[ndnSIM] Satisfy Interests with more than one producer
Alex Afanasyev
alexander.afanasyev at ucla.edu
Tue Apr 2 11:08:38 PDT 2013
Hi Yusung,
The answer is of course NO, since the Interests specifies one name, but the available data has different (does not matter implicit or explicit component) name.
What I'm seeing as advantage (and a "big" disadvantage at the same time) of using the implicit digest component is that routers are required to calculate this component based on the content. This prevents a producer from "lying" and setting one explicit digest, while the content corresponds to a completely different digest.
---
Alex
On Apr 1, 2013, at 6:31 PM, Yusung Kim <yskim525 at gmail.com> wrote:
> Hi Alex,
>
> It's right, each individual piece of content should have a unique name in NDN.
>
> We may explicitly add a digest component to the name as following;
>
> 1) /domain.com/video1.avi/sequence_num/explicit_producer1_digest
> 2) /domain.com/video1.avi/sequence_num/explicit_producer2_digest
>
>
> When User1 retrieved content by using the name 1) and the data is cached at routers ,
> if User2 sends an interest packet with the name 2), the interest cannot be served from the Content Store since the cache was stored by the name 1)
>
>
> How about using the implicit digest ?
>
> 3) /domain.com/video1.avi/sequence_num/implicit_producer1_digest
> 4) /domain.com/video1.avi/sequence_num/implicit_producer2_digest
>
> Once User1 retrieved content by using the name 3),
> Could User2 retrieve the cached data, even though User2 sends an interest with the name 4) ?
>
> If the answer is NO, what is the merit using the implicit digest instead of the explicit digest?
>
> Thank you,
>
> - Yusung Kim -
>
>
>
> On Mon, Apr 1, 2013 at 11:58 AM, Alex Afanasyev <alexander.afanasyev at ucla.edu> wrote:
> Hi Yusung,
>
> No, ndnSIM (as of right now) does not have a concept of the implicit digest. Ideally, each individual piece of content should have a unique name. If you really want to distinguish between data produced by Producer1 and Producer2, why not explicitly name these two data pieces differently? Alternatively, you can explicitly add a digest component to the name.
>
> ---
> Alex
>
> On Mar 31, 2013, at 7:50 PM, Yusung Kim <yskim525 at gmail.com> wrote:
>
>> Hi Alex and ndnSIM community.
>>
>> When using ndnSIM, is there the same function of the implicit digest to get specific content ?
>> ( the implicit digest is used in CCNx, right ? )
>>
>> In the your example topology,
>> Does Consumer need to select one producer between Producer1 and Producer2 using the implicit digest ?
>>
>> Thanks,
>>
>> - Yusung Kim -
>>
>>
>>
>> On Mon, Apr 1, 2013 at 4:11 AM, Alex Afanasyev <alexander.afanasyev at ucla.edu> wrote:
>> Hi Amin,
>>
>> Let me clarify a little bit with a small example:
>>
>> Consumer --- Router ----- Producer1
>> |
>> +--------- Producer2
>>
>> Assuming ns3::ndn::fw::Flooding strategy, Interests from the Consumer will reach both Producer1 and Producer2, and they both will send back a content object packet.
>>
>> Router, receiving the first packet (depending on the topology, could be from Producer1 or Producer2) will forward it to the consumer and remove* the PIT entry. When the second content object arrives to the Router (not the consumer), it will be discarded by the router, as unsolicited. (I would not call this as a drop, since it is relatively high-level decision to not forward the specific packet.)
>>
>> * PIT entry can be immediately removed (by default), or scheduled for removal within a short time interval (PitEntryPruningTimout). In either case, an extra content object will be discarded.
>>
>> ---
>> Alex
>>
>> On Mar 31, 2013, at 12:02 PM, Amin Karami <amin at ac.upc.edu> wrote:
>>
>>> In case of ns3::ndn::fw::Flooding, we will have several drops. Because when a consumer receives desired content from first sender/producer, consumer will drop other same contents. Yes? because the desired Interest has been satisfied and removed from PIT.
>>>
>>>
>>> /Amin
>>>
>>>
>>>
>>> On 03/31/2013 08:42 ب.ظ, Alex Afanasyev wrote:
>>>> Hi Amin,
>>>>
>>>> I is possible, but it depends on the forwarding strategy to deliver Interests to different producers. For example, if you choose ns3::ndn::fw::BestRoute, then Interests will only be delivered over the "shortest-metric" path and some of the producers will never see the Interests. If you use ns3::ndn::fw::Flooding, then all of the producers will receive Interests and it would depend on network topology (delays/losses) content object from which exactly producer will reach the consumer.
>>>>
>>>> In case if you have several consumers, depending on topology and forwarding strategy, they may be getting content objects from different producers.
>>>>
>>>> If you want only some Interests be satisfied by one producers and other by another, you may need to amend ndn::Producer implementation (or better create a new custom Producer app) by adding the appropriate logic.
>>>>
>>>> ---
>>>> Alex
>>>>
>>>> On Mar 31, 2013, at 11:35 AM, Amin Karami <amin at ac.upc.edu> wrote:
>>>>
>>>>> Hi friends,
>>>>> Is it possible to satisfy sent Interests from a consumer with more than one producer?
>>>>> for example, does the following code work correctly to satisfy Interests in /dst1 namespace with three producers?
>>>>> ndnGlobalRoutingHelper.AddOrigins ("/dst1", producer1);
>>>>> producerHelper.SetPrefix ("/dst1");
>>>>> producerHelper.Install (producer1);
>>>>>
>>>>> ndnGlobalRoutingHelper.AddOrigins ("/dst1", producer2);
>>>>> producerHelper.SetPrefix ("/dst1");
>>>>> producerHelper.Install (producer2);
>>>>>
>>>>> ndnGlobalRoutingHelper.AddOrigins ("/dst1", producer3);
>>>>> producerHelper.SetPrefix ("/dst1");
>>>>> producerHelper.Install (producer3);
>>>>>
>>>>>
>>>>> Best Regards,
>>>>> /Amin
>>>>>
>>>>> _______________________________________________
>>>>> ndnSIM mailing list
>>>>> ndnSIM at lists.cs.ucla.edu
>>>>> http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
>>>>
>>>
>>>
>>> --
>>>
>>> Best Regards,
>>>
>>> =======================================================
>>> Amin Karami, PhD student in Computer Architecture Department (DAC) at
>>> the Universitat Politècnica de Catalunya Barcelona Tech (UPC)
>>>
>>> e-mail: amin at ac.upc.edu | UPC-Campus Nord., Office: C6-E102
>>> phone: +34 93 40 11 638 | Jordi Girona, 1-3
>>> | 08034 Barcelona - SPAIN
>>> WWW: http://personals.ac.upc.edu/amin/
>>> =======================================================
>>>
>>
>>
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