[ndnSIM] RIB do not work well

Junxiao Shi shijunxiao at email.arizona.edu
Thu Apr 26 03:50:09 PDT 2018

Hi Mortaza

> In this scenario, there are three different routes to destination. one
> route with 3 hops to destination and 1 mbps data rate in bottleneck link,
> another with 4 hops and 1 mbps data rate in bottleneck link and the third
> one with 4 hops but 10 mbps data rate in bottleneck link.


# srcNode   dstNode     bandwidth   metric  delay   queue
> Src1        Rtr1        10Mbps     1        10ms    20
> Rtr1        Rtr2        10Mbps      1        10ms    20
> Rtr1        Rtr4       1Mbps         1        10ms    20
> Rtr3        Rtr4        10Mbps      1        10ms    20
> Rtr1        Rtr3        1Mbps        1        10ms    20
> Rtr2        Rtr4        10Mbps      1        10ms    20
> Dst1        Rtr4        10Mbps     1        10ms    20

Despite having different bandwidth, your "metric" setting did not reflect
that, so there's no way for RIB to tell their differences.
Both multicast and best route v4 strategies do not attempt to detect link
bandwidth or Interest satisfaction rate. Their decisions are solely based
on metric setting.
To fix this problem, set the metric to the inverse of bandwidth.

in addition I found that in multicast strategy, interests do not multicast.
> In fact, it works as the best strategy works.

>   ndn::GlobalRoutingHelper ndnGlobalRoutingHelper;
>   ndnGlobalRoutingHelper.InstallAll();

The GlobalRoutingHelper only installs a shortest route from every node to a
prefix. Even if you are using multicast strategy, the Interest goes on only
one path because there's only one nexthop in the FIB entry.

Yours, Junxiao
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