Chapter 21. Common administrative networking tasks

Sometimes you might need to perform administration tasks on the Red Hat OpenStack Platform Networking service (neutron) such as configuring the Layer 2 Population driver or specifying the name assigned to ports by the internal DNS.

21.1. Configuring the L2 population driver

The L2 Population driver is used in Networking service (neutron) ML2/OVS environments to enable broadcast, multicast, and unicast traffic to scale out on large overlay networks. By default, Open vSwitch GRE and VXLAN replicate broadcasts to every agent, including those that do not host the destination network. This design requires the acceptance of significant network and processing overhead. The alternative design introduced by the L2 Population driver implements a partial mesh for ARP resolution and MAC learning traffic; it also creates tunnels for a particular network only between the nodes that host the network. This traffic is sent only to the necessary agent by encapsulating it as a targeted unicast.

Prerequisites

  • You must have RHOSP administrator privileges.
  • The Networking service must be using the ML2/OVS mechanism driver.

Procedure

  1. Log in to the undercloud host as the stack user.

  2. Source the undercloud credentials file: 

    $ source ~/stackrc

  3. Create a custom YAML environment file.

    Example

    $ vi /home/stack/templates/my-environment.yaml

  4. Your environment file must contain the keywords parameter_defaults. Under these keywords, add the following lines: 

    parameter_defaults:
  NeutronMechanismDrivers: ['openvswitch', 'l2population']
  NeutronEnableL2Pop: 'True'
  NeutronEnableARPResponder: true

  5. Run the deployment command and include the core heat templates, environment files, and this new custom environment file.

    Important

    The order of the environment files is important because the parameters and resources defined in subsequent environment files take precedence.

    Example

    $ openstack overcloud deploy --templates \
-e <your_environment_files> \
-e /home/stack/templates/my-environment.yaml

Verification

  1. Obtain the IDs for the OVS agents. 

    $ openstack network agent list -c ID -c Binary

    Sample output

    +--------------------------------------+---------------------------+
| ID                                   | Binary                    |
+--------------------------------------+---------------------------+
| 003a8750-a6f9-468b-9321-a6c03c77aec7 | neutron-openvswitch-agent |
| 02bbbb8c-4b6b-4ce7-8335-d1132df31437 | neutron-l3-agent          |
| 0950e233-60b2-48de-94f6-483fd0af16ea | neutron-openvswitch-agent |
| 115c2b73-47f5-4262-bc66-8538d175029f | neutron-openvswitch-agent |
| 2a9b2a15-e96d-468c-8dc9-18d7c2d3f4bb | neutron-metadata-agent    |
| 3e29d033-c80b-4253-aaa4-22520599d62e | neutron-dhcp-agent        |
| 3ede0b64-213d-4a0d-9ab3-04b5dfd16baa | neutron-dhcp-agent        |
| 462199be-0d0f-4bba-94da-603f1c9e0ec4 | neutron-sriov-nic-agent   |
| 54f7c535-78cc-464c-bdaa-6044608a08d7 | neutron-l3-agent          |
| 6657d8cf-566f-47f4-856c-75600bf04828 | neutron-metadata-agent    |
| 733c66f1-a032-4948-ba18-7d1188a58483 | neutron-l3-agent          |
| 7e0a0ce3-7ebb-4bb3-9b89-8cccf8cb716e | neutron-openvswitch-agent |
| dfc36468-3a21-4a2d-84c3-2bc40f224235 | neutron-metadata-agent    |
| eb7d7c10-69a2-421e-bd9e-aec3edfe1b7c | neutron-openvswitch-agent |
| ef5219b4-ee49-4635-ad04-048291209373 | neutron-sriov-nic-agent   |
| f36c7af0-e20c-400b-8a37-4ffc5d4da7bd | neutron-dhcp-agent        |
+--------------------------------------+---------------------------+

  2. Using an ID from one of the OVS agents, confirm that the L2 Population driver is set on the OVS agent.

    Example

    This example verifies the configuration of the L2 Population driver on the neutron-openvswitch-agent with ID 003a8750-a6f9-468b-9321-a6c03c77aec7: 

