> > I'm sorry, I'm wondering which word in my recent message that said > > "I'm not aware of any generally available running code that will > > be changed in even one instruction by the final text - that is indeed > > a requirement for advancement to Internet Standard." > > is hard to understand. > > Help he understand, then. There is widely-deployed code that assumes that > the interface ID is 64 and does not work on anything other than 64 bit > prefix lengths. Currently that code is correct on all unicast space. If you > change RFC 4291, won't that code be incorrect? Since there are plenty of addresses with non 64bit IIDs in use, isn't that code by definition *already* broken? I don't see how changing the 4291bis document to reflect operational reality makes the code any more broken. Steinar Haug, AS2116