IPv6 Introduction

• What is IPv6

• Purpose of IPv6 (Why we need it)

• IPv6 Addressing Architecture

• IPv6 Header

• ICMP v6

• Neighbor Discovery (ND)

• Reference Site

What is IPv6

• IP version 6 (Now is IP version 4)

• IPng (IP The Next Generation)

• RFC791

• IPv4 header IPv6 header

• IPv4 structure IPv6 structure

• Plug and Play

IPv6 address allocation in Asia

資料來源： http://www.ipv6.org.tw/

IPv6 subnets in Taiwan

資料來源： http://www.ipv6.org.tw/

Purpose of IPv6

• IPv4 address bottleneck• CIDR (Classless Inter-Domain Routing)• NAT (Network Address Translation)• 3G and IA (Information Appliance)

• Network Security• IPsec (IP security)

• Wireless Mobile Issue• Triangle Issue

Purpose of IPv6 (cont.)

• Running out of address in IPv4– 32-bit vs. 128-bit– 75% IP addresses in America– 3G & IA production

• Multicast function is not useful

• Checksum in 2 Layers

• CIDR is the default usage (without netmask)

Purpose of IPv6 (cont.)

• Simply the complex Header

• Reduce router’s loading

• Extension Header

• More Security with IPsec

• QoS (Quality of Service)

• Auto-Configuration– Statefull (DHCPv6)– Stateless (RS,RA)

IPv6 Feature (cont.)

Routing Table

ARP Table

IPv4

Neighbor Cache

Destination Cache

IPv6

Prefix List

Default Router List

IPv6 Addressing Architecture

• IPv6 Address Rule• Unicast Address (RFC2374)

– Link local address– Site local address– Global address

• Anycast Address (RFC2526)• Multicast Address (RFC2375)

No Broadcast Here!!!!!!

IPv6 Address Rule

• The preferred form is x:x:x:x:x:x:x:x• X is 16 bit value

• Long strings of zero bits• 0:0:0:0:0:0:0:1 ::1

• “前導 0” could be skipped• FFEE:BBBB:00A0:0:0:0:0:1 FFEE:BBBB:A0::1

• The "::" can only appear once in an address

Unicast Address-Link local

• Link local address– Used on a single link– Prefix is 1111 1110 10– FE80:

• Usage Timing– Automatic Address Configuration– Neighbor Discovery

Unicast Address-Site local

• Site local address– Used on a single site– Prefix is 1111 1110 11– FEC0:

Unicast Address-Global

• Global address– Unique in Internet– Prefix is 001

Anycast Address

• When a unicast address is assigned to more than one interface, thus turning it into an anycast address, the nodes to which the address is assigned must be explicitly configured to know that it is an anycast address.

Anycast Usage

A

R1

R2

R3

B

Anycast Area

Lower Cost

Multicast Address

• flags 000T (focus on T value)– 0 permanently-assigned (well-known address)– 1 non-permanently-assigned (transient)

• scope– 1 ： node-local scope– 2 ： link-local scope– 5 ： site-local scope– 8 ： organization-local scope– Others ： reserved

Ex ： ff02::1 (link-local) all nodes multicast address

Interface ID

• Created from MAC address• EUI-64 Address

– Example for link-local: – MAC addr: 00-01-23-AA-BB-CC– EUI-64:– 00-01-23 AA-BB-CC– 00-01-23 FF-FE AA-BB-CC– 00-01-23 -FF-FE-AA-BB-CC– FE80::1:23FF:FEAA:BBCC/64 <- link-local addr.

IPv6-IPv4 comparison

IPv4• Unspecified Host

– 0.0.0.0

• Loopback– 127.X.X.X

• Broadcast– 192.168.0.255

• Netmask– 255.255.255.0

IPv6• Unspecified Host

– 0:0:0:0:0:0:0:0 (::)

• Loopback– ::1

• Multicast– FF02::1

• Netmask– Prefix Number

IPv6 Header

IPv4 Header

IPv6 Extension Headers

Routing Header

Routing Header

• Created only when use PATH MTU function

• PATH MTU ： Trying to find out the biggest MTU size. (RFC 1981)

Fragment Header

Fragment Procedure

All Data

ICMP v6

• Internet Control Message Protocol• RFC 2463

ICMP sample

A B

A Ping B

ICMP v4 vs. ICMP v6

• ICMP v4– echo message

• Type 8

– reply message• Type 0

– code 0

• ICMP v6– echo request

message• Type 128

– echo reply message

• Type 129

– Code 0

Neighbor Discovery (ND)

• RFC2461

• Corresponds to a combination of IPv4– ARP– ICMP Router Discovery– ICMP Redirect

Neighbor Discovery

• 5 messages– Neighbor Solicitation (NS)– Neighbor Advertisement (NA)– Router Solicitation (RS)– Router Advertisement (RA)– Redirect

• All these messages should fill 255 in hop limit field

• Link Layer address

RS (Type 134)

RA (Type 133)

Regular RA (Type 133)

Use multicast to send its prefix to link-local scope all-nodes

NS (Type 135)

NA (Type 136)

Reference Site

• www.ipv6.org.tw

• www.ietf.org