C
HAPTER
44
| DHCP Commands
DHCP Client
– 1387 –
flag (M flag) and Other Stateful Configuration flag (O flag) received in
Router Advertisement messages will determine the information this
switch should attempt to acquire from the DHCPv6 server as described
below.
â–
Both M and O flags are set to 1:
DHCPv6 is used for both address and other configuration settings.
This combination is known as DHCPv6 stateful, in which a DHCPv6
server assigns stateful addresses to IPv6 hosts.
â–
The M flag is set to 0, and the O flag is set to 1:
DHCPv6 is used only for other configuration settings.
Neighboring routers are configured to advertise non-link-local
address prefixes from which IPv6 hosts derive stateless addresses.
This combination is known as DHCPv6 stateless, in which a DHCPv6
server does not assign stateful addresses to IPv6 hosts, but does
assign stateless configuration settings.
â—† DHCPv6 clients build a list of servers by sending a solicit message and
collecting advertised message replies. These servers are then ranked
based on their advertised preference value. If the client needs to
acquire prefixes from servers, only servers that have advertised
prefixes are considered.
â—† If the rapid commit option has been enabled on the switch using the
ipv6 dhcp client rapid-commit vlan command, and on the DHCPv6
server, message exchange can be reduced from the normal four step
process to a two-step exchange of only solicit and reply messages.
EXAMPLE
The following command submits a client request on VLAN 1.
Console#ipv6 dhcp restart client vlan 1
Console#
RELATED COMMANDS
ipv6 address autoconfig (1408)
show ipv6 dhcp
duid
This command shows the DHCP Unique Identifier for this switch.
COMMAND MODE
Privileged Exec
COMMAND USAGE
â—† DHCPv6 clients and servers are identified by a DHCP Unique Identifier
(DUID) included in the client identifier and server identifier options.
Static or dynamic address prefixes may be assigned by a DHCPv6
server based on the client’s DUID.
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