The document is a concise overview of DHCPv6-PD (Prefix Delegation) for IPv6, aimed at large enterprises and service providers. It discusses the prerequisites for understanding DHCPv6-PD, its advantages, and when to implement it, along with a detailed explanation of the technical processes involved, including the interaction between clients and servers. References to relevant RFCs ensure compliance and understanding of protocol behaviors and options are provided.

1. DHCPV6-PD
IN 10 MINUTES
PREREQUISITES:
IPv6 and DHCP Basic knowledge
Fred Bovy EIRL. IPv6 For Life! (c) 2012
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2. HI!
MY NAME IS FRED
Fred Bovy EIRL. IPv6 For Life!
15 years ccie #3013
18 years ccsi #33517 (former #95003)
IPv6 Forum Gold Certified Engineer
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Email: fred@fredbovy.com
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3. WHY SHOULD WE USE
DHCP-PD?
Easier and More Flexible
for provisioning
Customer prefixes can be stored on a RADIUS
Server which tells the DHCPv6 Server which
prefix to assign and be loaded when the client
reboot its CPE or toggle its interface!
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4. WHO SHOULD USE
DHCP-PD?
Large Enterprises or SPs
To Connect
Customers, Branch or Home Offices
With DHCP-PD, Enterprises may have their /48
prefix(es) allocated on a RADIUS Servers and
Some other may use a pool of /56 to /64 prefixes
for the Home Offices
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5. WHEN SHOULD WE USE
DHCP-PD?
You can use it righ now?
Most Vendors are Ready!
With DHCP-PD, Enterprises may have their /48
prefix(es) allocated on a RADIUS Servers of SPs
and Some other may use a pool of /56 to /64
prefixes for the Home Offices
Also apply for Large Enterprises
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6. THE BIG PICTURE
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7. 2ND BLOCK BLOCK
2001:DB8:678:1000::/56
DHCPv6-PD Client is called the Requesting Router
DHCPv6-PD Server is called the Delegating Router
First Block IPv6 DHCP-PD Server
2001:db8:678::/56
DHCPv6-PD Client
Internet
DHCPv6 Relqy Relay_forward (Solicit IA_PD)
Relay_Reply(Advertise IA_PD)
FTTH
Request IA_PD
Reply IA_PD
ress
LL Add
P2 P 2001:341f::1:57/64
_ PD
Ad v
REP
T IA
_ PD
AS 341F
er t
Home Network
LY I
I CI
t IA
ise I
2001:db8:678::/64 2001:341F::/32
SOL
A_P
ues
A_P
R eq
D
D
2001:db8:678:1::/56
8 bits for Subnets IPv6 Private Network
IPv6
2001:db8:658::/48
Internet
AS 413
2001:413::/32
2001:db8:678:10::/64
IPv6
2001:db8:678:11::/64 Internet
...
AS 610
2001:610::/32
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8. DHCP-PD
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9. IDENTITY ASSOCIATION FOR
PREFIX DELEGATION
IA_PD option
Option_IA_PD option-length
IAID (4 Octets)
T1
IA_PD option IA_PD Prefix option
T2
Option_IA_PD option-length
OPTION_IAPREFIX option-length
IAID (4 Octets)
preferred-lifetime IP_PD-options
T1
valid-lifetime
+ =
T2
prefix-length
IPv6 prefix IA_PD Prefix option
(16 octets)
OPTION_IAPREFIX option-length
IA_PD-options
preferred-lifetime
IPprefix-options valid-lifetime
prefix-length
IPv6 prefix
(16 octets)
IPprefix-options
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10. The DHCPv6 PD clients configure its interface facing the Clients and
start sending RA with valid Parameters and Prefix.
