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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/