Chapter 12. Multiple networks 12.1. Understanding multiple networks In Kubernetes, container networking is delegated to networking plug-ins that implement the Container Network Interface (CNI). OpenShift Container Platform uses the Multus CNI plug-in to allow chaining of CNI plug-ins. During cluster installation, you configure your default pod network. The default network handles all ordinary network traffic for the cluster. You can define an additional network based on the available CNI plug-ins and attach one or more of these networks to your pods. You can define more than one additional network for your cluster, depending on your needs. This gives you flexibility when you configure pods that deliver network functionality, such as switching or routing. 12.1.1. Usage scenarios for an additional network You can use an additional network in situations where network isolation is needed, including data plane and control plane separation. Isolating network traffic is useful for the following performance and security reasons: Performance You can send traffic on two different planes to manage how much traffic is along each plane. Security You can send sensitive traffic onto a network plane that is managed specifically for security considerations, and you can separate private data that must not be shared between tenants or customers. All of the pods in the cluster still use the cluster-wide default network to maintain connectivity across the cluster. Every pod has an eth0 interface that is attached to the cluster-wide pod network. You can view the interfaces for a pod by using the oc exec -it <pod_name> -- ip a command. If you add additional network interfaces that use Multus CNI, they are named net1 , net2 , ... , netN . To attach additional network interfaces to a pod, you must create configurations that define how the interfaces are attached. You specify each interface by using a NetworkAttachmentDefinition custom resource (CR). A CNI configuration inside each of these CRs defines how that interface is created. 12.1.2. Additional networks in OpenShift Container Platform OpenShift Container Platform provides the following CNI plug-ins for creating additional networks in your cluster: bridge : Configure a bridge-based additional network to allow pods on the same host to communicate with each other and the host. host-device : Configure a host-device additional network to allow pods access to a physical Ethernet network device on the host system. ipvlan : Configure an ipvlan-based additional network to allow pods on a host to communicate with other hosts and pods on those hosts, similar to a macvlan-based additional network. Unlike a macvlan-based additional network, each pod shares the same MAC address as the parent physical network interface. macvlan : Configure a macvlan-based additional network to allow pods on a host to communicate with other hosts and pods on those hosts by using a physical network interface. Each pod that is attached to a macvlan-based additional network is provided a unique MAC address. SR-IOV : Configure an SR-IOV based additional network to allow pods to attach to a virtual function (VF) interface on SR-IOV capable hardware on the host system. 12.2. Configuring an additional network As a cluster administrator, you can configure an additional network for your cluster. The following network types are supported: Bridge Host device IPVLAN MACVLAN 12.2.1. Approaches to managing an additional network You can manage the life cycle of an additional network by two approaches. Each approach is mutually exclusive and you can only use one approach for managing an additional network at a time. For either approach, the additional network is managed by a Container Network Interface (CNI) plug-in that you configure. For an additional network, IP addresses are provisioned through an IP Address Management (IPAM) CNI plug-in that you configure as part of the additional network. The IPAM plug-in supports a variety of IP address assignment approaches including DHCP and static assignment. Modify the Cluster Network Operator (CNO) configuration: The CNO automatically creates and manages the NetworkAttachmentDefinition object. In addition to managing the object lifecycle the CNO ensures a DHCP is available for an additional network that uses a DHCP assigned IP address. Applying a YAML manifest: You can manage the additional network directly by creating an NetworkAttachmentDefinition object. This approach allows for the chaining of CNI plug-ins. 12.2.2. Configuration for an additional network attachment An additional network is configured via the NetworkAttachmentDefinition API in the k8s.cni.cncf.io API group. The configuration for the API is described in the following table: Table 12.1. NetworkAttachmentDefinition API fields Field Type Description metadata.name string The name for the additional network. metadata.namespace string The namespace that the object is associated with. spec.config string The CNI plug-in configuration in JSON format. 