Configuring a macvlan network - Multiple networks | Networking

Creating an additional network attachment with the macvlan CNI plug-in
- Configuration for macvlan CNI plug-in
- Configuration for ipam CNI plug-in
Next steps

As a cluster administrator, you can configure an additional network for your cluster using the macvlan CNI plug-in. When a pod is attached to the network, the plug-in creates a sub-interface from the parent interface on the host. A unique hardware mac address is generated for each sub-device.

The unique MAC addresses this plug-in generates for sub-interfaces might not be compatible with the security polices of your cloud provider.

Creating an additional network attachment with the macvlan CNI plug-in

The Cluster Network Operator (CNO) manages additional network definitions. When you specify an additional network to create, the CNO creates the NetworkAttachmentDefinition object automatically.

Do not edit the NetworkAttachmentDefinition objects that the Cluster Network Operator manages. Doing so might disrupt network traffic on your additional network.

Prerequisites

Install the OpenShift CLI (oc).
Log in as a user with cluster-admin privileges.

Procedure

To create an additional network for your cluster, complete the following steps:

Edit the CNO CR by running the following command:

$ oc edit networks.operator.openshift.io cluster

Modify the CR that you are creating by adding the configuration for the additional network you are creating, as in the following example CR.

The following YAML configures the macvlan CNI plug-in:

apiVersion: operator.openshift.io/v1
kind: Network
metadata:
  name: cluster
spec:
  additionalNetworks: (1)
  - name: test-network-1
    namespace: test-1
    type: SimpleMacvlan
    simpleMacvlanConfig:
      ipamConfig:
        type: static
        staticIPAMConfig:
          addresses:
          - address: 10.1.1.7/24

1	Specify the configuration for the additional network attachment definition.

Save your changes and quit the text editor to commit your changes.
Optional: Confirm that the CNO created the NetworkAttachmentDefinition object by running the following command. There might be a delay before the CNO creates the CR.
```
$ oc get network-attachment-definitions -n <namespace>
```
Example output
```
NAME                 AGE
test-network-1       14m
```

Configuration for macvlan CNI plug-in

The following YAML describes the configuration parameters for the macvlan Container Network Interface (CNI) plug-in:

macvlan YAML configuration

name: <name> (1)
namespace: <namespace> (2)
type: SimpleMacvlan
simpleMacvlanConfig:
  master: <master> (3)
  mode: <mode> (4)
  mtu: <mtu> (5)
  ipamConfig: (6)
    ...

1	Specify a name for the additional network attachment that you are creating. The name must be unique within the specified `namespace`.
2	Specify the namespace to create the network attachment in. If a value is not specified, the `default` namespace is used.
3	The ethernet interface to associate with the virtual interface. If a value for `master` is not specified, then the host system’s primary ethernet interface is used.
4	Configures traffic visibility on the virtual network. Must be either `bridge`, `passthru`, `private`, or `vepa`. If a value for `mode` is not provided, the default value is `bridge`.
5	Set the maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel.
6	Specify a configuration object for the ipam CNI plug-in. The plug-in manages IP address assignment for the attachment definition.

macvlan configuration example

The following example configures an additional network named macvlan-net:

name: macvlan-net
namespace: work-network
type: SimpleMacvlan
simpleMacvlanConfig:
  ipamConfig:
    type: DHCP

Configuration for ipam CNI plug-in

The ipam Container Network Interface (CNI) plug-in provides IP address management (IPAM) for other CNI plug-ins. You can configure ipam for either static IP address assignment or dynamic IP address assignment by using DHCP. The DHCP server you specify must be reachable from the additional network.

The following YAML configuration describes the parameters that you can set.

ipam CNI plug-in YAML configuration object

ipamConfig:
  type: <type> (1)
  ... (2)

1	Specify `static` to configure the plug-in to manage IP address assignment. Specify `DHCP` to allow a DHCP server to manage IP address assignment. You cannot specify any additional parameters if you specify a value of `DHCP`.
2	If you set the `type` parameter to `static`, then provide the `staticIPAMConfig` parameter.

Static ipam configuration YAML

The following YAML describes a configuration for static IP address assignment:

Static ipam configuration YAML

ipamConfig:
  type: static
  staticIPAMConfig:
    addresses: (1)
    - address: <address> (2)
      gateway: <gateway> (3)
    routes: (4)
    - destination: <destination> (5)
      gateway: <gateway> (6)
    dns: (7)
      nameservers: (8)
      - <nameserver>
      domain: <domain> (9)
      search: (10)
      - <search_domain>

1	A collection of mappings that define IP addresses to assign to the virtual interface. Both IPv4 and IPv6 IP addresses are supported.
2	An IP address and network prefix that you specify. For example, if you specify `10.10.21.10/24`, then the additional network is assigned an IP address of `10.10.21.10` and the netmask is `255.255.255.0`.
3	The default gateway to route egress network traffic to.
4	A collection of mappings describing routes to configure inside the pod.
5	The IP address range in CIDR format, such as `192.168.17.0/24`, or `0.0.0.0/0` for the default route.
6	The gateway where network traffic is routed.
7	Optional: The DNS configuration.
8	A collection of one or more IP addresses for to send DNS queries to.
9	The default domain to append to a host name. For example, if the domain is set to `example.com`, a DNS lookup query for `example-host` is rewritten as `example-host.example.com`.
10	An array of domain names to append to an unqualified host name, such as `example-host`, during a DNS lookup query.

Dynamic ipam configuration YAML

The following YAML describes a configuration for static IP address assignment:

Dynamic ipam configuration YAML

ipamConfig:
  type: DHCP

Static IP address assignment configuration example

The following example shows an ipam configuration for static IP addresses:

ipamConfig:
  type: static
  staticIPAMConfig:
    addresses:
    - address: 10.51.100.11
      gateway: 10.51.100.10
    routes:
    - destination: 0.0.0.0/0
      gateway: 10.51.100.1
    dns:
      nameservers:
      - 10.51.100.1
      - 10.51.100.2
      domain: testDNS.example
      search:
      - testdomain1.example
      - testdomain2.example

Dynamic IP address assignment configuration example

The following example shows an ipam configuration for DHCP:

ipamConfig:
  type: DHCP

Next steps

Attach a pod to an additional network.