[Ndn-interest] Hop-by-Hop Flow Balance

[Tai-Lin Chu]

> Not really. What you need is an ability to provoke a pull.

Do people who want PUSH consider that it is possible to use interest as a notification to provoke a pull?

(Producer sends an interest to consumer to say, “hey, I have something for you, please fetch it.")

> On Mar 15, 2016, at 9:55 AM, Dave Oran (oran) <oran at cisco.com> wrote:
> 
>> 
>> On Mar 15, 2016, at 9:22 AM, Ravi Ravindran <ravi.ravindran at gmail.com <mailto:ravi.ravindran at gmail.com>> wrote:
>> 
>> Another primitive that is missing in NDN/CCN is the need to PUSH content, most of the IoT and social networking applications requires this primitive.
> Not really. What you need is an ability to provoke a pull.
> 
>> Today the solutions include using the long-lived  interests or polling mechanisms which are not desirable, so if once such primitive is introduced this also questions the per-hop flow control objective.
>> 
> Not really. On the other hand it does require more aggressive congestion control on the Interest transmission.
> 
>> Regards,
>> Ravi
>> 
>> On Mon, Mar 14, 2016 at 4:09 PM, <Ignacio.Solis at parc.com> wrote:
>> [ Disclaimer: CCN currently uses flow balance as well ]
>> 
>> The current Hop-by-Hop Flow Balance is nonsense.
>> 
>> 
>> 
>> 
>> 
>> On 3/10/16, 11:46 PM, "Ndn-interest on behalf of Alex Afanasyev" <ndn-interest-bounces at lists.cs.ucla.edu on behalf of aa at CS.UCLA.EDU> wrote:
>>> [6] **Hop-by-Hop Flow Balance**:
>>>   Over each link, one interest packet should bring back no more than one data packet.
>> 
>> Seriously, who thinks this actually works?
>> 
>> Let me quote the webpage ( http://named-data.net/project/ndn-design-principles/ ):
>> "[6] Hop-by-Hop Flow Balancing: Over each link, one interest packet should bring back no more than one data packet.
>> Hop-by-hop flow balancing enables each node to control load over its links. By deciding to sending interest over a link, router commits bandwidth for the returned data. By limiting the number of interests sent, each router and client node in the network control how much data it will receive.
>> "
>> 
>> Either there is a lot of information missing here to justify why this is so, or this is very naïve.
>> 
>> First, if what you want to do is limit the number of content objects (or packets) returned, you don’t need to send one interest.  _Specially_ for NDN, which has prefix matching, you could send one interest with a count number (10) and expect to receive 10 content objects back.  There is no reason why I need to send 10 exact copies of the same interest.   Even if the interests had small variations, why send 10? Why not send 1 + the 10 deltas?   I guess it’s possible you may call that part of the “network adaptation layer”, who knows.
>> 
>> Also by requiring 1-to-1, you are always requiring an overhead (on the requester side) that is quite high. If you think of today’s type of networks, where a packet (internet sized) is around 1500 bytes, that means that even if we send interests of 30 bytes, we are incurring quite a bit of overhead in the upstream. This becomes considerable when doing high bandwidth video.
>> 
>> Please explain why the 1-to-1 is good.
>> 
>> Second, NDN allows very large packet sizes.  So, when I send 1 interest, I don’t now if what I’m going to get back is 1 byte or 18 exabytes.  How do routers use this information to control how much data they’re going to receive? Are they going to reserve 18 exabytes of traffic time?
>> 
>> If this principle were to be re-written as:
>> “Allow network nodes to participate in flow control” then the actual engineering solution might be able to achieve this.
>> 
>> Finally, at least we should acknowledge the limitations this type of approach requires; like symmetrical forwarding.
>> 
>> It would be awkward if the only way for NDN to work over Satellite links would be to break the principles.
>> 
>> Nacho
>> 
>> 
>> PS. Yes, there are people in this community who have looked at other ways to do flow-balance and flow-control. Maybe we should be learning from those and not just claiming as principle what we do today because we don’t want it questioned.
>> 
>> --
>> Nacho (Ignacio) Solis
>> Protocol Architect
>> Principal Scientist
>> Palo Alto Research Center (PARC)
>> +1(650)812-4458
>> Ignacio.Solis at parc.com
>> 
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