12.2.2.1. Configuration of an additional network through the Cluster Network Operator The configuration for an additional network attachment is specified as part of the Cluster Network Operator (CNO) configuration. The following YAML describes the configuration parameters for managing an additional network with the CNO: Cluster Network Operator configuration apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: # ... additionalNetworks: 1 - name: <name> 2 namespace: <namespace> 3 rawCNIConfig: |- 4 { ... } type: Raw 1 An array of one or more additional network configurations. 2 The name for the additional network attachment that you are creating. The name must be unique within the specified namespace . 3 The namespace to create the network attachment in. If you do not specify a value, then the default namespace is used. 4 A CNI plug-in configuration in JSON format. 12.2.2.2. Configuration of an additional network from a YAML manifest The configuration for an additional network is specified from a YAML configuration file, such as in the following example: apiVersion: k8s.cni.cncf.io/v1 kind: NetworkAttachmentDefinition metadata: name: <name> 1 spec: config: |- 2 { ... } 1 The name for the additional network attachment that you are creating. 2 A CNI plug-in configuration in JSON format. 12.2.3. Configurations for additional network types The specific configuration fields for additional networks is described in the following sections. 12.2.3.1. Configuration for a bridge additional network The following object describes the configuration parameters for the bridge CNI plug-in: Table 12.2. Bridge CNI plug-in JSON configuration object Field Type Description cniVersion string The CNI specification version. The 0.3.1 value is required. name string The value for the name parameter you provided previously for the CNO configuration. type string bridge string Specify the name of the virtual bridge to use. If the bridge interface does not exist on the host, it is created. The default value is cni0 . ipam object The configuration object for the IPAM CNI plug-in. The plug-in manages IP address assignment for the attachment definition. ipMasq boolean Set to true to enable IP masquerading for traffic that leaves the virtual network. The source IP address for all traffic is rewritten to the bridge's IP address. If the bridge does not have an IP address, this setting has no effect. The default value is false . isGateway boolean Set to true to assign an IP address to the bridge. The default value is false . isDefaultGateway boolean Set to true to configure the bridge as the default gateway for the virtual network. The default value is false . If isDefaultGateway is set to true , then isGateway is also set to true automatically. forceAddress boolean Set to true to allow assignment of a previously assigned IP address to the virtual bridge. When set to false , if an IPv4 address or an IPv6 address from overlapping subsets is assigned to the virtual bridge, an error occurs. The default value is false . hairpinMode boolean Set to true to allow the virtual bridge to send an Ethernet frame back through the virtual port it was received on. This mode is also known as reflective relay . The default value is false . promiscMode boolean Set to true to enable promiscuous mode on the bridge. The default value is false . vlan string Specify a virtual LAN (VLAN) tag as an integer value. By default, no VLAN tag is assigned. mtu string Set the maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. 12.2.3.1.1. bridge configuration example The following example configures an additional network named bridge-net : { "cniVersion": "0.3.1", "name": "work-network", "type": "bridge", "isGateway": true, "vlan": 2, "ipam": { "type": "dhcp" } } 12.2.3.2. Configuration for a host device additional network Note Specify your network device by setting only one of the following parameters: device , hwaddr , kernelpath , or pciBusID . The following object describes the configuration parameters for the host-device CNI plug-in: Table 12.3. Host device CNI plug-in JSON configuration object Field Type Description cniVersion string The CNI specification version. The 0.3.1 value is required. name string The value for the name parameter you provided previously for the CNO configuration. type string The name of the CNI plug-in to configure: host-device . device string Optional: The name of the device, such as eth0 . hwaddr string Optional: The device hardware MAC address. kernelpath string Optional: The Linux kernel device path, such as /sys/devices/pci0000:00/0000:00:1f.6 . pciBusID string Optional: The PCI address of the network device, such as 0000:00:1f.6 . ipam object The configuration object for the IPAM CNI plug-in. The plug-in manages IP address assignment for the attachment definition. 