Dhcpv6 Relay - ZyXEL Communications MES3500 series User Manual

Chapter 37 DHCP
dormitory rooms (VLAN 1) to the DHCP server with an IP address of 192.168.1.100. Requests from
the academic buildings (VLAN 2) are sent to the other DHCP server with an IP address of
172.16.10.100.
Figure 181 DHCP Relay for Two VLANs
DHCP: 192.168.1.100
VLAN 1
VLAN 2
DHCP: 172.16.10.100
For the example network, configure the VLAN Setting screen as shown.
Figure 182 DHCPv4 Relay for Two VLANs Configuration Example

37.5 DHCPv6 Relay

A DHCPv6 relay agent is on the same network as the DHCPv6 clients and helps forward messages
between the DHCPv6 server and clients. When a client cannot use its link-local address and a well-
known multicast address to locate a DHCPv6 server on its network, it then needs a DHCPv6 relay
agent to send a message to a DHCPv6 server that is not attached to the same network.
The DHCPv6 relay agent can add the remote identification (remote-ID) option and the interface-ID
option to the Relay-Forward DHCPv6 messages. The remote-ID option carries a user-defined string,
such as the system name. The interface-ID option provides slot number, port information and the
VLAN ID to the DHCPv6 server. The remote-ID option (if any) is stripped from the Relay-Reply
messages before the relay agent sends the packets to the clients. The DHCPv6 server copies the
interface-ID option from the Relay-Forward message into the Relay-Reply message and sends it to
the relay agent. The interface-ID should not change even after the relay agent restarts.
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