User's Manual

Configuration Guide of XGS-5240-Series
37-2
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 REQUEST message to request the address
which is advertised in the ADVERTISE message.
4. The selected DHCPv6 server then confirms the client about the IPv6 address and
any other configuration with the REPLY message.
The above four steps finish a Dynamic host configuration assignment process. However, if
the DHCPv6 server and the DHCPv6 client are not in the same network, the server will not
receive the DHCPv6 broadcast packets sent by the client, therefore no DHCPv6 packets will
be sent to the client by the server. In this case, a DHCPv6 relay is required to forward such
DHCPv6 packets so that the DHCPv6 packets exchange can be completed between the
DHCPv6 client and server.
At the time this manual is written, DHCPv6 server, relay and prefix delegation client have
been implemented on the switch. When the DHCPv6 relay receives any messages from the
DHCPv6 client, it will encapsulate the request in a Relay-forward packet and deliver it to the
next DHCPv6 relay or the DHCPv6 server. The DHCPv6 messages coming from the server
will be encapsulated as relay reply packets to the DHCPv6 relay. The relay then removes the
encapsulation and delivers it the DHCPv6 client or the next DHCPv6 relay in the network.
For DHCPv6 prefix delegation where DHCPv6 server is configured on the PE router and
DHCPv6 client it configured on the CPE router, the CPE router is able to send address prefix
allocation request to the PE router and get a pre-configured address prefix, but not set the
address prefix manually. The protocol negotiation between the client and the prefix delegation
client is quite similar to that when getting a DHCPv6 address. Then the CPE router divides the
allocated prefix – whose length should be less than 64 characters, into 64 subnets. The
divided address prefix will be advertised through routing advertisement messages (RA) to the
host directly connected to the client.
37.2 DHCPv6 Server Configuration
DHCPv6 server configuration task list as below:
1. To enable/disable DHCPv6 service
2. To configure DHCPv6 address pool
（1） To achieve/delete DHCPv6 address pool