Greetings: I am curious for perspectives on the use of non portable IP addresses for multi-homing. Can a provider forbid their customer from announcing allocated networks to another provider? Assume the following situation: ------------------------------ ISP A gets customer C to sign an agreement for service. ISP A allocates network A.B.C.0/20 to customer C. A.B.C.0/20 is a subnet of CIDR block A.B.0.0/16, allocated to ISP A by our friends at the InterNIC as a non-portable address space. It should be obvious that customer C is locked in for Y years, and is paying D dollars per year. Ok. With me so far? :-) So, customer C goes to ISP B, and says, I'd like to buy service from you, and announce network A.B.C.0/20 to you. Customer C informs ISP A, for niceties, and ISP A informs them that they cannot do this. If Customer C wants to announce routes to both ISP A and ISP B they must renumber. (source of IP Addresses for renumbering is left to your imagination, ISP A, B, or direct from InterNIC.) Can ISP A enforce this decree? I realize it depends upon the contract, but let's assume the contract doesn't specify. I would think that ISP A would not mind Customer C announcing the network to ISP B, but would make it clear that if Customer C stops the relationship with ISP A, then ISP A would reclaim the address space. Is this intelligent use of IP Address space, draconian practices to discourage multihoming, or probably a miscommunication? -alan -- Alan Hannan email: alan@mindvision.com.