IVI - IPv4/IPv6 Coexistence and Transition

Xing Li2009-03-04

Unexpected situation

Transition

• IPv4 and IPv6 is NOT compatible • There is NO flag day• Transition is REALLY difficult

IPv6 Road Map

Transition methods

• Dual-stack • Tunneling• Translation

IPv6 Workshop, Sigcomm 2007

Crossroad

Background

CERNET (IPv4)

Global IPv4

Global IPv4

CNGI-CERNET2 (IPv6)

Global IPv6

Global IPv6

IVI

2,000 universities connected20M users

100 universities connected400K users

IPv4-accessibleservers

The lessons learned• The only viable option for future Internet is IPv6

– The transitions can only starts when the part of it is pure IPv6• The scenarios of building new IPv6 network for the

unwired population– The cost-effective way for building a new infrastructure

• The natural transition– Construction and operation single stack costs less than dual-

stack– Construction and operation simple (stateless) network costs less

than complex (stateful) network • The resources should be shared via inter-communication

– The IPv6 servers should be IPv4 accessible – The IPv4 servers should be IPv6 accessible

IPv6 S Curve

2008

Many IPv4 ServersFew IPv6 Servers

Many IPv6 ServersFew IPv4 Servers

IPv6 promotion•Dual stack X•IPv6 single stack + IPv4 accessible √

The IVI model

Global IPv4Global IPv4IVI

networkIVI

network

Global IPv6 (non-IVI)

IVI

IVI address format

LIR Prefix IPv4 addr

0 32 40 72 96 127

Prefix part Host part

64

Entirely 0

For example LIR consists of ISP prefix (usually /32) and IVI flag

CERNET/CNGI-CERNET2’s selection– LIR = 2001:da8:ff00::/40– ISP’s IVI service IPv4 address mapping

• 202.38.108.0/24 2001:250:ffca:266c:0000::/64 – ISP’s non-IVI service IPv4 address mapping

• 202.38.96.0/20 2001:250:ffca:2660:0000::/60– Other ISP’s IPv4 address mapping

• 0.0.0.0 2001:da8:ff00::/40• 18.181.0.31/32 2001:250:ff12:b500:1f00::/72

Address Mapping (1)

IPG6

IPS6(i)

IVI4(i)

IVIG46(i) IVI6(i)

4 66 4

IPS4(i)

IPG4

Address Mapping (2)

IVIG46(i) IVI6(i) IVIG46(j) IVI6(j)

IPG4 IVI4(i)

6 4

IVI4(j)

4 64 6 6 4

IPS6(i) IPS6(j)

IPG6

Conceptual example

IPv6IPv4

Real IPv6 hostReal IPv4 host mirrored IPv6 host mirrored IPv4 host

IVI

IVI routing

Longest prefix match

IVIR1 R2IPv4IPv4 IVI IPv6IVI IPv6

2001:da8:ff00::/40

2001:da8:ffca:266c:0000::/640.0.0.0/0

202.38.108.0/24

IVI DNS service• Normal DNS

– Algorithm based

• DNS translation– Algorithm

basedIPv6 initiated

IPv4 initiated

Stateless (1:1) operation

• Stateless – SIIT extension

• Based on ISP’s prefix• The mapping between IPv4 and IVIIPv6 is

based on algorithm• Support both IPv6 initiated and IPv4

initiated communications

Stateful (1:N) operation

• Stateful – NAT-PT (NAPT-PT) improvement

• IPv4 address multiplexing• Based on ISP’s prefix• Support IPv6 initiated communication

IVI Reachability• 4Host1 IVI1 (stateless)• IVI1 4Host1 (stateless)

• 4Host1 --X 6Host1• 6Host1 4Host1 (stateful)

• 4Host1 4Host2• 4Host2 4Host1

• 6Host1 IVI1• IVI1 6Host1

• 6Host1 6Host2• 6Host2 6Host1

• IVI1 IVI2• IVI2 IVI1

IPv4 initiated communication (1:1)

