Re: [DNA] Comments on Combined DNA Solution draft

[Subba Reddy <subbareddy@samsung.com>]

Hi Brett,

> >>>2. Consider the following case.
> >>>Router R1 (of Link1) is sending Prefix P1 whose life time is 15
seconds.
> >>>A host H came to Link1 and included P1 in DNAHostPrefixList.
> >>>P1 expired gracefully and assigned to Link2. If H moves to Link2 and
> >>>receives complete RA, it will find the match in DNAHostPrefixList and
> >>>will assume same link. Host will not delete P1 since expiry time for
> >
> > entries
> >
> >>>in DNAHostPrefixList is 1.5 hours.
> >>
> >>No, the host will expire P1 at its expiry time as indicated by the
> >>liftime it learned in the RA it received on Link1.  (see 6.2.1, para 3)
> >
> >
> > If the prefix P1 is learned prefix for R1, then it will advertise P1 in
LPO.
> > Host (H) will not be receiving life time in the RA sent by R1. If H has
not
> > received
> > any RA with P1 in PIO within 15 seconds, it will not delete P1 from
> > DNAHostPrefixList for the next 1.5 hours.
>
> Ah, ok in that case that case you have a point.  Usually, the host
> would receive an RA from each of the routers on the link within 3
> seconds but I guess one or more of those could be lost.  I'm not
> sure how realistic such a short prefix lifetime is, but if folks think
> this is an issue, we could recommend that if hosts have an entry
> in their DNAHostPrefixList for which there has been no PIO received
> after X seconds, that they send another RS.
>
> My gut feeling is that this isn't worth worrying about.

In the following cases the above scenario may occur
When a prefix is expiring (valid life time is about to become 0)
    1. A host coming up in that link
        or
    2. A host coming from other link to that link
and then moved to a new link where this prefix is being assigned.

But, as you mentioned the probability is very less.
I am also not sure, whether to worry about this.

Thanks & Regards,
Subba Reddy