zyxel confidential ipv6: addressing milo liu sw2 zyxel communications corp. 3/6/2006

ZyXEL Confidential

IPv6: Addressing

Milo Liu

SW2

ZyXEL Communications Corp.

3/6/2006

ZyXEL Confidential

Outline

Review IPv4 addressing .

Basic IPv6 address concepts.

IPv6 address space.

Subnetting IPv6 space.

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IPv4 Address

32bit address space.

Subnet defined by a mask.

Unicast host address.

Multicast address.

Broadcast address.

Special address.

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IPv4 Address

32 bits address space.

• 11010010 01001001 10001100 00000010

• 210.73.140.2

Subnet mask (Network section and host section)

• A class (0xxxxxxx) + 24 bit

• B class (10xxxxxxxxxxxxxx) + 16bits

• C class (110xxxxxxxxxxxxxxxxxxxxx) + 8bits

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IPv4 Address

Multicast address.

• 1110xxxx + 24bits (223 ~ 240) .xxxxx

Broadcast address.

• 255.255.255.255

Loop-back address.

• 127.0.0.1 (localhost)

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IPv4 Addresses and IPv6 Equivalents

IPv4 Address IPv6 AddressInternet address classes N/AMulticast addresses (224.0.0.0/4) IPv6 multicast addresses (FF00::/8)Broadcast addresses N/AUnspecified address is 0.0.0.0 Unspecified address is ::Loopback address is 127.0.0.1 Loopback address is ::1Public IP addresses Aggregatable global unicast

addressesPrivate IP addresses Site-local addresses (FEC0::/48)APIPA addresses Link-local addresses (FE80::/64)Dotted decimal notation Colon hexadecimal formatSubnet mask or prefix length Prefix length notation only

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IPV6 Address syntax.

• 128bits space. (split by 16bits)

IPv6 Address concept

0010000111011010 0000000011010011 0000000000000000 00101111001110110000001010101010 0000000011111111 1111111000101000 100111000101101021DA:00D3:0000:2F3B:02AA:00FF:FE28:9C5A21DA:D3:0:2F3B:2AA:FF:FE28:9C5A

Prefix (n) Interface ID (128 - n)

128 bits

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IPv6 address syntax: Compressing Zeros

• FE80:0:0:0:2AA:FF:FE9A:4CA2 becomes

FE80::2AA:FF:FE9A:4CA2

• FF02:0:0:0:0:0:0:2

FF02::2

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Prefix is part of address where the bits have fixed values or are the bits of a route or subnet identifier.

IPv6 subnets or routes always uses address/prefix-length notation. (Classless

Inter-Domain Routing (CIDR) )

• 21DA:D3::/48 for a route

• 21DA:D3:0:2F3B::/64 for a subnet

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Classless Inter-Domain Routing (CIDR)

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IPv6 Addresses Application

Router 1

Subnet 2

Subnet 1

Router 2

Host A

Host B

Site: FEC0::1: 20D:60FF:FECB:6255

Link: FE80::20D:60FF:FECB:6255

Multicast: FF01::1 FF02::1

FF02::1:FFCB:6255

internet

Global: 3000:4D:C00:: 20D:60FF:FECB:6255

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IPv6 Address concept Subnet Mask: not required and as prefix of IPv6 address Type of address

• Unicast– Address of a single interface

– One-to-one delivery to single interface

• Multicast– Address of a set of interfaces

– One-to-many delivery to all interfaces in the set

• Anycast– Address of a set of interfaces

– One-to-one-of-many delivery to a single interface in the set that is closest

• No broadcast addresses

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Unicast address

• Aggregatable global unicast addresses

• Link-local addresses

• Site-local addresses

• Special addresses

• Compatibility addresses

• NSAP addresses

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IPv6 Address space

• 64bits (subnet section) + 64bits (interface se

ction)

Prefix Interface ID

64 bits 64 bits

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Unicast address

Aggregatable global unicast addresses

• Top-Level Aggregation ID (TLA ID)

• Next-Level Aggregation ID (NLA ID)

• Site-Level Aggregation ID (SLA ID)

• 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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Unicast address

