Quality Quorum <[EMAIL PROTECTED]> wrote:
|It seems to me that stability and security of internal enterprise
|addressing is a very serious requirement.
And why just enterprise? The stability of my home network is more important
to me than the stability of any enterprise network.
|Frankly, I do not see any way
|to avoid NAT6.
Without some other kind of local address space it does seem inevitable. It's
unfortunate that folks are considering ways to make applications NAT-hostile
to force us to depend on global addresses allocated by ISPs.
|Second isssue, which will IMHO force NAT6 is relative scarcity of global
|routing prefixes. In the current scheme of things we have only 25 bits to
|express routing topology (the rest is taken by admin and local) and
|it may prove to be too small.
Given the hierarchical allocations required by strict address aggregation,
pretty much any fixed number of bits is too few. Hierarchical allocations
are incredibly wasteful because they consume address space exponential in
the number of providers in the chain. They also tend to make the structure
of the market inflexible and require pre-definition of various "types" of
providers--something that would have been better left to that market. I
suspect that regardless of the intent, many consumer-level ISPs will operate
at the bottom of the chain (likely below the point that the architecture
considers suitable for ISPs). This will virtually guarantee an artificial
address scarcity at the end-user level. I've noticed that even the optimists
are no longer talking about /48s for dialup. Soon I expect that the reduced
claims of /64s will degenerate into /{128-n}s where n is directly related to
the "level of service."
It's really a shame that IPv6 took the path that it did. Originally it was
to be a clean and simple solution to the address shortage. Fixed-length
addresses and (supposedly initial) hierarchical allocation were virually
mandated by the simplicity requirement. The two alternatives that would
have provided far greater flexibility (*variable*-length hierarchical
addresses or fixed-length portable identifiers) appeared too complicated.
Over the years IPv6 has acquired the every-feature-but-the-kitchen-sink
syndrome, and the relative complexity of a more powerful addressing scheme
looks quite low in retrospect--but now it's too late to retrofit one. At
the same time we are discovering that merely increasing the (fixed) number
of address bits while perpetuating the allocation and routing procedures
that were originally intended as a temporary hack to keep old hardware running
doesn't offer the panacea we expected. The problem was never just (or even
mostly) the number of bits in an address. It was (and is) a complex combination
of techincal routing issues and market economics.
|I hope that by addressing this problem head on early in the process we can
|do implementations much less painful and better prerforming.
The problem was addressed early on with site-locals, but now they are being
restricted into uselessness. I have strong doubts that the discussion of
globally unique identifiers is anything more than a passing diversion. Every
time this has been discussed in the past it was shot down on the grounds that
it could subvert the all-important MLM^H^H^H hierarchical addressing scheme.
Dan Lanciani
ddl@danlan.*com
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