[ndnSIM] Setting up link metric

[Alex Afanasyev]

Hi Ahmed,

There isn't a priority, these are different metrics used for different purposes.

The one you configure in the topology file can be used by GlobalRoutingHelper to calculate routes and set up FIB entries.   What the helper does is obtains the configured costs, finds out (a set of) shortest paths, sums up the configured costs from the topology file, and calls FibHelper::AddRoute with the calculated cost.

You can rub FibHelper::AddRoute manually (or in addition to GlobalRoutingHelper-generated calls to it).  Whichever cost you specify in AddRoute, will be assigned to FIB entry.   There is no relation to the configured cost in the topology.

---
Alex

> On Feb 20, 2016, at 2:58 AM, Ahmed Sadek <don1559 at gmail.com> wrote:
> 
> Hi Spyridon ,
> 
> Thank you for your reply. I still don't understand. If using the FibHelper I set the metric between client 1-> Router 1 to be 100 and in the topology file I set up the metric between client 1-> Router 1 to be 200, so which one takes effect and why ?
> 
> Thanks!
> Ahmed
> 
> On Sat, Feb 20, 2016 at 4:49 AM, Spyridon (Spyros) Mastorakis <mastorakis at cs.ucla.edu> wrote:
> Hi Ahmed,
> 
> the first case refers to the establishment of a route that may be used for Interest forwarding. Specifically, the FibHelper will add the appropriate FIB entries on the routers across the specified path.
> 
> The second case refers to the physical properties (bandwidth, delay, queue size) of a link between two adjacent nodes.
> 
> Hope that this helps. Please let me know if you have any follow-up questions.
> 
> Spyridon (Spyros) Mastorakis
> Personal Website: http://cs.ucla.edu/~mastorakis/
> Internet Research Laboratory
> Computer Science Department
> UCLA
> 
> 
> 
> 
>> On Feb 16, 2016, at 3:48 AM, Ahmed Sadek <don1559 at gmail.com> wrote:
>> 
>> Dear All,
>> 
>> What is the difference between setting up the metric in the simulation file :
>> ndn::FibHelper::AddRoute("client", "/", "router1", 150);
>> 
>> Or in the topology file:
>> # srcNode   dstNode     bandwidth   metric  delay   queue
>> client      router1       20Mbps 	150		50ms	50
>> 
>> And which one take priority?
>> 
>> Thanks!
>> Ahmed
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