Brian, >>> Erik Nordmark wrote: >>> On the enterprise side I can see that folks have been >>> bitting or are concerned about renumbering costs if they >>> were to use PA addresses. >>> But I don't have any data on how many consider having one >>> PA prefix per ISP good enough since it allows some graceful >>> cutover when changing ISPs. >> Michel Py wrote: >> Not many. We have had many contributions that multiple >> addresses are a no-go to begin with.
> Brian E Carpenter wrote: > Er, multiple addresses are part of the IPv6 architecture. > And SCTP deals with them, even if TCP doesn't. It may be > something new and different, but there's no way you can > declare it a no-go. This coin has two sides. One side is what you say above, which is very true. To set the record straight: contrary to multi6, ipv6mh has acknowledged since the beginning that multi-address host solutions are part of the big picture. They are in the charter and are being discussed. In Atlanta, we had a 1hr+ presentation from Lode Coene about SCTP, another by Christian Huitema about his solution. I'm not saying that multi-address solutions are bad, I'm the one that made them part of the big multihoming picture. That being said, the other side of the coin is that most enterprise network managers don't want multi-address schemes, and for good reasons. A large organization implements, on one form or another: - Defense in depth. - Internal firewalling. - Policy routing. - Some model like core/distribution/access. - Traffic engineering. That means several hundreds or several thousands access-lists, firewall policies, route-maps, etc. If you have three addresses per host, you triple the configuration and double the complexity, not to mention troubleshooting nightmares because you will now have to figure out which address is being used before beginning to troubleshoot. Not good. In many large organizations, there is a split between the Systems manager that could be open to a multi-address solution and the Network manager that does not want it. They might be office buddies, but they also are mortal enemies because they compete for the same scarce budget dollars. Bottom line is that in most situations, the network administrator is the one that calls the shots in terms of addressing. 3 times the complexity is effectively a no-go. In short: multiple addresses on hosts are half of the solution, but the other half is a globally unique address used as an identifier in a dual-space system. Michel. -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------