IVI IPv6IPv6

IVI DNS

IPv6 IVI server

IPv4client

IPv4IPv4

Ask for A record

src=59.66.24.42 src=2001:250:ff3b:4218:2a00::ivi.sasm3.net dst=202.38.114.1 dst=2001:250:ffca:2672:0100::0

IPv4 to IPv6 translation

IPv6 to IPv4 translation

ivi.sasm3.net src=202.38.114.1 src=2001:250:ffca:2672:0100::0dst=59.66.24.42 dst=2001:250:ff3b:4218:2a00::

stateless

IPv6 initiated communication (1:1)

IVI IPv6IPv6

IVI DNS

IPv6 IVIclient

IPv4server

IPv4IPv4

GlobalDNS

Ask for AAAA record

Ask for AAAA record or A record

IPv6 to IPv4 translation

IPv4 to IPv6 translation

src=202.38.108.5 src=2001:da8:ffca:266c:0500::www.mit.edu dst=18.7.22.83 dst=2001:da8:ff12:0716:5300::

src=18.7.22.83 src=2001:da8:ff12:0716:5300::dst=202.38.108.5 dst=2001:da8:ffca:266c:0500::

stateless

IPv6 initiated communication (1:N)

IVI IPv6IPv6

IVI DNS

IPv6 non-IVIclient

IPv4server

IPv4IPv4

GlobalDNS

Ask for AAAA record

Ask for AAAA record or A record

IPv6 to IPv4 translation

IPv4 to IPv6 translation

src=202.38.102.1#2000 src=2001:da8::100#3000www.mit.edu dst=18.7.22.83#80

dst=2001:da8:ff12:0716:5300::#80

src=18.7.22.83#80 src=2001:da8:ff12:0716:5300::#80dst=202.38.108.5#2000 dst=2001:da8::100#3000

stateful

IPv4 pool 202.38.102.0/24

state

state

IVI ICMP extension• Operation

– IPv4 IPv6– IPv6 IPv4

i=2

i=1

2001:da8:ffca:266c:0500::4:0

2001:da8:ffca:266c:0500::4:1

2001:da8:ffca:266c:0500::4:2

2001:da8:ffca:266c:0500::4:3

202.38.108.5

84

85

86

87

8786

8584

i=0

i=3

IPv4 address

IPv6 address

port

port

Port number keep the same

Stateless 1:N operation

The multiplexing ratio

• If the multiplexing ratio is 256。• One IPv4 /8 can support 4.3 billion IPv6

hosts, same as the size of the global IPv4 space.

IVI multicast

• IVI supports PIM SSM– Group address mapping– RPF mapped IPv6 address– PIM Spare-mode ALG

Transition mechanisms

• When IPv4 addresses are running out– IPv4 + NAT

• Short term solution– Pure IPv6

• Cannot reach the global IPv4, unacceptable– Dual stack

• The cost increases, ISPs want others to deploy dual stack

– IVI IPv6• The cost is the same as the single stack, but the

IPv6 host can be reached by global IPv4

Dual stack

Dual stackDual stack

Global IPv4Global IPv4 Global IPv6Global IPv6

IPv4access network

IPv4 private network

IPv6access network

IPv6 enterprise network

IPv4+IPv6access network

IPv4+IPv6 enterprise network

• Not easy

IVI

Dual stackDual stack

Global IPv4Global IPv4 Global IPv6Global IPv6

IPv4access network

IPv4 private network

IPv6access network

IPv6 enterprise network

IPv4+IPv6access network

IPv4+IPv6 enterprise network

• Encourage transition

IVIIVI

Transition

Support IPv4 Support IPv6 (IVI)

SupportIPv6 (IVI)

Support IPv4

IPv4 area IPv6 area

Service

Netw

orkU

ser

V4 only Network V6 only Network

IVI

SupportIPv6 (non-IVI)

Support IPv6 (non-IVI)

Transition IPv4 IPv6

http://www.ivi2.org/IVI/