DHCP IP Pool Exhaustion

Products

• VMware NSX

Issue/Introduction

Title: Alarm for DHCP IP Pool exhaustion
Event ID: ip_pool_exhausted
Alarm Description

• Purpose: To indicate IP addresses in a DHCP IP Pool have been exhausted.
• Impact: In this case, the virtual machine intended for network connection will receive an Automatic Private IP Addressing (APIPA) and won't obtain a legitimate IP address from the DHCP server.

Environment

VCF 9.1

Resolution

For VCF 9.1 and higher:

• Retrieve the affected Org, Project, VPC and Subnet details from the Alarm message.
• GET IP pool usage statistics for DHCP server using /policy/api/v1/orgs/{org-id}/projects/{project-id}/vpcs/{vpc-id}/subnets/{subnet-id}/dhcp-server-config/stats.
• If allocated_number == consumed_number
  • Maximum possible workloads in the subnet have been reached. Consider deploying new VMs in a different subnet.
• If allocated_number > consumed_number
  • Compare outstanding leases against the active VMs using /policy/api/v1/orgs/{org-id}/projects/{project-id}/vpcs/{vpc-id}/subnets/{subnet-id}/state/dhcp-server-leases.
  • If the active VMs are lesser than the outstanding leases, follow either of the following 2 options:
    • Identify the inactive VM leases from GET /policy/api/v1/orgs/{org-id}/projects/{project-id}/vpcs/{vpc-id}/subnets/{subnet-id}/state/dhcp-server-leases and delete the leases using POST /policy/api/v1/orgs/{org-id}/projects/{project-id}/vpcs/{vpc-id}/subnets/{subnet-id}/actions/release-dhcp-server-leases
    • Reducing lease time in the service profile used by the VPC that the subnet belongs. This will result in lesser lease timeout upon next DHCP renewal from VMs.