Subnet Details

You can adjust several options for project network subnets, including DHCP, IP allocation pools, DNS server addresses, and host routes.

These options are available on the Subnet Details tab when you create or edit a project network subnet.

Note

IP addresses on project network subnets are always managed internally. For external address management, use project networks without subnets. For more information, see Project Network IP Address Management.

When creating a new IP subnet for a project network, you can specify the following attributes:

Enable DHCP

When this attribute is enabled, a virtual DHCP server becomes available when the subnet is created. It uses the (MAC address, IP address) pairs registered in the Neutron database to offer IP addresses in response to DHCP discovery requests broadcast on the subnet. DHCP discovery requests from unknown MAC addresses are ignored.

When the DHCP attribute is disabled, all DHCP and DNS services, and all static routes, if any, must be provisioned externally.

Allocation Pools

This a list attribute where each element in the list specifies an IP address range, or address pool, in the subnet address space that can be used for dynamic offering of IP addresses. By default, there is a single allocation pool comprised of the entire subnet’s IP address space, with the exception of the default gateway’s IP address.

An external, non-Neutron, DHCP server can be attached to a subnet to support specific deployment needs as required. For example, it can be configured to offer IP addresses on ranges outside the Neutron allocation pools to service physical devices attached to the project network, such as testing equipment and servers.

DNS Name Servers

You can reserve IP addresses for use by DNS servers.

Host Routes

You can use this to specify host connections to routers on the subnet.