DHCP¶

When using managedTap, SR-IOV, or DPDK type networks, KubeVirt's built-in DHCP cannot function in these network modes. Kube-OVN leverages OVN's DHCP capabilities to configure DHCP options at the subnet level, enabling virtual machines (VMs) under these network types to properly obtain IP addresses via DHCP. Additionally, Kube-OVN's DHCP supports advanced options such as DHCPv6, IPv6RA, DNS, and TFTP, allowing users to customize DHCP service behavior based on their needs.

Warning

For bridge type networks, KubeVirt's DHCP intercepts and responds to DHCP requests before Kube-OVN, making Kube-OVN's DHCP settings ineffective. To utilize Kube-OVN's advanced DHCP features, we recommend replacing bridge type networks with managedTap type networks. For managedTap network configuration, refer to Configuring the managedTap Network Binding Plugin.
Currently, only subnet-level DHCP configuration is supported; Pod-level DHCP configuration is not available.

The Subnet DHCP is configured as follows:

apiVersion: kubeovn.io/v1
kind: Subnet
metadata:
  name: sn-dual
spec:
  cidrBlock: "10.0.0.0/24,240e::a00/120"
  default: false
  disableGatewayCheck: true
  disableInterConnection: false
  excludeIps:
    - 10.0.0.1
    - 240e::a01
  gateway: 10.0.0.1,240e::a01
  gatewayNode: ''
  gatewayType: distributed
  natOutgoing: false
  private: false
  protocol: Dual
  provider: ovn
  vpc: vpc-test
  enableDHCP: true
  dhcpV4Options: "lease_time=3600,router=10.0.0.1,server_id=169.254.0.254,server_mac=00:00:00:2E:2F:B8"
  dhcpV6Options: "server_id=00:00:00:2E:2F:C5"
  enableIPv6RA: true
  ipv6RAConfigs: "address_mode=dhcpv6_stateful,max_interval=30,min_interval=5,send_periodic=true"

enableDHCP: Whether to enable the DHCP function for the subnet.
dhcpV4Options,dhcpV6Options: This field directly exposes DHCP-related options within ovn-nb, please read DHCP Options for more detail. The default value is "lease_time=3600, router=$ipv4_gateway, server_id=169.254.0.254, server_mac=$random_mac" and server_id=$random_mac.
enableIPv6RA: Whether to enable the route broadcast function of DHCPv6.
ipv6RAConfigs: This field directly exposes DHCP-related options within ovn-nb Logical_Router_Port, please read Logical Router Port for more detail. The default value is address_mode=dhcpv6_stateful, max_interval=30, min_interval=5, send_periodic=true.

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DHCP¶

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