22.1.1 Overview

An IPv6 DHCP relay forwards IPv6 DHCP packets to an IPv6 DHCP server when the IPv6 DHCP server and IPv6 DHCP clients are on different network segments. Forwarding is enabled by setting the destination specified in the configuration (IP address of the IPv6 DHCP server or IP address of the IPv6 DHCP relay that can forward packets to the network segment containing the IPv6 DHCP server) as the destination address of IPv6 DHCP packets.

An IPv6 DHCP relay running on the Switch can handle the two types of devices below for clients. Together, these clients are called IPv6 DHCP clients.

• IPv6 DHCP-PD (prefix delegation) clients

• IPv6 DHCP clients that request IPv6 addresses

Similarly, IPv6 DHCP-PD servers and IPv6 DHCP servers that distribute IPv6 addresses are collectively called IPv6 DHCP servers.

IPv6 DHCP clients use link-local multicasting to use the services provided by an IPv6 DHCP server. Therefore, the IPv6 DHCP server needs to exist on the same network segment as the IPv6 DHCP clients. However, when you use an IPv6 DHCP relay on the Switch, the IPv6 DHCP relay can forward the IPv6 DHCP packets sent by the IPv6 DHCP clients to a different network segment. This way, the IPv6 DHCP server in one network segment can provide services to the IPv6 DHCP clients on another network segment.

Note that in this chapter, the configuration diagrams use IPv6 DHCP-PD for the examples. IPv6 DHCP clients that request IPv6 addresses operate the same way with the exception of some functions such as automatic route generation linked with prefix distribution and the display of binding information by prefix distribution management.

The following figure shows different connection configurations with an IPv6 DHCP relay.

Figure 22-1: Connecting IPv6 DHCP Relays