    $ openstack network agent show 003a8750-a6f9-468b-9321-a6c03c77aec7 -c configuration -f json | grep l2_population

    Sample output

        "l2_population": true,

  3. Ensure that the ARP responder feature is enabled for the OVS agent.

    Example

    $ openstack network agent show 003a8750-a6f9-468b-9321-a6c03c77aec7 -c configuration -f json | grep arp_responder_enabled

    Sample output

        "arp_responder_enabled": true,

Additional resources

21.2. Tuning keepalived to avoid VRRP packet loss

If the number of highly available (HA) routers on a single host is high, when an HA router fail over occurs, the Virtual Router Redundancy Protocol (VRRP) messages might overflow the IRQ queues. This overflow stops Open vSwitch (OVS) from responding and forwarding those VRRP messages.

To avoid VRRP packet overload, you must increase the VRRP advertisement interval using the ha_vrrp_advert_int parameter in the ExtraConfig section for the Controller role.

Procedure

  1. Log in to the undercloud as the stack user, and source the stackrc file to enable the director command line tools.

    Example

    $ source ~/stackrc

  2. Create a custom YAML environment file.

    Example

    $ vi /home/stack/templates/my-neutron-environment.yaml

    Tip

    The Red Hat OpenStack Platform Orchestration service (heat) uses a set of plans called templates to install and configure your environment. You can customize aspects of the overcloud with a custom environment file, which is a special type of template that provides customization for your heat templates.

  3. In the YAML environment file, increase the VRRP advertisement interval using the ha_vrrp_advert_int argument with a value specific for your site. (The default is 2 seconds.)

    You can also set values for gratuitous ARP messages:

    ha_vrrp_garp_master_repeat
    The number of gratuitous ARP messages to send at one time after the transition to the master state. (The default is 5 messages.)
    ha_vrrp_garp_master_delay

    The delay for second set of gratuitous ARP messages after the lower priority advert is received in the master state. (The default is 5 seconds.)

    Example

    parameter_defaults:
  ControllerExtraConfig:
    neutron::agents::l3::ha_vrrp_advert_int: 7
    neutron::config::l3_agent_config:
      DEFAULT/ha_vrrp_garp_master_repeat:
        value: 5
      DEFAULT/ha_vrrp_garp_master_delay:
        value: 5

  4. Run the openstack overcloud deploy command and include the core heat templates, environment files, and this new custom environment file.

    Important

    The order of the environment files is important because 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/my-neutron-environment.yaml

Additional resources

21.3. Specifying the name that DNS assigns to ports

You can specify the name assigned to ports by the internal DNS when you enable the Red Hat OpenStack Platform (RHOSP) Networking service (neutron) DNS domain for ports extension (dns_domain_ports).

You enable the DNS domain for ports extension by declaring the RHOSP Orchestration (heat) NeutronPluginExtensions parameter in a YAML-formatted environment file. Using a corresponding parameter, NeutronDnsDomain, you specify your domain name, which overrides the default value, openstacklocal. After redeploying your overcloud, you can use the OpenStack Client port commands, port set or port create, with --dns-name to assign a port name.

Important

You must enable the DNS domain for ports extension (dns_domain_ports) for DNS to internally resolve names for ports in your RHOSP environment. Using the NeutronDnsDomain default value, openstacklocal, means that the Networking service does not internally resolve port names for DNS.

Also, when the DNS domain for ports extension is enabled, the Compute service automatically populates the dns_name attribute with the hostname attribute of the instance during the boot of VM instances. At the end of the boot process, dnsmasq recognizes the allocated ports by their instance hostname.

Procedure

  1. Log in to the undercloud as the stack user, and source the stackrc file to enable the director command line tools.

    Example

    $ source ~/stackrc

  2. Create a custom YAML environment file (my-neutron-environment.yaml).

    Note

    Values inside parentheses are sample values that are used in the example commands in this procedure. Substitute these sample values with values that are appropriate for your site.