Topologies Within Global Addresses

• Public Topology

• Site Topology

• Interface ID

TLA ID Interface ID

64 bits

SLA ID001 NLA ID

16 bits

Res

48 bits

Public Topology Site Topology Interface Identifier

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Unicast address

Link-local addresses

• Used between on-link neighbors and for

Neighbor Discovery

• Format Prefix 1111 1110 10– FE80::/64 prefix

• Used for local link only– Single subnet, no router

– Address autoconfiguration

– Neighbor Discovery

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Unicast address

Link-local addresses

1111 1110 10 Interface ID

10 bits 64 bits

000 . . . 000

54 bits

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Unicast address

Site-local addresses

• Used between nodes in the same site

• Format Prefix 1111 1110 11– FEC0::/48 prefix for site

• Used for local site only– Replacement for IPv4 private addresses

– Intranets not connected to the Internet

– Routers do not forward site-local traffic outside the

site

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Unicast address

Site-local addresses

1111 1110 11 Interface ID

10 bits 64 bits

000 . . . 000

38 bits

Subnet ID

16 bits

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Unicast address

Special addresses

• Unspecified address– 0:0:0:0:0:0:0:0 or ::

• Loopback address– 0:0:0:0:0:0:0:1 or ::1

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Unicast address

Compatibility Addresses• IPv4-compatible address

– 0:0:0:0:0:0:w.x.y.z or ::w.x.y.z

• IPv4-mapped address– 0:0:0:0:0:FFFF:w.x.y.z or ::FFFF:w.x.y.z

• 6over4 address– [64-bit prefix]:0:0:WWXX:YYZZ

• 6to4 address– 2002:WWXX:YYZZ:[SLA ID]:[Interface ID]

• ISATAP address– Interface ID of ::0:5EFE:w.x.y.z

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Multicast IPv6 Address

Defined multicast addresses

• All-Nodes addresses– FF01::1 (Node Local), FF02::1 (Link Local)

• All-Routers addresses– FF01::2 (Node Local), FF02::2 (Link Local), FF05::2

(Site Local)

1111 1111 Group ID

8 bits 112 bits

Flags

4 bits

Scope

4 bits

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Scope: 4bits

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Recommended Multicast IPv6 Addresses

• Single IPv6 multicast address maps to a

single Ethernet multicast MAC address

1111 1111 Group ID

8 bits 32 bits

Flags

4 bits

Scope

4 bits 80 bits

000 … 000

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Solicited-Node Address

• Acts as a pseudo-unicast address for very

efficient address resolution

• For FE80::2AA:FF:FE28:9C5A, the

corresponding solicited-node address is

FF02::1:FF28:9C5A

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Solicited-Node Address

Interface ID

64 bits

Unicast prefix

64 bits

FF02:

24 bits

:1:FF0:0:0:0

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Anycast IPv6 Address An anycast address is an address that is

assigned to a set of interfaces that typically belong to different nodes.

A packet sent to an anycast address is delivered to the closest interface.

Anycast addresses can be used only by a router, not a host, and anycast addresses must not be used as the source address of an IPv6 packet.

Subnet router anycast address

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IPv6 Addresses Application IPv6 Addresses for a Host

• Unicast addresses:– A link-local address for each interface

– Unicast addresses for each interface (site-local or global

addresses)

– A loopback address (::1)

• Listen Multicast addresses:– The node-local scope all-nodes multicast address (FF01::1)

– The link-local scope all-nodes multicast address (FF02::1)

– The solicited-node address for each unicast address

– The multicast addresses of joined groups

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IPv6 Addresses Application IPv6 Addresses for a Router

• Unicast addresses:– A link-local address for each interface

– Unicast addresses for each interface

– Loopback address (::1)

• Anycast addresses– Subnet-router anycast address

– Additional anycast addresses (optional)

• Listen Multicast addresses:– The node-local scope all-nodes multicast address (FF01::1)

– The node-local scope all-routers multicast address (FF01::2)

– The link-local scope all-nodes multicast address (FF02::1)

– The link-local scope all-routers multicast address (FF02::2)

– The site-local scope all-routers multicast address (FF05::2)

– The solicited-node address for each unicast address

– The multicast addresses of joined groups

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Router 1

Subnet 2

Subnet 1

Router 2

Host A

Host B




FF02::1:FFCB:6255

internet


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IPv6 Interface Identifiers Interface identifier based on:

• Extended Unique Identifier (EUI)-64 address– Either assigned to a network adapter card or derived from

