Transcript Dynamic host configuration protocol version 6 overview

IPv6 DHCP
By : Santosh Yadav
IIT Kanpur
IPv6 Dynamic Host
Configuration Protocol
Overview
Evolution Of DHCPv6
DHCPv6 Concepts
Installation
Configuration
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
Evolution Of DHCPv6
IP configuration in IPV6 is carried out by IPV6 autoconfiguration
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
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.
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.
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
Dhcpv6 Concepts…
DHCPv6 Basic Message Format
01234567012345670123456701234567
Msg-type
Transaction-id
Options (variable)
• SOLICIT
• ADVERTISE
• REQUEST
• CONFIRM
• RENEW
• REBIND
• REPLY
• RELEASE
• DECLINE
• RECONFIGURE
• INFORMATION-REQUEST
• RELAY-FORW
• RELAY-REPL
Message Type Option
Message
Type
Meaning
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.
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.
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
Dhcpv6 Concepts…
DHCPv6 option format and base option
01234567012345670123456701234567
Option-code
Option length
Options data(option –len octets)
• Client Identifier
• Server Identifier
• Identity Association for Non-temporary
Addresses
• Identity Association for Temporary
Addresses
• 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
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
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
DHCPv6 working
SOLICIT
TIME
ADVERTISE
ADVERTISE
Client select
one advertise
server B
DHCP
server
A
REQUEST
REPLY
Client Now use address and
parameter for lifetime
DHCP
DHCP
client Client renew life time server
RENEW
B
REPLY
Client releases address
when shutting down
RELEASE
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
Ongoing Project
 Previously DHCPv6 v1.001and now DHCPv6 2.001 available for
the HP-UX 11i v1 and HP-UX 11i v2 operating systems
http:/docs.hp.com
 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.
http://klub.com.pl/dhcpv6/
 Project UNIX name: dhcpv6
Operating System: All POSIX (Linux/BSD/UNIX-like OSes), Linux
http://dhcpv6.sourceforge.net/
Installation
Dhcpv6 server :
Update with dhcpv6-0.10-11_FC3.i386.rpm using
# rpm -U dhcpv6-0.10-11_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
Installation…
Dhcpv6 client :
Update with dhcpv6_client-0.10-11_FC3.i386.rpm using
# rpm -U dhcpv6_client-0.10-11_FC3.i386.rpm
Copy sample client configuration file
# cp dhcp6c.conf /etc/dhcp6c.conf
Start the client daemon using
# dhcp6c –dDf eth0
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
Configuration…
Server configuration...
File : /etc/dhcp6s.conf
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;
};
};
};
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
Configuration…
client configuration...
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;
};
};
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
Thank you for your attention
Any Question?