2 - 从政策看IPv6.pdf

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A Policy Look at IPv6
Richard Hill
April, 2003
munication Standardization Bureau
International munication Union
Based on a paper by John Klensin, available at:
http://web/itudoc/itu-2/infodocs/
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Outline
• What is IPv6
• Address space exhaustion
• Relationship to topology
• Alternatives to IPv6
• Network problems
• Space allocation policy
• Deployment difficulties
• Roadblocks and solutions
• ITU and IPv6
• About the ITU
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What is IPv6
• IPv6 ( Protocol, version 6) was
developed by the Engineering Task
Force (IETF), starting in 1993, in response
to a series of perceived problems, primarily
with exhaustion of the current, IP version 4
(IPv4), address space
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Address space exhaustion (1/3)
• Rate and scale of growth was
underestimated
• In 1970’s, 32-bit address space was thought
to be adequate for long term
• Class system (A, B, C)
• routing is closely tied to the
separation of routing within work and
routing works
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Address space exhaustion (2/3)
• Routing within works became
complex
• ting introduced
• Advent of PCs meant that each host could
no longer have a unique fixed IP address
– dynamic address assignment (but reachability?)
– private address spaces (but leakage if connected
to work)
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Address space exhaustion (3/3)
• In 1995, classless system was introduced
• RIRs became more conservative with
respect to address allocation
• Some believe IPv4 addresses will be
exhausted in 2-3 years, others in 10 years,
others sooner, others much later.
• Rate of exhaustion influenced by
technology (. NATing) and RIR policies
as well as growth
• Under-use of certain class A, B allocations
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Relationship to topology (1/3)
• An IP address is not similar to a telephone
number
• An IP address is a routing address
• In telephony terms:
– a telephone number is more like a domain name
– an IP address is more like