VNet and subnet planning

Whether you decide to use your own VNet for CDP or have CDP create one for you, you should carefully plan your network, calculating and verifying the limits of the VNet and subnets available in your Azure subscription to ensure that you have enough networking resources to create clusters in CDP.

When registering an Azure environment in CDP, you are asked to select a VNet and one or more subnets. You have two options:

  • CDP will create a new VNet and subnets
  • Select a VNet and subnets that you previously created

In both cases, use this guide to calculate and verify the limits of the VNet and subnets available in your Azure subscription to ensure that you have enough networking resources to create clusters in CDP.

Option 1: CDP creates the VNet and subnets

If you would like CDP to create a new VNet, you will need to specify a valid CIDR in IPv4 range that will be used to define the range of private IPs for VM instances provisioned into these subnets. This must be a /16 CIDR, but you can customize the IP Range (the default is 10.10.0.0).

You cannot use the following reserved CIDR blocks for your VPC:

  • 10.0.0.0/16
  • 10.244.0.0/16
  • 172.17.0.1/16
  • 10.20.0.0/16
  • 10.244.0.0/16

CDP will divide this address range as follows:

  • 32 x /24 subnets - Recommended for Machine Learning workspaces
  • 3 x /19 subnets - Recommended for Data Warehouse service
  • 3 x /19 subnets - Recommended for Data Lake and Data Hub
  • 3 x /24 subnets - Reserved for future use

If you would like to have a minimal virtual network instead, you can use the guide outlined in the next option.

Option 2: Existing VNet and subnets

If you would like to use an existing VNet, the subnet requirements vary based on the services used. Below is a guide for calculating network requirements per service.

In addition, make sure you follow the following guidelines:

  • You cannot use the following reserved CIDR blocks for your VPC:
    • 10.0.0.0/16
    • 10.244.0.0/16
    • 172.17.0.1/16
    • 10.20.0.0/16
    • 10.244.0.0/16
  • The Microsoft.Storage and Microsoft.SQL Service endpoints should be registered for all subnets that will be used by CDP.

Subnets for Data Lake and Data Hub

Both Data Lake and DataHub share the same subnet, so only one subnet is required.

Cloudera recommends a minimum of a /24 CIDR. If you would like to use a smaller subnet, use the following guidelines:

  • One IP address is used for each VM
  • One Light Duty Data Lake cluster uses three VMs
  • A typical Data Hub cluster uses a minimum of four VMs as a starting point, but this number can be dynamically scaled up or down
  • Make sure you allocate enough IPs to handle each cluster running at peak capacity

Subnets for Data Warehouse

The Data Warehouse service needs one subnet. You can choose the specific subnet used by DW when you activate Data Warehouse for an environment. This subnet should not be shared with any of the other CDP applications.

Cloudera recommends a /20 or larger subnet as it can be difficult to accurately predict the size of each VW due to autoscaling.

If you would like to size the subnets to a smaller CIDR, the following guidelines assume that you are activating your DW environment with the default settings (no overlay networks):

VM Purpose # VMs # pods per VM IPs per VM (1 for the instance + 1 per pod) Total IP addresses required
DW Shared Services - (Shared among all VWs in an environment) 3 30 31 93
Per Database Catalog

(One catalog is created by default, you can create additional catalogs)

2 30 31 62
Per Virtual Warehouse (XS) - without autoscaling* 2 10 11 22
Per Virtual Warehouse (S) - without autoscaling* 10 10 11 110
Per Virtual Warehouse (M) - without autoscaling* 20 10 11 220
Per Virtual Warehouse (L) - without autoscaling* 40 10 11 440
If you would like to use a smaller subnet, you can enable the Overlay Networks feature for DW, which will provision your AKS cluster with the kubenet network plugin instead of Azure CNI. When you use kubnet, you may need to manage the Azure Route Table (UDR) manually in accordance with AKS documentation. In this case, use the following table as your guideline:
VM Purpose # VMs Total IP addresses required
CDW Shared Services

(shared among all VWs in an environment)

3 3
Per Database Catalog

(One catalog is created by default, you can create additional catalogs)

2 2
Per Virtual Warehouse (XS) - without autoscaling* 2 2
Per Virtual Warehouse (S) - without autoscaling* 10 10
Per Virtual Warehouse (M) - without autoscaling* 20 20
Virtual Warehouse (L) - without autoscaling* 40 40

* Each autoscaling activity can be treated as deploying a new Virtual Warehouse. For example, when a XS Virtual Warehouse is scaled once, it uses four VMs instead of two.

Subnets for Machine Learning

You need one separate subnet delegated to the Azure NetApp Files service (all workspaces in a region will share this service). Cloudera recommends a /28 subnet for this purpose.

You also need one subnet per each workspace that you plan to run. ML uses the Kubenet plugin to AKS and the subnet used for a workspace cannot be shared with another workspace or another service. You can choose which subnet is used by a workspace at the time of provisioning. Cloudera recommends a /25 CIDR for these subnet, but if you would like to provide a custom range, the formula to calculate IP Addresses per workspace is as follows:
  • Each workspace can grow up to 30 CPU worker nodes and 30 GPU workers; each node consumes one IP address.
  • In addition, you need to allocate up to 11 IP address (6 infrastructure nodes and 5 for auxiliary networking usage).