With the configuration of a solicit-delay, the forwarding of a DHCP Solicit Message to the DHCP server is delayed resulting in a delayed DHCPv6 Advertise to the DHCP client. A solicit-delay (in deciseconds) can be configured for DHCP Solicit messages, as shown in the following examples:
originated by DHCP clients with odd or even MAC addresses
dhcp6
relay
advertise-selection
client-mac odd
solicit-delay 5
exit
exit
server 2001:db8::1
no shutdown
exit
exit
sent to a specific DHCP server (a delay for up to eight servers can be configured)
dhcp6
relay
advertise-selection
server 2001:db8::2
solicit-delay 5
exit
exit
server 2001:db8::1
server 2001:db8::2
no shutdown
exit
exit
for which no per client MAC or per DHCP server solicit-delay is configured (for example, a default solicit-delay)
dhcp6
relay
advertise-selection
solicit-delay 5
exit
server 2001:db8::1
no shutdown
exit
exit
With the configuration of a preference-option value, a DHCPv6 Preference Option (7) with the configured value is inserted in the Advertise Message to the DHCP client. A DHCPv6 client can use the preference value to select one out of multiple received Advertise messages. A preference-option value (0 to 255) can be configured for DHCP Advertise Messages, as shown in the following examples:
sent to DHCP clients with odd or even MAC addresses
dhcp6
relay
advertise-selection
client-mac odd
preference-option
value 200
exit
exit
exit
server 2001:db8::1
no shutdown
exit
exit
sent to a specific DHCP server (a preference-option value for up to eight servers can be configured)
dhcp6
relay
advertise-selection
server 2001:db8::2
preference-option
value 200
exit
exit
exit
server 2001:db8::1
server 2001:db8::2
no shutdown
exit
exit
for which no per client MAC or per DHCP server preference-option value is configured (for example, a default preference-option value)
dhcp6
relay
advertise-selection
preference-option
value 200
exit
exit
server 2001:db8::1
no shutdown
exit
Additional considerations:
A solicit-delay and preference-option value can be configured simultaneously.
Configuring a per DHCP server solicit-delay and preference-option value and a per DHCP client MAC address solicit-delay or preference-option value is mutually exclusive.
A default solicit-delay and preference-option value can be combined with either a per DHCP server or a per DHCP client MAC configuration.
When a new solicit message is received from the same client, such as a retransmitted message while a solicit-delay timer is running, the solicit-delay timer is stopped, the queued solicit message is discarded, and the new Solicit message is immediately forwarded without delay.