[Ndn-interest] NFD Interest Aggregation at Intermediate Router
lupos at tcd.ie
Wed Mar 13 16:46:30 PDT 2019
Sorry in advance if this has been discussed elsewhere, or if I am
overlooking something! I am currently working on a project using NDN and
have encountered a problem with interests not being aggregated as I
thought they would be. To highlight the issue consider the following case:
G --- E
In this example, G is the producer of some data under //test/g/, A and B
are consumers interested in the data G produces and E is an intermediate
router connecting G to A/B. Each of these nodes are running in a docker
container on the same machine and I set up the faces and routes before
hand using /nfdc/ in the following manner:
- On *nodeA*: /nfdc face create udp://nodee.com; nfdc route add /test/g
/- //On *node**B*: //nfdc face create udp://nodee.com; nfdc route add
/- //On *nodeE*: ///nfdc face create udp://nodeg.com; nfdc route add
Note I don't make faces / routes in the direction of the dataflow (i.e.
there is no premade face/route from E --> A) as I don't think they are
needed. Also these host names resolve correctly through the use of an
overlay network in docker.
Node G also runs NFD and a jNDN app which registers the prefix //test/g
/and I can control when to call /face.processEvents() /using a key
stroke, so that I can control when things happen.
I then ran this test with NFD's /Forwarder/ and /ContentStore/ modules
set to a log level of DEBUG so I could see what was going on:
- On *node A*: /ndnpeek /test/g/0 -l 1000000
/ - /This expresses an interest for //test/g/0/ with a long timeout
for those who might not be familiar
/ - /This reaches node E who creates a PIT entry and forwards it to
node G as expected
- This then reaches node G who's NFD forwards it on to the jNDN app
- However the app does *not* respond with the Data or even see
the Interest yet, as I will manually call /face.processEvents()/ with a
/- /On *node B*: /ndnpeek /test/g/0 -l 1000000/
- This again reaches node E
- Node E does *not* create a *new *PIT entry (or at least the
/nPitEntries/ from the output of /nfdc status/ doesn't change), but
presumably adds node B's face to the existing entry.
- *However, node E then forwards a _second_ Interest to G with the
same name of //test/g/0/*
**- This second interest reaches node G's NFD who proceeds to forward
the second interest to the jNDN app.
- This is the behavior I wasn't expecting!
- On *node G*: I finally call /face.processEvents()/
- Node G then sees the *two* Interests (which have the *exact same
name*) and responds to them with the appropriate Data
- Whichever Data packet reaches node G's NFD first is then
forwarded to node E and onto nodes A and B
- The Data packet that reaches node G's NFD second is then marked
as unsolicited and dropped by the NFD
Is this intended behavior or have I set something up wrong? The packet
produced by G is multicasted back to both A and B through E indicating
that the PIT entries are correct, but it seems odd that the application
level producer at node G must see both of these interests? For context I
am currently prototyping a small P2P multiplayer game that runs over
NDN, meaning Interest aggregation could save producers a lot of cycles
and network traffic.
The logs produced by the NFDs at each of the nodes are available at this
repo <https://github.com/stefano-lupo/NFD-Interest-Aggregation-Logs> if
anyone would like to take a look - I included copies which have only
(what I think is) the relevant information and some comments on what
Thanks in advance for any information.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Ndn-interest