12.2.3.2.1. host-device configuration example The following example configures an additional network named hostdev-net : { "cniVersion": "0.3.1", "name": "work-network", "type": "host-device", "device": "eth1", "ipam": { "type": "dhcp" } } 12.2.3.3. Configuration for an IPVLAN additional network The following object describes the configuration parameters for the IPVLAN CNI plug-in: Table 12.4. IPVLAN CNI plug-in JSON configuration object Field Type Description cniVersion string The CNI specification version. The 0.3.1 value is required. name string The value for the name parameter you provided previously for the CNO configuration. type string The name of the CNI plug-in to configure: ipvlan . mode string The operating mode for the virtual network. The value must be l2 , l3 , or l3s . The default value is l2 . master string The Ethernet interface to associate with the network attachment. If a master is not specified, the interface for the default network route is used. mtu integer Set the maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. ipam object The configuration object for the IPAM CNI plug-in. The plug-in manages IP address assignment for the attachment definition. Do not specify dhcp . Configuring IPVLAN with DHCP is not supported because IPVLAN interfaces share the MAC address with the host interface. 12.2.3.3.1. ipvlan configuration example The following example configures an additional network named ipvlan-net : { "cniVersion": "0.3.1", "name": "work-network", "type": "ipvlan", "master": "eth1", "mode": "l3", "ipam": { "type": "static", "addresses": [ { "address": "192.168.10.10/24" } ] } } 12.2.3.4. Configuration for a MACVLAN additional network The following object describes the configuration parameters for the macvlan CNI plug-in: Table 12.5. MACVLAN CNI plug-in JSON configuration object Field Type Description cniVersion string The CNI specification version. The 0.3.1 value is required. name string The value for the name parameter you provided previously for the CNO configuration. type string The name of the CNI plug-in to configure: macvlan . mode string Configures traffic visibility on the virtual network. Must be either bridge , passthru , private , or vepa . If a value is not provided, the default value is bridge . master string The Ethernet, bonded, or VLAN interface to associate with the virtual interface. If a value is not specified, then the host system's primary Ethernet interface is used. mtu string The maximum transmission unit (MTU) to the specified value. The default value is automatically set by the kernel. ipam object The configuration object for the IPAM CNI plug-in. The plug-in manages IP address assignment for the attachment definition. 12.2.3.4.1. macvlan configuration example The following example configures an additional network named macvlan-net : { "cniVersion": "0.3.1", "name": "macvlan-net", "type": "macvlan", "master": "eth1", "mode": "bridge", "ipam": { "type": "dhcp" } } 12.2.4. Configuration of IP address assignment for an additional network The IP address management (IPAM) Container Network Interface (CNI) plug-in provides IP addresses for other CNI plug-ins. You can use the following IP address assignment types: Static assignment. Dynamic assignment through a DHCP server. The DHCP server you specify must be reachable from the additional network. Dynamic assignment through the Whereabouts IPAM CNI plug-in. 12.2.4.1. Static IP address assignment configuration The following table describes the configuration for static IP address assignment: Table 12.6. ipam static configuration object Field Type Description type string The IPAM address type. The value static is required. addresses array An array of objects specifying IP addresses to assign to the virtual interface. Both IPv4 and IPv6 IP addresses are supported. routes array An array of objects specifying routes to configure inside the pod. dns array Optional: An array of objects specifying the DNS configuration. The addresses array requires objects with the following fields: Table 12.7. ipam.addresses[] array Field Type Description address string 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 . gateway string The default gateway to route egress network traffic to. Table 12.8. ipam.routes[] array Field Type Description dst string The IP address range in CIDR format, such as 192.168.17.0/24 or 0.0.0.0/0 for the default route. gw string The gateway where network traffic is routed. Table 12.9. ipam.dns object Field Type Description nameservers array An of array of one or more IP addresses for to send DNS queries to. domain array The default domain to append to a hostname. For example, if the domain is set to example.com , a DNS lookup query for example-host is rewritten as example-host.example.com . search array An array of domain names to append to an unqualified hostname, such as example-host , during a DNS lookup query. Static IP address assignment configuration example { "ipam": { "type": "static", "addresses": [ { "address": "191.168.1.7/24" } ] } } 12.2.4.2. Dynamic IP address (DHCP) assignment configuration The following JSON describes the configuration for dynamic IP address address assignment with DHCP. Renewal of DHCP leases A pod obtains its original DHCP lease when it is created. The lease must be periodically renewed by a minimal DHCP server deployment running on the cluster. To trigger the deployment of the DHCP server, you must create a shim network attachment by editing the Cluster Network Operator configuration, as in the following example: Example shim network attachment definition apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: additionalNetworks: - name: dhcp-shim namespace: