Shin, On 02/07/2008, at 12:49 PM, Shin Miyakawa wrote:
David,Ole raised the issue that a router would (almost by definition) need to implement a weak or semi-strong model, and I would support thisview. I do believe the CPE must support the sending of IP datagrams toInternet hosts (for ICMPv6, management, etc) but see an option of using a loopback interface for this purpose (from the subscriber's delegated prefix).Please note well that, if you'd like to assign a global IPv6 unicast addressto the LoopBack interface, because loopback is the diffrent from LAN links behind the CPE, we have to assign at least two /64 prefies to the CPE(one /64 for LAN, one /64 for loopback, assuming that a /64 is the minimal unitof prefix delegation).
Yes, agree.
This allows a single subscriber to be represented by one prefix that may be operationally beneficial, or provide a more scalable BNG architecture.So, this consumes more than "one Global address for the WAN interface with one /64 for LAN" (as I called this as "1+/64" or for some reason, "1+/64s") model. How do you think about this fact ?
Sorry Shin, I had thought the /64 was an example for any delegated prefix-length. For prefix-lengths shorter than /64 do you see different options?
Or forget about the loopback interface and use the CPE's LAN interface inthe weak host model case ?
This is an option as well if we are concerned about the use of an entire /64 for CPE management. Given there has been some discussion recently on-list about using a /64 on point-to-point links as best practice, it would seem to suggest that a /64 should not be considered an excessive waste of IPv6 resource. There is also a potential for the LAN interface to be in a down state, and for the service provider to require management of the device. By binding the global-scope management address to either the loopback or the WAN interface the service provider can ensure management irrespective of LAN interface state. Further, the customer may choose to address their LAN interface however they see fit, which may not suit a service provider. Thus I prefer the options of using loopback or WAN interface.
Again, I reiterate that I think both options are acceptable and may have different consequences that an operator should be informed on. I am not arguing against the /64+1 or even a /56+1, I am supporting the option of a link-local-only WAN interface.
Best Regards, -David