1. By : Santosh Yadav IIT Kanpur
IPv6 DHCP
By : Santosh Yadav
IIT Kanpur

2. IPv6 Dynamic Host Configuration Protocol Overview
Evolution Of DHCPv6
DHCPv6 Concepts
Installation
Configuration

3. Evolution Of DHCPv6
To boot the machines in a LAN, needs lot of network parameters to be configured in each machine.
In order to avoid this manual process, all the network parameters are put in a server and when a machine in LAN is booting, it will contact the server for the configuration parameters. This is called BOOTP server. Later it is extended to DHCP with additional features.
Generally called DHCP

4. Evolution Of DHCPv6
IP configuration in IPV6 is carried out by IPV6 auto-configuration
IPv6 auto-configuration
Stateless
nodes configure addresses themselves with
information from routers (if available);
no managed addresses
Stateful
nodes use DHCPv6 to obtain addresses.
Duplicate address detection (DAD) used to avoid
duplicated addresses

5. What is DHCPv6 ? The Dynamic Host Configuration Protocol for IPv6
Dhcpv6 Concepts
What is DHCPv6 ?
The Dynamic Host Configuration Protocol for IPv6
(DHCP) enables DHCP servers to pass configuration
parameters such as IPv6 network addresses to IPv6
nodes.
DHCPv6 protocol Released in RFC 3315
This protocol is a stateful counterpart to "IPv6 Stateless
Address Autoconfiguration" (RFC 2462).
Used separately or concurrently with the latter to obtain
configuration parameters.

6. The following lists the main differences between DHCPv4 and DHCPv6:
Dhcpv6 Concepts…
DHCPv6 Versus DHCPv4
The following lists the main differences between DHCPv4 and DHCPv6:
Unlike DHCPv4, IPv6 address allocation in DHCPv6 is
handled using a message option.
The message types, such as DHCPDISCOVER and
DHCPOFFER supported by DHCPv4 are removed in
DHCPv6. Instead, DHCPv6 servers are located by a client
SOLICIT message followed by a server ADVERTISE message
Unlike DHCPv4 clients, DHCPv6 clients can request multiple
IPv6 addresses.

7. A method of providing stateful IPv6 address configuration/assignment
Dhcpv6 Concepts…
Why we need dhcpv6 ?
A method of providing stateful IPv6 address configuration/assignment
Also provides “other” network information
DNS servers
NIS information
DHCP allows centralized control and
auditing of IP address assignments
Central point of control for resources
Dynamic DNS updates
More security versus stateless

8. Msg-type Transaction-id Options (variable)
Dhcpv6 Concepts…
DHCPv6 Basic Message Format
Msg-type
Transaction-id
Options (variable)
• SOLICIT
• ADVERTISE
• REQUEST
• CONFIRM
• RENEW
• REBIND
• REPLY
• RELEASE
• DECLINE
• RECONFIGURE
• INFORMATION-REQUEST
• RELAY-FORW
• RELAY-REPL

9. Message Type Option Meaning REBIND (6)
SOLICIT(1)
A client sends a Solicit message to locate servers.
ADVERTISE (2)
A server sends an Advertise message to indicate that it is available for DHCP service, in response to a Solicit message received from a client.
REQUEST (3)
A client sends a Request message to request configuration parameters, including IP addresses, from a specific server.
REPLY (4)
A server sends a Reply message containing assigned addresses and configuration parameters in response to a Solicit, Request, Renew, Rebind message received from a Client.
RENEW (5)
A client sends a Renew message to the server that originally provided the client's addresses and configuration parameters to extend the lifetimes on the addresses assigned to the client.
REBIND (6)
A client sends a Rebind message to any available server to extend the lifetimes on the addresses assigned to the client.

10. Messages exchanged using UDP
Dhcpv6 Concepts…
DHCP Messages
Messages exchanged using UDP
Client port – udp/546
Server Port – udp/547
Client uses Link-Local address or addresses determined using other methods to transmit and receive DHCP messages.
Server receives messages from clients using a reserved, Link-Scoped multicast address.

