Re: A common problem with SLAAC in "renumbering" scenarios

[Michael Richardson <[e-mail]>]

Brian E Carpenter <[e-mail]> wrote:
    >> The choices seem to be:
    >> 
    >> 1) ensuring that if a device is disconnected and then reconnects to
    >> the same network, the device will be given the same lease,

    > In the general case we can't "ensure" that. Firstly it may be against
    > business policy or privacy policy for some ISPs. Secondly even if it
    > was the intended policy, there can always be failure
    > scenarios.

Yes, but we know how to planned renumbering.

And, if we can get the prefix written to stable storage (as has been pointed
out, it only needs to be written when it actually changes), then we can deal
with the problem.

The only other thing that I can think of is to create a new option which is
something like "previous prefix"... or maybe "obsolete prefixes"

ISPs that
     a) control the CPE devices,
     b) want to use devices with no stable storage,
     c) also want to do flash renumbering
     d) and don't want to use really short lifeimes
can implement such a thing.

    > Thirdly, a host might be disconnected from one LAN and
    > reconnected to another one without knowing it. So even if this is the
    > recommended practice, no host can rely on it.

Yeah, but users mostly understand that this breaks things already.
Maybe this happens in WIFI more frequently than desired without user
intention, but in that case, both networks involved are probably pretty
fragile already.

-- 
]               Never tell me the odds!                 | ipv6 mesh networks [ 
]   Michael Richardson, Sandelman Software Works        | network architect  [ 
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