[ndnSIM] Shortest paths

[Klaus Schneider]

On 06/09/18 14:16, Chavoosh Ghasemi wrote:
> This is not general enough to write a patch, as one can define the 
> topology in either way (i.e. through a topology file or Config). Note 
> AnnotatedTopologyReader does not use Config to set up the topology.

Well in this case you can just reuse the value that you set in the 
config file. For example:

> int delayMs = 10
> 
> PointToPointHelper p2p;
> p2p.SetChannelAttribute ("Delay", TimeValue (MilliSeconds (delayMs)));
> 
> fibHelper.AddRoute(node, prefix, face, delayMs);



> A better solution would be finding the latency of attached links through 
> the node, itself.

Please see the second part of my email:

"Moreover, there's the GetAttribute() function: 
https://www.nsnam.org/docs/manual/html/attributes.html"

So it should look something like this (haven't tested it):

> 
> TimeValue currentDelay;
> ptpChannel->GetAttribute("Delay", currentDelay);

Best regards,
Klaus




> 
> On Thu, Sep 6, 2018 at 1:55 PM Klaus Schneider <klaus at cs.arizona.edu 
> <mailto:klaus at cs.arizona.edu>> wrote:
> 
>     If you use the AnnotatedTopologyReader, you can just set the metric to
>     the same value as the delay.
> 
>     Here's an example from http://ndnsim.net/current/examples.html
> 
>      >
>      > # link section defines point-to-point links between nodes and
>     characteristics of these links
>      > link
>      >
>      > # Each line should be in the following format (only first two are
>     required, the rest can be omitted)
>      > # srcNode   dstNode     bandwidth   metric  delay   queue
>      > # bandwidth: link bandwidth
>      > # metric: routing metric
>      > # delay:  link delay
>      > # queue:  MaxPackets for transmission queue on the link (both
>     directions)
>      > Node0       Node1       1Mbps       1       10ms    10
>      > Node0       Node3       1Mbps       1       10ms    10
> 
> 
>     Moreover, there's the GetAttribute() function:
>     https://www.nsnam.org/docs/manual/html/attributes.html
> 
> 
>     Best regards,
>     Klaus
> 
> 
> 
>     On 06/09/18 11:02, Chavoosh Ghasemi wrote:
>      > Is there any way to get the delay of links?
>      > It seems you cannot get it through PointToPointChannel as GetDelay
>      > method is protected.
>      >
>      >
>      > P.S. The following code does not work
>      >      auto t =
>      >
>     dynamic_cast<ns3::PointToPointChannel*>(&(*(transport->GetNetDevice()->GetChannel())));
>      >      t->GetDelay();
>      >
>      >
>      >
>      > On Wed, Sep 5, 2018 at 2:00 PM Alex Afanasyev <aa at cs.fiu.edu
>     <mailto:aa at cs.fiu.edu>
>      > <mailto:aa at cs.fiu.edu <mailto:aa at cs.fiu.edu>>> wrote:
>      >
>      >     It calculates based on the Face "metric", which by default
>     set to 1
>      >     for each Face (= incidentally, resulting in hop count).  If you
>      >     update Face metric with latency related metric represented as an
>      >     integert (unfortunately, we don't have anything that is already
>      >     available; patches welcome), you will get latency-based
>     calculation
>      >     of routes.
>      >
>      >     --
>      >     Alex
>      >
>      >>     On Sep 5, 2018, at 4:47 PM, chavoosh ghasemi
>      >>     <chavoosh.ghasemi.off at gmail.com
>     <mailto:chavoosh.ghasemi.off at gmail.com>
>      >>     <mailto:chavoosh.ghasemi.off at gmail.com
>     <mailto:chavoosh.ghasemi.off at gmail.com>>> wrote:
>      >>
>      >>     Hi,
>      >>
>      >>     Apparently, ndnGlobalRoutingHelper::CalculateRoutes() uses *hop
>      >>     count* as a metric to compute the shortest paths (correct me
>     if I
>      >>     am wrong).
>      >>     If that's the case, do we have any module (e.g. a helper) in
>      >>     ndnSIM that calculates shortest paths based on link latency?
>      >>
>      >>     Thanks,
>      >>     /- Chavoosh/
>      >>
>      >>     --
>      >>     /*Chavoosh Ghasemi*/
>      >>
>      >>     Ph.D. Student in Computer Networking
>      >>     University of Arizona - Computer Science Department*/
>      >>     /*
>      >>     */Address: Gould-Simpson 721B, /**/1040 E. 4th Street,
>      >>     /*
>      >>     */                 Tucson, AZ 85721
>      >>
>      >>     "The /quieter/ you become, the /more you can hear"//*
>      >>     _______________________________________________
>      >>     ndnSIM mailing list
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>     <mailto:ndnSIM at lists.cs.ucla.edu <mailto:ndnSIM at lists.cs.ucla.edu>>
>      >> http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
>      >
>      >     ______________
>      >     Alex Afanasyev
>      >     Assistant Professor, SCIS, Florida International University
>      >     11200 SW 8th Street, PG6 Room 140D, Miami, FL 33199
>      >     phone: +1.305.348.4960 (office); email: aa at cs.fiu.edu
>     <mailto:aa at cs.fiu.edu>
>      >     <mailto:aa at cs.fiu.edu <mailto:aa at cs.fiu.edu>>
>      >     web: https://users.cs.fiu.edu/~afanasyev/
>     <https://users.cs.fiu.edu/%7Eafanasyev/>
>      >     <https://users.cs.fiu.edu/%7Eafanasyev/>
>      >
>      >
>      >
>      >
>      > --
>      > /*Chavoosh Ghasemi*/
>      >
>      > Ph.D. Student in Computer Networking
>      > University of Arizona - Computer Science Department*/
>      > /*
>      > */Address: Gould-Simpson 718, /**/1040 E. 4th Street,
>      > /*
>      > */                 Tucson, AZ 85721
>      >
>      > "The /quieter/ you become, the /more you can hear"//*
>      >
>      >
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>      >
> 
> 
> 
> -- 
> /*Chavoosh Ghasemi*/
> 
> Ph.D. Student in Computer Networking
> University of Arizona - Computer Science Department*/
> /*
> */Address: Gould-Simpson 718, /**/1040 E. 4th Street,
> /*
> */                 Tucson, AZ 85721
> 
> "The /quieter/ you become, the /more you can hear"//*