Re: Adoption Call for "Improving the Robustness of Stateless Address Autoconfiguration (SLAAC) to Flash Renumbering Events"

[Philip Homburg <[e-mail]>]

>This document proposes significant changes to SLAAC to fix what could be 
>seen as an implementation problem in some edge routers.  This will 
>affect all IPv6 nodes, not only the ones communicating with these edge 
>routers.  This part of IPv6 is a mature standard.   It is not clear we 
>should modify all IPv6 hosts to deal with one corner case that may break 
>other things allowed by the standard.

I support adoption.

Just like PMTU blackholes, in theory, flash renumbering should not exist, but
in practice it does.

If we don't add support for flash renumbering, we can end up in a similar
sitation as PMTU blackholes: people start adding all kinds of weird workarounds
that overall make the system more complex.

>The changes proposed will make SLAAC more active, the changes include:
>
> o Reducing the default Valid Lifetime and Preferred Lifetime of PIOs
> o Caps the received Valid Lifetime and Preferred Lifetime of PIOs.
> o Frequent retransmission of configuration information
> o Routers send all options in RA messages

I don't particularly agree with all choices made in the draft. And some 
stuff could be redundant. If a host can handle flash renumbering on its own,
then there is not much need to change valid and preferred lifetimes.

There are alternatives that don't need a router to send all options in one
RA message.

>Some additional questions for the w.g. to consider:
> o Are there better approaches to address the underlying issue?
> o Do the proposed changes work in all deployments?
> o Are some proposed changes worth advancing even if the entirety may 
>not be? If so, which ones?

I think the key part of the draft is where the host figures out from received
RAs that a flash renumbering is going on. And change to valid and preferred
lifetimes is second to that.

I think the current proposed changes need some more work.