1. 8: DHCPv6 (Dynamic Host Configuration Protocol for IPv6)
Rick Graziani
Cabrillo College

2. For more information please check out my Cisco Press book and video series:
IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:
IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:

3. 8.1: Router Advertisement and DHCPv6

4. DHCPv6 Global Unicast Manual Dynamic Static IPv6 unnumbered SLAAC
Stateless
Stateful
Static
IPv6 unnumbered
SLAAC
DHCPv6
Similar to IPv4 unnumbered
Static + EUI 64
SLAAC + DHCPv6
DHCPv6-PD

5. Dynamic IPv4 Address Allocation
I need an IPv4 addressing information from a DHCP server.
DHCP Server
DHCP Client
Here is your IPv4 address, subnet mask, default gateway and DNS server addresses.

6. All Dynamic Addressing Begins with the RA Message
Multicast: To all IPv6 routers, I need IPv6 address information
ICMPv6 Router Advertisement
ICMPv6 Router Solicitation
DHCPv6 Server
Multicast: To all IPv6 devices,
let me tell you how to do this …
I might not even be needed. 
An ICMPv6 Router Advertisement (RA) suggests to all IPv6 devices on the link how it will receive IPv6 Address Information.
Sent periodically by an IPv6 router or…
… when the router receives a Router Solicitation message from a host.

7. Router Advertisement: 3 Options
Option 1 and 2: Stateless Address Autoconfiguration
DHCPv6 Server does not maintain state of addresses
Option 3: Stateful Address Configuration
Address received from DHCPv6 Server
DHCPv6
Router(config)# ipv6 unicast-routing
DHCPv6 Server
Option 1: SLAAC – No DHCPv6 (Default on Cisco routers)
“I’m everything you need (Prefix, Prefix-length, Default Gateway)”
Option 2: SLAAC + Stateless DHCPv6 for DNS address
“Here is my information but you need to get other information such as DNS addresses from a DHCPv6 server.” (DNS can be in RA)
Option 3: All addressing except default gateway use DHCPv6
“I can’t help you. Ask a DHCPv6 server for all your information.” RA
Option 1 mostly what you need. Still need DNS server and domain name info.
Router(config-if)# ipv6 nd ra dns server 2001:DB8:1::1 600

8. ICMPv6 Router Advertisement
RA Message Options
ICMPv6 Router Advertisement
Option 1, 2, or 3
DHCPv6 Server
The type of Router Advertisement option depends on two RA flags:
Other Configuration Flag and Managed Configuration Flag
Default: Both flags are set to 0 (Option 1)
Use me (RA) for all your addressing information, no additional information available via DHCPv6.
Other Configuration Flag when set to “1” (Option 2)
Use me (RA) for your address but you need to get OTHER information from a stateless DHCPv6 server.
Managed Configuration Flag when set to “1” (Option 3)
The client needs to get ALL of it’s MANAGED information from a stateful DHCPv6 server, except default gateway.

9. ICMPv6 Router Advertisement
RA Message Options
ICMPv6 Router Advertisement
Option 1, 2, or 3
DHCPv6 Server
Option
Other Configuration (“O”) Flag
Managed Configuration (“M”) Flag
Option 1: SLAAC – No DHCPv6 (Default on Cisco routers)
Option 2: SLAAC + Stateless DHCPv6 for DNS address 1
Option 3: All addressing except default gateway use DHCPv6

10. Option 3 and the “A” Flag 1 1 (default) Yes No
As a Windows host I will still use the RA prefix to create temporary (SLAAC) addresses)
ICMPv6 RA
M Flag = 1
A Flag = 1
G 0/1
DHCPv6
DHCPv6 Server
Option
Managed Configuration (“M”) Flag
Address Autoconfiguration (“A”) Flag
Prefix in RA can be used for SLAAC
Option 3: All addressing except default gateway use DHCPv6 1
1 (default)
Yes No
The autonomous address configuration (A) flag tells hosts that they can create an address for themselves by combining the prefix in the RA with an interface identifier.

11. Obtaining an IPv6 Address Automatically

12. 8.2: Stateless DHCPv6

13. DHCPv6 Global Unicast Manual Dynamic Static IPv6 unnumbered SLAAC
Stateless
Stateful
Static
IPv6 unnumbered
SLAAC
DHCPv6
Similar to IPv4 unnumbered
Static + EUI 64
SLAAC + DHCPv6
DHCPv6-PD
SLAAC was discussed in Lesson 7.

