add dynamic global routing example script
authorTom Henderson <tomh@tomh.org>
Thu, 11 Dec 2008 12:43:11 -0800
changeset 4012 7dc122811f0c
parent 4011 2fd3041c3c29
child 4013 c032743d087c
add dynamic global routing example script
AUTHORS
examples/dynamic-global-routing.cc
examples/global-routing-slash32.cc
examples/static-routing-slash32.cc
examples/wscript
src/routing/global-routing/global-router-interface.cc
--- a/AUTHORS	Wed Dec 10 21:11:05 2008 -0800
+++ b/AUTHORS	Thu Dec 11 12:43:11 2008 -0800
@@ -13,4 +13,5 @@
 David Gross (gdavid.devel@gmail.com)
 Mehdi Benamor (mehdi.benamor@telecom-bretagne.eu)
 Angelos Chatzipapas (chatzipa@ceid.upatras.gr)
+Luis Cortes (cortes@gatech.edu)
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/dynamic-global-routing.cc	Thu Dec 11 12:43:11 2008 -0800
@@ -0,0 +1,230 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Contributed by:  Luis Cortes (cortes@gatech.edu)
+ */
+
+
+// This script exercises global routing code in a mixed point-to-point
+// and csma/cd environment
+//
+// Network topology
+//
+//  n0
+//     \ p-p
+//      \          (shared csma/cd)
+//       n2 -------------------------n3
+//      /            |        | 
+//     / p-p        n4        n5 ---------- n6
+//   n1                             p-p
+//   |                                      |
+//   ----------------------------------------
+//                p-p
+//
+// - at time 1 CBR/UDP flow from n1 to n6's IP address on the n5/n6 link
+// - at time 10, start similar flow from n1 to n6's address on the n1/n6 link
+//
+//  Order of events
+//  At pre-simulation time, configure global routes.  Shortest path from
+//  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 RecomputeGlobalRoutes() 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 RecomputeGlobalRoutes() and traffic will start flowing 
+//    again on the original path
+//  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 RecomputeGlobalRoutes() and traffic will flow again
+//    through the path n1-n2-n5-n6
+//  At time 8s, bring the interface back up.
+//  At time 9s, call RecomputeGlobalRoutes() and traffic will flow again
+//    through the path n1-n6
+//  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 RecomputeGlobalRoutes() and traffic will
+//    start flowing again on the alternate path
+//  At time 14s, re-enable the n1/n6 interface to up.  Will not change routing
+//  At time 15s, call RecomputeGlobalRoutes() and traffic will start flowing 
+//    again on the original path
+//  At time 16s, stop the second flow.  
+
+// - Tracing of queues and packet receptions to file "dynamic-global-routing.tr"
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <cassert>
+
+#include "ns3/core-module.h"
+#include "ns3/simulator-module.h"
+#include "ns3/node-module.h"
+#include "ns3/helper-module.h"
+#include "ns3/global-route-manager.h"
+
+using namespace ns3;
+
+NS_LOG_COMPONENT_DEFINE ("DynamicGlobalRoutingExample");
+
+int 
+main (int argc, char *argv[])
+{
+  // Allow the user to override any of the defaults and the above
+  // Bind ()s at run-time, via command-line arguments
+  CommandLine cmd;
+  cmd.Parse (argc, argv);
+
+  NS_LOG_INFO ("Create nodes.");
+  NodeContainer c;
+  c.Create (7);
+  NodeContainer n0n2 = NodeContainer (c.Get (0), c.Get (2));
+  NodeContainer n1n2 = NodeContainer (c.Get (1), c.Get (2));
+  NodeContainer n5n6 = NodeContainer (c.Get (5), c.Get (6));
+  NodeContainer n1n6 = NodeContainer (c.Get (1), c.Get (6));
+  NodeContainer n2345 = NodeContainer (c.Get (2), c.Get (3), c.Get (4), c.Get (5));
+
+  InternetStackHelper internet;
+  internet.Install (c);
+
+  // We create the channels first without any IP addressing information
+  NS_LOG_INFO ("Create channels.");
+  PointToPointHelper p2p;
+  p2p.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
+  p2p.SetChannelAttribute ("Delay", StringValue ("2ms"));
+  NetDeviceContainer d0d2 = p2p.Install (n0n2);
+  NetDeviceContainer d1d6 = p2p.Install (n1n6);
+
+  NetDeviceContainer d1d2 = p2p.Install (n1n2);
+
+  p2p.SetDeviceAttribute ("DataRate", StringValue ("1500kbps"));
+  p2p.SetChannelAttribute ("Delay", StringValue ("10ms"));
+  NetDeviceContainer d5d6 = p2p.Install (n5n6);
+
+  // We create the channels first without any IP addressing information
+  CsmaHelper csma;
+  csma.SetChannelAttribute ("DataRate", StringValue ("5Mbps"));
+  csma.SetChannelAttribute ("Delay", StringValue ("2ms"));
+  NetDeviceContainer d2345 = csma.Install (n2345);
+  
+  // Later, we add IP addresses.  