    Example

    $ vi /home/stack/templates/my-neutron-environment.yaml

    Tip

    The undercloud includes a set of Orchestration service templates that form the plan for your overcloud creation. You can customize aspects of the overcloud with environment files, which are YAML-formatted files that override parameters and resources in the core Orchestration service template collection. You can include as many environment files as necessary.

  3. In the environment file, add a parameter_defaults section. Under this section, add the DNS domain for ports extension, dns_domain_ports.

    Example

    parameter_defaults:
  NeutronPluginExtensions: "qos,port_security,dns_domain_ports"

    Note

    If you set dns_domain_ports, ensure that the deployment does not also use dns_domain, the DNS Integration extension. These extensions are incompatible, and both extensions cannot be defined simultaneously.

  4. Also in the parameter_defaults section, add your domain name (example.com) using the NeutronDnsDomain parameter.

    Example

    parameter_defaults:
    NeutronPluginExtensions: "qos,port_security,dns_domain_ports"
    NeutronDnsDomain: "example.com"

  5. Run the openstack overcloud deploy command and include the core Orchestration templates, environment files, and this new environment file.

    Important

    The order of the environment files is important because 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/my-neutron-environment.yaml

Verification

  1. Log in to the overcloud, and create a new port (new_port) on a network (public). Assign a DNS name (my_port) to the port.

    Example

    $ source ~/overcloudrc
$ openstack port create --network public --dns-name my_port new_port

  2. Display the details for your port (new_port).

    Example

    $ openstack port show -c dns_assignment -c dns_domain -c dns_name -c name new_port

    Output

    +-------------------------+----------------------------------------------+
| Field                   | Value                                        |
+-------------------------+----------------------------------------------+
| dns_assignment          | fqdn='my_port.example.com',                  |
|                         | hostname='my_port',                          |
|                         | ip_address='10.65.176.113'                   |
| dns_domain              | example.com                                  |
| dns_name                | my_port                                      |
| name                    | new_port                                     |
+-------------------------+----------------------------------------------+

    Under dns_assignment, the fully qualified domain name (fqdn) value for the port contains a concatenation of the DNS name (my_port) and the domain name (example.com) that you set earlier with NeutronDnsDomain.

  3. Create a new VM instance (my_vm) using the port (new_port) that you just created.

    Example

    $ openstack server create --image rhel --flavor m1.small --port new_port my_vm

  4. Display the details for your port (new_port).

    Example

    $ openstack port show -c dns_assignment -c dns_domain -c dns_name -c name new_port

    Output

    +-------------------------+----------------------------------------------+
| Field                   | Value                                        |
+-------------------------+----------------------------------------------+
| dns_assignment          | fqdn='my_vm.example.com',                    |
|                         | hostname='my_vm',                            |
|                         | ip_address='10.65.176.113'                   |
| dns_domain              | example.com                                  |
| dns_name                | my_vm                                        |
| name                    | new_port                                     |
+-------------------------+----------------------------------------------+

    Note that the Compute service changes the dns_name attribute from its original value (my_port) to the name of the instance with which the port is associated (my_vm).

Additional resources

21.4. Assigning DHCP attributes to ports

You can use Red Hat Openstack Plaform (RHOSP) Networking service (neutron) extensions to add networking functions. You can use the extra DHCP option extension (extra_dhcp_opt) to configure ports of DHCP clients with DHCP attributes. For example, you can add a PXE boot option such as tftp-server, server-ip-address, or bootfile-name to a DHCP client port.

The value of the extra_dhcp_opt attribute is an array of DHCP option objects, where each object contains an opt_name and an opt_value. IPv4 is the default version, but you can change this to IPv6 by including a third option, ip-version=6.

When a VM instance starts, the RHOSP Networking service supplies port information to the instance using DHCP protocol. If you add DHCP information to a port already connected to a running instance, the instance only uses the new DHCP port information when the instance is restarted.

