And the global routing table grows.

We asked Sprint for an exception to their routing policy in a case that would clearly reduce routing table size. They said no. Everyone is free to draw their own conclusions regarding Sprint's policies and the real motivations behind them.

In message <199604030045.QAA03247@lint.cisco.com>, Paul Ferguson writes:

At 04:26 PM 4/2/96 -0800, Michael Dillon wrote:

...

On Tue, 2 Apr 1996, Curtis Villamizar wrote:

...

If the providers were to relax the requirements to renumber when moving to another provider or when dual homing, the problem of the TWD would not be growing at its current rate.

Hmmm.... ISP has T1 to SPRINT, wants to switch to MCI, SPRINT says, OK you have a choice, either renumber or pay us to route your traffic to MCI via a private exchange point so we don't have to knock holes in our aggregate. That way you can use SPRINT's addresses and MCI's T1, but for a fee.

And the global routing table grows.

- paul

Paul, Provider X takes on some number of customers N that want prefixes and think they may later dual home or want to leave the option of changing providers without renumbering open. Substitute for X as you see fit. If provider X insists that small providers or small to medium business customers must renumber to leave a CIDR aggregate the smaller organization go off and get "portable" address allocations which put them in the unaggregatable toxic waste dump (TWD). If so, they will also try as hard as they can to get a /19. Some of the small prefixes go out of business. Some grow and become dual homed. Some switch providers. Most just don't change. In either case, TWD allocation or out of a provider aggregate, a dual homed customer requires an additional prefix (to get routing right). If a small prefix changes providers and is TWD allocated, they already have a unique route. If they were allocated from a large provider aggregate, one more prefix is needed. If they were allocated from a large provider aggregate and are given a generous grace period, some will renumber quickly, some not at all (continuous requests to extend the grace period). Lets assume they are never forced (grace period extensions are granted). If the number of small prefixes that resort to the TWD as a result of strong renumbering policies exceeds the number of small prefixes that move out of aggregates without eventually renumbering, then there the strong renumbering policy actually promotes more growth in the routing table size. In the short term, the difference may not be all that substantial. Longer term, if the provider community can cooperate to aggregate better then many of the extra routes caused by prefixes changing providers can be aggregated back together over a multple AS aggregation boundary. Since you made the comment "And the global routing table grows", do you feel what I described above is invalid? If so, what assumptions are you making differently? Do you feel people will never renumber if given a grace period, even if renumbering becomes easier with time? Curtis