I think this is a tangent to the CIDR discussion, but the situation that Owen describes below occured a few times when I was at Merit. In those cases what I did was to contact all of the parties (PA, PB and the customer, sometimes all on the phone together for additional entertainment). Often the argument can be resolved right away but if not, it was a difficult call. Since Merit supports the NSF's policies, if the customer was a research/education AUP organization, the decision was weighted to the benefit of the customer. If it was purely a commercial business argument, we would sit for a while to see if there would be a settlement before taking any stand. Mark
Here's what happens... When a customer switches from provider-A (PA) to provider-B (PB)
PB sends NACR for customer networks (CNETS) to ANS ANS sends NACR to PA for approval PA sends approval to ANS (or not, at PA's discretion) ANS processes NACR
If PA decides not to approve the NACR, the NACR does not happen. The issue can eventually be forced, and it is usually easier to renumber the customer. Some less professional providers have done this. Other providers have gone so far as to issue their customers individual 8 bit subnets of class B networks owned by the provider. In fact, some providers (reasonably so, IMHO) refuse to approve a NACR until the leaving customer has paid their final bill (or the bill up to current, anyway). Afterall, turning someone off for not paying for service IS a reasonable collections tactic. It's used by almost every utility, and Network Service Providers, although competitive, are basically a utility. If the network number moves somewhere else, then the old provider has no ability to shut down the connection.
Owen DeLong Netcom Network Operations