Some of the more common DHCP port attributes are: bootfile-name, dns-server, domain-name, mtu, server-ip-address, and tftp-server. For the complete set of acceptable values for opt_name, refer to the DHCP specification.

Prerequisites

  • You must have RHOSP administrator privileges.

Procedure

  1. Log in to the undercloud host as the stack user.

  2. Source the undercloud credentials file: 

    $ source ~/stackrc

  3. Create a custom YAML environment file.

    Example

    $ vi /home/stack/templates/my-environment.yaml

  4. Your environment file must contain the keywords parameter_defaults. Under these keywords, add the extra DHCP option extension, extra_dhcp_opt.

    Example

    parameter_defaults:
  NeutronPluginExtensions: "qos,port_security,extra_dhcp_opt"

  5. Run the deployment command and include the core heat templates, environment files, and this new custom environment file.

    Important

    The order of the environment files is important because 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/octavia.yaml \
-e /home/stack/templates/my-environment.yaml

Verification

  1. Source your credentials file.

    Example

    $ source ~/overcloudrc

  2. Create a new port (new_port) on a network (public). Assign a valid attribute from the DHCP specification to the new port.

    Example

    $ openstack port create --extra-dhcp-option \
name=domain-name,value=test.domain --extra-dhcp-option \
name=ntp-server,value=192.0.2.123 --network public new_port

  3. Display the details for your port (new_port).

    Example

    $ openstack port show new_port -c extra_dhcp_opts

    Sample output

    +-----------------+-----------------------------------------------------------------+
| Field           | Value                                                           |
+-----------------+-----------------------------------------------------------------+
| extra_dhcp_opts | ip_version='4', opt_name='domain-name', opt_value='test.domain' |
|                 | ip_version='4', opt_name='ntp-server', opt_value='192.0.2.123'  |
+-----------------+-----------------------------------------------------------------+

Additional resources

21.5. Enabling NUMA affinity on ports

To enable users to create instances with NUMA affinity on the port, you must load the Red Hat Openstack Plaform (RHOSP) Networking service (neutron) extension, port_numa_affinity_policy.

Prerequisites

  • Access to the undercloud host and credentials for the stack user.

Procedure

  1. Log in to the undercloud host as the stack user.

  2. Source the undercloud credentials file: 

    $ source ~/stackrc

  3. To enable the port_numa_affinity_policy extension, open the environment file where the NeutronPluginExtensions parameter is defined, and add port_numa_affinity_policy to the list: 

    parameter_defaults:
  NeutronPluginExtensions: "qos,port_numa_affinity_policy"

  4. Add the environment file that you modified to the stack with your other environment files, and redeploy the overcloud:

    Important

    The order of the environment files is important because the parameters and resources defined in subsequent environment files take precedence. 

    $ openstack overcloud deploy --templates \
-e <your_environment_files> \
-e /home/stack/templates/<custom_environment_file>.yaml

Verification

  1. Source your credentials file.

    Example

    $ source ~/overcloudrc

  2. Create a new port.

    When you create a port, use one of the following options to specify the NUMA affinity policy to apply to the port:

    • --numa-policy-required - NUMA affinity policy required to schedule this port.
    • --numa-policy-preferred - NUMA affinity policy preferred to schedule this port.

    • --numa-policy-legacy - NUMA affinity policy using legacy mode to schedule this port.

      Example

      $ openstack port create --network public \
  --numa-policy-legacy  myNUMAAffinityPort

  3. Display the details for your port.

    Example

    $ openstack port show myNUMAAffinityPort -c numa_affinity_policy

    Sample output

    When the extension is loaded, the Value column should read, legacy, preferred or required. If the extension has failed to load, Value reads None: 

    +----------------------+--------+
| Field                | Value  |
+----------------------+--------+
| numa_affinity_policy | legacy |
+----------------------+--------+

Additional resources

21.6. Loading kernel modules

Some features in Red Hat OpenStack Platform (RHOSP) require certain kernel modules to be loaded. For example, the OVS firewall driver requires you to load the nf_conntrack_proto_gre kernel module to support GRE tunneling between two VM instances.

