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29.1 Introduction to DHCPv6
DHCP v6 [RFC3315] is the IPv6 version for Dynamic Host Configuration Protocol (DHCP). It is a protocol
that assigns IP v6 address as well as other network configuration parameters such as DNS address, and
domain name to DHCP v6 client, DHCP v6 is a conditional auto address configuration prot ocol relative to IP v6.
In the conditional address configuration process, DHCP v6 server assigns a complete IP v6 address to client,
and provides DNS address, domain name and other configuration information, maybe the DHCP v6 packet
can transmit through relay delegation, at last the binding of IP v6 address and client can be recorded by
DHCP v6 server, all that can enhance the management of network; DHCP v6 server can also provide non state
DHCP v6 service, that is only assigns DNS address and domain name and other configuration information but
not assigns IP v6 address, it can solve the bug of IP v6 auto address configuration in non state; DHCP v6 can
provide extend function of DHCP v6 prefix delegation, upstream rout e can assign address prefix to
downstream route automatically, that achieve the IP v6 address auto assignment in levels of network
environment, and resolved the problem of ISP and IP v6 network dispose.
There are three entities in the DHCP v6 prot ocol – the client, the relay and the server. The DHCP v6 prot ocol is
based on the UDP protocol. The DHCP v6 client sends request messages to the DHCP server or DHCP relay
with the destination port as 547, and the DHCP v6 server and relay send replying messages with the
destination port as 546. The DHCP v6 client sends solicit or request messages with the multicast address –
ff02::1:2 for DHCP relay and server.
DHCP v6 CLIE NT
When a DHCP v6 client tries to request an IP v6 address and other configurations from the DHCP v6 server,
the client has to find the location of the DHCP server, and then request configurations from the DHCP server.
1.
In the time of located server, the DHCP client tries to find a DHCP v6 server by broadcasting a
SOLICIT packet to all the DHCP delay delegation and server with broadcast address as FF02::1:2.
2.
Any DHCP server which receives the request, will reply the client with an ADVERTISE message,
which includes the identity of the server –DUID, and its priority.
3.
It is possible that the client receives multiple ADVERTISE messages. The client should select one
and reply it with a REQUES T message to request the address which is advertised in the
ADVERTISE message.
4.
The selected DHCP v6 server then confirms the client about the IP v6 address and any other
configuration with the REP LY message.
Chapter 29 DHCPv6 Configuration
Solicit (Muticast)
Advertise (Unicast)
Request (Muticast)
Reply (Unicast)
Figure 29-1-1
DHCP v6 SERVER
DHCP v6 negotiation
29-1
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