HP-UX Reference (11i v2 07/12) - 1M System Administration Commands A-M (vol 3)

d
dhcpv6d(1M) dhcpv6d(1M)
NAME
dhcpv6d - Dynamic Host Configuration Protocol Server daemon for IPv6
SYNOPSIS
/usr/sbin/dhcpv6d
[-d][-c config_file]
/usr/sbin/dhcpv6d -k
/usr/sbin/dhcpv6d -r
DESCRIPTION
The dhcpv6d server daemon is the IPv6 version of the bootpd daemon. This version supports the follow-
ing features:
• Dynamic renumbering
• Relay preconfiguration with server addresses, or use of multicast addresses
• Multiple IP addresses for an interface
The
dhcpv6d daemon is run as a stand-alone daemon and not spawned by
inetd.
Options
-d Toggle debugging on or off.
-c config_file Specify an alternate configuration file for the server. The default configuration file is
/etc/dhcpv6tab.
-r Re-read the configuration file and trigger the server to send a reconfig-init message to
the clients when the configuration file has any new or updated information.
-k Kill the server gracefully.
Configuration
When an unconfigured host needs to be configured, it checks for router advertisements. From the router
advertisement, depending on the prefix obtained, the host will generate either a site-local or a global
address.
If there are no routers on the link on which the host is located, it uses dhcpv6client
to configure itself.
The client forms a SOLICIT message and sends it to the pre-determined ALL DHCP agents address. In
response to this, the client will receive ADVERTISE messages from a few DHCP servers. The client will
select the server based on the preference values in advertise messages. Refer to the "Configuraion File" sec-
tion for information on how to set the DHCP’s server preference value.
In response to the ADVERTISE message, the client will send a REQUEST message to the server either
directly if the server is on the same link as that of the client or through the on-link relay. The server
responds with REPLY message containing the requested configuration parameters.
The DHCP server assigns addresses to the clients using "Identity Association (IA)", which is a collection of
addresses assigned to a client. The client uses the addresses in the IA to configure its interfaces.
If the client determines that the address allocated to it by the server is already in use, it will send a
RELEASE message to the server.
To extend the lifetime of the addresses assigned to an IA, the client sends a RENEW message to the server,
which contains the IA and the associated addresses. The server will determine the new lifetimes for the
addresses on the IA based on the server’s administrative configuration. The server will respond to this mes-
sage with a REPLY message. The server controls the time at which the client contacts the server to extend
the lifetimes on assigned addresses through the T1 and T2 parameters that are assigned to the IA. The
client initiates a RENEW message at time T1.
If the server to which the RENEW message is sent does not respond, then the client will increase the
timeout and wait for a response. The client continues sending the message until the expiration of T2. But at
time T2 for the IA, the client initiates a REBIND message. This message is sent to all the servers in the
domain. The server will respond to this message and will renew the lifetime of the assigned addresses. If
the client does not receive a response to its REBIND message, it tries resending the message until the
expiration of lifetimes of all the addresses in IA. The client will choose one of the following alternatives:
• Some addresses in the IA may have lifetimes that extend beyond the lease of the IA. The client may
choose to continue to use those addresses.
174 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: December 2007 Update