IEEE 802 addresses

• Temporarily assigned, randomly generated value that changes over time

• A value assigned by a stateful address configuration protocol

• A value assigned during a Point-to-Point Protocol connection establishment

• A manually configured value

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IEEE EUI-64 Addresses

Extended Unique Identifier

Company ID

Extension ID

ccccccug cccccccc cccccccc

24 bits 40 bits

xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx

IEEE-administered company ID Manufacturer-selected extension ID

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IPv6 Interface Identifiers

Extended Unique Identifier (EUI)-64 address

• Extended Unique Identifier

• Company ID

• Extension ID

ccccccug cccccccc cccccccc

24 bits 40 bits

xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx


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Conversion of an IEEE 802 Address to an EUI-64 Address

Host A has the MAC address of 00-0D-60-CB-62-55

• 1. Convert to EUI-64 format– 00-0D-60-FF-FE-CB-62-55

• 2. Complement the U/L bit– The first byte in binary form is 00000000. When the seventh

bit is complemented, it becomes 00000010 (0x02).

– Result is 02-0D-60-FF-FE-CB-62-55

• 3. Convert to colon hexadecimal notation– 20D:60FF:FECB:6255

Link-local address for node with the MAC address of 00-0D-60-CB-62-55 is FE80:: 20D:60FF:FECB:6255.

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00000000 00001101 01100000 11001011 1100010 101010111111111 11111110

0xFF 0xFE

EUI-64 Address

00000000 00001101 01100000

24 bits 24 bits

11001011 1100010 1010101


IEEE 802 Address

00000010 00001101 01100000

64 bits

11111111 11111110 11001011 1100010 1010101

IPv6 Interface Identifier

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Temporary Address Interface Identifiers

Random IPv6 interface identifier

• Prevent identification of traffic regardless of the

prefix

• Initial value based on random number

• Future values based on MD5 hash of history value

and EUI-64-based interface identifier

Result is a temporary address

• Generated from public address prefixes using

stateless address autoconfiguration

• Changes over time

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IPv6 Multicast Address

33-33-

8 16 24 32

FF...:

Ethernet Multicast Address

Mapping IPv6 Multicast Addresses to Ethernet Addresses

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Router 1

Subnet 2

Subnet 1

Router 2

Host A

Host B




FF02::1:FFCB:6255

internet


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Subnetting the IPv6 Address Space

Subnetting for NLA IDs

[16-bit prefix]:00

f r

s

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Subnetting the IPv6 Address Space

Subnetting for SLA IDs

[48-bit prefix]: ::

f

s

r

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Expression Based on s (the number of bits chosen for subnetting), m (the

prefix length of the network prefix being subnetted), and F (the hexadecimal value of the subnet being subnetted), calculate the following: • f = m - 48

• f is the number of bits within the subnet ID that are already fixed.

• n = 2s

• n is the number of network prefixes that are obtained.

• i = 216-(f+s)

• i is the incremental value between each successive subnet ID expressed in hexadecimal form.

• l = 48 + f + s

• l is the prefix length of the new subnetted network prefixes.

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Example

To perform a 3-bit subnetting of the site-local network prefix FEC0:0:0:C000::/51, we first calculate the values of the number of prefixes, the increment, and the new prefix length. Our starting values are F = 0xC000, s = 3, and f = 51 - 48 = 3. The number of prefixes is 8 (n = 23). The increment is 0x400 (i = 216-(3+3) = 1024 = 0x400). The new prefix length is 54 (l = 48 + 3 + 3).

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Q&A

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Date Subject Lecturer

Introduction to IPv6

IPv6 Addressing

IPv6 Header & Extensions

Neighbor Discovery Protocol

Multicast Listener Discovery

IPv6 Routing

ICMPv6

Address Autoconfigurator

Joe Zhao

Milo Liu

Joe Zhao

Feng Zhou

Billy Bian

Jeffrey Zhou

Feng Zhou

Milo Liu

03/10

03/16

03/23

03/23

03/30

03/30

04/06

04/06

Training course arrangement

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Date Subject Lecturer

Setting Up an IPv6 Test Lab

IPv6 Migration Mechanisms

IPv6 Mobility

Joe Zhou

Milo Liu

04/13

04/20

Training course arrangement

zyxel confidential ipv6: addressing milo liu sw2 zyxel communications corp. 3/6/2006

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