[ndnSIM] limitations at router or channels?

John Baugh jpbaugh at umich.edu
Thu Jun 15 02:32:49 PDT 2017


Greetings friends,

This is probably something simple, but I'm just not able to figure it out.

I've created:

   - 8 consumers
      - All of their CS limits are set to 0 so they won't cache anything
      themselves
      - This is to ensure that they will keep requesting the same objects
      over and over again so I can look at the router's incoming frequency of
      interests
   - 1 router
      - This does have a CS limit set to a positive number (5, 10, etc. -
      doesn't seem to matter)
   - 1 producer
   - 2 "intermediate nodes" with neither a consumer or producer app helper
   installed
      - I've set their cache limit to 0, just like the consumers

*I run the app for 30 simulator seconds.*

Here is what I'm getting in 2 different scenarios:


   1. In scenario 1, I don't use the "intermediate nodes" at all.  I
   connect all 8 consumers directly to the router, and then the router to the
   producer

   Given a rate of 30 (Frequency attribute set to 30), The frequency of
   requests for the same content object coming in are 900 from each
Face.  *This
   is what I expect*.

   2. In scenario 2, I connect 4 consumers to intermediate node 1, and 4
   consumers to intermediate node 2.  Then, the intermediate nodes are
   directly connected to the "router", and the router is connected to the
   producer.

   Given the same rate (30), running the app for 30 seconds, and knowing
   that I only have two incoming faces to the router (one from each
   intermediate node), the frequency of requests for content objects coming in
   is 450 for each of the links.

While I suspect the "450" from each link * 2 = 900 has some connection to
this whole situation, I'm a little confused.  If *each of the consumers *is
requesting a content object at 30 / second, for 30 seconds, *each consumer* is
requesting that object *900 times*.  This shouldn't change between
scenarios 1 and 2.

Therefore, if there are two links involved here, I expect the same overall
requests (8 consumers * 900 = 7,200 overall interests being received at the
router.  So half (3,600) should be coming in to Intermediate node 1, and
forwarded to the router, and the other have (3,600) should be coming in
from Intermediate node 2, and forwarded to the router.

But in scenario (2), I'm only getting a total of 900 overall interests
received!  I tried modifying the link speed and other attributes like that
but it doesn't seem to do anything.

Ideas?

John
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