Next Generation IP< IPv6 >

National Dong Hwa University

Director of Computer Center

Han-Chieh Chao

中華民國八十九年十月十九日

TANET2000 TWNIC IPv6 研討會

Overview

• Limitations of current Internet Protocol (IP)• How many address do we need?• IPv6 addressing• IPv6 header format• IPv6 features• Mobile IPv6• IPv6 v.s. IPv4• Summary

IPv4 Addresses

• Example: 203.64.105.100=1100 1011:0100 0000:0110 1001:0110 0100 = CB:40:69:64 (32 bits)

• Maximum = 232 = 4 Billion

• Class A Network: 15 Million nodes

• Class B Network: 64,000 nodes or less

• Class C Network: 250 nodes or less

IPv4 Address

• Class A

• Class B

• Class C

• Class D

0 Network Local

10 Network Local

110 Network Local

1110 Host Group (Multicast)

1 17 24

2

8

14

213

16

284

bits

bits

bits

bits

IPv4 Address

• Local = Subnet + Host (Variable length)

Router Router

Subnet

IPv4 Address Format

• Three all-zero network numbers are reserved• 127 Class A + 16,381 Class B + 2,097,151 Class C

Network = 2,113,659 networks total• Class B is most popular• 20% of Class B were assigned by 7/90 and

doubling every 14 months => Will exhaust by 3/94• Question: Estimate how big will you become?

Answer: more than 256!Class C is too small. Class B is just right.

How many address?

• 10 Billion people by 2020• Each person will be served by more than one com

puter• Assuming 100 computers per person => 1012 comp

uters

• More addresses maybe required since – Multiple interfaces per node

– Multiple addresses per interfaces

How many address?

• Some believe 26 to 28 address per host• Safety margin => 1015 addresses• IPng Requirements => 1012 end systems and 109 n

etworks. Desirable 1012 to 1015 networks

Address Size

• H Ratio = log10(number of objects)/available bits

• 2n objects with n bits: H Ratio = log102 = 0.30103

• French telephone moved from 8 to 9 digits at 107 households => H = 0.26 (assuming 3.3 bits/digit)

• US telephone expanded area codes with 108 subscribers => H = 0.24

• SITA expanded 7-character address at 64k nodes => H = 0.14 (assuming 5 bits/char)

Address Size

• Physics/space science net stopped at 15000 nodes using 16-bit addresses => H = 0.26

• 3 Million Internet hosts currently using 32-bit addresses => H = 0.20 => A few more years to go

IPv6 Address

• 128-bit long. Fixed size • 2128 = 3.4×1038 addresses => 665×1021 addresses p

er m2 of earth surface• If assigned at the rate of 106/s, it would take 20 y

ears • Expected to support 8×1017 to 2×1033 addresses 8×

1017 => 1,564 address per m2 • Allows multiple interfaces per host• Allows multiple addresses per interface

IPv6 Address

• Allows unicast, multicast, anycast • Allows provider based, site-local, link-local • 85% of the space is unassigned

Colon-Hex Notation

• Dot-Decimal: 203.64.105.100• Colon-Hex:

FEDC:0000:0000:0000:3243:0000:0000:ABCD – Can skip leading zeros of each word

– Can skip one sequence of zero words, e.g., FEDC::3243:0000:0000::ABCD

– Can leave the last 32 bits in dot-decimal, e.g., ::203.64.105.100

– Can specify a prefix by /length, e.g., 2345:BA23:7::/40

IPv6 Prefix Allocation

IPv6 Addressing Model• Addresses are assigned to interfaces

– No change from IPv4 Model

• Interface can have multiple addresses

• Addresses have scope– Link Local– Site Local– Global

• Addresses have lifetime– Valid and Preferred lifetime

Link-LocalSite-LocalGlobal

Local-Use Address

• Link Local: Not forwarded outside the link,

FE80::xxx

• Site Local: Not forwarded outside the site,

FEC0::xxx

1111 1110 10 0 Interface ID 10 n 118-n bits

1111 1110 11 0 Subnet ID Interface IDbitsn10 m 118-n-m

Multicast Address

• T=0 => Permanent (well-known) multicast address, T=1 => Transient

• Scope: 1 Node-local, 2 Link-local, 5 Site-local,8 Organization-local, E Global

• Predefined: 1=>All nodes, 2=>Routers, 1:0=>DHCP Servers

1111 1111 Flags Scope Group ID

0 0 0 T

4bits8bits 112bits4bits

Multicast Address

• Example: 43 => Network Time Protocol Servers– FF01::43 => All NTP servers on this node – FF02::43 => All NTP servers on this link – FF05::43 => All NTP servers in this site – FF08::43 => All NTP servers in this organization – FF0F::43 => All NTP servers in the Internet

IPv4 Header20 Octets+Options : 13 fields, include 3 flag bits

0 bits 31

Ver IHL Total Length

Identifier Flags Fragment Offset

32 bit Source Address

32 bit Destination Address

4 8 2416

Service Type

Options and Padding

Time to Live Header ChecksumProtocol

RemovedChanged

IPv6 Header40 Octets, 8 fields

0 31

Version Class Flow Label

Payload Length Next Header Hop Limit

128 bit Source Address

128 bit Destination Address

4 12 2416

Protocol and Header Types

IPv6 Header

Next = TCP

TCP Header

IPv6 Header

Next = Routing

TCP HeaderRouting HdrNext = TCP

IPv6 Header

Next = Security

TCP HeaderSecurity HdrNext = Frag

Application Data

Application Data

Fragment HdrNext = TCP

DataFrag

IPv6 Extension Headers• IP options have been moved to a set of optional Extension

Headers

• Extension Headers are chained together

Routing Header

Next Header Routing Type Num. Address

Reserved Strict/Loose bit mask

Address 1

Address 2

Next Address

Address n

…..