+  NS_LOG_INFO ("Assign IP Addresses.");
+  Ipv4AddressHelper ipv4;
+  ipv4.SetBase ("10.1.1.0", "255.255.255.0");
+  ipv4.Assign (d0d2);
+
+  ipv4.SetBase ("10.1.2.0", "255.255.255.0");
+  ipv4.Assign (d1d2);
+
+  ipv4.SetBase ("10.1.3.0", "255.255.255.0");
+  Ipv4InterfaceContainer i5i6 = ipv4.Assign (d5d6);
+
+  ipv4.SetBase ("10.250.1.0", "255.255.255.0");
+  ipv4.Assign (d2345);
+
+  ipv4.SetBase ("172.16.1.0", "255.255.255.0");
+  Ipv4InterfaceContainer i1i6 = ipv4.Assign (d1d6);
+
+  // Create router nodes, initialize routing database and set up the routing
+  // tables in the nodes.
+  GlobalRouteManager::PopulateRoutingTables ();
+
+  // Create the OnOff application to send UDP datagrams of size
+  // 210 bytes at a rate of 448 Kb/s
+  NS_LOG_INFO ("Create Applications.");
+  uint16_t port = 9;   // Discard port (RFC 863)
+  OnOffHelper onoff ("ns3::UdpSocketFactory",
+                     InetSocketAddress (i5i6.GetAddress (1), port));
+  onoff.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (1)));
+  onoff.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
+  onoff.SetAttribute ("DataRate", StringValue ("2kbps"));
+  onoff.SetAttribute ("PacketSize", UintegerValue (50));
+
+  ApplicationContainer apps = onoff.Install (c.Get (1));
+  apps.Start (Seconds (1.0));
+  apps.Stop (Seconds (10.0));
+
+  // Create a second OnOff application to send UDP datagrams of size
+  // 210 bytes at a rate of 448 Kb/s
+  OnOffHelper onoff2 ("ns3::UdpSocketFactory",
+                     InetSocketAddress (i1i6.GetAddress (1), port));
+  onoff2.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (1)));
+  onoff2.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
+  onoff2.SetAttribute ("DataRate", StringValue ("2kbps"));
+  onoff2.SetAttribute ("PacketSize", UintegerValue (50));
+
+  ApplicationContainer apps2 = onoff2.Install (c.Get (1));
+  apps2.Start (Seconds (11.0));
+  apps2.Stop (Seconds (16.0));
+
+  // Create an optional packet sink to receive these packets
+  PacketSinkHelper sink ("ns3::UdpSocketFactory",
+    Address (InetSocketAddress (Ipv4Address::GetAny (), port)));
+  apps = sink.Install (c.Get (6));
+  apps.Start (Seconds (1.0));
+  apps.Stop (Seconds (10.0));
+
+  PacketSinkHelper sink2 ("ns3::UdpSocketFactory",
+    Address (InetSocketAddress (Ipv4Address::GetAny (), port)));
+  apps2 = sink2.Install (c.Get (6));
+  apps2.Start (Seconds (11.0));
+  apps2.Stop (Seconds (16.0));
+
+
+  std::ofstream ascii;
+  ascii.open ("dynamic-global-routing.tr");
+  PointToPointHelper::EnablePcapAll ("dynamic-global-routing");
+  PointToPointHelper::EnableAsciiAll (ascii);
+  CsmaHelper::EnablePcapAll ("dynamic-global-routing");
+  CsmaHelper::EnableAsciiAll (ascii);
+  InternetStackHelper::EnableAsciiAll (ascii);
+ 
+  Ptr<Node> n1 = c.Get (1);
+  Ptr<Ipv4> ipv41 = n1->GetObject<Ipv4> ();
+  // The first ifIndex is 0 for loopback, then the first p2p is numbered 1,
+  // then the next p2p is numbered 2
+  uint32_t ipv4ifIndex1 = 2;
+
+  Simulator::Schedule (Seconds (2),&Ipv4::SetDown,ipv41, ipv4ifIndex1);
+  Simulator::Schedule (Seconds (3),&GlobalRouteManager::RecomputeRoutingTables);
+  Simulator::Schedule (Seconds (4),&Ipv4::SetUp,ipv41, ipv4ifIndex1);
+  Simulator::Schedule (Seconds (5),&GlobalRouteManager::RecomputeRoutingTables);
+
+  Ptr<Node> n6 = c.Get (6);
+  Ptr<Ipv4> ipv46 = n6->GetObject<Ipv4> ();
+  // The first ifIndex is 0 for loopback, then the first p2p is numbered 1,
+  // then the next p2p is numbered 2
+  uint32_t ipv4ifIndex6 = 2;
+  Simulator::Schedule (Seconds (6),&Ipv4::SetDown,ipv46, ipv4ifIndex6);
