> Speaking personally, I find the notion of treating the ITR capability as a 
> LCAF included in the request message to be very undesirable.  It clearly can 
> work.  But it looks like a fairly bad misuse of the tools. One which will 
> cause us trouble down the road.

Perhaps you are right. That and the previous lack of interest, is why I let the 
effort go and didn't persue it further.

Dino

> 
> Yours,
> Joel
> 
> On 11/20/13 1:17 PM, Dino Farinacci wrote:
>>> Dino,
>>> 
>>> Sorry for the delay, I see this proposition just now.
>>> 
>>> Do you propose this capability in the context of VPN and/or NSC?
>> 
>> I didn't have anything specific in mind. I just wanted an ITR/ETR pair to 
>> know if they could do a feature and what to do if one supported the feature 
>> and the other one did not.
>> 
>>> I would have a question, if there is capability, it means that there
>>> is a possibility to meet no capability so in this case what is
>>> replied?  An record with 0 locators?  no answer?  a special answer
>> 
>> Always reply, but state what you support so the capabilities bits can be 
>> compared at the ITR to see what is in common.
>> 
>>> saying "bad luck no match for the capability"?  If 0 locators then it
>> 
>> There is always a baseline for what you support. That is what is in RFC 
>> 6830. So if an ITR wanted Geo-Coordinates returned in a RLOC-record, and the 
>> ETR did not support that, it would return an RLOC-record with a single-tuple 
>> (with just an AFI-encoded RLOC address) versus the two-tuple (with the 
>> AFI-encoded RLOC address and the LCAF-encoded Geo-Coordinates). And then the 
>> ITR would just encapsulate to the RLOC as it does today.
>> 
>>> is a negative reply but conceptually this is not a negative reply.  If
>>> no answer, then the requester will keep continuing sending requests.
>>> If a new message, what kind of message?
>> 
>> There is no need for a new message. That would complicate matters and create 
>> more combinations to deal with when receiving responses.
>> 
>> Dino
>> 
>>> 
>>> Thanks,
>>> 
>>> Damien Saucez
>>> 
>>> On 12 Sep 2013, at 20:29, Dino Farinacci <[email protected]> wrote:
>>> 
>>>> So wouldn't be useful if an ITR which sends a Map-Request to the mapping 
>>>> system, could say "I know Mr. ETR that you have registered a bunch of 
>>>> stuff to the mapping system, but can you return just the stuff I care 
>>>> about and more importantly the stuff I support in my implementation?".
>>>> 
>>>> So I was thinking (and talking to several others about this), if we could 
>>>> have a Capabilities Type LCAF that is encoded in an address field of the 
>>>> Map-Request. I would like to propose that it get encoded in the ITR-RLOCs 
>>>> field of a Map-Request. This way, each ITR in the ITR-RLOCs list could 
>>>> tell a Map-Replier what they support.
>>>> 
>>>> I would propose that the Capabilities Type LCAF be encoded as a 
>>>> bit-string. Where each bit position indicates the LCAF Type value. We 
>>>> would have 2 fields, an EID field and a RLOC field so it can be conveyed 
>>>> which Types are supported for EID encoded fields or RLOC encoded fields in 
>>>> any LISP control message.
>>>> 
>>>> It would be required of every implementation to support the Capabilities 
>>>> Type LCAF if nothing else would be supported. That would get the 
>>>> implementations to do the general parsing work so they could skip over 
>>>> LCAFs they don't understand and get to the ones they do understand while 
>>>> conveying what they support.
>>>> 
>>>> Also I find that this may be useful for this world of multiple 
>>>> encapsulations. Rather than register UDP port numbers, a decapsulator 
>>>> could convey what encapsulations it supports (i.e. L3-LISP, L2-LISP, 
>>>> VXLAN, NVGRE, IPsec, GRE, whatever-new-thing-nv03-comes-up-with).
>>>> 
>>>> The Capabilities Type LCAF could also be used by the mapping system. So 
>>>> when an ETR sends an Info-Request, an Info-Reply from the map-server could 
>>>> tell the registering system what LCAFs it supported. Ditto, for asking 
>>>> map-resolvers what types of EID encodings they could support (maybe the 
>>>> mapping system can support more LCAF encodings then the map-resolvers, so 
>>>> you can choose a different map-resolver if you wanted more).
>>>> 
>>>> And arguably, the Capabilities Type LCAF could be put in RLOC-probes. It 
>>>> could go anywhere with the address you wanted to encode as a 2-tuple.
>>>> 
>>>> Comments?
>>>> 
>>>> If people are interested I can draft up the details for the -03 version. 
>>>> Or if you think we should post the -03 version just with the current 
>>>> changes, I can do that. And also comment if you think we should go with 
>>>> the JSON Data Model Type for -03 or put it into -04 with perhaps this 
>>>> Capabilities LCAF.
>>>> 
>>>> Thanks,
>>>> Dino
>>>> _______________________________________________
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>>>> https://www.ietf.org/mailman/listinfo/lisp
>>> 
>> 
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