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Chapter 5. Managing floating IP addresses

In addition to a having a private, fixed IP address, VM instances can have a public, or floating IP address to communicate with other networks. The information in this section describes how to create and manage floating IPs with the Red Hat OpenStack Platform (RHOSP) Networking service (neutron).

5.1. Creating floating IP pools

You can use floating IP addresses to direct ingress network traffic to your OpenStack instances. First, you must define a pool of validly routable external IP addresses, which you can then assign to instances dynamically. OpenStack Networking routes all incoming traffic destined for that floating IP to the instance that you associate with the floating IP.

Note

OpenStack Networking allocates floating IP addresses to all projects (tenants) from the same IP ranges in CIDR format. As a result, all projects can consume floating IPs from every floating IP subnet. You can manage this behavior using quotas for specific projects. For example, you can set the default to 10 for ProjectA and ProjectB, while setting the quota for ProjectC to 0.

Procedure

  • When you create an external subnet, you can also define the floating IP allocation pool.

    $ openstack subnet create --no-dhcp --allocation-pool start=IP_ADDRESS,end=IP_ADDRESS --gateway IP_ADDRESS --network SUBNET_RANGE NETWORK_NAME

    If the subnet hosts only floating IP addresses, consider disabling DHCP allocation with the --no-dhcp option in the openstack subnet create command.

    Example

    $ openstack subnet create --no-dhcp --allocation_pool start=192.168.100.20,end=192.168.100.100 --gateway 192.168.100.1 --network 192.168.100.0/24 public

Verification

  • You can verify that the pool is configured properly by assigning a random floating IP to an instance. (See the later link that follows.)

Additional resources

5.2. Assigning a specific floating IP

You can assign a specific floating IP address to a VM instance.

Procedure

  • Allocate a floating IP address to an instance by using the openstack server add floating ip command.

    Example

    $ openstack server add floating ip prod-serv1 192.0.2.200

Validation steps

  • Confirm that your floating IP is associated with your instance by using the openstack server show command.

    Example

    $ openstack server show prod-serv1

    Sample output

    +-----------------------------+------------------------------------------+
    | Field                       | Value                                    |
    +-----------------------------+------------------------------------------+
    | OS-DCF:diskConfig           | MANUAL                                   |
    | OS-EXT-AZ:availability_zone | nova                                     |
    | OS-EXT-STS:power_state      | Running                                  |
    | OS-EXT-STS:task_state       | None                                     |
    | OS-EXT-STS:vm_state         | active                                   |
    | OS-SRV-USG:launched_at      | 2021-08-11T14:45:37.000000               |
    | OS-SRV-USG:terminated_at    | None                                     |
    | accessIPv4                  |                                          |
    | accessIPv6                  |                                          |
    | addresses                   | public=198.51.100.56,192.0.2.200         |
    |                             |                                          |
    | config_drive                |                                          |
    | created                     | 2021-08-11T14:44:54Z                     |
    | flavor                      | review-ephemeral                         |
    |                             | (8130dd45-78f6-44dc-8173-4d6426b8e520)   |
    | hostId                      | 2308c8d8f60ed5394b1525122fb5bf8ea55c78b8 |
    |                             | 0ec6157eca4488c9                         |
    | id                          | aef3ca09-887d-4d20-872d-1d1b49081958     |
    | image                       | rhel8                                    |
    |                             | (20724bfe-93a9-4341-a5a3-78b37b3a5dfb)   |
    | key_name                    | example-keypair                          |
    | name                        | prod-serv1                               |
    | progress                    | 0                                        |
    | project_id                  | bd7a8c4a19424cf09a82627566b434fa         |
    | properties                  |                                          |
    | security_groups             | name='default'                           |
    | status                      | ACTIVE                                   |
    | updated                     | 2021-08-11T14:45:37Z                     |
    | user_id                     | 4b7e19a0d723310fd92911eb2fe59743a3a5cd32 |
    |                             | 45f76ffced91096196f646b5                 |
    | volumes_attached            |                                          |
    +-----------------------------+------------------------------------------+

Additional resources

5.3. Creating an advanced network

Advanced network options are available for administrators, when creating a network in the Dashboard from the Admin view. Use these options to specify projects and to define the network type that you want to use.