14. RA Message Option 1 and 2: Stateless Address Autoconfiguration
DHCPv6 Server does not maintain state of addresses
Option 3: Stateful Address Configuration
Address received from DHCPv6 Server
DHCPv6
Router(config)# ipv6 unicast-routing
DHCPv6 Server
Option 1: SLAAC – No DHCPv6 (Default on Cisco routers)
“I’m everything you need (Prefix, Prefix-length, Default Gateway)”
Option 2: SLAAC + Stateless DHCPv6 for DNS address
“Here is my information but you need to get other information such as DNS addresses from a DHCPv6 server.” (DNS can be in RA)
Option 3: All addressing except default gateway use DHCPv6
“I can’t help you. Ask a DHCPv6 server for all your information.” RA

15. Router as a Stateless DHCPv6 Server
ICMPv6 Router Solicitation 1
ICMPv6 Router Advertisement
IPv6 Router & DHCPv6 Server 2
Option 2: Stateless DHCPv6
O Flag = 1, M Flag = 0
Note: Domain name and DNS server list may be included if router (and end system) support RFC 6106 IPv6 RA Options for DNS Configuration.
DHCPv6
I created my own address (Stateless),
and have the default gateway, but I need a DNS address…
SOLICIT
To all DHCPv6 Servers 3
ADVERTISE
Unicast 4
INFORMATION REQUEST
To all DHCPv6 Servers 5
DHCPv6 messages are similar to DHCPv4. The Information Request is used for Stateless DHCPv6 whereas a REQUEST message is used for Stateful DHCPv6.
REPLY
Unicast 6

16. Setting the Other Configuration Flag
ICMPv6 Router Advertisement
Option 2: Stateless DHCPv6
O Flag = 1, M Flag = 0
Router(config)# interface gigabitethernet 0/0
Router(config-if)# ipv6 nd other-config-flag

17. SLAAC for Addressing & DNS for Other Information
2001:DB8:CAFE:1::/64
MAC: D2-8C-E0-4C 1
RA Message: Stateless DHCPv6
To: FF02::1 (All-IPv6 devices)
From: FE80::1 (Link-local address)
Prefix: 2001:DB8:CAFE:1::
Prefix-length: /64
Other Configuration Flag: 1 2 RA
Prefix: 2001:DB8:CAFE:1::
Prefix-length: /64
Default Gateway: FE80::1
Global Unicast Address:
2001:DB8:CAFE:1: + Interface ID
2001:DB8:CAFE:1:6909:cb1c:36a0:a595
DHCPv6
For DNS 3
EUI-64 Process or Random 64-bit value
Stateless DHCPv6 Server

18. Configuring Router as a Stateless DHCPv6 Server
0 = 1
IPv6 Router & DHCPv6 Server
DHCPv6
Step 1: Enable IPv6 routing to send ICMPv6 Router Advertisement
Router(config)# ipv6 unicast-routing
Step 2: Configure “stateless” DHCPv6 and parameters
Router(config)# ipv6 dhcp pool pool-name
Router(config-dhcpv6)# dns-server dns-server-address
Router(config-dhcpv6)# domain-name domain-name
Step 3: Configure interface: RA message and DHCPv6 server
Router(config)# interface type number
Router(config-if)# ipv6 nd other-config-flag
Router(config-if)# ipv6 dhcp server pool-name
No client address information.

19. Configuring Router as a Stateless DHCPv6 Server
IPv6 Router & DHCPv6 Server
2001:DB8:CAFE:1/64
G0/0 :1
RA Message
O Flag = 1, M Flag = 0
DNS Server
DHCPv6
2001:DB8:CAFE:9::99
I created my own address (Stateless),
and now I need to get a DNS address using stateless DHCPv6.

20. Configuring Router as a Stateless DHCPv6 Server
DNS Server
G0/0 :1
2001:DB8:CAFE:1/64
2001:DB8:CAFE:9::99 RA
O = 1
DHCPv6
Router(config)# ipv6 unicast-routing
Router(config)# ipv6 dhcp pool IPV6-STATELESS
Router(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
Router(config-dhcpv6)# domain-name
Router(config)# interface GigabitEthernet 0/0
Router(config-if)# ipv6 address 2001:DB8:CAFE:1::1/64
Router(config-if)# ipv6 address FE80::1 link-local
Router(config-if)# ipv6 nd other-config-flag
Router(config-if)# ipv6 dhcp server IPV6-STATELESS

21. Verifying Stateless DHCPv6 Server Configuration
DNS Server
G0/0 :1
2001:DB8:CAFE:1/64
2001:DB8:CAFE:9::99 RA
O = 1
DHCPv6
PC> ipconfig /all
Physical Address : B-88-0E-40
IPv6 Address : 2001:db8:cafe:1:6909:cb1c:36a0:a595
Default Gateway : fe80::1
DNS Servers : 2001:db8:cafe:9::99
Connection-specific DNS Suffix Search List:
Random 64 bits
Privacy extension used – no FF-FE and no relation to MAC address

22. Verifying Stateless DHCPv6 Server Configuration
DNS Server
G0/0 :1
2001:DB8:CAFE:1/64
2001:DB8:CAFE:9::99 RA
O = 1
DHCPv6
Router# show ipv6 interface gigabitethernet 0/0
GigabitEthernet 0/0 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::1
Global unicast address(es):
2001:DB8:CAFE:1::1, subnet is 2001:DB8:CAFE:1::/64
<Output omitted>
Hosts use stateless autoconfig for addresses.
Hosts use DHCP to obtain other configuration.
Router#

