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Chapter 10. Configuring Quality of Service (QoS) policies
With Red Hat OpenStack Platform network quality-of-service (QoS) policies, an OpenStack administrator can offer varying service levels by applying rate limits to egress traffic for instances. As a result of implementing a QoS policy, any traffic that exceeds the specified rate is consequently dropped.
10.1. QoS policy scope
You can apply QoS policies to individual ports, or to a particular tenant network, where ports with no specific policy attached inherit the policy.
10.2. Creating and applying a QoS policy and rule
To create a quality of service (QoS) policy and rule and apply the policy to a port, complete the following steps:
If the
qos
extension is not already enabled for OpenStack Networking in /etc/neutron/plugins/ml2/<agent_name>_agent.ini, then follow these steps:Create a custom Heat environment file, and add the following lines:
parameter_defaults: NeutronSriovAgentExtensions: 'qos'
ImportantYAML files are extremely sensitive about where in the file a parameter is placed. Make sure that
parameter_defaults:
starts in the first column (no leading whitespace characters), and your parameter value pair starts in column three (the parameter has two whitespace characters in front of it).Run the Red Hat OpenStack Platform director command,
openstack overcloud deploy
and include all your current environment files and this custom new one.For more information, see "Modifying the overcloud environment" in the Director Installation and Usage guide.
Review the list of tenants and determine the id of where you need to create QoS policy:
# openstack project list +----------------------------------+----------+ | ID | Name | +----------------------------------+----------+ | 4b0b98f8c6c040f38ba4f7146e8680f5 | auditors | | 519e6344f82e4c079c8e2eabb690023b | services | | 80bf5732752a41128e612fe615c886c6 | demo | | 98a2f53c20ce4d50a40dac4a38016c69 | admin | +----------------------------------+----------+
Create a QoS policy named
bw-limiter
in theadmin
tenant:# openstack network qos policy create --project 98a2f53c20ce4d50a40dac4a38016c69 bw-limiter
Configure the policing rules for the
bw-limiter
policy:# openstack network qos rule create --type bandwidth-limit --max-kbps 3000 --max-burst-kbits 30000 bw-limiter
Configure a neutron port to apply the
bw-limiter
policy:# openstack port set --qos-policy bw-limiter port_name_or_id
Review the QoS rule. For example:
# openstack network qos policy show 9be535c3-daa2-4d7b-88ea-e8de16 +-------------------+---------------------------------+ | Field | Value | +-------------------+---------------------------------+ | id | 9be535c3-daa2-4d7b-88ea-e8de16 | | rule_type | bandwidth_limit | | description | | | max_kbps | 3000 | | max_burst_kbps | 300 | +-------------------+---------------------------------+
These values allow you to configure the policing algorithm accordingly:
-
max_kbps
- the maximum rate (in Kbps) that the instance is allowed to send. -
max_burst_kbps
- the maximum amount of data (in kbits) that the port could send in a instant if the token buffer was full. The token buffer is replenished at a "max_kbps" rate.
10.3. DSCP marking for egress traffic
You can use differentiated services code point (DSCP) to implement quality-of-service (QoS) policies on your network by embedding relevant values in the IP headers. The Networking service (neutron) QoS policies can use DSCP marking to manage egress traffic on neutron ports and networks.
Procedure
If you are:
- using ML2/OVN, skip to step 2.
- using ML2/OVS without a tunneling protocol, skip to step 2.
using ML2/OVS with a tunneling protocol (VXLAN and GRE), then perform the following steps:
Log in to the undercloud host as the
stack
user.$ source ~/stackrc
Create a custom YAML environment file.
Example
$ vi /home/stack/templates/my-neutron-environment.yaml
In the YAML environment file under
parameter_defaults
, add the following lines:parameter_defaults: ControllerExtraConfig: neutron::config::server_config: agent/dscp_inherit: value: true
When
dscp_inherit
istrue
, the Networking service copies the DSCP value of the inner header to the outer header.Run the deployment command and include the core heat templates, environment files, and this new custom environment file.
ImportantThe order of the environment files is important as the parameters and resources defined in subsequent environment files take precedence.
Example
$ openstack overcloud deploy --templates \ -e [your-environment-files] \ -e /usr/share/openstack-tripleo-heat-templates/environments/services/ \ neutron-ovs.yaml \ -e /home/stack/templates/my-neutron-environment.yaml
Source your credentials file.
Example
$ source ~/overcloudrc
Create a new QoS policy:
Example
openstack network qos policy create --project 98a2f53c20ce4d50a40dac4a38016c69 qos-web-servers
Create a DSCP rule and apply it to a policy.
Example
In this example, a DSCP rule is created using DSCP mark
18
and is applied to theqos-web-servers
policy:openstack network qos rule create --type dscp-marking --dscp-mark 18 qos-web-servers
Sample output
Created a new dscp_marking_rule: +-----------+--------------------------------------+ | Field | Value | +-----------+--------------------------------------+ | dscp_mark | 18 | | id | d7f976ec-7fab-4e60-af70-f59bf88198e6 | +-----------+--------------------------------------+
You can change the DSCP value assigned to a rule.
Example
openstack network qos rule set --dscp-mark 22 qos-web-servers d7f976ec-7fab-4e60-af70-f59bf88198e6
You can delete a DSCP rule.
Example
openstack network qos rule delete qos-web-servers d7f976ec-7fab-4e60-af70-f59bf88198e6
Verification
Confirm that the DSCP rule (d7f976ec-7fab-4e60-af70-f59bf88198e6) is applied to the QoS policy (qos-web-servers).
Example
openstack network qos rule list qos-web-servers
Sample output
+-----------+--------------------------------------+ | dscp_mark | id | +-----------+--------------------------------------+ | 18 | d7f976ec-7fab-4e60-af70-f59bf88198e6 | +-----------+--------------------------------------+
Additional resources
- Environment files in the Advanced Overcloud Customization guide
- Including Environment Files in Overcloud Creation in the Advanced Overcloud Customization guide
- network qos rule create in the Command Line Interface Reference
- network qos rule set in the Command Line Interface Reference
- network qos rule delete in the Command Line Interface Reference
- network qos rule list in the Command Line Interface Reference
10.4. RBAC for QoS Policies
You can add a role-based access control (RBAC) for quality-of-service (QoS) policies. As a result, you can now make QoS policies available to certain projects.
For example, you can now create a QoS policy that allows for lower-priority network traffic, and have it only apply to certain projects. Run the following command to assign the bw-limiter
policy to the project, demo
:
# openstack network rbac create --type qos_policy --target-project 80bf5732752a41128e612fe615c886c6 --action access_as_shared rbac_name