R0# set fc4 loss-priority low code-points 100user@R0# set fc5 loss-priority low code-points 101user@R0# set fc6 loss-priority low code-points 110user@R0# set fc7 loss-priority low code-points 111
  3. Define mapping of forwarding classes to queue numbers.
    [edit class-of-service forwarding-classes class]user@R0# set fc0 queue-num 0user@R0# set fc1 queue-num 1user@R0# set fc2 queue-num 2user@R0# set fc3 queue-num 3user@R0# set fc4 queue-num 4user@R0# set fc5 queue-num 5user@R0# set fc6 queue-num 6user@R0# set fc7 queue-num 7
  4. Configure traffic shaping and scheduling profiles.
    [edit class-of-service traffic-control-profiles]user@R0# set TCP scheduler-map map_iflsuser@R0# set TCP shaping-rate 1g
  5. Apply the class-of-service options to interfaces.
    [edit class-of-service interfaces]user@R0# set so-4/1/0 unit 0 classifiers inet-precedence inet_classyuser@R0# set so-4/1/1 unit 0 output-traffic-control-profile TCP
  6. Configure eight packet schedulers with scheduling priority and transmission rates.
    [edit class-of-service schedulers]user@R0# set s0 transmit-rate percent 25user@R0# set s0 priority strict-highuser@R0# set s1 transmit-rate percent 20user@R0# set s1 priority highuser@R0# set s2 transmit-rate percent 15user@R0# set s2 priority highuser@R0# set s3 transmit-rate percent 35user@R0# set s3 priority medium-highuser@R0# set s4 transmit-rate percent 0user@R0# set s4 priority medium-lowuser@R0# set s5 transmit-rate percent 15user@R0# set s5 priority lowuser@R0# set s6 transmit-rate percent 15user@R0# set s6 priority lowuser@R0# set s7 transmit-rate percent 15user@R0# set s7 priority low
  7. Define mapping of forwarding classes to packet schedulers.
    [edit class-of-service scheduler-maps]user@R0# set map_ifls forwarding-class fc0 scheduler s0user@R0# set map_ifls forwarding-class fc1 scheduler s1user@R0# set map_ifls forwarding-class fc2 scheduler s2user@R0# set map_ifls forwarding-class fc3 scheduler s3user@R0# set map_ifls forwarding-class fc4 scheduler s4user@R0# set map_ifls forwarding-class fc5 scheduler s5user@R0# set map_ifls forwarding-class fc6 scheduler s6user@R0# set map_ifls forwarding-class fc7 scheduler s7

Results

From configuration mode, confirm your configuration by entering the show class-of-service command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

class-of-service {classifiers {inet-precedence inet_classy {forwarding-class fc0 {loss-priority low code-points 000;}forwarding-class fc1 {loss-priority low code-points 001;}forwarding-class fc2 {loss-priority low code-points 010;}forwarding-class fc3 {loss-priority low code-points 011;}forwarding-class fc4 {loss-priority low code-points 100;}forwarding-class fc5 {loss-priority low code-points 101;}forwarding-class fc6 {loss-priority low code-points 110;}forwarding-class fc7 {loss-priority low code-points 111;}}}forwarding-classes {class fc0 queue-num 0;class fc1 queue-num 1;class fc2 queue-num 2;class fc3 queue-num 3;class fc4 queue-num 4;class fc5 queue-num 5;class fc6 queue-num 6;class fc7 queue-num 7;}traffic-control-profiles {TCP {scheduler-map map_ifls;shaping-rate 1g;}}interfaces {so-4/1/0 {unit 0 {classifiers {inet-precedence inet_classy;}}}so-4/1/1 {unit 0 {output-traffic-control-profile TCP;}}}schedulers {s0 {transmit-rate percent 25;priority strict-high;}s1 {transmit-rate percent 20;priority high;}s2 {transmit-rate percent 15;priority high;}s3 {transmit-rate percent 35;priority medium-high;}s4 {transmit-rate percent 10;priority medium-low;}s5 {transmit-rate percent 15;priority low;}s6 {transmit-rate percent 15;priority low;}s7 {transmit-rate percent 15;priority low;}}scheduler-maps {map_ifls {forwarding-class fc0 scheduler s0;forwarding-class fc1 scheduler s1;forwarding-class fc2 scheduler s2;forwarding-class fc3 scheduler s3;forwarding-class fc4 scheduler s4;forwarding-class fc5 scheduler s5;forwarding-class fc6 scheduler s6;forwarding-class fc7 scheduler s7;}}}

If you are done configuring the device, enter commit from configuration mode.

Verification

Confirm that the configuration is working properly.

Verifying Queue Transmission Rate Oversubscription

Purpose

Verify that the SONET/SDH OC48/STM16 IQE PIC supports 300 percent oversubscription.

Action

Configure the queue transmission rates such that they are oversubscribed up to 300 percent.

The sum of transmission rates of all queues can be less than or equal to 300 percent. The sum of transmission rates of all queues in each priority group should be less than or equal to 100 percent.

In this example, Router R0 interfaces have been oversubscribed by 150 percent of the available bandwidth. The sum of transmission rates of all the queues in each of the priority groups are:

  • Strict-High—(q0) 25%
  • High, Medium-High, Medium-Low—(q1, q2, q3, and q4) 80%
  • Low—(q5, q6, and q7) 45%

When the sum of transmission rates of all queues in any of the priority groups exceeds 100 percent, the commit fails.

For example, if the transmission rate of q1 is 30 percent, the sum of the transmission rates of all queues (q1, q2, q3, and q4) in the High-Medium priority group is 110 percent. At the time of commit, the following error is displayed:

Total bandwidth allocation for high-med priority queues exceeds 100 percent for scheduler-map map_ifls
error: configuration check-out failed

Meaning

When the sum of transmission rates of all queues exceeds 100 percent, a new priority group is created for all Low priority queues. The queue transmission rates in the Low priority group can add up to 100 percent.

 

Related Documentation

 

Published: 2013-07-31

Previous Page Next Page