23. 8.3: Stateful DHCPv6

24. RA Message Option 1 and 2: Stateless Address Autoconfiguration
DHCPv6 Server does not maintain state of addresses
Option 3: Stateful Address Configuration
Address received from DHCPv6 Server
DHCPv6
Router(config)# ipv6 unicast-routing
DHCPv6 Server
Option 1: SLAAC – No DHCPv6 (Default on Cisco routers)
“I’m everything you need (Prefix, Prefix-length, Default Gateway)”
Option 2: SLAAC + Stateless DHCPv6 for DNS address
“Here is my information but you need to get other information such as DNS addresses from a DHCPv6 server.” (DNS can be in RA)
Option 3: All addressing except default gateway use DHCPv6
“I can’t help you. Ask a DHCPv6 server for all your information.” RA

25. Router as a Stateful DHCPv6 Server
ICMPv6 Router Solicitation 1
ICMPv6 Router Advertisement
IPv6 Router & DHCPv6 Server 2
Option 3: Stateful DHCPv6
O Flag = 0, M Flag = 1
DHCPv6
I’m only using the default gateway address from the RA. I need to contact a stateful DHCPv6 server for all my addressing.
SOLICIT
To all DHCPv6 Servers 3
ADVERTISE
Unicast 4
REQUEST
To all DHCPv6 Servers 5
REPLY
Unicast 6

26. Setting the Managed Configuration Flag
ICMPv6 Router Advertisement
DHCPv6
DHCPv6 Server
Option 3 Stateful DHCPv6
O Flag = 0, M Flag = 1
Router(config)# interface gigabitethernet 0/1
Router(config-if)# ipv6 nd managed-config-flag

27. Stateful DHCPv6 without SLAAC
As a Windows host I will still use the RA prefix to create temporary (SLAAC) addresses)
G 0/1
ICMPv6 Router Advertisement
DHCPv6
Option 3 Stateful DHCPv6
O Flag = 0, M Flag = 1
No SLAAC: A Flag = 0
DHCPv6 Server
Router(config)# interface gigabitethernet 0/1
Router(config-if)# ipv6 nd managed-config-flag
Router(config-if)# ipv6 nd prefix prefix/length no-autoconfig
no-autoconfig (Optional) Indicates to hosts on the local link that the specified prefix cannot be used for IPv6 autoconfiguration (SLAAC).
The prefix will be advertised with the A-bit clear (autonomous address-configuration flag).
The ipv6 nd prefix 2001:DB8:CAFE:120::/64 no-autoconfig command (set A flag off), coupled with the M flag set on, succeeds in getting Windows 7 to just populate one address, while still installing a default route on the client.
Temporary addresses[edit]
The globally unique and static MAC addresses, used by stateless address autoconfiguration to create interface identifiers, offer an opportunity to track user equipment—across time and IPv6 network prefix changes—and so users.[33] To reduce the prospect of a user identity being permanently tied to an IPv6 address portion, a node may create temporary addresses with interface identifiers based on time-varying random bit strings[34] and relatively short lifetimes (hours to days), after which they are replaced with new addresses.
Temporary addresses may be used as source address for originating connections, while external hosts use a public address by querying the Domain Name System.
Network interfaces configured for IPv6 use temporary addresses by default in OS X Lion or later Apple systems, and in Windows Vista, Windows 2008 Server or later Microsoft systems.
SLAAC and DHCPv6 address - clear the A flag in the RA

28. Stateful DHCPv6 1 2 RA RA Message: Stateful DHCPv6
As a Windows host I will still use the RA prefix to create temporary (SLAAC) addresses)
2001:DB8:CAFE:2::/64 1
RA Message: Stateful DHCPv6
To: FF02::1 (All-IPv6 devices)
From: FE80::1 (Link-local address)
Prefix: 2001:DB8:CAFE:2::
Prefix-length: /64
Managed Configuration Flag: 1
Autonomous Address Flag: 0 2 RA
Default Gateway: FE80::1
Global Unicast Address: DHCPv6
DHCPv6
Stateful DHCPv6 Server

29. Configuring Router as a Stateful DHCPv6 Server
M = 1 A=1
IPv6 Router & DHCPv6 Server
DHCPv6
Step 1: Enable IPv6 routing to send ICMPv6 Router Advertisement
Router(config)# ipv6 unicast-routing
Step 2: Configure “stateful” DHCPv6 and parameters
Router(config)# ipv6 dhcp pool pool-name
Router(config-dhcpv6)# address prefix prefix/length
Router(config-dhcpv6)# dns-server dns-server-address
Router(config-dhcpv6)# domain-name domain-name
Step 3: Configure interface: RA message and DHCPv6 server
Router(config)# interface type number
Router(config-if)# ipv6 nd managed-config-flag
Router(config-if)# ipv6 nd prefix prefix/prefix-length no-autoconfig
Router(config-if)# ipv6 dhcp server pool-name
Client address information.
Address prefix command includes an option for setting the lifetime of the address, using the lifetime option.