+  Simulator::Schedule (Seconds (7),&GlobalRouteManager::RecomputeRoutingTables);
+  Simulator::Schedule (Seconds (8),&Ipv4::SetUp,ipv46, ipv4ifIndex6);
+  Simulator::Schedule (Seconds (9),&GlobalRouteManager::RecomputeRoutingTables);
+
+  Simulator::Schedule (Seconds (12),&Ipv4::SetDown,ipv41, ipv4ifIndex1);
+  Simulator::Schedule (Seconds (13),&GlobalRouteManager::RecomputeRoutingTables);
+  Simulator::Schedule (Seconds (14),&Ipv4::SetUp,ipv41, ipv4ifIndex1);
+  Simulator::Schedule (Seconds (15),&GlobalRouteManager::RecomputeRoutingTables);
+
+  NS_LOG_INFO ("Run Simulation.");
+  Simulator::Run ();
+  Simulator::Destroy ();
+  NS_LOG_INFO ("Done.");
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/global-routing-slash32.cc	Thu Dec 11 12:43:11 2008 -0800
@@ -0,0 +1,135 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+// Test program for this 3-router scenario, using global routing
+//
+// (a.a.a.a/32)A<--x.x.x.0/30-->B<--y.y.y.0/30-->C(c.c.c.c/32)
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <cassert>
+
+#include "ns3/csma-net-device.h"
+#include "ns3/core-module.h"
+#include "ns3/simulator-module.h"
+#include "ns3/node-module.h"
+#include "ns3/helper-module.h"
+#include "ns3/global-route-manager.h"
+
+using namespace ns3;
+
+NS_LOG_COMPONENT_DEFINE ("GlobalRouterSlash32Test");
+
+int 
+main (int argc, char *argv[])
+{
+  // Make the random number generators generate reproducible results.
+  //
+  RandomVariable::UseGlobalSeed (1, 1, 2, 3, 5, 8);
+
+  // Allow the user to override any of the defaults and the above
+  // DefaultValue::Bind ()s at run-time, via command-line arguments
+  CommandLine cmd;
+  cmd.Parse (argc, argv);
+
+  Ptr<Node> nA = CreateObject<Node> ();
+  Ptr<Node> nB = CreateObject<Node> ();
+  Ptr<Node> nC = CreateObject<Node> ();
+
+  NodeContainer c = NodeContainer (nA, nB, nC);
+
+  InternetStackHelper internet;
+  internet.Install (c);
+
+  // Point-to-point links
+  NodeContainer nAnB = NodeContainer (nA, nB);
+  NodeContainer nBnC = NodeContainer (nB, nC);
+
+  // We create the channels first without any IP addressing information
+  PointToPointHelper p2p;
+  p2p.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
+  p2p.SetChannelAttribute ("Delay", StringValue ("2ms"));
+  NetDeviceContainer dAdB = p2p.Install (nAnB);
+
+  NetDeviceContainer dBdC = p2p.Install (nBnC);;
+  
+  Ptr<CsmaNetDevice> deviceA = CreateObject<CsmaNetDevice> ();
+  deviceA->SetAddress (Mac48Address::Allocate ());
+  nA->AddDevice (deviceA);
+
+  Ptr<CsmaNetDevice> deviceC = CreateObject<CsmaNetDevice> ();
+  deviceC->SetAddress (Mac48Address::Allocate ());
+  nC->AddDevice (deviceC);
+
+  // Later, we add IP addresses.  
+  Ipv4AddressHelper ipv4;
+  ipv4.SetBase ("10.1.1.0", "255.255.255.252");
+  Ipv4InterfaceContainer iAiB = ipv4.Assign (dAdB);
+
+  ipv4.SetBase ("10.1.1.4", "255.255.255.252");
+  Ipv4InterfaceContainer iBiC = ipv4.Assign (dBdC);
+
+  Ptr<Ipv4> ipv4A = nA->GetObject<Ipv4> ();
+  Ptr<Ipv4> ipv4C = nC->GetObject<Ipv4> ();
+  
+  int32_t ifIndexA = ipv4A->AddInterface (deviceA);
+  int32_t ifIndexC = ipv4C->AddInterface (deviceC);
+    
+  ipv4A->SetAddress (ifIndexA, Ipv4Address ("172.16.1.1"));
+  ipv4A->SetNetworkMask (ifIndexA, Ipv4Mask ("255.255.255.255"));
+  ipv4A->SetMetric (ifIndexA, 1);
+  ipv4A->SetUp (ifIndexA);
+
+  ipv4C->SetAddress (ifIndexC, Ipv4Address ("192.168.1.1"));
+  ipv4C->SetNetworkMask (ifIndexC, Ipv4Mask ("255.255.255.255"));
+  ipv4C->SetMetric (ifIndexC, 1);
+  ipv4C->SetUp (ifIndexC);
+ 
+  // Create router nodes, initialize routing database and set up the routing
+  // tables in the nodes.
