Vijaya Bhaskar A K

Internet Services

Jan 5, 2000

DHCPv6 and Address Configuration

IPv6 Addressing Architecture

• Unicast Address

• Multicast Address

• Anycast Address

Unicast Address

•Unspecified Address (0:0:0:0:0:0:0:0)

•Loopback Address (0:0:0:0:0:0:0:1)

•IPv4 Embedded IPv4 address

•IPv4 compatible IPv6 Address (e.g.) ::15.10.23.2

•IPv4 mapped IPv6 Address (e.g.) ::ffff:15.10.23.2

•Aggregatable Global Unicast Address

•Link Local Address (prefix is fe80)

•Site Local Address (prefix is fec0)

Multicast and Anycast Address

•Multicast

•Link local (prefix is FF02)

•Site local (prefix is FF05)

•Globally unique (prefix is FF0E)

•Anycast

•Allocated in Unicast Space

•(e.g.) Subnet Router Anycast Address

subnet-prefix(n bits)+0s(128-n bits)

Life Times of IP Addresses

• Valid Life Time

• Preferred Life Time

IPv6 Address Configuration

• Stateful Autoconfiguration

• Stateless Autoconfiguration

Stateless Autoconfiguration

• Advantages

• Simple to use

• No need of Servers

Stateless Autoconfiguration

• Disadvantages

• Inefficient use of address space

• Lack of Network Access Control

• Manages Only Addresses

• No Authentication

Reconfiguration in DHCPv6

• Server plays active role

• Used by Network Administrator in

network renumbering

Stateful Autoconfiguration

• Dynamic Host Configuration Protocol for IPv6 (DHCPv6)

• Client / Server Model of Architecture

• Centralized Address Management

DHCP Message Transactions

DHCPv6CLIENT

DHCPv6AGENT

DHCPv6SERVER

DHCP Solicit

DHCP Advertise

DHCP Advertise

DHCP Solicit

DHCP Message Transactions

DHCPv6CLIENT

DHCPv6AGENT

DHCPv6SERVER

DHCP Request

DHCP Reply

DHCP Reply

DHCP Request

DHCP Message Transactions

DHCPv6CLIENT

DHCPv6AGENT

DHCPv6SERVER

DHCP Release

DHCP Reply

DHCP Reply

DHCP Release

DHCP Message Transactions

DHCPv6 CLIENT

DHCPv6SERVER

DHCP Reconfigure- init DHCP ReplyDHCP Request

Identity Association

•Identifies Client bindings

•IA constitutes following fields

•UUID

•Time values T1 and T2

•IP Addresses

Features of DHCPv6

•Multiple IP addresses per interface

•Authentication

•Reconfiguration

•Freedom from BOOTP Compatibility

•Dynamic DNS Updates

Authentication in DHCPv6

•Need for authentication

•ensures the parameters are obtained from authoritative servers

•prevents denial of service attacks

•Authentication Mechanism

•HMAC using keyed-MD5

•Replay Protection

Current Standards

• Internet Draft on DHCPv6 draft-ietf-dhc-dhcpv6-16.txt

• Internet Draft on DHCPv6 Extensions draft-ietf-dhc-dhcpv6exts-12.txt

Features of the New Draft

•Common DHCP message headers

•Removal of Reconfigure and Reconfigure Reply messages

•New Relay behavior - Encapsulated message

•Introduction of Identity Association