zyxel confidential address autoconfiguration feng zou sw2 zyxel communications corp. 04/11/2006

ZyXEL Confidential

Address Autoconfiguration

Feng Zou

SW2

ZyXEL Communications Corp.

04/11/2006

ZyXEL Confidential

Outline

Why We Need Address Autoconfiguration?

IPv6 Address Structure Review

How to Autoconfiguration?

Autoconfiguration Process

Autoconfigured Address States

Types of Autoconfiguration

Q&A

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Why We Need Address Autoconfiguration?

The size of an address in IPv6 is 128 bits Each interface have multiple IPv6 addresses

It’s difficult to configure those IP addresses manually

MAC: 00-B0-D0-23-47-33

FE80::2B0:D0FF:FE23:4733 (link-local address)

FEC0::F282:2B0:D0FF:FE23:4733 (site-local address)3FFE:2900:D005:F282:2B0:D0FF:FE23:4733

(global address)

FF02::1:FF23:4733 (solicited-node address)

Host A

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Link-local address

• FE80 :: XXXX:XXXX:XXXX:XXXX

(Fixed Prefix) (Interface ID)

1111 1110 10 Interface ID

10 bits 64 bits

000 . . . 000

54 bits

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Site-local address

• FEC0 :: SSSS : XXXX:XXXX:XXXX:XXXX

(Fixed) (Subnet ID)

Prefix (Interface ID)

1111 1110 11 Interface ID

10 bits 64 bits

000 . . . 000

38 bits

Subnet ID

16 bits

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Aggregatable global address

• Prefix + Interface ID

TLA ID Interface ID

13 bits 64 bits

SLA ID

24 bits

001 NLA ID

16 bits

Res

8 bits

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Solicited-node address

• FF02::1:FF XX:XXXX

(Fixed Prefix) (last 24 bits of Interface ID)

104 bits

Interface ID

64 bits

Unicast prefix

64 bits

FF02:

24 bits

:1:FF0:0:0:0 XX:XXXX

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ccccccug cccccccc cccccccc xxxxxxxx xxxxxxxx xxxxxxxx11111111 11111110

0xFF 0xFEEUI-64 Address

ccccccug cccccccc cccccccc

24 bits 24 bits

xxxxxxxx xxxxxxxx xxxxxxxx

IEEE 802 Address (MAC)

ccccccUg cccccccc cccccccc

64 bits

11111111 11111110 xxxxxxxx xxxxxxxx xxxxxxxx

Interface ID

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How to Autoconfigure AddressIPv6 address: Prefix + Interface ID

Interface ID is converted from MAC Link-local address

• Prefix FE80:: is fixed• Can be determined even without a router and a DHCPv6

server Site-local address ,aggregatable global address

• Prefix can be determined by Prefix Information options in Router Advertisement message

Other configuration parameters

• Other configuration parameters include hop limit, reachable time, retransmission timer, MTU…

• Can be determined by Router Advertisement message

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Autoconfiguration ProcessFor IPv6 node: 1. Derive tentative link-local address based on FE80::/64 and

a EUI-64-derived Interface ID. 2. Using Duplicate Address Detection to verify the uniqueness

of the tentative link-local address. 3. If a Neighbor Advertisement message is received, address

auto-configuration stops. Manual configure or assign a new Interface ID (must do Duplicate Address Detection either) to this interface.

4. If NO Neighbor Advertisement message is received, the tentative link-local address is valid and the link-layer multicast address of the corresponding solicited-node address is registered.

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Autoconfiguration ProcessFor IPv6 host: 1. The host sends a Router Solicitation message. 2. If NO Router Advertisement messages are received, the

host uses a stateful address auto-configuration protocol to obtain addresses and other configuration parameters.

3. If a Router Advertisement message is received, the host sets configuration parameters (hop limit, reachable time, retransmission timer, MTU…).

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Autoconfiguration Process 4. For each Prefix Information option present:

• If the On-Link flag is set to 1, the prefix is added to the prefix list.• If the Autonomous flag is set to 1, the prefix and an appropriate Interface ID

are used to derive a tentative address.• Use duplicate address detection to verify the uniqueness of the tentative

address.– If the tentative address is in use, don’t use the address to initialize the

interface.

– If the tentative address is not in use, the address is initialized. If needed, registers the new link-layer multicast address of the corresponding solicited-node address.

5. If the Managed Address Configuration flag is set to 1, a stateful address auto-configuration protocol is used to obtain additional addresses.

6. If the Other Stateful Configuration flag is set to 1, a stateful address auto-configuration protocol is used to obtain additional configuration parameters.

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Use stateful addressconfiguration protocol.

Derive link-local address:FE80::[Interface ID]

Send multicast Neighbor Solicitation with

Target Address set to derived link-local address.

Neighbor Advertisement

response received?

Yes

No

Initialize link-local address.

Send Router Solicitation.

Set Hop Limit, Reachable Time, Retrans Timer, MTU.

Are PrefixInformation

optionspresent?

Yes

NoStop address autoconfiguration.

A

Router Advertisement

response received?

No

Yes

Use stateful addressconfiguration protocol.

Is Other

Stateful Configuration

flag set to 1?

Yes

No

Stop address autoconfiguration.

Is Managed Address

Configuration flagset to 1?

No

Yes

B

Deal with Prefix Info Options

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Is On-Link flagset to 1?

Yes

No

Add prefix to prefix list.

