ipv6 - kasetsart university · tcp/udp application ipv6 link. 38 nipv6 tunnel over ipv4 ipv6...
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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
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