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IPv6

รศ. ดร. อนันต์ ผลเพิ.มAsso. Prof. Anan Phonphoem, Ph.D.

anan.p@ku.ac.thhttp://www.cpe.ku.ac.th/~anan

Computer Engineering DepartmentKasetsart University, Bangkok, Thailand

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Outlinen What is wrong with IPv4 ?n NATn Features of IPv6n IPv6 Transition

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TCP/IP Protocol Stack - Data Flow

Application5

4 Transport

3 Network

2 Data Link

1 Physical

Hello

1001101001011101011

Hello5432 T

Hello543

4 Hello5

5 HelloTCP or UDP Header

IP Header

Ethernet Header

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IPv4 Header

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What is wrong with IPv4 ?n Internet growthn New applications – Real time app.n Network Changesn Need for corporations

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IPv6 Vision (Internet for 10 Billion nodes)

Always-on Identity Auto-Configure

MobileAlways-on Security

privacy

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Rationale for IPv6n IPv4 address space consumption

n Now ~10 years free space remainingn Unused addresses reclaimedn Just projection! – reality will be different

n Loss of “end to end” connectivityn Widespread use of NAT due to ISP policies and

marketingn Additional complexity and performance degradation

Network Address Translation (NAT)

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Network Address Translation (NAT)

n Private Networkn Good practice to use private address

n Map local addresses to (real) public IP address(es)

n Security (not expose internal details)n Alleviate IP depletion

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Private IP address

Class RFC 1918 CIDR prefixA 10.0.0.0 – 10.255.255.255 10.0.0.0/8

B 172.16.0.0 – 172.31.255.255 172.16.0.0/12

C 192.168.0.0 – 192.168.255.255 192.168.0.0/16

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Stub Network

n Operates at the border of a stub network

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ADSL Router

WLAN ADSL Router

Stub Network Example ADSL Connection

ADSL Modem InternetISP

Telephone Line

ADSL Modem

ADSL Modem

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NAT

“One” or “Pool” of IP addresses

Example

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Internet

Site using private addresses

172.18.3.1

172.18.3.2

172.18.3.20

Source: 172.18.3.1 Source: 200.24.5.8

Destination: 200.24.5.8Destination: 172.18.3.1

200.24.5.8172.18.3.254

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Basic Address Translation

Internet

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NAPT

n Network Address and Port Translationn Sometimes just call “NAT”n Two or more host at a site

Internet

10.0.0.2

10.0.0.1

10.0.0.3

128.10.19.20

:30000

:30000

:32000

:40001:40002:40003

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The NAT “Problem”

Internet

10.0.0.1

61.100.32.128NAT

?Extn 10

PhoneNetwork

10 4567 9876PABX

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Features of IPv6

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IPv6 feature summaryn Increased size of address spacen Header simplificationn Extended Address Hierarchy n Auto-configuration / Renumberingn QoS (Integrated/Differentiated servicesn IPSec (As for IPv4)

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IPv6 addressing modeln Unicast

n single interfacen Anycast

n any one of severaln same locationn replicate services (servers)

n Multicastn all of a group of interfacesn replaces IPv4 “broadcast”

n See RFC 3513

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IPv4 vs IPv6IPv4: 32 bits

• 232 addresses= 4,294,967,296 addresses= 4 billion addresses

IPv6: 128 bits

• 2128 addresses?= 340,282,366,920,938,463,463,374,607,431,770,000,000= 340 billion billion billion billion addresses?

• No, due to IPv6 address structure…

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IPv6 Addressing

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128 bits

How much IPv6?