default type: Raw rawCNIConfig: |- { "name": "dhcp-shim", "cniVersion": "0.3.1", "type": "bridge", "ipam": { "type": "dhcp" } } # ... Table 12.10. ipam DHCP configuration object Field Type Description type string The IPAM address type. The value dhcp is required. Dynamic IP address (DHCP) assignment configuration example { "ipam": { "type": "dhcp" } } 12.2.4.3. Dynamic IP address assignment configuration with Whereabouts The Whereabouts CNI plug-in allows the dynamic assignment of an IP address to an additional network without the use of a DHCP server. The following table describes the configuration for dynamic IP address assignment with Whereabouts: Table 12.11. ipam whereabouts configuration object Field Type Description type string The IPAM address type. The value whereabouts is required. range string An IP address and range in CIDR notation. IP addresses are assigned from within this range of addresses. exclude array Optional: A list of zero ore more IP addresses and ranges in CIDR notation. IP addresses within an excluded address range are not assigned. Dynamic IP address assignment configuration example that uses Whereabouts { "ipam": { "type": "whereabouts", "range": "192.0.2.192/27", "exclude": [ "192.0.2.192/30", "192.0.2.196/32" ] } } 12.2.5. Creating an additional network attachment with the Cluster Network Operator The Cluster Network Operator (CNO) manages additional network definitions. When you specify an additional network to create, the CNO creates the NetworkAttachmentDefinition object automatically. Important 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 edit the CNO configuration, enter the following command: USD oc edit networks.operator.openshift.io cluster Modify the CR that you are creating by adding the configuration for the additional network that you are creating, as in the following example CR. apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: # ... additionalNetworks: - name: tertiary-net namespace: project2 type: Raw rawCNIConfig: |- { "cniVersion": "0.3.1", "name": "tertiary-net", "type": "ipvlan", "master": "eth1", "mode": "l2", "ipam": { "type": "static", "addresses": [ { "address": "192.168.1.23/24" } ] } } Save your changes and quit the text editor to commit your changes. Verification Confirm that the CNO created the NetworkAttachmentDefinition object by running the following command. There might be a delay before the CNO creates the object. USD oc get network-attachment-definitions -n <namespace> where: <namespace> Specifies the namespace for the network attachment that you added to the CNO configuration. Example output NAME AGE test-network-1 14m 12.2.6. Creating an additional network attachment by applying a YAML manifest Prerequisites Install the OpenShift CLI ( oc ). Log in as a user with cluster-admin privileges. Procedure Create a YAML file with your additional network configuration, such as in the following example: apiVersion: k8s.cni.cncf.io/v1 kind: NetworkAttachmentDefinition metadata: name: -net spec: config: |- { "cniVersion": "0.3.1", "name": "work-network", "type": "host-device", "device": "eth1", "ipam": { "type": "dhcp" } } To create the additional network, enter the following command: USD oc apply -f <file>.yaml where: <file> Specifies the name of the file contained the YAML manifest. 12.3. About virtual routing and forwarding 12.3.1. About virtual routing and forwarding Virtual routing and forwarding (VRF) devices combined with IP rules provide the ability to create virtual routing and forwarding domains. VRF reduces the number of permissions needed by CNF, and provides increased visibility of the network topology of secondary networks. VRF is used to provide multi-tenancy functionality, for example, where each tenant has its own unique routing tables and requires different default gateways. Processes can bind a socket to the VRF device. Packets through the binded socket use the routing table associated with the VRF device. An important feature of VRF is that it impacts only OSI model layer 3 traffic and above so L2 tools, such as LLDP, are not affected. This allows higher priority IP rules such as policy based routing to take precedence over the VRF device rules directing specific traffic. 12.3.1.1. Benefits of secondary networks for pods for telecommunications operators In telecommunications use cases, each CNF can potentially be connected to multiple different networks sharing the same address space. These secondary networks can potentially conflict with the cluster's main network CIDR. Using the CNI VRF plug-in, network functions can be connected to different customers' infrastructure using the same IP address, keeping different customers isolated. IP addresses are overlapped with OpenShift Container Platform IP space. The CNI VRF plug-in also reduces the number of permissions needed by CNF and increases the visibility of network topologies of secondary networks. 12.4. Attaching a pod to an additional network As a cluster user you can attach a pod to an additional network. 