30. Configuring Router as a Stateful DHCPv6 Server
DNS Server
G0/1 :1
2001:DB8:CAFE:2/64
2001:DB8:CAFE:9::99 RA
M = 1
DHCPv6
Router(config)# ipv6 unicast-routing
Router(config)# ipv6 dhcp pool IPV6-STATEFUL
Router(config-dhcpv6)# address prefix 2001:DB8:CAFE:2:DEED::/80
Router(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
Router(config-dhcpv6)# domain-name
Router(config)# interface GigabitEthernet 0/1
Router(config-if)# ipv6 address 2001:DB8:CAFE:2::1/64
Router(config-if)# ipv6 address FE80::1 link-local
Router(config-if)# ipv6 nd managed-config-flag
Router(config-if)# ipv6 dhcp server IPV6-STATEFUL

31. Including Only Valid Addresses to Be Assigned
With IPv4, a router enabled as a DHCPv4 server we specifically EXCLUDE addresses from being assigned.
All other addresses are INCLUDED as possible assigned addresses.
Router-IPV4(config)# ip dhcp excluded-address
With IPv6, a router enabled as a DHCPv6 server we specifically INCLUDE addresses to be assigned.
All other addresses are EXCLUDED as possible assigned addresses.
Using the prefix length of the LAN may include the router’s address and other statically assigned addresses.
Router(config-dhcpv6)# address prefix 2001:DB8:CAFE:2::/64
Router(config-dhcpv6)# address prefix 2001:DB8:CAFE:2:DEED::/80

32. Including Specific Addresses
Router(config-dhcpv6)# address prefix 2001:DB8:CAFE:2:DEED::/80
2001:DB8:CAFE:2::/64
2001:DB8:CAFE:2:0:0:0:0
2001:DB8:CAFE:2:FFFF:FFFF:FFFF:FFFF
2001:DB8:CAFE:2:DEED::/80
2001:DB8:CAFE:2:DEED:0:0:0
2001:DB8:CAFE:2:DEED:0:0:1
2001:DB8:CAFE:2:DEED:0:0:
Available addresses for this network
/64
/80
INCLUDED assigned addresses will have these 80 bits.
All other addresses are EXCLUDED

33. Verifying Stateful DHCPv6 Server Configuration
DNS Server
G0/1 :1
2001:DB8:CAFE:2/64
2001:DB8:CAFE:9::99 RA
M = 1
DHCPv6
PC> ipconfig /all
Physical Address : B-88-0E-40
IPv6 Address : 2001:db8:cafe:2:deed:2de8:cfd8:5
Default Gateway : fe80::1
DNS Servers : 2001:db8:cafe:9::99
Connection-specific DNS Suffix Search List:

34. Verifying Stateful DHCPv6 Server Configuration
DNS Server
G0/1 :1
2001:DB8:CAFE:2/64
2001:DB8:CAFE:9::99 RA
M = 1
DHCPv6
Router# show ipv6 interface gigabitethernet 0/1
GigabitEthernet 0/1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::1
Global unicast address(es):
2001:DB8:CAFE:2::1, subnet is 2001:DB8:CAFE:2::/64
<output omitted>
Hosts use DHCP to obtain routable addresses.
Router#

35. Stateless and Stateful DHCPv6 Server
Router(config)# ipv6 unicast-routing
Router(config)# ipv6 dhcp pool IPV6-STATELESS
Router(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
Router(config-dhcpv6)# domain-name
Router(config)# ipv6 dhcp pool IPV6-STATEFUL
Router(config-dhcpv6)# address prefix 2001:DB8:CAFE:2:DEED::/80
Router(config)# interface GigabitEthernet 0/0
Router(config-if)# ipv6 address 2001:DB8:CAFE:1::1/64
Router(config-if)# ipv6 address FE80::1 link-local
Router(config-if)# ipv6 nd other-config-flag
Router(config-if)# ipv6 dhcp server IPV6-STATELESS
Router(config)# interface GigabitEthernet 0/1
Router(config-if)# ipv6 address 2001:DB8:CAFE:2::1/64
Router(config-if)# ipv6 nd managed-config-flag
Router(config-if)# ipv6 dhcp server IPV6-STATEFUL
Stateless and Stateful DHCPv6 Server
G0/0
Stateless
G0/1
Stateful

36. 8.4: DHCPv6 Relay

37. Forwarding DHCPv6 Messages:1
G0/1 :1
2001:DB8:CAFE:2/64
RELAY-FORWARD
DHCPv6
DHCPv6 Server
2001:DB8:CAFE:9::55
Router(config)# interface GigabitEthernet 0/1
Router(config-if)# ipv6 dhcp relay destination ipv6-address [exit-int]
Relay agent creates a RELAY-FORWARD message containing the original DHCPv6 message from the client and forwards the message to a server.
The ipv6-address can be:
Unicast or multicast IPv6 address
Link-scope: The output interface must be specified for this kind of address.
From the client perspective similar forwarding DHCPv4 messages with the ip helper command.
Managed-config-flag for stateful or other-config-flag for stateless.
The relay agent creates a RELAY-FORWARD message containing the original
SOLICIT message from the client and forwards the message to a server using
the All_DHCP_Servers multicast address FF05::1:3 with site-local scope. The
relay agent can also be configured to use a unicast address for the DHCPv6
server.