It is used by the Client for Autoconfiguration (SLAAC)
2001:341f::/32 DHCP-PD Server
2001:db8:678:1000:/56
2001:db8:678:1001::1/64
(SLAAC)
DHCP-PD Relay
DHCPv6 Client DHCPv6-PD Client
IPv6
Internet
RA 2001:341f::1:57/64
The Router configure one interface
with a /64 prefix from the block received and start
transmitting RA
Router Advertisement
M-bit=0, O-bit=0
SLLA=fe80::1
MTU=1500, Hop Limit=64, H-bit=0 (not a Home Agent), O-bit=0, M-bit=0 (No DHCPv6)
Router Lifetime=3600
Retransmit Time=0 (unspecified), Reachability Timer=0 (unspecified)
PrefixList
2001:db8:678:1000::/64
Preferred Lifetime = 620
Valid Lifetime = 3600
Autonomous bit=1, On-Link bit=1
The Workstation received the and c,onfigure various parameters from the RA Received: MTU, Hop Limit, no change on
the NUD Parameters which are unspecified. It also receives a Prefix which has the SLAAC bits on and a non null Valid
Timer
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11. VALID
Tent Preferred Deprecated Invalid
Preferred Lifetime
Valid Lifetime
T1
T2
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12. RELIABILITY
• RT Retransmission timeout
• IRT Initial retransmission time
• MRC Maximum retransmission count
• MRT Maximum retransmission time
• MRD Maximum retransmission duration
• RAND Randomization factor the application itself.
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13. Each Client has 2 Timers set for each address except the Temporary.
When T1 Expires, the client must RENEW its address with its DHCP Server
When T2 Expires, it must REBIND with Any Existing Server
When T1 Expires 1
Reniew 2001:db8:678:1000:/56 Block
2001:db8:678:1000::1/64
(SLAAC)
Reply 2001:db8:678:1000:/56 Block
DHCP-PD Relay
2
DHCPv6-PD Client
DHCPv6 Client
Use LL for the p2p Link Address to SP
IPv6
Internet
2001:db8:678:0:1::547
First Subnet
2001:db8:678::/64 2001:db8:678:1300::/56
8 bits for Subnets
2001:db8:678:1100::/56
8 bits for Subnets IPv6 Private 2001:db8:678:1030::/64
2001:db8:678:31:1031::/64
Network
2001:db8:678:1000:/56
2001:db8:678:1200::/56
8 bits for Subnets
2001:db8:678:1010::/64
2001:db8:678:1011::/64 2001:db8:678:1020::/64
... 2001:db8:678:1021::/64
...
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14. DHCP-PD CLIENT CONFIG
SLAAC 2001:db8:678:1::/48 DHCP-PD Server
2001:341f::/32
ALL from RA
2001:db8:678::1/64
The Best if you don’t need (SLAAC) DHCPv6-PD Client DHCP-PD Relay
Parameters (hop
IPv6 Limit, MTU), Prefixes,
special config Router Advertisement
Prefix-List
Internet
default route, DNS
2001:db8:678::/64
M=0, O=0
2001:341f::1:57/64
2001:db8:678:1::/56
Server Addresses...
First Subnet
2001:db8:678::/64 2001:db8:678:2::/56
2001:db8:679:3::/56
Stateless 2001:db8:678::1/64
2001:341f::/32
DHCP-PD Server
DHCPv6 (SLAAC)
DHCPv6 Client
DHCPv6-Lite Server
DHCPv6-PD Client DHCP-PD Relay
Addresses, parameters
Router Advertisement IPv6 (hop Limit, MTU) de-
The Most Powerful as with
Prefix-List
2001:db8:678::/64 Internet fault Route from RA.
Then DHCPv6 for SIP
M=0, O=1
2001:341f::1:57/64
DHCP you can provide
many information
First Subnet
2001:db8:678::/64
2001:db8:678:1::/56
2001:db8:678:2::/56
Server and DNS
2001:db8:679:3::/56
Server Addresses!
Stateful Irrelevant for DHCP-PD!