12.4.1. Adding a pod to an additional network You can add a pod to an additional network. The pod continues to send normal cluster-related network traffic over the default network. When a pod is created additional networks are attached to it. However, if a pod already exists, you cannot attach additional networks to it. The pod must be in the same namespace as the additional network. Prerequisites Install the OpenShift CLI ( oc ). Log in to the cluster. Procedure Add an annotation to the Pod object. Only one of the following annotation formats can be used: To attach an additional network without any customization, add an annotation with the following format. Replace <network> with the name of the additional network to associate with the pod: metadata: annotations: k8s.v1.cni.cncf.io/networks: <network>[,<network>,...] 1 1 To specify more than one additional network, separate each network with a comma. Do not include whitespace between the comma. If you specify the same additional network multiple times, that pod will have multiple network interfaces attached to that network. To attach an additional network with customizations, add an annotation with the following format: metadata: annotations: k8s.v1.cni.cncf.io/networks: |- [ { "name": "<network>", 1 "namespace": "<namespace>", 2 "default-route": ["<default-route>"] 3 } ] 1 Specify the name of the additional network defined by a NetworkAttachmentDefinition object. 2 Specify the namespace where the NetworkAttachmentDefinition object is defined. 3 Optional: Specify an override for the default route, such as 192.168.17.1 . To create the pod, enter the following command. Replace <name> with the name of the pod. USD oc create -f <name>.yaml Optional: To Confirm that the annotation exists in the Pod CR, enter the following command, replacing <name> with the name of the pod. USD oc get pod <name> -o yaml In the following example, the example-pod pod is attached to the net1 additional network: USD oc get pod example-pod -o yaml apiVersion: v1 kind: Pod metadata: annotations: k8s.v1.cni.cncf.io/networks: macvlan-bridge k8s.v1.cni.cncf.io/networks-status: |- 1 [{ "name": "openshift-sdn", "interface": "eth0", "ips": [ "10.128.2.14" ], "default": true, "dns": {} },{ "name": "macvlan-bridge", "interface": "net1", "ips": [ "20.2.2.100" ], "mac": "22:2f:60:a5:f8:00", "dns": {} }] name: example-pod namespace: default spec: ... status: ... 1 The k8s.v1.cni.cncf.io/networks-status parameter is a JSON array of objects. Each object describes the status of an additional network attached to the pod. The annotation value is stored as a plain text value. 12.4.1.1. Specifying pod-specific addressing and routing options When attaching a pod to an additional network, you may want to specify further properties about that network in a particular pod. This allows you to change some aspects of routing, as well as specify static IP addresses and MAC addresses. To accomplish this, you can use the JSON formatted annotations. Prerequisites The pod must be in the same namespace as the additional network. Install the OpenShift Command-line Interface ( oc ). You must log in to the cluster. Procedure To add a pod to an additional network while specifying addressing and/or routing options, complete the following steps: Edit the Pod resource definition. If you are editing an existing Pod resource, run the following command to edit its definition in the default editor. Replace <name> with the name of the Pod resource to edit. USD oc edit pod <name> In the Pod resource definition, add the k8s.v1.cni.cncf.io/networks parameter to the pod metadata mapping. The k8s.v1.cni.cncf.io/networks accepts a JSON string of a list of objects that reference the name of NetworkAttachmentDefinition custom resource (CR) names in addition to specifying additional properties. metadata: annotations: k8s.v1.cni.cncf.io/networks: '[<network>[,<network>,...]]' 1 1 Replace <network> with a JSON object as shown in the following examples. The single quotes are required. In the following example the annotation specifies which network attachment will have the default route, using the default-route parameter. apiVersion: v1 kind: Pod metadata: name: example-pod annotations: k8s.v1.cni.cncf.io/networks: ' { "name": "net1" }, { "name": "net2", 1 "default-route": ["192.0.2.1"] 2 }' spec: containers: - name: example-pod command: ["/bin/bash", "-c", "sleep 2000000000000"] image: centos/tools 1 The name key is the name of the additional network to associate with the pod. 2 The default-route key specifies a value of a gateway for traffic to be routed over if no other routing entry is present in the routing table. If more than one default-route key is specified, this will cause the pod to fail to become active. The default route will cause any traffic that is not specified in other routes to be routed to the gateway. Important Setting the default route to an interface other than the default network interface for OpenShift Container Platform may cause traffic that is anticipated for pod-to-pod traffic to be routed over another interface. To verify the routing properties of a pod, the oc command may be used to execute the ip command within a pod. USD oc exec -it <pod_name> -- ip route Note You may also reference the pod's k8s.v1.cni.cncf.io/networks-status to see