Derive stateless address:Prefix + Interface ID

Initialize stateless address.

Neighbor Advertisement

response received?

No

Yes Do not initialize stateless address.

Are there more

Prefix Information options to process?

No

Yes

A

B

Get first Prefix Information option.

Send multicast Neighbor Solicitation with Target Address set to derived stateless address.

Is Autonomous

flagset to 1?

No

Yes Go to next Prefix Information option.

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① Send Multicast Listener Report

Ethernet Header• Destination MAC is 33-33-FF-23-47-33IPv6 Header• Source Address is ::• Destination Address is FF02::1:FF23:4733• Hop limit is 1Multicast Listener Report Header• Multicast Address is FF02::1:FF23:4733

Router

Host A

MAC: 00-B0-D0-23-47-33IP: ::

MAC: 0010FFD658C0IP: FE80::210:FFFF:FED6:58C0

FEC0:0:0:F282:210:FFFF:FED6:58C03FFE:2900:D005:F282:210:FFFF:FED6:58C0

Host B

Multicast Listener Report

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② Send Router Solicitation

Router

Host A

MAC: 00-B0-D0-23-47-33IP: ::

Host B

Router Solicitation

Ethernet Header• Destination MAC is 33-33-00-00-00-02IPv6 Header• Source Address is :: • Destination Address is FF02::2• Hop limit is 255Router Solicitation Header



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③ Send Neighbor Solicitation

Router

Host A

MAC: 00-B0-D0-23-47-33IP: ::

Host B

Ethernet Header• Destination MAC is 33-33-FF-23-47-33IPv6 Header• Source Address is ::• Destination Address is FF02::1:FF23:4733• Hop limit is 255Neighbor Solicitation Header• Target Address is FE80::2B0:D0FF:FE23:4733

Neighbor Solicitation



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④ Send Router Advertisement

Router

Host A

MAC: 00-B0-D0-23-47-33IP: ::

Host B

Router Advertisement

Ethernet Header• Destination MAC is 33-33-00-00-00-01IPv6 Header• Source Address is FE80::210:FFFF:FED6:58C0• Destination Address is FF02::1• Hop limit is 255Router Advertisement Header• Current Hop Limit = 64• Router Lifetime = 1800• Source Link-Layer Address is 00-10-FF-D6-58-C0• Prefix Information is for FEC0:0:0:F282::

•Valid Lifetime = 2592000•Preferred Lifetime = 604800

• Prefix Information is for 3FFE:2900:D005:F282::



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⑤ Send Neighbor Solicitation

Router

Host A

MAC: 00-B0-D0-23-47-33IP: ::

Host B

Ethernet Header• Destination MAC is 33-33-FF-23-47-33IPv6 Header• Source Address is ::• Destination Address is FF02::1:FF23:4733• Hop limit is 255Neighbor Solicitation Header• Target Address is FEC0::F282:2B0:D0FF:FE23:4733




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⑥ Send Neighbor Solicitation

Router

Host A

MAC: 00-B0-D0-23-47-33IP: ::

Host B

Ethernet Header• Destination MAC is 33-33-FF-23-47-33IPv6 Header• Source Address is ::• Destination Address is FF02::1:FF23:4733• Hop limit is 255Neighbor Solicitation Header• Target Address is 3FFE:2900:D005:F282:2B0:D0FF:FE23:4733




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Router

Host A

MAC: 00-B0-D0-23-47-33IP: FE80::2B0:D0FF:FE23:4733

FEC0::F282:2B0:D0FF:FE23:4733 3FFE:2900:D005:F282:2B0:D0FF:FE23:4733

Host B

⑦ NO Neighbor Advertisement message received



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Autoconfigured Address States Tentative

• The address is in the process of being verified as unique Valid

• An address from which unicast traffic can be sent and received

• Preferred state– An address for which uniqueness has been verified, unrestricted

use

• Deprecated state– An address that is still valid, but is discouraged for new

communication

Invalid

• An address for which a node can no longer send or receive unicast traffic

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Autoconfigured Address States

Tentative Preferred Deprecated Invalid

Preferred Lifetime

Valid

Valid Lifetime

time

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Types of Autoconfiguration Stateless

• Receipt of Router Advertisement messages with one or more Prefix Information options

Stateful

• Use of a stateful address configuration protocol such as DHCPv6

Both

• Receipt of Router Advertisement messages and stateful configuration protocol

For all types, a link-local address is always configured automatically.

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Q & A

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IPv6 Training Courses

Date Subject Lecturer

Introduction to IPv6

IPv6 Addressing

IPv6 Header & Extensions

Neighbor Discovery Protocol

Multicast Listener Discovery

IPv6 Routing

ICMPv6

Address Autoconfiguration

Joe Zhao

Milo Liu

Joe Zhao

Feng Zhou

Billy Bian

Jeffrey Zhou

Feng Zhou

Milo Liu

03/10

03/16

03/23

03/27

03/30

04/06

04/11

04/13

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IPv6 Training Courses

Date Subject Lecturer

Setting Up an IPv6 Test Lab

IPv6 Migration Mechanisms

IPv6 Mobility

Joe Zhao

Milo Liu

04/20

04/27

zyxel confidential address autoconfiguration feng zou sw2 zyxel communications corp. 04/11/2006

Documents

address ipv6 address

bits of interface id

bits interface id

node address ff02

node address host

global address ff02

tentative linklocal

linklocal address fec0