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IPv6 DHCP Protocol Overview

You can configure NIOS appliances to support DHCP for IPv6 (DHCPv6), the protocol for providing DHCP services for IPv6 networks.
The DHCPv6 client-server model is similar to that of IPv4. DHCP clients and servers use a reserved, link-scoped multicast address to exchange DHCP messages. When a DHCP client needs to send messages to a DHCP server that is not attached to the same link, a DHCP relay agent can be used to relay messages between the client and server.
Each IPv6 DHCP server and client has a unique DHCP unique identifier (DUID). DHCP servers use DUIDs to identify clients when providing configuration parameters, and clients use DUIDs to identify the source of the DHCP messages from servers.
As illustrated in Figure 25.2, a DHCP client that needs an IPv6 address sends a Solicit message to the well-known multicast address. DHCPv6 servers then send Advertise messages to the client to indicate that they are available. The client sends a Request message to a specific DHCPv6 server to request IP addresses and configuration parameters. The DHCPv6 server responds with a Reply message that contains the IP addresses and configuration parameters. You can view statistics about the IPv6 messages on the Dashboard.
Figure 25.2 Client DHCPv6 Configuration Workflow



Infoblox DHCP servers also supports stateless configuration in which a DHCP client does not need IP addresses, but needs configuration information only. The DHCP client sends an Information-Request packet to obtain configuration information, and the server sends a Reply message with the requested information. For more information, refer to RFC 2462, IPv6 Stateless Address Autoconfiguration.

IPv6 Address Structure

An IPv6 address consists of the following:

  • Global Routing Prefix — Global routing prefix is a (typically hierarchically-structured) value assigned to a site. For example, an ISP can delegate a prefix to your site, which you can then divide into subnets.
  • Subnet ID — Subnet ID is an identifier of a link within the site.
  • Interface ID — Interface Identifier. This portion of the address identifies the interface on the subnet. This is equivalent to the host identifier for IPv4 addresses.


Figure 25.3 IPv6 Address Structure

 
When you enter an IPv6 address in Grid Manager, you can use double colons to compress a contiguous sequence of zeros. You can also omit any leading zeros in a four-hexadecimal group. For example, the complete IPv6 address 2006:0000:0000:0123:4567:89ab:0000:cdef can be shortened to 2006::123:4567:89ab:0:cdef. Note that if there are multiple noncontiguous groups of zeros, the double colon can only be used for one group to avoid ambiguity. The NIOS appliance displays an IPv6 address in its shortened form, regardless of its form when it was entered.