bug 702: make global routing robust to link/device events

examples/routing/dynamic-global-routing.cc

@@ -18,7 +18,10 @@
 
 
 // This script exercises global routing code in a mixed point-to-point
-// and csma/cd environment
+// and csma/cd environment.  We bring up and down interfaces and observe
+// the effect on global routing.  We explicitly enable the attribute
+// to respond to interface events, so that routes are recomputed
+// automatically.
 //
 // Network topology
 //
@@ -41,33 +44,20 @@
 //  n1 to n6 is via the direct point-to-point link
 //  At time 1s, start CBR traffic flow from n1 to n6
 //  At time 2s, set the n1 point-to-point interface to down.  Packets
-//    will start to be dropped 
-//  At time 3s, call RecomputeRoutingTables() and traffic will
-//    start flowing again on the alternate path
-//  At time 4s, re-enable the n1/n6 interface to up.  Will not change routing
-//  At time 5s, call RecomputeRoutingTables() and traffic will start flowing 
-//    again on the original path
+//    will be diverted to the n1-n2-n5-n6 path
+//  At time 4s, re-enable the n1/n6 interface to up.  n1-n6 route restored.
 //  At time 6s, set the n6-n1 point-to-point Ipv4 interface to down (note, this
-//    keeps the point-to-point link "up" from n1's perspective).  Packets
-//    will traverse the link and be dropped at n6 upon receipt.  These drops
-//    are not visible in the pcap trace but in the ascii trace.
-//  At time 7s, call RecomputeRoutingTables() and traffic will flow again
-//    through the path n1-n2-n5-n6
-//  At time 8s, bring the interface back up.
-//  At time 9s, call RecomputeRoutingTables() and traffic will flow again
-//    through the path n1-n6
+//    keeps the point-to-point link "up" from n1's perspective).  Traffic will
+//    flow through the path n1-n2-n5-n6
+//  At time 8s, bring the interface back up.  Path n1-n6 is restored
 //  At time 10s, stop the first flow.  
 //  At time 11s, start a new flow, but to n6's other IP address (the one
 //    on the n1/n6 p2p link)
 //  At time 12s, bring the n1 interface down between n1 and n6.  Packets
-//    will start to be dropped 
-//  At time 13s, call RecomputeRoutingTables() and traffic will
-//    start flowing again on the alternate path
+//    will be diverted to the alternate path
 //  At time 14s, re-enable the n1/n6 interface to up.  This will change 
 //    routing back to n1-n6 since the interface up notification will cause
 //    a new local interface route, at higher priority than global routing
-//  At time 15s, call RecomputeRoutingTables(), but there is no effect
-//    since global routing is lower in priority than static routing
 //  At time 16s, stop the second flow.  
 
 // - Tracing of queues and packet receptions to file "dynamic-global-routing.tr"
@@ -89,6 +79,10 @@ NS_LOG_COMPONENT_DEFINE ("DynamicGlobalRoutingExample");
 int 
 main (int argc, char *argv[])
 {
+  // The below value configures the default behavior of global routing.
+  // By default, it is disabled.  To respond to interface events, set to true
+  Config::SetDefault ("ns3::Ipv4GlobalRouting::RespondToInterfaceEvents", BooleanValue (true));
+
   // Allow the user to override any of the defaults and the above
   // Bind ()s at run-time, via command-line arguments
   CommandLine cmd;
@@ -206,9 +200,7 @@ main (int argc, char *argv[])
   uint32_t ipv4ifIndex1 = 2;
 
   Simulator::Schedule (Seconds (2),&Ipv4::SetDown,ipv41, ipv4ifIndex1);
-  Simulator::Schedule (Seconds (3),&Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
   Simulator::Schedule (Seconds (4),&Ipv4::SetUp,ipv41, ipv4ifIndex1);
-  Simulator::Schedule (Seconds (5),&Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
 
   Ptr<Node> n6 = c.Get (6);
   Ptr<Ipv4> ipv46 = n6->GetObject<Ipv4> ();
@@ -216,14 +208,10 @@ main (int argc, char *argv[])
   // then the next p2p is numbered 2
   uint32_t ipv4ifIndex6 = 2;
   Simulator::Schedule (Seconds (6),&Ipv4::SetDown,ipv46, ipv4ifIndex6);
-  Simulator::Schedule (Seconds (7),&Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
   Simulator::Schedule (Seconds (8),&Ipv4::SetUp,ipv46, ipv4ifIndex6);
-  Simulator::Schedule (Seconds (9),&Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
 
   Simulator::Schedule (Seconds (12),&Ipv4::SetDown,ipv41, ipv4ifIndex1);
-  Simulator::Schedule (Seconds (13),&Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
   Simulator::Schedule (Seconds (14),&Ipv4::SetUp,ipv41, ipv4ifIndex1);
-  Simulator::Schedule (Seconds (15),&Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
 
   NS_LOG_INFO ("Run Simulation.");
   Simulator::Run ();