> > The address *is* a valid identifier in the IP architecture. > > Er, um, well of an interface maybe. But what you > really want is a host identifier, which is the source > of lots of trouble... it is well-understood and generally agreed that the overloading of IP IP addresses to be both host identifers and location identifers causes some trouble. what is less well-understood is how much trouble the alternatives cause - either lack of a suitable endpoint identifier, or the trouble associated with providing suitable endpoint identifiers. Keith