Yakov, I think were at least I run into Sean's well summarized position is not in the temporal non-uniqueness, but with the topological non-uniqueness. Note that temporal non-uniqueness is currently very large granularity and generally non-survivable. Topologically non-unique addresses appear to me to compromise a fundamental principle of the Internet, and an intrinsic component of what makes it valuable. Can anyone speak to why topological non-uniqueness works and preserves the value of the system without adding so much additional per packet complexity as to collapse under its own load at high volumes and rates? Having to contend with seperate "useage spaces" seems to me to be somewhat like being taken off the power grid - it can be done, and it will work, but it tends to require devices that are large, complex and service many people (ie. private power stations and corporate firewalls). Eric Carroll eric.carroll@acm.org Tekton Internet Associates