DHCPv6 2001:341f::/32 DHCP-PD Server
Parameters (hop
2001:db8:678::1 (DHCPv6) DHCPv6 Server
Limit, MTU) default
DHCP-PD Relay
Route from RA
DHCPv6 Client
DHCPv6-PD Client
IPv6
Then DHCPv6 for
Router Advertisement
Prefix-List
2001:db8:678::/64 Internet
M=1, O=1
2001:341f::1:57/64 SIP Server and
First Subnet
2001:db8:678::/64
2001:db8:678:1::/56 DNS Server Ad-
dresses!
2001:db8:678:2::/56
2001:db8:679:3::/56
Setting the O bit is not useful here as the
Managed bit (M-bit) takes all DHCP can
give... But it is a best practice that I
recommend in case of a bad implementation!
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15. This is the process from connection beginning to the end.
When everything is OK!
2001:341f::/32 DHCP-PD Server
2001:db8:678::/48
2001:db8:678::1/64
(SLAAC)
DHCPv6 Client DHCP-PD Relay
IPv6
Internet
DHCPv6-PD Client 2001:341f::1:57/64
May Use LL for the p2p Link Address
RA after 8
1 2
Solicit IA_PD with ORO= PD to Dest ff02::1:2 Relay-Forward[Solicit IA_PD]
INITIALISATION
Relay-Reply
4 3 [Advertize IA_PD with Delegation Options]
Advertise IA_PD with Delegation Options
5 6 Relay-Forward [Request IA_PD]
Request IA_PD
Reply IA_PD 2001:db8:678::/48 Block
8 7 Relay-reply[Relay IA_PD
2001:db8:678::/48 Block]
9
Reniew IA_PD 2001:db8:678::/48 Block
10 Relay-Forward [Renew IA_PD]
When
T1
12 11 Relay-Forward
(Reply IA_PD 2001:db8:678::/48 Block)
Expires Reply IA_PD 2001:db8:678::/48 Block
Release 14
Release IA_PD 2001:db8:678::/48 Block
15
Relay-forward [Release IA_PD 2001:db8:678::/48 Block]
Block
Reply IA_PD 2001:db8:678::/48 Block Status=OK Client DUID Server DUID 15
Relay-Reply [Release IA_PD 200...........]
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16. In this case, the Server has been reconfigured to specify a new
Prefix.
The old one may be advertized with a 0 for the Preferred Lifetime
and one day for the Valid Lifetime...
2001:341f::/32 DHCP-PD Server
2001:db8:78FA::/48
2001:db8:777f:5A01::1/64 (SLAAC)
DHCPv6 Client DHCP-PD Relay
DHCPv6-PD IPv6
Client Internet
2001:341f::1:57/64
RA
Relay-Forward(Reconfigure MSG Option=RENEW)
Reconfigure MSG Option=RENEW
Reniew (IA_PD 2001:db8:::/48) Reniew (IA_PD 2001:db8:678::/48)
Relay_Forward (Reply IA_PD 2001:db8:777F:5A00/56)
Reply MSG IA_PD 2001:db8:777f:5A00/56
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17. MOST IMPORTANT DHCPV6 RFC
IPv6 Prefix Options for DHCPv6
http://tools.ietf.org/html/rfc3633
http://tools.ietf.org/html/rfc6603
See RFC3633 IANA Considerations
IANA has assigned option codes to:
OPTION_IA_PD (25)
OPTION_IAPREFIX (26)
from the option-code space as defined in section 24.3, "DHCP Options" of RFC 3315.
IANA has assigned status code 6 to:
! Delegating router has no prefixes available to assign to the IAPD(s)
from the status-code space as defined in section 24.4, "Status Codes of RFC 3315.
Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
http://tools.ietf.org/html/rfc3315
Stateless DHCP Service for IPv6
http://tools.ietf.org/html/rfc3736
DNS Configuration Options for DHCPv6
http://tools.ietf.org/html/rfc3646
I
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18. 18
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