Types of DHCP on a Segment

NSX-T Data Center supports three types of DHCP on a segment: DHCP local server, Gateway DHCP, and DHCP relay.

DHCP Local Server

As the name suggests, it is a DHCP server that is local to the segment and not available to the other segments in the network. A local DHCP server provides a dynamic IP assignment service only to the VMs that are attached to the segment. The IP address of a local DHCP server must be in the subnet that is configured on the segment.

Gateway DHCP

It is analogous to a central DHCP service that dynamically assigns IP and other network configuration to the VMs on all the segments that are connected to the gateway and using Gateway DHCP. Depending on the type of DHCP profile you attach to the gateway, you can configure a Gateway DHCP server or a Gateway DHCP relay on the segment. By default, segments that are connected to a tier-1 or tier-0 gateway use Gateway DHCP. The IP address of a Gateway DHCP server can be different from the subnets that are configured in the segments.

DHCP Relay

It is a DHCP relay service that is local to the segment and not available to the other segments in the network. The DHCP relay service relays the DHCP requests of the VMs that are attached to the segment to the remote DHCP servers. The remote DHCP servers can be in any subnet, outside the SDDC, or in the physical network.

You can configure DHCP on each segment regardless of whether the segment is connected to a gateway. Both DHCP for IPv4 (DHCPv4) and DHCP for IPv6 (DHCPv6) servers are supported.

For a gateway-connected segment, all the three DHCP types are supported. However, Gateway DHCP is supported only in the IPv4 subnet of a segment.

For a standalone segment that is not connected to a gateway, only local DHCP server is supported.

The following restrictions apply to DHCPv6 server configuration on an IPv6 subnet:

• Segments configured with an IPv6 subnet can have either a local DHCPv6 server or a DHCPv6 relay. Gateway DHCPv6 is not supported.
• DHCPv6 Options (classless static routes and generic options) are not supported.