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CIDR Blocks in VPCs

Learn how VPCs use CIDR notation to define address ranges

CoreWeave VPCs use CIDR notation to define IP address ranges for the hosts, Pods, Load Balancers, and other Services used in each VPC.

Understanding CIDR blocks is especially useful for customers who need to know IP ranges in advance of integrating with existing environments, such as with Direct Connect.

Configuring CIDR blocks in VPCs​

Below is an example YAML configuration for a single VPC containing multiple clusters, indicating the assignment of different CIDR ranges for different resources:

Example vpc.yaml
organizations:

  abc123:

    vpcs:

      default-us-east-04:

        hostPrefixes:

          - 10.176.192.0/18

        pubImport: true

        site: us-east-04

    clusters:

      poc-gpu:

        version: v1.30

        site: us-east-04

        vpc: default-us-east-04

        podCIDR: 10.24.0.0/13

        serviceCIDR: 10.32.0.0/22

        internalLbCIDR: 10.32.4.0/22

      poc-cpu:

        version: v1.30

        site: us-east-04

        vpc: default-us-east-04

        podCIDR: 10.48.0.0/13

        serviceCIDR: 10.56.0.0/22

        internalLbCIDR: 10.56.4.0/22

CIDR block size guidelines​

CIDR blocks for Nodes, Pods, Services, and Load Balancers have different subnet allocation limits. The following guidelines are based on the maximum number of resources that can be accommodated in each CIDR block:

KeyValueDescription
hostPrefixes/18An /18 CIDR block accommodates clusters with up to 4,000 Nodes. Each Node requires 2 IP addresses.
podCIDR/13A /13 CIDR block allows up to 100 Pods per Node.
serviceCIDR/22A /22 CIDR block allows up to 1000 Services.
internalLbCIDR/22A /22 CIDR block allows up to 1000 Load Balancers.
Info

Customers with smaller environments may be able to use smaller CIDR ranges. For example, if the cluster is planned to have only 500 Nodes, a large CIDR block isn't required - however, using smaller CIDR ranges may limit future expansion, as Service IPs must be contiguous.

Additional resources​

How-to guides​

References​

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