1. Ole Trøan, cisco Engineering
IP fundamentalist With help from:
2011-11-22 Randy Bush (Dr Vision)
Dan Wing (Mr NAT)
Mark Townsley (Mr Tunnel)
Geoff Huston (Dr Doom)
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2. The “inevitability” of
technological
evolution?
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3. The “inevitability” of
technological
evolution?
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5. “I’m driving at 100 kph, and I
see a wall 100m ahead of me.
I’m not there yet; I’ll worry
about that tomorrow…”
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9. • Enthusiasts working in corporations, friendly to “new stuff”
• Encouraged by government regulation / procurement
requirements
• Out of fear (let’s be ready if this IPv6 thing happens…)
• New opportunities. If we are early into IPv6 we may have an
advantage.
• Green field. Let’s not bother with legacy stuff in a new network
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18. “
SAME
TIME
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19. The challenge often lies in
managing the transition
from one technology to
another
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20. To get from “here” to “there” requires an
excursion through an environment of
The CGNs, CDNs,often lies similar middleware
challenge ALGs and in
„solutions‟ to IPv4 address exhaustion
managing the transition from
one technology to another
IPv6
CGNs
IPv4
ALGs CDNs
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21. But will this be merely a IPv6
temporary phase of
transition?
CGNs
IPv4
ALGs CDNs
Transition requires the network owner to undertake capital
investment in network service infrastructure to support IPv4 address
sharing/rationing.
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22. The challenge often lies in
managing the transition from
one technology to another
IPv6
CGNs
IPv4
ALGs CDNs
The risk in this transition phase is that the Internet
heads off in a completely different direction!
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23. 201x? IPv6
ARIN
LACNIC
AFRINIC
CGNs RIPE NCC
IPv4
ALGs CDNs
APNIC
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26. 128 bits
32 bits
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30. Service Continuity
They are NOT
Transitioning to IPv6”
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33. “
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34. • IPv6 service (to end users)
6rd, L2TP, (IPv6 in IP, GRE, ISATAP, Teredo, Tunnel brokers)
• IPv4 exhaustion (IP address sharing)
A+P: Mapping of Address and port (Shared IPv4 address over IPv6)
CGN / SD-NAT
DS-lite
• “Interoperate”:
IPv6 to IPv4 connectivity
NAT64, TRT, Application proxies
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36. Tunnels act like the
layer below that which
they are carrying
Often not perfectly, but
“good enough” for a
specific purpose
IP tunnels act like Data
Link Layers
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37. All problems in
computer science
can be solved by
another level of
indirection…
…except for the
problem of too
many levels of
indirection
- David Wheeler
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38. They have a
wide variety
of uses…

39. Private IPv4
IPv6
Private IPv4
IPv6
IPv6 IPv6
IPv4
IPv4
Private IPv4
IPv6
Subscribers Providers Internet
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40. Source: Shin Miyakawa, NTT Communications
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41. Obtain IPv4 Addresses (RIR, address broker)
IPv4
CGN, N
AT44, IPv4 Address Sharing
IPv4 SD-NAT
Address
Run-Out 6rd Dual MAP(
+ Stack 4rd/
CGN Lite dIVI)
IPv6 native 6rd
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42. IPv4
IPv6
NAT64
IPv4-only hosts IPv6-only hosts
• NAT Purpose 2: connect IPv6 to IPv4
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43. • NAT64 is not perfect
• IPv6 and IPv4 are not compatible
Fragmentation (IPv4: network fragments, IPv6: hosts fragment)
minimum MTU (IPv4: 576, IPv6: 1280)
IPv4 options versus IPv6 extensions
• Like NAT44:
NAT64 can also bring Application Layer Gateway (ALG) issues
Complicates troubleshooting and abuse handling
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44. • Traditional Voice has stupid edge devices, phone
instruments, and a very smart expensive core
• The Internet has a smart edge, computers with
operating systems, applications, …, and a simple
stupid core, which just does packet forwarding
• Adding an entirely new Internet service is just a
matter of distributing an application to a few
consenting desktops (until NATs)
• Compare that to adding a service to Voice
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46. translate tunnel native routing
worst best
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47. IPv4-Only
Network
Dual Stack
NAT Network
IPv4-Only
Network IPv6-Only
PE
PE
NAT CE CE
IPv4-Only Dual-Stack IPv6-Only
Users Users Users
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48. IPv4-Only Dual Stack Dual Stack Dual Stack
Network Network Network Network
Dual Stack
NAT Network 6↔4
I
IPv4-Only IPv6 IPv6
Network Only IPv6-Only
Only
PE
PE
NAT CE CE CE CE
IPv4-Only Dual-Stack Dual-Stack Dual-Stack IPv6-Only
Users Users Users Users Users
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49. • IP address sharing is necessary to keep business running
• Necessary to keep end users happy (long tail IPv4)
• It is never ideal
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50. Choose mechanisms which
are progress towards IPv6
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51. Prefer Mechanisms Which
are simple, Stateless,
Use IPv6 not IPv4, …
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52. Keep state at the edge not
the core
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53. Use Mechanisms Which
Preserve e2e and the
Other Basic Principles as
Much as Possible
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