38. Forwarding DHCPv6 Messages using unicast:1
G0/1 :1
2001:DB8:CAFE:2/64
RELAY-FORWARD
DHCPv6
DHCPv6 Server
2001:DB8:CAFE:9::55
To: 2001:DB8:CAFE:9::55
Router(config)# ipv6 unicast-routing
Router(config)# interface GigabitEthernet 0/1
Router(config-if)# ipv6 nd managed-config-flag
Router(config-if)# ipv6 dhcp relay destination 2001:DB8:CAFE:9::55 g0/0
Only required if link-local
unicast is used
When the destination of the DHCP server is a global unicast address, no multicast routing is required.

39. Forwarding DHCPv6 Messages using Multicast:1
G0/1 :1
2001:DB8:CAFE:2/64
RELAY-FORWARD
DHCPv6
DHCPv6 Server
2001:DB8:CAFE:9::55
To FF05::1:3 All-DHCPv6 Servers
Router(config)# ipv6 unicast-routing
Router(config)# ipv6 multicast-routing
Router(config)# interface GigabitEthernet 0/1
Router(config-if)# ipv6 nd managed-config-flag
Router(config-if)# ipv6 dhcp relay destination FF05::1:3
When the destination of the DHCP server is FF05::1:3 (All-DHCPv6 Servers) multicast address, then we need multicast routing enabled for IPv6.

40. 8.5: DHCPv6 Prefix Delegation Process

41. DHCPv4 and Private Addresses for the Home
NAT
ISP
G0/1
G0/1
HOME
G0/0
DHCPv4
Public IPv4 Address
for the interface
Private IPv4 Address
DHCPv4 /8
/12
/16
ISP only has to deliver a public IPv4 address for Home router interface.
DHCPv4 and RFC 1918 private address space is used for home network.
NAT is used for translation – but has its drawbacks!
No NAT between private-public IPv6 (always in debate)
ISP doesn’t have to worry about the home network address. RFC 1918 takes care of that.

42. The World of IPv6 and DHCPv6-PD Complete IPv6 Reachability
Delegating Router (DR)
Requesting Router (RR)
G0/1
G0/1
ISP-DR
HOME-RR
G0/0
Global IPv6 Address
Global IPv6 Address
IPv6 end-to-end reachability:
Home network gets its own IPv6 prefix (public address)
No NAT
Uses DHCPv6-PD (Prefix Delegation)
ISP router is known as the Delegating Router (DR)
HOME router is known as the Requesting Router (RR)

43. HOME Router’s ISP Facing Interface
Delegating Router (DR)
Requesting Router (RR)
G0/1
G0/1
ISP-DR
HOME-RR
G0/0 ?
IPv6 Address for the interface:
SLAAC
DHCPv6 (Stateful or Stateless)
First, HOME’s ISP facing interface needs an IPv6 address.
Similar to any IPv6 client it may dynamically get an address using:
SLAAC - Using prefix in RA
Stateless DHCPv6 – SLAAC but DHCPv6 for DNS address
Stateful DHCPv6 - Like DHCPv4
What about the address for the HOME LAN?

44. DHCPv6-PD Steps Overview
Delegating Router (DR)
Requesting Router (RR)
G0/1
G0/1
ISP-DR
HOME-RR
G0/0
Global IPv6 Address
Global IPv6 Address
HOME-RR first gets an IPv6 address on its ISP-facing interface, then:
Step 1: Request a Prefix for its LAN(s)
Step 2: Subnet the prefix for its LANs (optional) – Get a /48 but assign /64s
Step 3: Assign an IPv6 address from the prefix to its LAN interface
Advertises the prefix in a Router Advertisement to devices on the LAN

45. DHCPv6-PD REPLY with /48 prefix
DHCPv6 Steps 1 and 2
Delegating Router (DR)
Requesting Router (RR)
G0/1
ISP-DR
G0/1
HOME-RR
G0/0
DHCPv6-PD REQUEST 1
G0/2
DHCPv6-PD REPLY with /48 prefix 2
Step 1. HOME asks the ISP for an address to allocate for it’s LANs
DHCPv6-PD is initiated by the RR
Step 2. ISP delegates an IPv6 prefix for HOME
Example: ISP sends HOME a /48 prefix