which additional network has been assigned the default route, by the presence of the default-route key in the JSON-formatted list of objects. To set a static IP address or MAC address for a pod you can use the JSON formatted annotations. This requires you create networks that specifically allow for this functionality. This can be specified in a rawCNIConfig for the CNO. Edit the CNO CR by running the following command: USD oc edit networks.operator.openshift.io cluster The following YAML describes the configuration parameters for the CNO: Cluster Network Operator YAML configuration name: <name> 1 namespace: <namespace> 2 rawCNIConfig: '{ 3 ... }' type: Raw 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 you do not specify a value, then the default namespace is used. 3 Specify the CNI plug-in configuration in JSON format, which is based on the following template. The following object describes the configuration parameters for utilizing static MAC address and IP address using the macvlan CNI plug-in: macvlan CNI plug-in JSON configuration object using static IP and MAC address { "cniVersion": "0.3.1", "name": "<name>", 1 "plugins": [{ 2 "type": "macvlan", "capabilities": { "ips": true }, 3 "master": "eth0", 4 "mode": "bridge", "ipam": { "type": "static" } }, { "capabilities": { "mac": true }, 5 "type": "tuning" }] } 1 Specifies the name for the additional network attachment to create. The name must be unique within the specified namespace . 2 Specifies an array of CNI plug-in configurations. The first object specifies a macvlan plug-in configuration and the second object specifies a tuning plug-in configuration. 3 Specifies that a request is made to enable the static IP address functionality of the CNI plug-in runtime configuration capabilities. 4 Specifies the interface that the macvlan plug-in uses. 5 Specifies that a request is made to enable the static MAC address functionality of a CNI plug-in. The above network attachment can be referenced in a JSON formatted annotation, along with keys to specify which static IP and MAC address will be assigned to a given pod. Edit the pod with: USD oc edit pod <name> macvlan CNI plug-in JSON configuration object using static IP and MAC address apiVersion: v1 kind: Pod metadata: name: example-pod annotations: k8s.v1.cni.cncf.io/networks: '[ { "name": "<name>", 1 "ips": [ "192.0.2.205/24" ], 2 "mac": "CA:FE:C0:FF:EE:00" 3 } ]' 1 Use the <name> as provided when creating the rawCNIConfig above. 2 Provide an IP address including the subnet mask. 3 Provide the MAC address. Note Static IP addresses and MAC addresses do not have to be used at the same time, you may use them individually, or together. To verify the IP address and MAC properties of a pod with additional networks, use the oc command to execute the ip command within a pod. USD oc exec -it <pod_name> -- ip a 12.5. Removing a pod from an additional network As a cluster user you can remove a pod from an additional network. 12.5.1. Removing a pod from an additional network You can remove a pod from an additional network only by deleting the pod. Prerequisites An additional network is attached to the pod. Install the OpenShift CLI ( oc ). Log in to the cluster. Procedure To delete the pod, enter the following command: USD oc delete pod <name> -n <namespace> <name> is the name of the pod. <namespace> is the namespace that contains the pod. 12.6. Editing an additional network As a cluster administrator you can modify the configuration for an existing additional network. 12.6.1. Modifying an additional network attachment definition As a cluster administrator, you can make changes to an existing additional network. Any existing pods attached to the additional network will not be updated. Prerequisites You have configured an additional network for your cluster. Install the OpenShift CLI ( oc ). Log in as a user with cluster-admin privileges. Procedure To edit an additional network for your cluster, complete the following steps: Run the following command to edit the Cluster Network Operator (CNO) CR in your default text editor: USD oc edit networks.operator.openshift.io cluster In the additionalNetworks collection, update the additional network with your changes. Save your changes and quit the text editor to commit your changes. Optional: Confirm that the CNO updated the NetworkAttachmentDefinition object by running the following command. Replace <network-name> with the name of the additional network to display. There might be a delay before the CNO updates the NetworkAttachmentDefinition object to reflect your changes. USD oc get network-attachment-definitions <network-name> -o yaml For example, the following console output displays a NetworkAttachmentDefinition object that is named net1 : USD oc get network-attachment-definitions net1 -o go-template='{{printf "%s\n" .spec.config}}' { "cniVersion": "0.3.1", "type": "macvlan", "master": "ens5", "mode": "bridge", "ipam": {"type":"static","routes":[{"dst":"0.0.0.0/0","gw":"10.128.2.1"}],"addresses":[{"address":"10.128.2.100/23","gateway":"10.128.2.1"}],"dns":{"nameservers":["172.30.0.10"],"domain":"us-west-2.compute.internal","search":["us-west-2.compute.internal"]}} } 12.7. Removing an additional network As a cluster administrator you can remove an additional network attachment. 