Alain Durand

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IPv6 transition strategies
Alain Durand Staff Engineer Sun Microsystems,
Inc. Co-chair of the IETF NGtrans working group
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Outline

• History
• Why is it a difficult problem?
• Approach
• NGtrans story
• Tools
• Case study

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History

• Previous Internet transition 1983
• Transition from NCP to TCP happened overnight.It
  was a nightmare...
• There was only few hundred hosts at the time...
• Lessons learned
• There would be no D day in IPv4 to IPv6
  transition.
• Some transition mechanisms MUST be defined
  toallow IPv4 and IPv6 hosts to talk to each
  other.

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Why is it a difficult problem?

• IPv4 is a huge success story 150 millions
  hosts
• IPv6 "had" a chicken and egg problem.
• Early IPv6 adopters face Meltcafe law
• "The value of a network is proportionalto the
  square of the number of users."
• We are still very early in the transition.
• We are talking about a 10 year process

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Approach

• Strategies
• From the core out
• From the edges in
• Constraints
• Do not disrupt IPv4 traffic
• Incremental deployment
• Solutions
• Not one tool, but a toolbox

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NGtrans storyPart 1 the network

• Use IPv6 in IPv4 tunnels.
• Use the Internet as a media.
• Use IPv6 over any layer 2 links.
• It is just another layer3 protocol.
• Reuse the physical infrastructure.

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NGtrans storyPart 2 the stacks

• "Hosts" "Routers" will get hybrid stacks.
• The IPv4 part will not necessarily be configured.
• Tunnels will be used to bypass IPv4 only routers.
• Those stacks may come as software upgrades.
• Some hardware change may be necessary.
• New device may choose to implementan IPv6-only
  stack.
• e.g. cellular phones.

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NGtrans storyPart 3 the applications

• IPv6 ready applications are needed.
• Some sort of interoperability is neededin
  between IPv4 and IPv6.
• Interoperability has a cost. 100
  interoperabilityis not always necessary/possible.
  Network architect would pick the right toolto
  achieve the desired level of interoperability.

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Basic mechanismHybrid stack (a.k.a. dual stack)

• A node can "talk" IPv4 IPv6.
• New applications support both IPv4 IPv6.
• No need for two set of applications, one for v4,
  one for v6.

Application
TCP/UDP
IPv6
IPv4
LAN
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Basic mechanismTunnel

• IPv6 packets are "encapsulated" withinIPv4
  packets.

TCP/UDP
Payload
IPv4
IPv6
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Network tools

• Automatic tunnels
• Very little usage.
• 6over4
• Interesting within an IPv4 multicast site.
• Configured tunnels
• Widely deployed in the 6bone.
• Require manual configuration.
• Tunnel Broker
• 6to4

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Connecting two IPv6 cloudsConfigured tunnel
IPv4
tunnel
IPv6
IPv6
hybrid stack routers
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Connecting an isolated hostTunnel Broker/1
tunnel broker
IPv4 Internet
tunnel request
IPv6 Internet
isolated hybrid stack host
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Tunnel Broker/2
tunnel broker
IPv4 Internet
tunnel config
tunnel config
IPv6 Internet
isolated hybrid stack host
tunnel server
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Tunnel Broker/3
IPv4 Internet
IPv6 Internet
tunnel
isolated hybrid stack host
tunnel server
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6to4 mechanism

• One IPv4 global address gt one /48 IPv6
  site prefix

ISPv4 assigned
managed
auto-configured
pre-defined
2001
IPv4
SLA
Interface ID
48 bits
16 bits
64 bits

• Stateless tunnels span over the IPv4
  infrastructure without configuration to reach
  other 6to4 domains.

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Building automatic extranetsConnecting IPv6
cloudswith 6to4
6to4 hybrid- stack routers
IPv4
6to4
tunnels
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Other tools
Non translator
Translator

• IP level
• SIIT
• NAT-PT
• TCP level
• TCP-relays
• SOCKS
• Application level
• Bump in the API
• Proxies

• DSTM(Dual StackTransition Mechanism)

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Case study phase 0IPv4 site
IPv4 site
NFS
v4
pop
web
v4
proxy
IPv4 Internet
client
v4
client
Exit router NATv4 ALGs
v4
Private address space
IPv4 only host
IPv4 only router
IPv4 only network
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Case study phase 1hybrid stack servers routers
NFS
v4/v6
v4/v6 routers
web
pop
v4/v6
proxy
IPv4 Internet
client
v4
v4 routers
client
Exit router NATv4 ALGs
v4
v4/v6 site
Hybrid v4/v6 host
Hybrid v6/v6 router
Hybrid v4/v6 network
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Case study phase 2hybrid stack clients
NFS
v4/v6
v4/v6 routers
pop
web
v4/v6
proxy
IPv4 Internet
client
client
v4/v6
client
Exit router NATv4 ALGs
v4 router
v4
v4/v6 site
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Case study phase 36to4 connection
IPv4 Internet
NFS
v4/v6
v4/v6 routers
web
pop
v4/v6
Other6to4 sites
proxy
6to4 tunnels
client
client
v4/v6
client
Exit router NATv4 6to4 router ALGs
v4 router
v4
v4/v6 site
IPv6 tunnel over IPv4
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Case study phase 3bisBuilding extranets
IPv4 Internet
NFS
NFS
v4/v6
v4/v6
v4/v6 routers
v4/v6 routers
6to4 tunnel
pop
web
pop
web
v4/v6
v4/v6
proxy
proxy
client
client
client
client
v4/v6
v4/v6
client
client
v4 router
v4 router
v4
v4
Exit routers NATv4 ALGs 6to4 router
v4/v6 site A
v4/v6 site B
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Case study phase 4IPv6 only hosts
IPv4 Internet
NFS
v4/v6
v4/v6 routers
pop
web
v4/v6
Other6to4 sites
proxy
6to4 tunnels
client
client
v4/v6
client
Exit router NATv4 ALGs 6to4 router
v6 only router
v6
v4/v6 site
IPv6 only host
IPv6 only router
IPv6 only network
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Case study phase 5IPv6 only hosts to IPv4
servers
IPv4 Internet
printer
v4
v4 router
print server
Other6to4 sites
proxy
6to4 tunnels
v4/v6
v4/v6 router
client
Exit router NATv4 v4/v6 ALGs 6to4 router
v6 router
v6
v4/v6 site
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Case study phase 6Native IPv6 connection
IPv4 Internet
web
NFS
v4/v6
v4/v6 routers
6to4 tunnels
pop
web
v4/v6
proxy
IPv6Site
IPv6 ISPs
client
client
v4/v6
client
v6 only router
v6
Exit v4/v6 router NATv4 v4/v6 ALGs 6to4 router
v4/v6 site
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Case study phase 99IPv6 site / IPv6 Internet
IPv6 Internet
NFS
v6
IPv4 Internet
NAT-PT or proxies
v6 routers
pop
web
v6
client
client
v6
client
Exit router to IPv6 ISP
v6 routers
v6
IPv6 site
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References

• http//playground.sun.com/ipng
• http//www.6bone.net
• http//www.6bone.net/ngtrans
• http//www.ipv6forum.com

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