11. All_DHCP_Relay_Agents_and_Servers
Dhcpv6 Concepts…
DHCP Multicast Addresses
All_DHCP_Relay_Agents_and_Servers
Link-scoped multicast address used by a client to communicate with on-link relay agents and servers
FF02::1:2
All_DHCP_Servers
Site-scoped multicast address used by a relay agent to communicate with servers
FF05::1:3

12. Options data(option –len octets)
Dhcpv6 Concepts…
DHCPv6 option format and base option
Option-code
Option length
Options data(option –len octets)
• Client Identifier
• Server Identifier
• Identity Association for Non-temporary
Addresses
• Identity Association for Temporary
• IA Address
• Option Request
• Preference
• Elapsed Time
• Relay Message
• Authentication
• Server Unicast
• Status Code
• Rapid Commit
• User Class
• Vendor Class
• Vendor-specific Information
• Interface-Id
• Reconfigure Message
• Reconfigure Accept

13. Dhcpv6 Concepts…
DHCP Unique Identifer (DUID)
Each DHCP client and server has a DUID. DHCP servers use DUIDs to identify clients for the selection of configuration parameters and in client Identity Associations.
Unique across all clients and servers
Should not change over time (if possible)
Must be < 128 octets long

14. Client must associate at least one distinct IA with each
Dhcpv6 Concepts…
Identity Association
An identity association (IA) is a construct through which a server and client can identify, group, and manage a set of related IP addresses.
Client must associate at least one distinct IA with each
network interface requesting assignment of IP
addresses from DHCP server (IAID)
Must be associated with exactly one interface
Must be consistent across restarts by the client

15. DHCPv6 working DHCP client DHCP server B DHCP server A T I M E SOLICIT
ADVERTISE
ADVERTISE
REQUEST
Client select one advertise server B
REPLY
Client Now use address and parameter for lifetime
Client renew life time
RENEW
REPLY
Client releases address when shutting down
RELEASE

16. Dhcpv6 Concepts…
Dhcpv6 operation :
Client sends messages to link-local multicast address
Server unicasts response to client
Information-Request / Reply - provide client configuration
information but no addresses
Confirm / Reply - assist in determining whether client moved
Reconfigure - allow servers to initiate a client reconfiguration
Basic client/server authentication capabilities in base
standard.
DHCP Unique Identifier (DUID) used to identify clients &
servers
Identity Association ID (IAID) used to identify a collection of
addresses
Relay Agents used when server not on-link
Relay Agents may be chained

17. Ongoing Project
Previously DHCPv6 v1.001and now DHCPv available for the HP-UX 11i v1 and HP-UX 11i v2 operating systems
Dibbler is a portable DHCPv6 implementation on Linux 2.4/2.6 and Windows XP and Windows 2003.
This project was started as master thesis by Tomasz Mrugalski and Marek Senderski of Computer Science faculty on Gdansk University of Technology.
Project UNIX name: dhcpv6
Operating System: All POSIX (Linux/BSD/UNIX-like OSes), Linux

18. Update with dhcpv6-0.10-11_FC3.i386.rpm using
Installation
Dhcpv6 server :
Update with dhcpv _FC3.i386.rpm using
# rpm -U dhcpv _FC3.i386.rpm
Create a database directory
#mkdir /var/db/dhcpv6
Copy sample server configuration file
# cp dhcp6s.conf /etc/dhcp6s.conf
Start the server daemon using
# dhcp6s –dDf eth0

19. Update with dhcpv6_client-0.10-11_FC3.i386.rpm using
Installation…
Dhcpv6 client :
Update with dhcpv6_client _FC3.i386.rpm using
# rpm -U dhcpv6_client _FC3.i386.rpm
Copy sample client configuration file
# cp dhcp6c.conf /etc/dhcp6c.conf
Start the client daemon using
# dhcp6c –dDf eth0

20. In Fedora core 3 following files are configured :
Configuration
In Fedora core 3 following files are configured :
Server configuration :
/etc/sysconfig/dhcp6s
/etc/dhcp6s.conf
File : /etc/sysconfig/dhcp6s
Specify the interface for dhcp6s
DHCP6SIF=eth0

21. Server configuration... File : /etc/dhcp6s.conf Configuration…
interface eth0 {
server-preference 255;
renew-time 60;
rebind-time 90;
prefer-life-time 130;
valid-life-time 200;
allow rapid-commit;
link BBB {
pool{
range 2001:0E30:1402:2::4 to 2001:0E30:1402:2::ffff/64;
prefix 2001:0E30:1402::/48; };

22. In Fedora core 3 following files are configured :
Configuration…
In Fedora core 3 following files are configured :
Client configuration :
/etc/sysconfig/network-scripts/ifcfg-eth0
/etc/dhcp6c.conf
File : /etc/sysconfig/network-scripts/ifcfg-eth0
IPV6INIT=yes
DHCP6C=yes

23. client configuration... Configuration… interface eth0 {
File : /etc/dhcp6c.conf
interface eth0 {
#information-only;
send rapid-commit;
#request prefix-delegation;
#request temp-address;
address {
2001:0E30:1402:1:9656:3:4:56/64; };

24. Testing Start the server daemon in debug mode in foreground
#dhcp6s –dDf eth0
Restart the network service of client
#service network restart
See the address assignment
#ifconfig

25. Thank you for your attention
Any Question?