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76 lines
4.3 KiB
Plaintext
76 lines
4.3 KiB
Plaintext
:_mod-docs-content-type: ASSEMBLY
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[id="microshift-cni"]
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= About the OVN-Kubernetes network plugin
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include::_attributes/attributes-microshift.adoc[]
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:context: microshift-about-ovn-k-plugin
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toc::[]
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The OVN-Kubernetes Container Network Interface (CNI) plugin is the default networking solution for a {microshift-short} node. OVN-Kubernetes is a virtualized network for pods and services that is based on Open Virtual Network (OVN).
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* Default network configuration and connections are applied automatically in {microshift-short} with the `microshift-networking` RPM during installation.
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* A node that uses the OVN-Kubernetes network plugin also runs Open vSwitch (OVS) on the node.
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* OVN-K configures OVS on the node to implement the declared network configuration.
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* Host physical interfaces are not bound by default to the OVN-K gateway bridge, `br-ex`. You can use standard tools on the host for managing the default gateway, such as the Network Manager CLI (`nmcli`).
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* Changing the CNI is not supported on {microshift-short}.
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Using configuration files or custom scripts, you can configure the following networking settings:
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* You can use subnet CIDR ranges to allocate IP addresses to pods.
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* You can change the maximum transmission unit (MTU) value.
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* You can configure firewall ingress and egress.
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* You can define network policies in the {microshift-short}, including ingress and egress rules.
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* You can use the {microshift-short} Multus plugin to chain other CNI plugins.
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* You can configure or remove the ingress router.
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include::modules/microshift-cni-customization-matrix.adoc[leveloffset=+1]
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include::modules/microshift-default-settings.adoc[leveloffset=+2]
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[id="microshift-network-features_{context}"]
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== Network features
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Networking features available with {microshift-short} {product-version} include:
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* Kubernetes network policy
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* Dynamic node IP
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* Custom gateway interface
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* Second gateway interface
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* Node network on specified host interface
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* Blocking external access to NodePort service on specific host interfaces
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Networking features not available with {microshift-short} {product-version}:
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* Egress IP/firewall/QoS: disabled
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* Hybrid networking: not supported
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* IPsec: not supported
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* Hardware offload: not supported
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[id="microshift-ip-forward_{context}"]
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== IP forward
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The host network `sysctl net.ipv4.ip_forward` kernel parameter is automatically enabled by the `ovnkube-master` container when started. This is required to forward incoming traffic to the CNI. For example, accessing the NodePort service from outside of a node fails if `ip_forward` is disabled.
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[id="microshift-network-performance_{context}"]
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== Network performance optimizations
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By default, three performance optimizations are applied to OVS services to minimize resource consumption:
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* CPU affinity to `ovs-vswitchd.service` and `ovsdb-server.service`
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* `no-mlockall` to `openvswitch.service`
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* Limit handler and `revalidator` threads to `ovs-vswitchd.service`
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include::modules/microshift-nw-components-svcs.adoc[leveloffset=+1]
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[id="microshift-bridge-mapping_{context}"]
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== Bridge mappings
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Bridge mappings allow provider network traffic to reach the physical network. Traffic leaves the provider network and arrives at the `br-int` bridge. A patch port between `br-int` and `br-ex` then allows the traffic to traverse to and from the provider network and the edge network. Kubernetes pods are connected to the `br-int` bridge through virtual ethernet pair: one end of the virtual ethernet pair is attached to the pod namespace, and the other end is attached to the `br-int` bridge.
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include::modules/microshift-nw-topology.adoc[leveloffset=+1]
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[id="_additional-resources_microshift-cni_{context}"]
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[role="_additional-resources"]
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== Additional resources
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* xref:../microshift_configuring/microshift-using-config-yaml.adoc#microshift-using-config-yaml[Customizing {microshift-short} by using the configuration file]
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* xref:../microshift_networking/microshift-networking-settings.adoc#microshift-understanding-networking-settings[Understanding networking settings]
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* xref:../microshift_networking/microshift_multiple_networks/microshift-cni-multus.adoc#microshift-cni-multus[About using multiple networks]
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* xref:../microshift_networking/microshift_network_policy/microshift-network-policy-index.adoc#microshift-network-policies[About network policies]
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