3 Level Tree topology TCP OnOffHelper issue

[vikasha...@gmail.com]

Hi,

I am trying to setup a mobility model with 3 level complete binary tree topology where all the leaf nodes are Wifi Acess Points (APs). I have attached the pictorial representation of topology as attachment "Tree-Topology.png". I am using Topology Reader for reading the nodes and links. The topology file "Inet_tree_topo.txt" is also attached. I think the topology creation is fine. I am using OLSR routing which suits my need as I needed dynamic routing where the wifi APs update their route on their association with the Wifi station. The problem i am facing currently is with creation of TCP sink and OnOffHelper. I am creating TCP packet sink on the wifi station and installing OnOffHelper on the root node(marked as server in topology diagram). When i am running the simulation the mobility is working fine(Wifi association is happening based on mobility) but the OnOffHelper installed in the root node is not generating TCP packets. In the pcap log files i can only see routing messages being exchanged. I am attaching the script "p2p-wifi-tree-topo.cc". Please have a look and suggest what is wrong.

Thanks and Regards,

Vikash Shah.

University of Arizona,

Computer Science Department.

[Konstantinos]

Hi,

I didn't run your scenario to test it, but simply by inspecting it, I noticed two issues.

OLSR Convergence... You are starting your OnOffApplication at t=1sec. There is no valid path YET towards the STA. You will need to give some time for the network to prepare at least an initial path, which may not be valid for long if you have mobility, but at least there will be a 'next hop'.

Second, since you are using multiple networks, you have to enable HNA.  

See the example in /src/olsr/examples/olsr-hna.cc for the alternative methods to enable it.

Regards,

K

[vikasha...@gmail.com]

Hi Konstantinos,

I am starting the OnOffApplication at t=30sec and with that TCP packets are sent and received to leaf nodes but not the Wifi Sta. If I understood the olsr-hna.cc example correctly, there are two ways to announce that wifi Sta is reachable:

1) I have to make all Wifi AP interfaces and Wifi Sta as non-Olsr device and once the Wifi Sta is associated with one of the Wifi AP, the wifi AP should announce the network prefix that is reachable via itself. Also once the Wifi Sta is not associated with the Wifi AP, the announcement needs to be withdrawn. I am not sure how to do this. Is there any example which I can look into? Also does the Wifi AP and Wifi Sta should be in the same subnet?

2) Make Wifi Sta as non-Olsr device and on association with a Wifi AP, the wifi Sta announces its network prefix. Is there a way to receive callback on wifi AP and Wifi Sta association?

Is there a simple way to make the above topology work? I tried not using multiple networks and its not working with that change.

Thanks and Regards,
Vikash Shah.