46. DHCPv6-PD REPLY with /48 prefix
DHCPv6 Step 3
Delegating Router (DR)
Requesting Router (RR) 3
RA with prefix
RA with /64 prefix
G0/1
ISP-DR
G0/1
HOME-RR
G0/0 3
DHCPv6-PD REQUEST
RA with /64 prefix 1
G0/2
DHCPv6-PD REPLY with /48 prefix 2
Step 3. HOME advertises prefix using SLAAC RA messages (currently only option)
HOME assigns an address from the prefix to its LAN interface and…
advertises the prefix out its interface using ICMPv6 RA messages
HOME assigns the prefix or subnets of the prefix to one or more interfaces
Example: HOME interfaces are assigned /64 subnets from the /48 prefix

47. 8.6: DHCPv6-PD Configuration Example

48. Prefix Delegation for the HOME
Our Example
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0 :1
ISP-DR
HOME-RR
Router Advertisement
2001:DB8:FEED:6::/64
SLAAC
SLAAC
Prefix Delegation for the HOME
2001:DB8:AB00:/48
Router Advertisement
2001:DB8:AB00:1::/64
DHCPv6-PD
HOME’s G0/1 interface gets an address using SLAAC
ISP delegates 2001:DB8:AB00::/48 prefix to HOME for its LANs using DHCP-PD
HOME will use the 2001:DB8:AB00:1::/64 subnet for its G0/0 LAN.
Assign :1 to the G0/0 interface
HOME will send 2001:DB8:AB00:1::/64 prefix and other information in RA.

49. Another Look at the Process
ICMPv6 Router Solicitation
Other options are Stateless and Stateful DHCPv6
ICMPv6 Router Advertisement
G0/1
G0/1
EUI-64
G0/0 :1
ISP-DR
HOME-RR
SOLICIT: Prefix Delegation request
RR must be enabled with the PD option
ADVERTISE
DHCPv6-PD
REQUEST
REPLY: Include Prefix
ICMPv6 Router Advertisement (RA)
Rapid commit configuration option can be used to eliminate middle two steps
SLAAC

50. HOME-RR Configuration (1 of 2)
EUI-64
G0/0
ISP-DR
HOME-RR
Router Solicitation
Router Advertisement
DHCPv6-PD Request
HOME(config)# ipv6 unicast-routing ! Required to send RA
! for LAN (next slide)
HOME(config)# interface gig 0/1
HOME(config-if)# ipv6 address autoconfig default ! Use RA & add default
HOME(config-if)# ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP ! Request DHCPv6-PD
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64 ! Next slide
Rapid commit option can be used with the ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP command
Enabling the ipv6 dhcp client pdcommand starts the DHCP for IPv6 client process if this process is not yet running.
The ipv6 dhcp client pdcommand enables request for prefix delegation through the interface on which this command is configured. When prefix delegation is enabled and a prefix is successfully acquired, the prefix is stored in the IPv6 general prefix pool with an internal name defined by the ipv6-prefixargument. Other commands and applications (such as the ipv6 address command) can then refer to the prefixes in the general prefix pool.
The hint keyword with the ipv6-prefix argument enables the configuration of an IPv6 prefix that will be included in DHCP for IPv6 solicit and request messages sent by the DHCP for IPv6 client on the interface as a hint to prefix-delegating routers. Multiple prefixes can be configured by issuing the ipv6 dhcp client pd hintipv6-prefix command multiple times. The new prefixes will not overwrite old ones.
The rapid-commit keyword enables the use of the two-message exchange for prefix delegation and other configuration. If it is enabled, the client will include the rapid commit option in a solicit message.
The DHCP for IPv6 client, server, and relay functions are mutually exclusive on an interface. When one of these functions is already enabled and a user tries to configure a different function on the same interface, one of the following messages is displayed: "Interface is in DHCP client mode," "Interface is in DHCP server mode," or "Interface is in DHCP relay mode."
Examples
The following example enables prefix delegation:
Router(config-if)# ipv6 dhcp client pd dhcp-prefix
The following example configures a hint for prefix-delegating routers:
Router(config-if)# ipv6 dhcp client pd hint 2001:0DB8:1/48

