[ndnSIM] Problem in Forwarding module

[Spyridon (Spyros) Mastorakis]

Hi,

> On Mar 14, 2018, at 12:19 AM, Mortaza Nikzad <mrtz_azad at yahoo.com> wrote:
> 
> Hi
> thanks for your reply Spyridon.
> I understand that this example is from ndnSIM-v.1, so I installed it and run the example there. It works well but with a customary forwarding strategy not best rout strategy. It would be good if the documentation about this example be correct. 
> now my question is that why as a good rule of thumb did not use from received nack from upstream face to correct the chosen face? I try to follow it in my work.

If the NACK indicates congestion, then long story short, an approach like that should work.

> 
> I also understand the best rout forwarding strategy do not work well and actually do not choose the least cost link. I tested it in a simple topology as: one consumer, one producer and two path from consumer to producer with different data rate. I unexpectedly saw that the best rout chosen the worse path. Can anyone here tell me why? and is this problem related to forwarding strategy or route calculator?  
> thanks

Each FIB entry has next-hops. Each next-hop has a cost. This cost can be associated either with delay or bandwidth parameters. The current implementation selects the path with the smallest delay (i.e., the path with the smallest delay will have the lowest cost).

If you want to take the link bandwidth into account, you will have to modify the GlobalRoutingHelper:

https://github.com/named-data-ndnSIM/ndnSIM/blob/master/helper/ndn-global-routing-helper.cpp#L283

Thanks,

Spyridon (Spyros) Mastorakis
Personal Website: http://cs.ucla.edu/~mastorakis/ <http://cs.ucla.edu/~mastorakis/>
Internet Research Laboratory
Computer Science Department
UCLA




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