2 Technical Note
DHCPv6
C613-05019-00 REV A
25 August 2003
What can DHCPv6 do?
When the router is configured as a DHCP6 server it can:
■ delegate prefixes to IPv6 subnets
This allows for an ease of address configuration. For example, if a company
moves ISPs they would require a different prefix to be assigned to the main
router. The router would then advertise this prefix and no reconfiguration
of the hosts should be necessary (apart from applications that rely on certain
addresses).
■ assign normal and temporary IPv6 addresses to devices.
An IPv6 address is a hexadecimal string, made up from eight pairs of octets
separated by colons, for example 3ffe:2::0:1. For more information about
IPv6 addresses, see the IPv6 chapter in your Allied Telesyn Software
Reference Manual. Normal addresses are renewed by the server for as long
as the device requires an address. Temporary addresses are assigned for a
limited time (lease time) and are usually allocated for privacy reasons, as
outlined in RFC 3041 “Privacy Extensions for Stateless Address
Autoconfiguration in IPv6”.
DHCP6 uses multicast and unicast addresses for communication similar to the
IPv4 broadcast address. Addresses reserved are:
■ FF02::1:2
This link scope multicast address is used by clients to communicate with
DHCP6 servers
■ FF05::1:3
This site scope multicast address is used by clients to communicate with
DHCP6 servers. When DHCP6 is configured, the router listens on this
address.
Security
The DHCP6 server and client allow for DHCP6 message authentication for
security purposes. The server and client maintain a pair of ‘keys’ and a ‘key-id’.
You can create the key on the server and copy it to the client, or the other way
around.
You can create a key and give it a key-id using the CREATE ENCO KEY
command, and then link each key to the required DHCP6 client using the
command ADD DHCP6 KEY.
IP Address Assignment Configuration
Example
This example illustrates the steps required to configure a DHCP6 server and
DHCP6 client.
DHCP6 Server Configuration
1. Enable the IPv6 module.
Enable IPv6, using the command:
ENABLE IPV6
