On Mar 19, 2008, at 4:56 PM, Brian E Carpenter wrote: >> - use a ULA source address if and only if the destination is a ULA >> in the same prefix > > I think that is broken. There's a reason ULAs are defined as global > addresses.
but they are *not* global addresses. If they were, they would be UGAs, not ULAs. What they are is local addresses with undefined scope. Routing may or may not be stable between a system using a ULA and another system that doesn't have an address in that prefix. The only way for the system using the ULA to know is for it to have configuration that tells it, or to receive a message from the remote system (one that it can know with assurance doesn't have a spoofed source address) that is sent to its ULA address. Hence,if it is selecting an address, it should go by the Robustness Principle. It should accept a message from the peer sent to its ULA address, but it should itself do something it has assurance will work correctly. It should only send from a ULA if it knows that the peer has an address in the same prefix, and it can only know that by configuration or by observation that the peer is using the same prefix. -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
