Robert ELz made most of the points I'd want to make, but for:
Vernon Schryver wrote:
...
- claim much better QoS mechanisms
IPv6 doesn't. IPv6 offers *exactly* the same QOS mechanisms as IPv4,
namely IP Integrated Services and IP Differentiated Services. (There
is also the flow label field in IPv6, but there are as yet no detailed
specs of how it will be used and no false claims either).
...
- suffer standards committee bloat and silliness, such as the typical
standards committee doubling of the IPv6 address from 64 to
128 bits,
This was very specifically to enable an adequate (64 bit) locator
component and an adequate (64 bit) identifier component in the address.
And this was based on experience with several datagram network architectures
of the past. The only realistic alternative was variable length addresses.
But since we settled this in 1994, it seems somewhat beside the point.
Brian
the lunacy of 48 byte cells and the 54 flavors of AAL.
- no one yet understands how to really make IPv6 or AAL work or even
play nice with IPv4 during a transition. (The big unknowns I see
with both are in application code. I have some application code
that is supposed to do both IPv4 and IPv6, but ....)
The differences are
- IPv6 is tolerates applications that want datagram-like service
- some relatively minor technical details such as cell overhead
and stupid ATM switches that didn't drop entire upper layer
packets when one cell is lost.
- ATM switches were supposed to be unlike IPv4 routers, or infinitely
fast and too cheap need purchase orders because the telcos would
be buying so many of them, but turned out more like telco CO's.
IPv6 routers are supposed to be just like IPv4 routers.
- non-technical forces that might actually cause IPv6 to replace IPv4.
They can be summarized as IPv6 came from the IETF while ATM was
from the other guys
Vernon Schryver vjs(_at_)rhyolite(_dot_)com
--
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Brian E Carpenter
Program Director, Internet Standards & Technology, IBM
On assignment for IBM at http://www.iCAIR.org
Board Chairman, Internet Society http://www.isoc.org
Non-IBM email: brian(_at_)icair(_dot_)org