12.7.1. Removing an additional network attachment definition As a cluster administrator, you can remove an additional network from your OpenShift Container Platform cluster. The additional network is not removed from any pods it is attached to. Prerequisites Install the OpenShift CLI ( oc ). Log in as a user with cluster-admin privileges. Procedure To remove an additional network from your cluster, complete the following steps: Edit the Cluster Network Operator (CNO) in your default text editor by running the following command: USD oc edit networks.operator.openshift.io cluster Modify the CR by removing the configuration from the additionalNetworks collection for the network attachment definition you are removing. apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: additionalNetworks: [] 1 1 If you are removing the configuration mapping for the only additional network attachment definition in the additionalNetworks collection, you must specify an empty collection. Save your changes and quit the text editor to commit your changes. Optional: Confirm that the additional network CR was deleted by running the following command: USD oc get network-attachment-definition --all-namespaces 12.8. Assigning a secondary network to a VRF Important CNI VRF plug-in is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process. For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/ . 12.8.1. Assigning a secondary network to a VRF As a cluster administrator, you can configure an additional network for your VRF domain by using the CNI VRF plug-in. The virtual network created by this plug-in is associated with a physical interface that you specify. Note Applications that use VRFs need to bind to a specific device. The common usage is to use the SO_BINDTODEVICE option for a socket. SO_BINDTODEVICE binds the socket to a device that is specified in the passed interface name, for example, eth1 . To use SO_BINDTODEVICE , the application must have CAP_NET_RAW capabilities. 12.8.1.1. Creating an additional network attachment with the CNI VRF plug-in The Cluster Network Operator (CNO) manages additional network definitions. When you specify an additional network to create, the CNO creates the NetworkAttachmentDefinition custom resource (CR) automatically. Note Do not edit the NetworkAttachmentDefinition CRs that the Cluster Network Operator manages. Doing so might disrupt network traffic on your additional network. To create an additional network attachment with the CNI VRF plug-in, perform the following procedure. Prerequisites Install the OpenShift Container Platform CLI (oc). Log in to the OpenShift cluster as a user with cluster-admin privileges. Procedure Create the Network custom resource (CR) for the additional network attachment and insert the rawCNIConfig configuration for the additional network, as in the following example CR. Save the YAML as the file additional-network-attachment.yaml . apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: additionalNetworks: - name: test-network-1 namespace: additional-network-1 type: Raw rawCNIConfig: '{ "cniVersion": "0.3.1", "name": "macvlan-vrf", "plugins": [ 1 { "type": "macvlan", 2 "master": "eth1", "ipam": { "type": "static", "addresses": [ { "address": "191.168.1.23/24" } ] } }, { "type": "vrf", "vrfname": "example-vrf-name", 3 "table": 1001 4 }] }' 1 plugins must be a list. The first item in the list must be the secondary network underpinning the VRF network. The second item in the list is the VRF plugin configuration. 2 type must be set to vrf . 3 vrfname is the name of the VRF that the interface is assigned to. If it does not exist in the pod, it is created. 4 Optional. table is the routing table ID. By default, the tableid parameter is used. If it is not specified, the CNI assigns a free routing table ID to the VRF. Note VRF functions correctly only when the resource is of type netdevice . Create the Network resource: USD oc create -f additional-network-attachment.yaml Confirm that the CNO created the NetworkAttachmentDefinition CR by running the following command. Replace <namespace> with the namespace that you specified when configuring the network attachment, for example, additional-network-1 . USD oc get network-attachment-definitions -n <namespace> Example output NAME AGE additional-network-1 14m Note There might be a delay before the CNO creates the CR. Verifying that the additional VRF network attachment is successful To verify that the VRF CNI is correctly configured and the additional network attachment is attached, do the following: Create a network that uses the VRF CNI. Assign the network to a pod. Verify that the pod network attachment is connected to the VRF additional network. Remote shell into the pod and run the following command: USD ip vrf show Example output Name Table ----------------------- red 10 Confirm the VRF interface is master of the secondary interface: USD ip link Example output 5: net1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master red state UP mode

Commands:
