[ndnSIM] Interest forwarding

[Junxiao Shi]

Hi Boussada

CCNx's AnswerOriginKind
<https://github.com/ProjectCCNx/ccnx/blob/ccnx-0.8.2/doc/technical/InterestMessage.txt#L119>does
not restrict which *user* (producer or cache) could answer an Interest. It
is a bitmask containing the following:

   - 1 = Answer from existing content store
   - 2 = Answers may be generated
   - 4 = Answer may be "stale"
   - 16 = Mark as stale in content store (must have Scope 0) __Status:__
   _hack_


When designing NDN protocol, we believed:

   - It is harmful to disallow answering from a Content Store, because (1)
   it can lead to attacks on a producer (2) it disallows localized recovery
   after a Data packet loss. Thus, bit 1 is unnecessary.
   - It is useless to disallow a producer from generating content, because
   the purpose of an Interest is to retrieve Data no matter where it came
   from. Thus, bit 2 is unnecessary.
   Use cases of checking Content Store only arose later on, but these use
   cases were only for checking local Content Store, so there were no need to
   standardize it in network wire format.
   - It is useful to allow stale content. Thus, bit 4 is necessary. This
   became the MustBeFresh selector.
   - It is unnecessary to standardize bit 16 because it is entirely within
   the local node.

Finally, AnswerOriginKind was shrunk into MustBeFresh selector.

Yours, Junxiao

On Mon, Aug 28, 2017 at 4:07 AM, Boussada Rihab <rihab.boussada at hotmail.com>
wrote:

> Thus, there is no field called "answer orgin kind" in ndnsim as in ccnx?
>
> ------------------------------
> *From:* Junxiao Shi <shijunxiao at email.arizona.edu>
> *Sent:* Monday, August 28, 2017 12:00 PM
> *To:* Boussada Rihab; ndnsim at lists.cs.ucla.edu
> *Subject:* Re: [ndnSIM] Interest forwarding
>
> The consumer may set PublisherPublicKeyLocator selector, so that producers
> without a proper public key would not respond to the Interest.
>
>
> On Mon, Aug 28, 2017 at 03:52 Boussada Rihab <rihab.boussada at hotmail.com>
> wrote:
>
>> Please how can I impose that only a specific user can answer to the
>> considered Interest.
>>
>>
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