51. HOME-RR Configuration (1 of 2)
EUI-64
G0/0
ISP-DR
HOME-RR
HOME(config)# ipv6 unicast-routing ! Required to send RA
! for LAN (next slide)
HOME(config)# interface gig 0/1
HOME(config-if)# ipv6 address autoconfig default ! Use RA & add default
HOME(config-if)# ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP ! Request DHCPv6-PD
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64 ! Next slide
HOME(config-if)# ipv6 nd other-config-flag ! Talk to stateless DHCPv6
HOME(config-if)# ipv6 dhcp server IPV6-STATELESS ! I’m a stateless DHCPv6 svr
HOME(config)# ipv6 dhcp pool IPV6-STATELESS
HOME(config-dhcpv6)# import dns-server ! Use my DNS server info
HOME(config-dhcpv6)# import domain-name ! Use my DNS server info
Rapid commit option can be used with the ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP command
Enabling the ipv6 dhcp client pdcommand starts the DHCP for IPv6 client process if this process is not yet running.
The ipv6 dhcp client pdcommand enables request for prefix delegation through the interface on which this command is configured. When prefix delegation is enabled and a prefix is successfully acquired, the prefix is stored in the IPv6 general prefix pool with an internal name defined by the ipv6-prefixargument. Other commands and applications (such as the ipv6 address command) can then refer to the prefixes in the general prefix pool.
The hint keyword with the ipv6-prefix argument enables the configuration of an IPv6 prefix that will be included in DHCP for IPv6 solicit and request messages sent by the DHCP for IPv6 client on the interface as a hint to prefix-delegating routers. Multiple prefixes can be configured by issuing the ipv6 dhcp client pd hintipv6-prefix command multiple times. The new prefixes will not overwrite old ones.
The rapid-commit keyword enables the use of the two-message exchange for prefix delegation and other configuration. If it is enabled, the client will include the rapid commit option in a solicit message.
The DHCP for IPv6 client, server, and relay functions are mutually exclusive on an interface. When one of these functions is already enabled and a user tries to configure a different function on the same interface, one of the following messages is displayed: "Interface is in DHCP client mode," "Interface is in DHCP server mode," or "Interface is in DHCP relay mode."
Examples
The following example enables prefix delegation:
Router(config-if)# ipv6 dhcp client pd dhcp-prefix
The following example configures a hint for prefix-delegating routers:
Router(config-if)# ipv6 dhcp client pd hint 2001:0DB8:1/48

52. HOME-RR Configuration (2 of 2)
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
DHCPv6-PD Request
Router Advertisement
DHCPv6-PD Reply
2001:DB8:AB00:1::/64
2001:DB8:AB00::/48
HOME(config)# ipv6 unicast-routing ! Required to send RA
! for LAN (next slide)
HOME(config)# interface gig 0/1
HOME(config-if)# ipv6 address autoconfig default ! Use RA & add default
HOME(config-if)# ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP ! Request DHCPv6-PD
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64 ! For RA
Prefix Length
First 48 bits uses prefix in DHCPv6-PD 2001:DB8:AB00::
Subnet-ID
Interface ID

53. ISP-DR Configuration (1 of 2)
2001:DB8:FEED:6::/64
G0/1
G0/1
EUI-64
G0/0 RA
ISP-DR
HOME-RR
DHCPv6-PD Request
DNS
Server
DHCPv6-PD Reply
2001:DB8:AB00::/48
2001:DB8:AB00::/48
ISP(config)# ipv6 unicast-routing
ISP(config)# interface gig 0/1
ISP(config-if)# ipv6 address 2001:db8:feed:6::1/64
ISP(config-if)# ipv6 address fe80::feed:1 link-local
ISP(config-if)# ipv6 dhcp server DHCPV6-CLIENT-ADDRESS
ISP(config)# ipv6 dhcp pool DHCPV6-CLIENT-ADDRESS
ISP(config-dhcpv6)# prefix-delegation pool DHCPV6-PD-POOL
ISP(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
ISP(config-dhcpv6)# domain-name example.com
ISP(config)# ipv6 local pool DHCPV6-PD-POOL 2001:DB8:AB00::/40 48
ISP acting only as a DHCPv6-PD server.
Pool can include address prefix command if stateful DHCPv6 is used instead of SLAAC.
DNS and Domain name is for DHCPv6-PD for LAN??

54. ISP-DR Configuration (2 of 2)
2001:DB8:FEED:6::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
2001:DB8:AB00::/40
DHCPv6-PD Reply
2001:DB8:AB00::/48
2001:DB8:AB01::/48
2001:DB8:AB02::/48 …
2001:DB8:ABFF::/48
2001:DB8:AB00::/48
ISP(config)# ipv6 dhcp pool DHCPV6-CLIENT-ADDRESS
ISP(config-dhcpv6)# prefix-delegation pool DHCPV6-PD-POOL
ISP(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
ISP(config-dhcpv6)# domain-name example.com
ISP(config)# ipv6 local pool DHCPV6-PD-POOL 2001:DB8:AB00::/ ! PD pool
From the /40 each DHCPv6-PD client will get a /48
Reserve a /40 to allocate addresses for ISP’s DHCPv6-PD clients 2001:DB8:ABxx::/40

55. HOME-RR Applies DHCPv6-PD Information on G0/0
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
DHCPv6-PD Reply
Router Advertisement
2001:DB8:AB00::/48
2001:DB8:AB00:1::/64
Prefix
ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64
First 48 bits uses prefix in DHCPv6-PD 2001:DB8:AB00::
Subnet-ID
Interface ID
ISP(config)# ipv6 dhcp pool DHCPV6-CLIENT-ADDRESS
ISP(config-dhcpv6)# prefix-delegation pool DHCPV6-PD-POOL
ISP(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
ISP(config)# ipv6 local pool DHCPV6-PD-POOL 2001:DB8:AB00::/ ! PD pool

