Re: [DNA] how much effort to deal with "unplanned renumbering"

[Greg Daley <gregd@research.panasonic.com>]

Hi Thomas,

Thomas Narten wrote:
[cut]
> 
>> Also during the absence, a router/prefix may be removed from the link
>> with the RA/PIO with explicit indicaiton. Since the host didn't
>> receive the explict indication such as PIO with lifetime=0, it may
>> falsely assume that router/ prefix is still there.
> 
> I think we need to think hard about how much we are going to
> complicate DNA to deal with "broken renumbering attempts", which are
> not supposed to happen in the first place. The IPv6 protocols do not
> really support taking away a prefix prematurely, and when this
> happens, things aren't guarnteed to work. Thus, this is not advisable
> in general.
> 
> So we should explicitely discuss to what degree DNA needs to support
> such events, especially if they are not expected to be common.
> 
> Thomas
> 

This is an issue which is addressed in the draft-pentland-dna-protocol3
document (accepted as WG draft), and was resolved by the DT.

The DNA protocol describes how existing ND timers are used, and also
places a time limit on the retention of inappropriate prefix
information.

Additionally, if a trusted Complete Router Advertisement is sent,
DNA systems will discard any prefix information regarding a
disused address prefix, regardless of whether the host saw the
prefix advertised with decreased lifetime.

(It's done already - and not too complicated).

Greg