Re: [lisp] Gen-ART IETF Last Call review of draft-ietf-lisp-ddt-08

[Dino Farinacci <[e-mail]>]

Right. Agree with your interpretation. I hope authors can make this clear based on your suggestions. 

Thanks,
Dino

> On Jan 17, 2017, at 7:06 PM, Dale R. Worley <[e-mail]> wrote:
> 
> Dino Farinacci <[e-mail]> writes:
>>> Both of these servers process Map-Request messages, albeit with
>>> different semantics.  Hence the D bit in Map-Request messages is needed
>>> to differentiate which server is to process a given Map-Request message.
>> 
>> The reason I explained the above was that the D-bit tells the receiver
>> of a Map-Request what type of message to return regardless of the
>> colocation status of the servers.
> 
> OK, that's close to the distinction I was making.  The defining text is
> probably from section 5:
> 
>   D: The "DDT-originated" flag.  It is set by a DDT client to indicate
>      that the receiver SHOULD return Map-Referral messages as
>      appropriate.  Use of the flag is further described in
>      Section 7.3.1.  This bit is allocated from LISP message header
>      bits marked as Reserved in [RFC6830].
> 
> But when I read it, the phrase "the receiver SHOULD return Map-Referral
> messages as appropriate" wasn't at all clear.  I assume now that what it
> means is, "should return Map-Referral messages *as described in this
> document*, whereas D=0 means it should be processed as described in RFC
> 6833".  The defining characteristic isn't the type of messages to be
> returned but which processing to apply, as a DDT server and a Map-Server
> are very different things (defined in different RFCs!).
> 
> Dale