Procedure

  1. In the dashboard, select Admin > Networks > Create Network > Project.
  2. Select the project that you want to host the new network with the Project drop-down list.
  3. Review the options in Provider Network Type:

    • Local - Traffic remains on the local Compute host and is effectively isolated from any external networks.
    • Flat - Traffic remains on a single network and can also be shared with the host. No VLAN tagging or other network segregation takes place.
    • VLAN - Create a network using a VLAN ID that corresponds to a VLAN present in the physical network. This option allows instances to communicate with systems on the same layer 2 VLAN.
    • GRE - Use a network overlay that spans multiple nodes for private communication between instances. Traffic egressing the overlay must be routed.
    • VXLAN - Similar to GRE, and uses a network overlay to span multiple nodes for private communication between instances. Traffic egressing the overlay must be routed.
  4. Click Create Network.

    Review the Project Network Topology to validate that the network has been successfully created.

5.4. Assigning a random floating IP

You can dynamically allocate floating IP addresses to VM instances from a pool of external IP addresses.

Prerequisites

Procedure

  1. Enter the following command to allocate a floating IP address from the pool. In this example, the network is named public.

    Example

    $ openstack floating ip create public

    Sample output

    In the following example, the newly allocated floating IP is 192.0.2.200. You can assign it to an instance.

    +---------------------+--------------------------------------------------+
    | Field               | Value                                            |
    +---------------------+--------------------------------------------------+
    | fixed_ip_address    | None                                             |
    | floating_ip_address | 192.0.2.200                                      |
    | floating_network_id | f0dcc603-f693-4258-a940-0a31fd4b80d9             |
    | id                  | 6352284c-c5df-4792-b168-e6f6348e2620             |
    | port_id             | None                                             |
    | router_id           | None                                             |
    | status              | ACTIVE                                           |
    +---------------------+--------------------------------------------------+
  2. Enter the following command to locate your instance:

    $ openstack server list

    Sample output

    +-------------+-------------+--------+-------------+-------+-------------+
    | ID          | Name        | Status | Networks    | Image | Flavor      |
    +-------------+-------------+--------+-------------+-------+-------------+
    | aef3ca09-88 | prod-serv1  | ACTIVE | public=198. | rhel8 | review-     |
    | 7d-4d20-872 |             |        | 51.100.56   |       | ephemeral   |
    | d-1d1b49081 |             |        |             |       |             |
    | 958         |             |        |             |       |             |
    |             |             |        |             |       |             |
    +-------------+-------------+--------+-------------+-------+-------------+

  3. Associate the instance name or ID with the floating IP.

    Example

    $ openstack server add floating ip prod-serv1 192.0.2.200

Validation steps

  • Enter the following command to confirm that your floating IP is associated with your instance.

    Example

    $ openstack server show prod-serv1

    Sample output

    +-----------------------------+------------------------------------------+
    | Field                       | Value                                    |
    +-----------------------------+------------------------------------------+
    | OS-DCF:diskConfig           | MANUAL                                   |
    | OS-EXT-AZ:availability_zone | nova                                     |
    | OS-EXT-STS:power_state      | Running                                  |
    | OS-EXT-STS:task_state       | None                                     |
    | OS-EXT-STS:vm_state         | active                                   |
    | OS-SRV-USG:launched_at      | 2021-08-11T14:45:37.000000               |
    | OS-SRV-USG:terminated_at    | None                                     |
    | accessIPv4                  |                                          |
    | accessIPv6                  |                                          |
    | addresses                   | public=198.51.100.56,192.0.2.200         |
    |                             |                                          |
    | config_drive                |                                          |
    | created                     | 2021-08-11T14:44:54Z                     |
    | flavor                      | review-ephemeral                         |
    |                             | (8130dd45-78f6-44dc-8173-4d6426b8e520)   |
    | hostId                      | 2308c8d8f60ed5394b1525122fb5bf8ea55c78b8 |
    |                             | 0ec6157eca4488c9                         |
    | id                          | aef3ca09-887d-4d20-872d-1d1b49081958     |
    | image                       | rhel8                                    |
    |                             | (20724bfe-93a9-4341-a5a3-78b37b3a5dfb)   |
    | key_name                    | example-keypair                          |
    | name                        | prod-serv1                               |
    | progress                    | 0                                        |
    | project_id                  | bd7a8c4a19424cf09a82627566b434fa         |
    | properties                  |                                          |
    | security_groups             | name='default'                           |
    | status                      | ACTIVE                                   |
    | updated                     | 2021-08-11T14:45:37Z                     |
    | user_id                     | 4b7e19a0d723310fd92911eb2fe59743a3a5cd32 |
    |                             | 45f76ffced91096196f646b5                 |
    | volumes_attached            |                                          |
    +-----------------------------+------------------------------------------+

