Thus spake "Tony Li" <tli(_at_)cisco(_dot_)com>
On Oct 9, 2007, at 11:29 AM, David Conrad wrote:
On Oct 9, 2007, at 9:43 AM, Tony Li wrote:
Any new design would have necessarily required more bits to address
more end systems. Making legacy systems interact
with these additional addressing bits without some form of
gateway, NAT or other translation would indeed be challenging.
You're literally trying to expand the size of the namespace that
a legacy implementation will recognize.
32 bit AS numbers.
Fortunately, the legacy BGP implementations don't need to
recognize the new part of the namespace. They only see the
legacy space, including AS_TRANS. The new namespace is
translated (with major amounts of information loss) into the old
namespace for their benefit. This still doesn't provide a
mechanism for legacy systems to interact directly with new
systems. For example, you can't have a legacy system directly
peer with a system using a 32 bit AS number. Instead, it has
to be remapped to AS_TRANS.
So, it's just NAT for BGP. ;-)
Does that mean the IETF is going to deprecate 32-bit ASNs like was done to
NAT-PT? ;-)
Perhaps, if the folks hadn't been so dogmatically against NAT at the time,
the v4-to-v6 transition model would have worked similarly and we'd be done
with it by now...
S
Stephen Sprunk "God does not play dice." --Albert Einstein
CCIE #3723 "God is an inveterate gambler, and He throws the
K5SSS dice at every possible opportunity." --Stephen Hawking
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