By using a special Orchestration service (heat) parameter, ExtraKernelModules, you can ensure that heat stores configuration information about the required kernel modules needed for features like GRE tunneling. Later, during normal module management, these required kernel modules are loaded.

Procedure

  1. On the undercloud host, logged in as the stack user, create a custom YAML environment file.

    Example

    $ vi /home/stack/templates/my-modules-environment.yaml

    Tip

    Heat uses a set of plans called templates to install and configure your environment. You can customize aspects of the overcloud with a custom environment file, which is a special type of template that provides customization for your heat templates.

  2. In the YAML environment file under parameter_defaults, set ExtraKernelModules to the name of the module that you want to load.

    Example

    ComputeParameters:
  ExtraKernelModules:
    nf_conntrack_proto_gre: {}
ControllerParameters:
  ExtraKernelModules:
    nf_conntrack_proto_gre: {}

  3. Run the openstack overcloud deploy command and include the core heat templates, environment files, and this new custom environment file.

    Important

    The 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/my-modules-environment.yaml

Verification

  • If heat has properly loaded the module, you should see output when you run the lsmod command on the Compute node:

    Example

    sudo lsmod | grep nf_conntrack_proto_gre

Additional resources

21.7. Limiting queries to the metadata service

To protect the RHOSP environment against cyber threats such as denial of service (DoS) attacks, the Networking service (neutron) offers administrators the ability to limit the rate at which VM instances can query the Compute metadata service. Administrators do this by assigning values to a set of parameters in the metadata_rate_limiting section of the neutron.conf configuration file. The Networking service uses these parameters to configure HAProxy servers to perform the rate limiting. The HAProxy servers run inside L3 routers and DHCP agents in the OVS back end, and inside the metadata service in the OVN back end.

Prerequisites

  • You have access to the RHOSP Compute nodes and permission to update configuration files.
  • Your RHOSP environment uses IPv4 networking. Currently, the Networking service does not support metadata rate limiting on IPv6 networks.
  • This procedure requires you to restart the OVN metadata service or the OVS metadata agent. Schedule this activity for a maintenance window to minimize the operational impact of any potential disruption.

Procedure

  1. On every Compute node, in the metadata_rate_limiting section of /var/lib/config-data/puppet-generated/neutron/etc/neutron/neutron.conf, set values for the following parameters:

    rate_limit_enabled
    enables you to limit the rate of metadata requests. The default value is false. Set the value to true to enable metadata rate limiting.
    ip_versions
    the IP version, 4, used for metadata IP addresses on which you want to control query rates. RHOSP does not yet support metadata rate limiting for IPv6 networks.
    base_window_duration
    the time span, in seconds, during which query requests are limited. The default value is 10 seconds.
    base_query_rate_limit
    the maximum number of requests allowed during the base_window_duration. The default value is 10 requests.
    burst_window_duration
    the time span, in seconds, that a request rate higher than the base_window_duration is allowed. The default value is 10 seconds.
    burst_query_rate_limit

    the maximum number of requests allowed during the burst_window_duration. The default value is 10 requests.

    Example

    In this example, the Networking service is configured for a base time and rate that allows instances to query the IPv4 metadata service IP address 6 times over a 60 second period. The Networking service is also configured for a burst time and rate that allows a higher rate of 2 queries during shorter periods of 10 seconds each: 

    [metadata_rate_limiting]
rate_limit_enabled = True
ip_versions = 4
base_window_duration = 60
base_query_rate_limit = 6
burst_window_duration = 10
burst_query_rate_limit = 2

  2. Restart the metadata service.

    Depending on the Networking service mechanism driver your deployment uses, do one of the following:

    ML2/OVN

    On the Compute nodes, restart tripleo_ovn_metadata_agent.service.

    ML2/OVS

    On the Compute nodes, restart tripleo_neutron_metadata_agent.service.