Topological Interface/0 /64 /128

Infrastructure Site/0 /64/48

• 248 site addresses= 281,474,976,710,656= 281 thousand billion site addresses

• 264 “subnet” addresses= 18,446,744,073,709,551,616= 18 billion billion subnet addresses

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IPv6 address format

n 8 groups of 4 hexadecimal digitsn Each group represents 16 bitsn Separator is “:”n Case-independent

128 bits2001:0DA8:E800:0000:0260:3EFF:FE47:0001

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2001:0DA8:E800:0000:0000:0000:0000:0001

2001:0DA8:E800:0000:0260:3EFF:FE47:0001

IPv6 address format

2001:DA8:E800:0:260:3EFF:FE47:1

2001:0DA8:E800:0000:0000:0000:0000:0001

2001:0DA8:E800:0000:0260:3EFF:FE47:0001

2001:DA8:E800::1

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Special Addressn Unspecified address

n 0:0:0:0:0:0:0:0 è ::n Source add. (when own add. is unknown)

n Loopback addressn 0:0:0:0:0:0:0:1 è ::1n For testingn Datagram is delivered to local machine

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Unicast Address Hierarchyn Individual network interface

n Single connection between computer & network

n Individual siten Set of computers in a single organization

n Globally-known public topologyn Publicly available “section” of the Internetn Two types (ISP and exchange)

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Unicast Address from node’s point of view

n No internal structure

n Simple Structure with subnet prefix

n Interface identifier is unique for the linkn IEEE EUI-64 format

Node Address

0 127

Subnet Prefix

0 127

Interface ID

n

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IPv6 headern IPv6 header is simpler than IPv4

n IPv4: 14 fields, variable length (20 bytes +)n IPv6: 8 fields, fixed length (40 bytes)

n Header fields eliminated in IPv6n Header Lengthn Identificationn Flagn Fragmentation Offsetn Checksum

n Header fields enhanced in IPv6n Traffic Classn Flow Label

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Basic HeadersIPv4

IPv6

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Structure of Datagram

n Base Header is fixedn 40 Octets longn Options are in an extension header

n Several extension headers

Base Header Extensions TCP/UDP Data

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Basic Headers (Fields)n Version (4 bits) – only field to keep same

position and namen Class (8 bits) – new fieldn Flow Label (20 bits) – new fieldn Payload Length (16 bits) – length of data,

slightly different from total lengthn Next Header (8 bits) – type of the next header,

new idean Hop Limit (8 bits) – was time-to-live, renamedn Source address (128 bits)n Destination address (128 bits)

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Header Simplification n Fixed length of all fields, not like old options

field – IHL, or header length irrelevantn Remove Header Checksum – rely on

checksums at other layersn No hop-by-hop fragmentation – fragment

offset irrelevant – MTU discoveryn Add extension headers – next header type

(sort of a protocol type, or replacement for options)

n Basic Principle: Routers along the way should do minimal processing

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Extension Headers Typesn Routing Headern Fragmentation Headern Hop-by-Hop Options Headern Destinations Options Headern Authentication Headern Encrypted Security Payload Header

Base Header Extensions TCP/UDP Data

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Changes from IPv4 to IPv6n Expanded addressing capabilitiesn Header format simplificationn Improved support for extensions and

optionsn Flow labeling capabilityn Authentication and privacy capabilities

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IPv6 transitionn Dual stack hosts

n Two TCP/IP stacks co-exists on one hostn Supporting IPv4 and IPv6n Client uses whichever protocol it wishes

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IPv6 transition

IPv4 IPv6

www.apnic.net??

IPv4

TCP/UDPApplication

IPv6Link

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n IPv6 tunnel over IPv4

IPv6 transition

IPv4Network

IPv6 IPv6

IPv6 Header Data

IPv4 Header IPv6 Header Data

IPv6 Header Data

tunnel

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Referencesn “Tutorial - IPv6 Address Management” by Paul

Wilson, Director General, APNIC

n “IPv6 Tutorial/Workshop” by Rick Summerhill, Great Plains Network, and Dale Finkelson, U of

Nebraska at Lincoln

n “IPv6 21st Century Internet” by IPv6 Forumn “IPv6 Education and Deployment Efforts in Japan”

by Takashi Arano, NTT Communications

n http://www.isoc.org/inet2000/cdproceedings/1e/1e

_4.htm