Wifi AP topology setup issue

[vikasha...@gmail.com]

Hi,

I am trying to build a mobility model with  simple 1 level tree where there are three nodes (1 root and 2 leaves) connected via point-to-point link. The two leaves are also wifi access points. And there is a wifi station which is moving with a constant velocity in a straight line parallel to position of APs. I have attached the topology diagram as "Simple Wifi Topology.png". I am able to successfully place the APs and wifi stations and the mobility is also working fine with first AP and wifi station. I have installed TCP application source at the root node and TCP application sink at the wifi station. The problem I am facing currently is once the wifi station moves out of the range of first Wifi AP (Wifi AP1) and enters the range of second Wifi AP (Wifi AP2), there is a wifi association happening which is evident from pcap logs but after that there is no packet received from the root node. Also i found one problem that after association of wifi station with wifi AP2, as per my understanding the routing table should be updated which shows that the wifi station is now connected to Wifi AP2 and any packets should be forwarded to Wifi AP2 which will forward the packets to Wifi station. But the point-to-point interface of the Wifi AP2 which is connected to the root is not receiving any packets from root. I am using "Ipv4GlobalRoutingHelper" for routing. Please have a look at the attached script and suggest what can be done.

Thanks and Regards,
Vikash Shah,
University of Arizona,
Computer Science Department.

[pdbarnes]

IIRC GlobalRouting is static: it walks the current topology, creates the routing tables, then it's done.  If the topology changes, the routing tables don't get updated automatically.  

You probably have three options:  

1. Hook some callback related to the new association, and rerun GlobalRouting to update the routing tables
   
2. Switch to NixVector routing, then hook some callback related to the new association and flush the NixVector caches. NixVector will then construct new routes as it needs them
3. Switch to a real (reactive) routing protocol

Peter

[vikasha...@gmail.com]

Thanks Peter for the prompt reply! I opted for option 3 and used Olsr and it seems to be working.


Thanks and Regards,
Vikash Shah.