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Copy file name to clipboardExpand all lines: articles/aks/azure-cni-overview.md
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@@ -46,7 +46,7 @@ IP addresses for the pods and the cluster's nodes are assigned from the specifie
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> The number of IP addresses required should include considerations for upgrade and scaling operations. If you set the IP address range to only support a fixed number of nodes, you can't upgrade or scale your cluster.
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> * When you **upgrade** your AKS cluster, a new node is deployed into the cluster. Services and workloads begin to run on the new node, and an older node is removed from the cluster. This rolling upgrade process requires a minimum of one additional block of IP addresses to be available. Your node count is then `n + 1`.
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> * This consideration is particularly important when you use Windows Server node pools. Windows Server nodes in AKS do not automatically apply Windows Updates, instead you perform an upgrade on the node pool. This upgrade deploys new nodes with the latest Window Server 2019 base node image and security patches. For more information on upgrading a Windows Server node pool, see [Upgrade a node pool in AKS][nodepool-upgrade].
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> * This consideration is particularly important when you use Windows Server node pools. Windows Server nodes in AKS do not automatically apply Windows Updates. Instead, you perform an upgrade on the node pool. This upgrade deploys new nodes with the latest Window Server 2019 base node image and security patches. For more information on upgrading a Windows Server node pool, see [Upgrade a node pool in AKS][nodepool-upgrade].
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> * When you **scale** an AKS cluster, a new node is deployed into the cluster. Services and workloads begin to run on the new node. Your IP address range needs to take into considerations how you might want to scale up the number of nodes and pods your cluster can support. One additional node for upgrade operations should also be included. Your node count is then `n + number-of-additional-scaled-nodes-you-anticipate + 1`.
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| Address range / Azure resource | Limits and sizing |
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| --------- | ------------- |
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| Virtual network | The Azure virtual network can be as large as /8, but is limited to 65,536 configured IP addresses. Consider all your networking needs, including communicating with services in other virtual networks, before configuring your address space. For example, if you configure too large of an address space, you might run into issues with overlapping other address spaces within your network.|
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| Subnet | Must be large enough to accommodate the nodes, pods, and all Kubernetes and Azure resources that might be provisioned in your cluster. For example, if you deploy an internal Azure Load Balancer, its front-end IPs are allocated from the cluster subnet, not public IPs. The subnet size should also take into account upgrade operations or future scaling needs.<p/> Use the following equation to calculate the *minimum* subnet size including an extra node for upgrade operations: `(number of nodes + 1) + ((number of nodes + 1) * maximum pods per node that you configure)`<p/> Example for a 50 node cluster: `(51) + (51 * 30 (default)) = 1,581` (/21 or larger)<p/>Example for a 50 node cluster that also includes preparation to scale up an extra 10 nodes: `(61) + (61 * 30 (default)) = 1,891` (/21 or larger)<p>If you don't specify a maximum number of pods per node when you create your cluster, the maximum number of pods per node is set to *30*. The minimum number of IP addresses required is based on that value. If you calculate your minimum IP address requirements on a different maximum value, see [how to configure the maximum number of pods per node](#configure-maximum---new-clusters) to set this value when you deploy your cluster. |
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| Subnet | Must be large enough to accommodate the nodes, pods, and all Kubernetes and Azure resources that might be provisioned in your cluster. For example, if you deploy an internal Azure Load Balancer, its front-end IPs are allocated from the cluster subnet, not public IPs. The subnet size should also take into account upgrade operations or future scaling needs.<p/> Use the following equation to calculate the *minimum* subnet size including an extra node for upgrade operations: `(number of nodes + 1) + ((number of nodes + 1) * maximum pods per node that you configure)`<p/> Example for a 50 node cluster: `(51) + (51 * 30 (default)) = 1,581` (/21 or larger)<p/>Example for a 50 node cluster that also includes preparation to scale up an extra 10 nodes: `(61) + (61 * 30 (default)) = 1,891` (/21 or larger)<p>If you don't specify a maximum number of pods per node when you create your cluster, the maximum number of pods per node is set to *30*. The minimum number of IP addresses required is based on that value. If you calculate your minimum IP address requirements on a different maximum value, see [Maximum pods per node](#maximum-pods-per-node) to set this value when you deploy your cluster. |
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| Kubernetes service address range | Any network element on or connected to this virtual network must not use this range. Service address CIDR must be smaller than /12. You can reuse this range across different AKS clusters. |
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| Kubernetes DNS service IP address | IP address within the Kubernetes service address range that is used by cluster service discovery. Don't use the first IP address in your address range. The first address in your subnet range is used for the *kubernetes.default.svc.cluster.local* address. |
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| Portal | 110 | 110 (configurable in the Node Pools tab) | Yes (up to 250) |
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### Configure maximum - new clusters
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### Configure maximum pods per node for new clusters
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You're able to configure the maximum number of pods per node at cluster deployment time or as you add new node pools. You can set the maximum pods per node value as high as 250.
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You can configure the maximum number of pods per node either at cluster deployment time or as you add new node pools. You can set the maximum pods per node value as high as 250.
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If you don't specify maxPods when creating new node pools, you receive a default value of 30 for Azure CNI.
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If you don't specify *maxPods* when creating new node pools, you receive a default value of 30 for Azure CNI.
