Dhcp Version 6

IPv6 DHCP configuration (/etc/dhcp/dhcpd6.conf) has the following sections:

Global options
Cablelabs options
Subnets
Hosts

Global options provided by the Dhcpd distribution package. IP6M adds its own data via include:

include "/etc/dhcp/ip6m-dhcpd6.conf";

at the end of the default dhcpd6.conf file. The content of this file is the following. A complete, working example of this config file can be found in IP6M under the " /ip6m_dhcp/dhcpd6" path if the "ip6m_testdata" module is enabled.

Cablelabs options definition

# declare the option space where the CableLabs options live
option space docsis code width 2 length width 2 hash size 100;
option docsis.tftp-servers code 32 = array of ip6-address;
option docsis.configuration-file code 33 = text;
option docsis.syslog-servers code 34 = array of ip6-address;
option docsis.device-id code 36 = string;
option docsis.time-servers code 37 = array of ip6-address;
option docsis.time-offset code 38 = signed integer 32;
option vsio.docsis code 4491 = encapsulate docsis;

Subnets

Similar to the IPv4 configuration, a subnet declaration is needed for the server's local network. This assumes, that the server has its IPv6 address assigned from the 2001:db8::/64 network, e.g.: 2001:db8::10/64

subnet6 2001:db8::/64 {
	range6 2001:db8::100 2001:db8::110;
}

Subnet declaration for a network behind a Docsis CMTS with IPv6 prefix delegating:

subnet6 2001:db8:4:11::/64 {
	range6 2001:db8:4:11::2 2001:db8:4:11::100;
	prefix6 2001:db8:4:100:: 2001:db8:4:200:: /64;
	option docsis.syslog-servers 2001:db8::10;
	option docsis.time-servers 2001:db8::10;
	option docsis.tftp-servers 2001:db8::10;
	option docsis.time-offset 3600;
}

Hosts in this subnet receive IP address from range 2001:db8:4:11::2 -> 2001:db8:4:11::100 and a delegated /64 prefix from the 2001:db8:4:100:: to 2001:db8:4:200:: range. This prefix is used in the customer's local network to assign unique, public IP addresses to every host. This is the main difference between IPv4 and IPv6 nowadays, when IPv4 networks use private ip addresses translated to the one public address assigned to the CPE router.

Hosts

host modem-2 {
	hardware ethernet 44:32:c8:21:09:e7;
	fixed-address6 2001:db8:4:11::4432:c821:09e7;
	option docsis.configuration-file "cm/cm-2.cfg";
}
host modem-3 {
	hardware ethernet 44:32:c8:41:8c:67;
	fixed-address6 2001:db8:4:11::4432:c841:8c67;
	option docsis.configuration-file "cm/cm-3.cfg";
}
host modem-4 {
	hardware ethernet 00:1e:6b:e6:b4:a5;
	fixed-address6 2001:db8:4:11::001e:6be6:b4a5;
	option docsis.configuration-file "cm/cm-4.cfg";
}

Host declarations for Docsis cable modems are very similar to the IPv4 version. IP6M calculates fix IP addresses from the cable modem's mac address.

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