[ndnSIM] Question on FIB matching

Asit Chakraborti Asit.sc.Chakraborti at huawei.com
Wed May 8 17:08:09 PDT 2013

Hi Alex,

Thanks for the response, that makes sense. I needed to process the interests differently and was planning to create a new
Forwarding strategy, however, the interests got dropped and didn't get delivered to the new strategy as there was no
FIB match. Either I have to modify the common code to allow PIT entries with no matching FIB (not sure how badly that
would violate the entire model), or may be I will try to have dummy "/" entries in the FIB...


From: Alexander Afanasyev [mailto:cawka1 at gmail.com] On Behalf Of Alex Afanasyev
Sent: Wednesday, May 08, 2013 4:28 PM
To: Asit Chakraborti
Cc: ndnsim at lists.cs.ucla.edu
Subject: Re: [ndnSIM] Question on FIB matching

Hi Asit,

The currently implemented way always attempts to lookup FIB and create PIT entry for incoming interest, and if there is a CS match, such a PIT entry will be immediately satisfied.

The main reason behind this implementation is to unify metric calculation: for every interest there will always be either new or existing PIT entry, and every satisfied interest can be tracked via PIT entry satisfaction.  It is technically possible to change the implementation, but I'm not yet sure if this would get any major benefits.

As for last question.  Yes, it is assumed that there is always some FIB entry, at least a default entry for root prefix, that can match incoming interests.  And if there is no such entry, then NDN router is not willing to do anything with such interests.

Do you have a specific scenario where this assumption doesn't hold?  It is relatively easy to create an alternative forwarding strategy with slightly different processing logic.


On May 8, 2013, at 3:31 PM, Asit Chakraborti <Asit.sc.Chakraborti at huawei.com<mailto:Asit.sc.Chakraborti at huawei.com>> wrote:

Hi Alex,

My understanding of the code could be wrong, but it seems we require a FIB match on an incoming
Interest even before a CS match. Any historical reason behind this ? Or is it just the fact that with
the current model and APIs, a FIB entry usually exists if the content is in content store ?

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