TWiki > Simulation > Tutorials > AddingASimpleRoutingTable	TWiki webs: Main | TWiki | Know | Sandbox
	Simulation . { Changes | Index | Search | Go }

Step 13: Adding a Routing Table

Thus far messages have been delivered to destinations by nodes simply checking to see if the message is destined for themselves, and if not, forwarding them out to a randomly selected interface in the hope that they will reach their destination eventually. Store-and-forward type packet-switched networks are somewhat more deterministic. To make our simulation more like a real network we will add a rudimentary routing table to each node.

In this exercise routing tables will be pre-calculated and entered as parameters in the omnetpp.ini file. Each node will store an array that says which gate to send a message out for a specified destination node.

We use the routing tables by replacing the random gate code in the function forward_message() with the following lines:

   // Gate selection from the routing table.
   TicTocMsg13 *ttmsg = check_and_cast<TicTocMsg13 *> (msg);
   int k = rt[ttmsg->getDestination()];

Here are the files required to run this simulation:

• omnetpp.ini
• tictoc13.ned
• tictoc13.msg
• txc13.cc

(Thanks to BrettPentland for suggesting and implementing this part of the tutorial.)