15. Slope QoS Policies

This section provides information to configure slope QoS policies using the command line interface.

15.1. Overview

Default buffer pool exists (logically) at each port. Each physical port has two associated pool objects:

  1. access port egress pool
  2. access-uplink port egress pool

By default, each queue on the access port and access-uplink port is associated with slope-policy default which disables the high-slope, low-slope and non-TCP slope parameters within the pool.

15.1.1. Configuration Guidelines

This section provides configuration guidelines for slope QoS policies.

15.1.1.1. For 7210 SAS-M Network Mode

Following slopes are used based on the traffic encapsulation:

  1. For traffic received with MPLS encapsulation (For example: MPLS traffic received on network port ingress, and others) non-TCP slope is used.
  2. For TCP traffic received with less than or equal to 2 VLAN tags (For example: VLAN ethernet traffic received on SAP ingress, and others) TCP- slopes (either high or low) is used.
  3. For non-TCP traffic received with less than or equal to 2 VLAN tags (For example: VLAN ethernet traffic received on SAP ingress, and others) non-TCP slope is used.
  4. For all traffic received with 3 or more VLAN tags (For example: VLAN ethernet traffic received on SAP ingress, and others) non-TCP slope is used.

15.1.1.2. For 7210 SAS-M Access-uplink Mode

Following slopes are used based on the traffic encapsulation:

  1. For TCP traffic received with less than or equal to 2 VLAN tags (For example: VLAN ethernet traffic received on SAP ingress, and others) TCP- slopes (either high or low) is used.
  2. For non-TCP traffic received with less than or equal to 2 VLAN tags (For example: VLAN ethernet traffic received on SAP ingress, and others) non-TCP slope is used.
  3. For all traffic received with 3 or more VLAN tags (For example: VLAN ethernet traffic received on SAP ingress, and others) non-TCP slope is used.

15.1.1.3. WRED Slope Enhancement

In 7210 SAS release 6.0, the user is provided with an option to use only 2 WRED slopes per queue (port egress queues), which allows differentiating in-profile and out-of-profile traffic flows. This is supported in both 7210 SAS-M access-uplink mode and network mode.

Table 66 compares the WRED slope used for different traffic flows. The slope does not get enabled by default. In order to maintain backward compatibility, the value is set to use 3 slopes (that is, tcp-non-tcp) and user has to change it explicitly to use 2 slopes on 7210 SAS-M nodes.

Table 66:  Slope Behavior Table 

Slopes

Slope Option

TCP-non-TCP

(Uses 3 WRED Slopes per Queue)

High-Low

(Uses 2 WRED Slopes per Queue)

SAP Ingress TCP/IP traffic

(Number of VLAN tags ≤ 2)

High-priority TCP slope or low-priority TCP slope, based on packet profile

High-priority or low-priority slope, based on packet profile

SAP Ingress non-TCP traffic

(Number of VLAN tags does not matter)

Non-TCP slope - No in/out profile differentiation

High-priority or low-priority slope, based on packet profile

SAP Ingress TCP/IP traffic

(Number of VLAN tags > 2)

Non-TCP slope - No in/out profile differentiation

High-priority or low-priority slope, based on packet profile

MPLS LER originating traffic

High-priority TCP slope or low-priority TCP slope, based on packet profile

High-priority or low-priority slope, based on packet profile

MPLS LER terminating traffic

Non-TCP slope - No in/out profile differentiation

High-priority or low-priority slope, based on packet profile

MPLS LSR traffic

Non-TCP slope - No in/out profile differentiation

High-priority or low-priority slope, based on packet profile

15.1.2. WRED Support on 7210 SAS-T Access-uplink Mode

On 7210 SAS-T, 2 WRED slopes are supported per queue, one each for in-profile or high-priority traffic and out-of-profile or low-priority traffic.

In 7210 SAS-T devices, the hardware supports a limited amount of profiles, out of which some are reserved for system internal use and the rest is available for user configuration. It is not possible to allocate a unique profile for each and every queue available on 7210 SAS-T. Multiple queues will need to share the same WRED profile. Software manages the allocation of hardware WRED profiles based on user configuration. It automatically allocates a single WRED hardware profile if multiple queues use the same slope parameters (that is, max-average, start-average, drop probability and time average factor). Only if these parameters differ, it allocates a different hardware WRED profile for use by the queue.

Note:

The WRED state (for example, average queue size) is maintained independently for each queue in the hardware.

A WRED profile (that is, each high-slope and low-slope) allows to specify the slope parameters such as max-average, start-average, drop probability and time average factor (TAF).

15.1.3. Basic Configurations

A basic slope QoS policy must conform to the following:

  1. Each slope policy must have a unique policy ID.
  2. High slope, low slope and non-TCP slope are shut down (default).
  3. Default values can be modified but parameters cannot be deleted.

15.1.3.1. Create a Slope QoS Policy

Configuring and applying slope policies is optional. If no slope policy is explicitly applied to a port, a default slope policy is applied.