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A minimum value for maximum pods per node is enforced to guarantee space for system pods critical to cluster health. The minimum value that can be set for maximum pods per node is 10 if and only if the configuration of each node pool has space for a minimum of 30 pods. For example, setting the maximum pods per node to the minimum of 10 requires each individual node pool to have a minimum of three nodes. This requirement applies for each new node pool created as well, so if 10 is defined as maximum pods per node each subsequent node pool added must have at least three nodes.
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| Kubenet | 10 | 250 |
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> [!NOTE]
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> The minimum value in the previous table is strictly enforced by the AKS service. You can not set a maxPods value lower than the minimum shown as doing so can prevent the cluster from starting.
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> The minimum value in the previous table is strictly enforced by the AKS service. You can not set a value for *maxPods* that is lower than the minimum shown, as doing so can prevent the cluster from starting.
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***Azure CLI**: Specify the `--max-pods` argument when you deploy a cluster with the [`az aks create`][az-aks-create] command. The maximum value is 250.
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***Azure CLI**: Specify the `--max-pods` argument when you deploy a cluster with the [az aks create][az-aks-create] command. The maximum value is 250.
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***Resource Manager template**: Specify the `maxPods` property in the [ManagedClusterAgentPoolProfile] object when you deploy a cluster with a Resource Manager template. The maximum value is 250.
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***Azure portal**: Change the `Max pods per node` field in the node pool settings when creating a cluster or adding a new node pool.
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### Configure maximum - existing clusters
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The maxPod per node setting can be defined when you create a new node pool. If you need to increase the maxPod per node setting on an existing cluster, add a new node pool with the new desired maxPod count. After migrating your pods to the new pool, delete the older pool. To delete any older pool in a cluster, ensure you're setting node pool modes as defined in the [system node pools document][system-node-pools].
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### Configure maximum pods per node for existing clusters
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The *maxPods* per node setting can be defined when you create a new node pool. If you need to increase the *maxPods* setting on an existing cluster, add a new node pool with the new desired *maxPods* count. After migrating your pods to the new pool, delete the older pool. To delete any older pool in a cluster, ensure you're setting node pool modes as defined in the [system node pools document][system-node-pools].
Copy file name to clipboardExpand all lines: articles/aks/concepts-network.md
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@@ -4,7 +4,6 @@ description: Learn about networking in Azure Kubernetes Service (AKS), including
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ms.topic: conceptual
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ms.date: 12/26/2023
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# Networking concepts for applications in Azure Kubernetes Service (AKS)
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*[Ingress controllers](#ingress-controllers)
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*[Network policies](#network-policies)
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## Kubernetes basics
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## Kubernetes networking basics
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Kubernetes employs a virtual networking layer to manage access within and between your applications or their components. This involves the following key aspects:
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-**Kubernetes nodes and virtual network**: Kubernetes nodes are connected to a virtual network. This setup enables pods (basic units of deployment in Kubernetes) to have both inbound and outbound connectivity.
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The following behavior differences exist between kubenet and Azure CNI:
| Pod-VM connectivity; VM in the same virtual network | Works when initiated by pod | Works both ways | Works when initiated by pod | Works when initiated by pod|
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| Pod-VM connectivity; VM in peered virtual network | Works when initiated by pod | Works both ways | Works when initiated by pod | Works when initiated by pod|
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| On-premises access using VPN or Express Route | Works when initiated by pod | Works both ways | Works when initiated by pod | Works when initiated by pod|
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| Expose Kubernetes services using a load balancer service, App Gateway, or ingress controller | Supported | Supported|[No Application Gateway Ingress Controller (AGIC) support][azure-cni-overlay-limitations]| Same limitations when using Overlay mode |
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| Support for Windows node pools | Not Supported | Supported | Supported |[Available only for Linux and not for Windows.][azure-cni-powered-by-cilium-limitations]|
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Regarding DNS, with both kubenet and Azure CNI pluginsDNS are offered by CoreDNS, a deployment running in AKS with its own autoscaler. For more information on CoreDNS on Kubernetes, see [Customizing DNS Service](https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/). CoreDNS by default is configured to forward unknown domains to the DNS functionality of the Azure Virtual Network where the AKS cluster is deployed. Hence, Azure DNS and Private Zones will work for pods running in AKS.
| Pod-VM connectivity; VM in the same virtual network | Works when initiated by pod | Works both ways | Works when initiated by pod | Works when initiated by pod |
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| Pod-VM connectivity; VM in peered virtual network | Works when initiated by pod | Works both ways | Works when initiated by pod | Works when initiated by pod |
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| On-premises access using VPN or Express Route | Works when initiated by pod | Works both ways | Works when initiated by pod | Works when initiated by pod |
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| Expose Kubernetes services using a load balancer service, App Gateway, or ingress controller | Supported | Supported |[No Application Gateway Ingress Controller (AGIC) support][azure-cni-overlay-limitations]| Same limitations when using Overlay mode |
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| Support for Windows node pools | Not Supported | Supported | Supported |[Available only for Linux and not for Windows.][azure-cni-powered-by-cilium-limitations]|
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For both kubenet and Azure CNI plugins, the DNS service is provided by CoreDNS, a deployment running in AKS with its own autoscaler. For more information on CoreDNS on Kubernetes, see [Customizing DNS Service](https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/). CoreDNS by default is configured to forward unknown domains to the DNS functionality of the Azure Virtual Network where the AKS cluster is deployed. Hence, Azure DNS and Private Zones will work for pods running in AKS.
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For more information on Azure CNI and kubenet and to help determine which option is best for you, see [Configure Azure CNI networking in AKS][azure-cni-aks] and [Use kubenet networking in AKS][aks-configure-kubenet-networking].
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