Re: [DNA] leaving out options on Landmark RA = Yes(draft-pentland-dna-protocol-00.txt)?

[Erik Nordmark <erik.nordmark@sun.com>]

Greg Daley wrote:

> Comment:
> 
> The descriptions here ignore SEND options, which need to be included
> if SEND is used.  This will increase the size of the RA.

Probably.
I haven't looked at exactly what SEND information would be needed in the 
different cases of an RA being sent.
If the host didn't move, the RAs will in most cases be sent from routers 
that the host has previously received RAs from, thus the SEND 
information can be minimized.
But when the landmark indicates that the host has moved it makes sense 
for the RAs to include more SEND information if that makes a SEND host 
complete the movement faster.

Is anybody looking at the details of how SEND and DNA can interact 
efficiently?

> Question:
> 
> Can we have standards language for this?
> 
> There's no flexibility in the description of what options are
> able to be included in the "Yes" Landmark. That sounds like a
> MUST NOT include other PIO, DNAO. etc.

In think the text in section 3 is fine with its use of English, because 
it tries to introduce the concepts by saying what typically happens.
But in the core of the draft it makes sense being more specific.

> Personally, I'd prefer something saying something like
> 
> "RAs with the 'Yes' Flag set in a Landmark option MAY leave out all
> configuration related options such as PIOs, DNAOs, Advertisement
> Intervals etc, since this information is assumed to have
> already been received to be able to construct a matching
> Landmark Router Solicitation".
> 
> I'd prefer MAY to SHOULD or MUST, since it's an optimization,
> and the presence of additional options doesn't harm hosts.

My gut feel is that we should make it a SHOULD NOT, because the host 
doesn't have any need for this extra stuff, and one of the DNA goals is 
to be efficient.

> In RADVD, it's easier for me to not remove the other options
> in the RA just because the Landmark option Yes flag is set.

And the purpose of a SHOULD NOT would be to make you do the work :-), so 
that we can get an efficient way to do DNA.

    Erik