Re: [lisp] On the use of priority associated to RLOCs

[Joel Halpern <[e-mail]>]

Personally, I find this to be an inappropriate overlaoding of the 
Priority.  While overloading is not uncommon, it often causes problems 
with protocols and I would prefer that we not do so.

Yours,

Joel

On 5/23/2023 2:57 PM, Dino Farinacci wrote:
> Maybe I can provide some color, so folks know why this design decision was made.
>
> (1) An xTR behind a NAT will register its global RLOC (and port) and the RTRs it has learned to the mapping system.
> (2) When another ITR wants to encapsulate to this xTR, it CANNOT do so with the global RLOC.
> (3) When an RTR wants to encapsulate to this xTR, it CAN do so with the global RLOC.
> (4) So when either the ITR or RTR do a Map-Request lookup, the map-server returns a PARTIAL RLOC-set to the requester. That is, it returns the global RLOC(s) to the RTR and the RTR RLOC(s) to the ITR.
>
> For the map-server to know in an RLOC-set which RLOCs belong to RTRs, they are registered with RLOC priority 254.
>
> Dino
>
>> On May 23, 2023, at 7:07 AM, Luigi Iannone <[e-mail]> wrote:
>>
>> Hi All,
>>
>>
>> TL;DR: Should the priority associated to RLOCs be used to indicate something else?
>>
>> Long Version:
>>
>> As you may (or may not) know Dino submitted the lispers.net NAT traversal solution (https://datatracker.ietf.org/doc/draft-farinacci-lisp-lispers-net-nat/ ) for publication on the Independent Stream (https://www.rfc-editor.org/about/independent/).
>>
>> Current ISE Editor is Eliot Lear (well known by old lispers like me ;-) )
>>
>> During the review of the document an interesting question came up:
>>
>> Lispers.net NAT traversal uses priority 254 to indicate that the RLOC belongs to a RTR.
>>
>> No text in old and new specs suggest a usage of the priority to deliver something different than the priority itself.
>> Even the value 255 is related to priority: do not use this RLOC = no priority.
>>
>> It goes without saying that there is no IANA registry about special value of priority associated to RLOCs.
>>
>> At the same time there is no text that explicitly states “priority indicates only the priority and CANNOT be used for something else”.
>>
>> So the question is: Should we (the WG) consider that priorities can be used to indicate something different from priority?
>>
>> If not: we may want to write it down somewhere.
>>
>> If yes: Well…. This deserves a longer discussion (may be to be included in the new charter…).
>>
>> Thoughts ?
>>
>> Ciao
>>
>> Luigi
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