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: # additionalNetworks: 1 - name: <name> 2 namespace: <namespace> 3 rawCNIConfig: |- 4 { } type: Raw
apiVersion: k8s.cni.cncf.io/v1 kind: NetworkAttachmentDefinition metadata: name: <name> 1 spec: config: |- 2 { }
{ "cniVersion": "0.3.1", "name": "work-network", "type": "bridge", "isGateway": true, "vlan": 2, "ipam": { "type": "dhcp" } }
{ "cniVersion": "0.3.1", "name": "work-network", "type": "host-device", "device": "eth1", "ipam": { "type": "dhcp" } }
{ "cniVersion": "0.3.1", "name": "work-network", "type": "ipvlan", "master": "eth1", "mode": "l3", "ipam": { "type": "static", "addresses": [ { "address": "192.168.10.10/24" } ] } }
{ "cniVersion": "0.3.1", "name": "macvlan-net", "type": "macvlan", "master": "eth1", "mode": "bridge", "ipam": { "type": "dhcp" } }
{ "ipam": { "type": "static", "addresses": [ { "address": "191.168.1.7/24" } ] } }
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: additionalNetworks: - name: dhcp-shim namespace: default type: Raw rawCNIConfig: |- { "name": "dhcp-shim", "cniVersion": "0.3.1", "type": "bridge", "ipam": { "type": "dhcp" } } #
{ "ipam": { "type": "dhcp" } }
{ "ipam": { "type": "whereabouts", "range": "192.0.2.192/27", "exclude": [ "192.0.2.192/30", "192.0.2.196/32" ] } }
oc edit networks.operator.openshift.io cluster
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: # additionalNetworks: - name: tertiary-net namespace: project2 type: Raw rawCNIConfig: |- { "cniVersion": "0.3.1", "name": "tertiary-net", "type": "ipvlan", "master": "eth1", "mode": "l2", "ipam": { "type": "static", "addresses": [ { "address": "192.168.1.23/24" } ] } }
oc get network-attachment-definitions -n <namespace>
NAME AGE test-network-1 14m
apiVersion: k8s.cni.cncf.io/v1 kind: NetworkAttachmentDefinition metadata: name: next-net spec: config: |- { "cniVersion": "0.3.1", "name": "work-network", "type": "host-device", "device": "eth1", "ipam": { "type": "dhcp" } }
oc apply -f <file>.yaml
metadata: annotations: k8s.v1.cni.cncf.io/networks: <network>[,<network>,...] 1
metadata: annotations: k8s.v1.cni.cncf.io/networks: |- [ { "name": "<network>", 1 "namespace": "<namespace>", 2 "default-route": ["<default-route>"] 3 } ]
oc create -f <name>.yaml
oc get pod <name> -o yaml
oc get pod example-pod -o yaml apiVersion: v1 kind: Pod metadata: annotations: k8s.v1.cni.cncf.io/networks: macvlan-bridge k8s.v1.cni.cncf.io/networks-status: |- 1 [{ "name": "openshift-sdn", "interface": "eth0", "ips": [ "10.128.2.14" ], "default": true, "dns": {} },{ "name": "macvlan-bridge", "interface": "net1", "ips": [ "20.2.2.100" ], "mac": "22:2f:60:a5:f8:00", "dns": {} }] name: example-pod namespace: default spec: status:
oc edit pod <name>
metadata: annotations: k8s.v1.cni.cncf.io/networks: '[<network>[,<network>,...]]' 1
apiVersion: v1 kind: Pod metadata: name: example-pod annotations: k8s.v1.cni.cncf.io/networks: ' { "name": "net1" }, { "name": "net2", 1 "default-route": ["192.0.2.1"] 2 }' spec: containers: - name: example-pod command: ["/bin/bash", "-c", "sleep 2000000000000"] image: centos/tools
oc exec -it <pod_name> -- ip route
oc edit networks.operator.openshift.io cluster
name: <name> 1 namespace: <namespace> 2 rawCNIConfig: '{ 3 }' type: Raw
{ "cniVersion": "0.3.1", "name": "<name>", 1 "plugins": [{ 2 "type": "macvlan", "capabilities": { "ips": true }, 3 "master": "eth0", 4 "mode": "bridge", "ipam": { "type": "static" } }, { "capabilities": { "mac": true }, 5 "type": "tuning" }] }
oc edit pod <name>
apiVersion: v1 kind: Pod metadata: name: example-pod annotations: k8s.v1.cni.cncf.io/networks: '[ { "name": "<name>", 1 "ips": [ "192.0.2.205/24" ], 2 "mac": "CA:FE:C0:FF:EE:00" 3 } ]'
oc exec -it <pod_name> -- ip a
oc delete pod <name> -n <namespace>
oc edit networks.operator.openshift.io cluster
oc get network-attachment-definitions <network-name> -o yaml
oc get network-attachment-definitions net1 -o go-template='{{printf "%s\n" .spec.config}}' { "cniVersion": "0.3.1", "type": "macvlan", "master": "ens5", "mode": "bridge", "ipam": {"type":"static","routes":[{"dst":"0.0.0.0/0","gw":"10.128.2.1"}],"addresses":[{"address":"10.128.2.100/23","gateway":"10.128.2.1"}],"dns":{"nameservers":["172.30.0.10"],"domain":"us-west-2.compute.internal","search":["us-west-2.compute.internal"]}} }
oc edit networks.operator.openshift.io cluster
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: additionalNetworks: [] 1
oc get network-attachment-definition --all-namespaces
apiVersion: operator.openshift.io/v1 kind: Network metadata: name: cluster spec: additionalNetworks: - name: test-network-1 namespace: additional-network-1 type: Raw rawCNIConfig: '{ "cniVersion": "0.3.1", "name": "macvlan-vrf", "plugins": [ 1 { "type": "macvlan", 2 "master": "eth1", "ipam": { "type": "static", "addresses": [ { "address": "191.168.1.23/24" } ] } }, { "type": "vrf", "vrfname": "example-vrf-name", 3 "table": 1001 4 }] }'
oc create -f additional-network-attachment.yaml
oc get network-attachment-definitions -n <namespace>
NAME AGE additional-network-1 14m
ip vrf show
Name Table ----------------------- red 10
ip link
5: net1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master red state UP mode