56. 8.7: Verifying DHCPv6-PD

57. Verifying ISP-DR DHCPv6 Pool
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
ISP# show ipv6 dhcp interface gig 0/1
GigabitEthernet0/1 is in server mode
Using pool: DHCPV6-CLIENT-ADDRESS
Preference value: 0
Hint from client: ignored
Rapid-Commit: disabled
ISP#
ISP(config)# interface gig 0/1
ISP(config-if)# ipv6 dhcp server DHCPV6-CLIENT-ADDRESS
ISP(config)# ipv6 dhcp pool DHCPV6-CLIENT-ADDRESS
ISP(config-dhcpv6)# prefix-delegation pool DHCPV6-PD-POOL
ISP(config-dhcpv6)# dns-server 2001:DB8:CAFE:9::99
ISP(config)# ipv6 local pool DHCPV6-PD-POOL 2001:DB8:AB00::/40 48

58. Verifying ISP-DR DHCPv6 Pool Information
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
ISP# show ipv6 local pool DHCPV6-PD-POOL
Prefix is 2001:DB8:AB00::/40 assign /48 prefix
1 entries in use, 255 available, 0 rejected
0 entries cached, 1000 maximum
User Prefix Interface
A923B29E
2001:DB8:AB00::/48
ISP#
Reserve a /40 to allocate addresses for ISP’s DHCPv6-PD clients 2001:DB8:ABxx::/40
From the /40 each DHCPv6-PD client will get a /48
ISP(config)# ipv6 local pool DHCPV6-PD-POOL 2001:DB8:AB00::/40 48

59. Verifying HOME-RR Addresses
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
HOME# show ipv6 interface brief
GigabitEthernet0/0 [up/up]
FE80::1
2001:DB8:AB00:1::1
GigabitEthernet0/1 [up/up]
FE80::8A5A:92FF:FE3B:29E1
2001:DB8:FEED:6:8A5A:92FF:FE3B:29E1
HOME-RR#
DHCPv6-PD
SLAAC
HOME(config)# ipv6 unicast-routing
HOME(config)# interface gig 0/1
HOME(config-if)# ipv6 address autoconfig default
HOME(config-if)# ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64
Other options can include the use of a general prefix. For simplicity, that option was not used.

60. Verifying HOME-RR Addresses
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
Router Advertisement
HOME# show ipv6 interface gig 0/0
GigabitEthernet0/0 is up, line protocol is up
General-prefix in use for addressing
Global unicast address(es):
2001:DB8:AB00:1::1, subnet is 2001:DB8:AB00:1::/64 [CAL/PRE]
<Output ommited>
Hosts use stateless autoconfig for addresses.
HOME#
2001:DB8:AB00:1::/64
HOME(config)# ipv6 unicast-routing
HOME(config)# interface gig 0/1
HOME(config-if)# ipv6 address autoconfig default
HOME(config-if)# ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64

61. Verifying HOME-RR Routing Table
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
Default Route X
HOME# show ipv6 route
IPv6 Routing Table - default - 7 entries
Codes: ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr – Redirect
ND ::/0 [2/0]
via FE80::FEED:1, GigabitEthernet0/1
S :DB8:AB00::/48 [1/0]
via Null0, directly connected
<Output omitted>
HOME#
2001:DB8:AB00::/48
HOME(config)# ipv6 unicast-routing
HOME(config)# interface gig 0/1
HOME(config-if)# ipv6 address autoconfig default
HOME(config-if)# ipv6 dhcp client pd DHCPV6-PREFIX-FROM-ISP
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64
Default route because of default option
Discard route gets added automatically – HOME gets entire /48 and any packets not known by the routing table for the network, will not use the default route and will be dropped.

62. Static Link-Local Address Configured
2001:DB8:FEED:6::/64
2001:DB8:AB00:1::/64
G0/1
G0/1
EUI-64
G0/0
ISP-DR
HOME-RR
::1
HOME(config)# interface gig 0/0
HOME(config-if)# ipv6 address DHCPV6-PREFIX-FROM-ISP 0:0:0:1::1/64
HOME(config-if)# ipv6 address fe80::1 link-local
PC> ipconfig
Windows IP Configuration
Ethernet adapter Local Area Connection:
IPv6 Address :db8:ab00:1:1005:b37e:7e61:7ceb
Link-local IPv6 Address fe80::1005:b37e:7e61:7ceb
Default Gateway fe80::1
Default route because of default option
Discard route gets added automatically – HOME gets entire /48 and any packets not known by the routing table for the network, will not use the default route and will be dropped.
For a recognizable default gateway address

63. For more information please check out my Cisco Press book and video series:
IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:
IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6
By Rick Graziani
ISBN-10:

64. 8: DHCPv6 (Dynamic Host Configuration Protocol for IPv6)
Rick Graziani
Cabrillo College