Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 1739)

DHCP for IPv6 (DHCPv6) Introduction and Configuration
Software Reference for x310 Series Switches
C613-50046-01 REV A AlliedWare Plus TM Operating System - Version 5.4.4C 65.3
DHCPv6 Messages
DHCPv6 uses multicast and unicast addresses for communication. A multicast address
provides the equivalent functionality to an IPv4 broadcast address. It identifies a group of
interfaces, and packets are sent to all interfaces in that group. Addresses reserved for
DHCPv6 messages are:
■ ff02::1:2. This link-scope multicast address is used by clients to communicate with
DHCPv6 servers. When the DHCPv6 module is enabled the switch listens to this
address.
■ ff05::1:3. This site-scope multicast address is used by clients to communicate with
DHCPv6 servers. When the DHCPv6 module is enabled the switch listens to this
address.
An IPv6 address may be assigned to the DHCPv6 Client for a limited or unlimited time. If
the address lifetime is limited, it has a preferred lifetime and a (generally longer) valid
lifetime.
Preferred IPv6 addresses are available to interfaces for unrestricted use and are deprecated
when the preferred timer expires.
Deprecated IPv6 addresses are available for use and are discouraged but not forbidden. A
deprecated address should not be used as a source address, but packets sent from
deprecated addresses are delivered as expected.
An IPv6 address becomes invalid and is not available to an interface when the valid
lifetime timer expires. Invalid addresses should not appear as the source or destination for
a packet.
Once half the time between address assignment and the preferred lifetime has passed (the
T1 time), the client sends a Renew message to the server, requesting an extension to the
address lifetime.
If the client has not received a reply after 80% of the valid lifetime has passed (the T2 time),
it sends a multicast Rebind message to discover another DHCPv6 Server
In a DHCPv6 Client/DHCPv6 Server environment, DHCPv6 messages are sent from the
DHCPv6 Clients to DHCPv6 Server destination UDP port 547. DHCPv6 Servers respond to
DHCPv6 Client destination UDP port 546.
DHCPv6 Message Types
See the below list of DHCPv6 Message Types supported in AlliedWare Plus:
■ SOLICIT:
A DHCPv6 Client sends a SOLICIT message to locate DHCPv6 Servers.
■ ADVERTISE:
A DHCPv6 Server sends an ADVERTISE message to indicate that it is available for
DHCPv6 service in response to a SOLICIT message received from a DHCPv6 Client.
■ REQUEST:
A DHCPv6 Client sends a REQUEST message to request configuration parameters,
including IPv6 addresses.