Additional resources

5.5. Creating multiple floating IP pools

OpenStack Networking supports one floating IP pool for each L3 agent. Therefore, you must scale your L3 agents to create additional floating IP pools.

Procedure

  • Make sure that in /var/lib/config-data/neutron/etc/neutron/neutron.conf the property handle_internal_only_routers is set to True for only one L3 agent in your environment. This option configures the L3 agent to manage only non-external routers.

5.6. Bridging the physical network

Bridge your virtual network to the physical network to enable connectivity to and from virtual instances.

In this procedure, the example physical interface, eth0, is mapped to the bridge, br-ex; the virtual bridge acts as the intermediary between the physical network and any virtual networks.

As a result, all traffic traversing eth0 uses the configured Open vSwitch to reach instances.

To map a physical NIC to the virtual Open vSwitch bridge, complete the following steps:

Procedure

  1. Open /etc/sysconfig/network-scripts/ifcfg-eth0 in a text editor, and update the following parameters with values appropriate for the network at your site:

    • IPADDR
    • NETMASK GATEWAY
    • DNS1 (name server)

      Here is an example:

      # vi /etc/sysconfig/network-scripts/ifcfg-eth0
      DEVICE=eth0
      TYPE=OVSPort
      DEVICETYPE=ovs
      OVS_BRIDGE=br-ex
      ONBOOT=yes
  2. Open /etc/sysconfig/network-scripts/ifcfg-br-ex in a text editor and update the virtual bridge parameters with the IP address values that were previously allocated to eth0:

    # vi /etc/sysconfig/network-scripts/ifcfg-br-ex
    DEVICE=br-ex
    DEVICETYPE=ovs
    TYPE=OVSBridge
    BOOTPROTO=static
    IPADDR=192.168.120.10
    NETMASK=255.255.255.0
    GATEWAY=192.168.120.1
    DNS1=192.168.120.1
    ONBOOT=yes

    You can now assign floating IP addresses to instances and make them available to the physical network.

Additional resources

5.7. Adding an interface

You can use interfaces to interconnect routers with subnets so that routers can direct any traffic that instances send to destinations outside of their intermediate subnet.

To add a router interface and connect the new interface to a subnet, complete these steps:

Note

This procedure uses the Network Topology feature. Using this feature, you can see a graphical representation of all your virtual routers and networks while you to perform network management tasks.

  1. In the dashboard, select Project > Network > Network Topology.
  2. Locate the router that you want to manage, hover your mouse over it, and click Add Interface.
  3. Specify the Subnet that you want to connect to the router.

    You can also specify an IP address. The address is useful for testing and troubleshooting purposes, since a successful ping to this interface indicates that the traffic is routing as expected.

  4. Click Add interface.

    The Network Topology diagram automatically updates to reflect the new interface connection between the router and subnet.

5.8. Deleting an interface

You can remove an interface to a subnet if you no longer require the router to direct traffic for the subnet.

To delete an interface, complete the following steps:

  1. In the dashboard, select Project > Network > Routers.
  2. Click the name of the router that hosts the interface that you want to delete.
  3. Select the interface type (Internal Interface), and click Delete Interfaces.