Routing Header

• Strict => Discard if Address[Next-Address] neighbor

• Type = 0 => Current source routing • Type > 0 => Policy based routing (later) • New Functionality: Provider selection, Host

mobility, Auto-readdressing (route to new address)

IPv6 Features

• Larger Addresses• Flexible header format • Improved options • Support for resource allocation • Provision for protocol extension • Built-in Security: Both authentication and

confidentiality

Address Autoconfiguration

• Allow plug and play• BOOTP and DHCP are used in IPv4 • DHCPng will be used with IPv6 • Two Methods: Stateless and Stateful• Stateless:

– A system uses link-local address as source and multicasts to "All routers on this link"

– Router replies and provides all the needed prefix info– All prefixes have a associated lifetime – System can use link-local address permanently if no router

Address Autoconfiguration

• Stateful: – Problem w stateless: Anyone can connect

– Routers ask the new system to go DHCP server (by setting managed configuration bit)

– System multicasts to "All DHCP servers" – DHCP server assigns an address

Automatic Renumbering

• Renumbering IPv6 Hosts is easy– Add a new Prefix to the Router

– Reduce the Lifetime of the old prefix

– As nodes depreciate the old prefix the new Prefix will start to be used for new connections

• Renumbering in IPv6 is designed to happen!• An end of ISP “lock in”!

– Improved competition

Putting the IT Director back in control

• IPv6 Address Scope– Some addresses are GLOBAL– Others are Link or Site LOCAL – Addressing Plan also controls network access

• Configuration Policy Control– Stateless – Stateful (DHCPv6)

• Routers Dictate the Configuration Policy– Router Managers are “in control” of the network– Routers also dictate MTU size for the Link

Mobile IPv6

• IPv6 Mobility is based on core features of IPv6– The base IPv6 was designed to support Mobility

– Mobility is not an “Add-on” features• All IPv6 Networks are IPv6-Mobile Ready

• All IPv6 nodes are IPv6-Mobile Ready

• All IPv6 LANs / Subnets are IPv6 Mobile Ready

• IPv6 Neighbor Discovery and Address Autoconfiguration allow hosts to operate in any location without any special support

Mobile IPv6

• No single point of failure (Home Agent)• More Scalable : Better Performance

– Less traffic through Home Link

– Less redirection / re-routing (Traffic Optimisation)

Mobile IPv6 Status

• Interactions with IPsec fully worked out

• Mobile IPv6 testing event– Bull, Ericsson, NEC, INRIA

• Internet Draft is ready for Last Call

IPv6 - Mandates Security

• Security features are standardized and mandated– All implementations must offer them– No Change to applications

• Authentication (Packet signing)• Encryption (Data Confidentiality)• End-to-End security Model

– Protects DHCP– Protects DNS– Protects IPv6 Mobility– Protects End-to-End traffic over IPv4 networks

IPv6 v.s. IPv4

• 1995 v.s. 1975 • IPv6 only twice the size of IPv4 header • Only version number has the same position and m

eaning as in IPv4 • Removed: header length, type of service, identific

ation, flags, fragment offset, header checksum • Datagram length replaced by payload length • Protocol type replaced by next header

IPv6 v.s. IPv4

• Time to live replaced by hop limit • Added: Priority and flow label • All fixed size fields• No optional fields. Replaced by extension headers• 8-bit hop limit = 255 hops max (Limits looping) • Next Header = 6 (TCP), 17 (UDP)

IPv6 Features and Advantages

• Larger Address Space• Efficient and Extensible IP datagram• Efficient Route Computation and Aggregation• Improved Host and Router Discovery• Mandated New Stateless and Stateful Address A

utoconfiguration• Mandated Security for IP datagrams• Easy renumbering

Transition Mechanisms• Dual-IP Hosts, Routers, Name servers • Tunneling IPv6 over IPv4 • Hosts and Routers can be gradually upgraded to IPv6 • It is better (though not required) to upgrade routers

before upgrading hosts

HITACHI Toolnet6 http://www.hitachi.co.jp/Prod/comp/network/pexv6-e.htm

Interoperability

• 6over4– Isolated v6 to isolated v6 node– IPv4 used as link layer

• 6to4– v6 domain to v6 domain– IPv4 used as transport tunnel

• NAT-PT– v6 only to v4 only

• SIIT, AIIH, DTI, BIS, …

Application Issues

• Most application protocols will have to be upgraded: FTP, SMTP, Telnet, Rlogin

• 27 of 51 Full Internet standards, 6 of 20 draft standards, 25 of 130 proposed standards will be revised for IPv6

• No checksum => checksum at upper layer is mandatory, even in UDP

• non-IETF standards: X-Open, Kerberos, ... will be updated

• Should be able to request and receive new DNS records

Implementation

• 4.4-lite BSD by US Naval Research Laboratory • UNIX, OpenVMS by DEC • DOS/WINDOWS by FTP Software • HP-UX SICS (Swedish Institute of Comp. Science) • Linux • NetBSD by INRIA Rocquencourt • Solaris 2 by Sun • Streams by Mentat

Summary

• IPv6 uses 128-bit addresses • Allows provider-based, site-local, link-local, multi

cast, anycast addresses • Fixed header size. Extension headers instead of op

tions. Extension headers for provider selection, security

• Allows autoconfiguration • Dual IP router and host implementations for transi

tion