To create a new slope policy, define the following:

  1. A slope policy ID value. The system will not dynamically assign a value.
  2. Include a description. The description provides a brief overview of policy features.
  3. The high slope for the high priority Random Early Detection (RED) slope graph.
  4. The low slope for the low priority Random Early Detection (RED) slope graph.
  5. The non-TCP slope for the non-TCP Random Early Detection (RED) slope graph.
  6. The time average factor (TAF), a weighting exponent used to determine the portion of the shared buffer instantaneous utilization and shared buffer average utilization used to calculate the new shared buffer average utilization.

Use the following CLI syntax to configure a slope policy for 7210 SAS-M:

CLI Syntax:
config>qos
slope-policy name
description description-string
high-slope
start-avg percent
max-avg percent
max-prob percent
no shutdown
low-slope
start-avg percent
max-avg percent
max-prob percent
no shutdown
non-tcp-slope
start-avg percent
max-avg percent
max-prob percent
no shutdown
time-average-factor taf

The following displays the slope policy configuration for 7210 SAS-M:

A:ALA-7>config>qo>slope-policy# info
----------------------------------------------
            description "slope policy SlopePolicy1"
            high-slope
                no shutdown
            exit
            low-slope
                no shutdown
            exit
non-tcp-slope
           no shutdown
          exit
----------------------------------------------
A:ALA-7>config>qos>slope-policy
 

Use the following CLI syntax to configure a slope policy for 7210 SAS-T, 7210 SAS-Sx/S 1/10GE and 7210 SAS-Sx 10/100GE:

CLI Syntax:
config>qos
slope-policy name
description description-string
high-slope
start-avg percent
max-avg percent
max-prob percent
no shutdown
low-slope
start-avg percent
max-avg percent
max-prob percent
no shutdown
time-average-factor taf

The following displays the slope policy configuration for 7210 SAS-T, 7210 SAS-Sx/S 1/10GE and 7210 SAS-Sx 10/100GE:

*A:hw_sass_duth>config>qos>slope-policy# info detail
----------------------------------------------
            no description
            queue "1"
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
# 

15.1.3.2. Applying Slope Policies

Apply slope policies to the egress buffer pool on the access and network ports.

15.1.3.2.1. Ports

The following CLI syntax examples may be used to apply slope policies to ports:

CLI Syntax:
config>port>access>egress>pool>slope-policy name
config>port>network>egress>pool>slope-policy name

15.1.4. Default Slope Policy Values

The default access egress and network egress policies are identified as policy-id “default”. The default policies cannot be edited or deleted. The following table displays default policy parameters:

 
A:ALA>config>qos# slope-policy default 
A:ALA>config>qos>slope-policy# info detail 
----------------------------------------------
            description "Default slope policy."
            queue "1" 
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit                      
            queue "2" 
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "3" 
                high-slope            
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "4" 
                high-slope
                    shutdown
                    start-avg 70      
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "5" 
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75       
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "6" 
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope             
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "7" 
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50      
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "8" 
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75       
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
----------------------------------------------
A:ALA>config>qos>slope-policy#

15.2. Service Management Tasks

15.2.1. Deleting QoS Policies

A slope policy is associated by default with access and network egress pools. A default policy may be replaced with a non-default policy, but a policy cannot be entirely removed from the configuration. When a non-default policy is removed, the policy association reverts to the default slope policy policy-id default. A QoS policy cannot be deleted until it is removed from all ports where it is applied or if the policies are using the slope-policy.

ALA-7>config>qos# no slope-policy slopePolicy1
MINOR: QOS #1902 Slope policy has references
ALA-7>config>qos#

15.2.1.1. Ports

The following CLI syntax examples can be used to remove slope policies from ports:

CLI Syntax:
config>port>access>egress>pool# no slope-policy name
config>port>network>egress>pool# no slope-policy name

15.2.1.2. Remove a Policy from the QoS Configuration

To delete a slope policy, enter the following command:

CLI Syntax:
config>qos# no slope-policy policy-id
Example:
config>qos# no slope-policy slopePolicy1

15.2.2. Copying and Overwriting QoS Policies

You can copy an existing slope policy, rename it with a new policy ID value, or overwrite an existing policy ID. The overwrite option must be specified or an error occurs if the destination policy ID exists.

CLI Syntax:
config>qos> copy {slope-policy} source-policy-id dest-policy-id [overwrite]

The following output displays the copied policies for:

 
A:ALA-7210M>config>qos#
----------------------------------------------
...
      description "Default slope policy."
            queue "1"
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "2"
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "3"
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "4"
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
            queue "5"
                high-slope
                    shutdown
                    start-avg 70
                    max-avg 90
                    max-prob 75
                exit
                low-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                non-tcp-slope
                    shutdown
                    start-avg 50
                    max-avg 75
                    max-prob 75
                exit
                time-average-factor 7
            exit
...
----------------------------------------------
A:ALA-7210M>config>qos#
 

15.2.3. Editing QoS Policies

You can change existing policies and entries in the CLI or NMS. The changes are applied immediately to all services where this policy is applied. To prevent configuration errors copy the policy to a work area, make the edits, and then write over the original policy.