Re: [DNA] Issue 6: DNAHostLinkIDList

[JinHyeock Choi <jinchoe@gmail.com>]

Dear Sathya

> Since I didn't hear any other objections, I am going start closing the
> issues using the suggested changes, except for this issue on
> DNAHostLinkIDList.
>
> My proposal for removing DNAHostLinkIDList is as follows:
> We remove the concept of identifying a particular prefix as LinkID
> prefix and mandate the inclusion of the smallest prefix in all RA
> messages. On the host side, we only need to check if there is a prefix
> included in the RA that is in the DNAHostPrefixList. This will work if
> we make sure that when there is a change in the smallest prefix, the RA
> includes the previous smallest and the current smallest (similar to what
> is done when the LinkID changes now). So, the algorithm will be:
>
> For non-landmark RA or a NO landmark response:
> Router SHOULD try to send a completeRA.
> If the completeRA is not possible due size restriction, the RA MUST
> include the smallest prefix.
> If the smallest prefix was first seen within 1.5 hours ago, then the
> second smallest prefix MUST be included in the RA.
> If the second smallest prefix was first seen within 1.5 hours ago, then
> the third smallest prefix MUST be included in the RA.
> And so on... (I don't like that this is open ended, but thats how things
> are right now with including LinkIDs)
>
> For unsolicited RA:
> MAY be a completeRA.
>
> If not a completeRA, same rules as above to include the smallest prefix(es).
>
> What I am trying to do here should be obvious. The functionality is
> exactly the same as the LinkID component of the current draft, but there
> is no explicit marking as such and more importantly no explicit LinkID
> check at the host. The overlapping prefix check covers that for us,
> removes the need for a DNAHostLinkIDList, thus simplifying the operation
> significantly on the host side.
>
> For future non-prefix linkIDs, they can be included in the LPO and they
> MUST be 128 bits long. Since LPO cannot be used to configure addresses
> this won't cause any trouble and cannot overlap with other prefixes
> since they are 128 bits.
>
> I would like to know if people think this is workable - am I overlooking
> something?

I think the above is workable but have a few concerns.

1.

>                                                     This will work if
> we make sure that when there is a change in the smallest prefix, the RA
> includes the previous smallest and the current smallest (similar to what
> is done when the LinkID changes now). So, the algorithm will be:

For the above, DNA routers should manage "the smallest prefix list"
which it recently advertised.

2. RA should include the indication that this RA includes the smallest prefix.

A DNA router and a non-DNA router may co-exist on a link. If the
non-DNA router advertises an RA without the smallest prefix, that may
cause a host to make a mistake.

The inclusion of the smallest prefix can be indicated with
either 1) DNA router bit in RA or 2) a new bit in PIO.

For the first, a host assumes that the RA from the DNA router includes
the smallest prefix automatically.

For the second, a host assumes that the RA includes the smallest
prefix only when there is a smallest prefix bit in PIO/ or LPIO.

Thanks for your kind consideration.

Best Regards

JinHyeock