imagine there is a company having huge allocation/assignment. Some happens (i.e. crisis), they lost a significant number of clients, so they have a lot of free IP space. Is there any policy ENFORCES this company to return unused address space?
No. Policies do not enforce anything. Policies are like laws. They are just words on paper. Enforcement has to come from somewhere else. If you read RIPE policies carefully, you will see that you do not have to have a technical requirement today for every address that you receive from RIPE. If RIPE is willing to give addresses to some organizations which will not be used for many months, or years, then it is difficult to force any organization to return addresses when they experience a temporary downturn. Also, remember that most RIPE members will reserve unused addresses for several months after disconnecting a customer, before they assign those to other customers. In the case of a dispute between RIPE and a member organization, you cannot expect quick results. There will almost always be a language barrier between RIPE and the member organization. The multilingual hostmasters are probably not the right people to be in the middle of a dispute. There are subtle difference in translating a lot of the terminology that we use, for instance assign and allocate have almost identical meanings in English, so I don't expect translated terms to make any sense outside of the RIPE context. Let's face it, we are running out of IPv4 and the special efforts that RIPE has made in the past year or so, has only caused this runout date to become sooner for all but the smallest organizations. IPv6 is the only way out of this mess. Attempting to enforce some sort of efficient-use policy for IPv4 is wasted effort. --Michael Dillon