Footnote to last post with refs and gifs:
The oversimplified statement below:
........................ can see that the optimal goal of a provider
at each layer is to accept routing information from networks that
are only 1 level less than their position in the hierarchy. Of course,
there are numerous other variations to the them, but the end results
are basically the same.
Please keep in mind, that routing information also must be shared with
peer networks at the higher levels as well. The point of the discussion
is not to specify all requirements of peer-to-peer routing; but only
to point out, in a simple model the basics of hierarchical routing to
(and try to keep an eye on the SuperBowl, BTW....)
Also as a footnote, please keep in mind that targeting specific ISPs
for routing policy issues is problematic because SOMEONE (ie. at the
upper level of the hierarchical model) has to carry the "load" for
all the grand-fathered and fragmented address space (which BTW they
have little tangible control). It is a difficult job given that
the ISPs have little choice in alternative routing protocols
and their tool kit is bare (presently).
Also keep in mind, however, that to advocate CIDR or CIDR like routing
policy and support the development of NATs and DHCP and then show
emotion when incredulous engineers point out the problems with this
approach by stating that "we do not have an implementable solution"
is a bit of irony; for the simple reason that just as we do not have
workable alternatives for IP hierarchical routing, the same holds
true for NAT, DHCP, and numerous other proposals and technical details
to "fix" the problem, but the overall direction and momentum of the
current track is clear by the actions of the WGs and inactivity of
Finally, one obvious way to solve the problem that would create much
controversy with the higher level commercial players is to build another
large aggregate provider(s) at the top of the hierarchy with a very
rigid set of constraints and move the existing elephants down a level
to default status That way the highest level in the hierarchy could
remain very very clean and efficient. Plus, in parallel, develop a
much more fair and efficient policy of address space allocation
(which BTW, I have no suggestion or solution to offer either).
The idea, of course, only works in theory and on paper, because of
commercial constraints and interests.