+  GlobalRouteManager::PopulateRoutingTables ();
+
+  // Create the OnOff application to send UDP datagrams of size
+  // 210 bytes at a rate of 448 Kb/s
+  uint16_t port = 9;   // Discard port (RFC 863)
+  OnOffHelper onoff ("ns3::UdpSocketFactory", 
+    Address (InetSocketAddress (Ipv4Address("192.168.1.1"), port)));
+  onoff.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (1)));
+  onoff.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
+  onoff.SetAttribute ("DataRate", DataRateValue (DataRate (6000)));
+  ApplicationContainer apps = onoff.Install (nA);
+  apps.Start (Seconds (1.0));
+  apps.Stop (Seconds (10.0));
+
+  // Create a packet sink to receive these packets
+  PacketSinkHelper sink ("ns3::UdpSocketFactory",
+    Address (InetSocketAddress (Ipv4Address::GetAny (), port)));
+  apps = sink.Install (nC);
+  apps.Start (Seconds (1.0));
+  apps.Stop (Seconds (10.0));
+
+  std::ofstream ascii;
+  ascii.open ("global-routing-slash32.tr");
+  PointToPointHelper::EnablePcapAll ("global-routing-slash32");
+  PointToPointHelper::EnableAsciiAll (ascii);
+
+  Simulator::Run ();
+  Simulator::Destroy ();
+
+  return 0;
+}
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/static-routing-slash32.cc	Thu Dec 11 12:43:11 2008 -0800
@@ -0,0 +1,137 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+// Test program for this 3-router scenario, using static routing
+//
+// (a.a.a.a/32)A<--x.x.x.0/30-->B<--y.y.y.0/30-->C(c.c.c.c/32)
+
+#include <iostream>
+#include <fstream>
+#include <string>
+#include <cassert>
+
+#include "ns3/csma-net-device.h"
+#include "ns3/core-module.h"
+#include "ns3/simulator-module.h"
+#include "ns3/node-module.h"
+#include "ns3/helper-module.h"
+
+using namespace ns3;
+
+NS_LOG_COMPONENT_DEFINE ("StaticRoutingSlash32Test");
+
+int 
+main (int argc, char *argv[])
+{
+  // Make the random number generators generate reproducible results.
+  //
+  RandomVariable::UseGlobalSeed (1, 1, 2, 3, 5, 8);
+
+  // Allow the user to override any of the defaults and the above
+  // DefaultValue::Bind ()s at run-time, via command-line arguments
+  CommandLine cmd;
+  cmd.Parse (argc, argv);
+
+  Ptr<Node> nA = CreateObject<Node> ();
+  Ptr<Node> nB = CreateObject<Node> ();
+  Ptr<Node> nC = CreateObject<Node> ();
+
+  NodeContainer c = NodeContainer (nA, nB, nC);
+
+  InternetStackHelper internet;
+  internet.Install (c);
+
+  // Point-to-point links
+  NodeContainer nAnB = NodeContainer (nA, nB);
+  NodeContainer nBnC = NodeContainer (nB, nC);
+
+  // We create the channels first without any IP addressing information
+  PointToPointHelper p2p;
+  p2p.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
+  p2p.SetChannelAttribute ("Delay", StringValue ("2ms"));
+  NetDeviceContainer dAdB = p2p.Install (nAnB);
+
+  NetDeviceContainer dBdC = p2p.Install (nBnC);;
+  
+  Ptr<CsmaNetDevice> deviceA = CreateObject<CsmaNetDevice> ();
+  deviceA->SetAddress (Mac48Address::Allocate ());
+  nA->AddDevice (deviceA);
+
+  Ptr<CsmaNetDevice> deviceC = CreateObject<CsmaNetDevice> ();
+  deviceC->SetAddress (Mac48Address::Allocate ());
+  nC->AddDevice (deviceC);
+
+  // Later, we add IP addresses.  
+  Ipv4AddressHelper ipv4;
+  ipv4.SetBase ("10.1.1.0", "255.255.255.252");
+  Ipv4InterfaceContainer iAiB = ipv4.Assign (dAdB);
+
+  ipv4.SetBase ("10.1.1.4", "255.255.255.252");
+  Ipv4InterfaceContainer iBiC = ipv4.Assign (dBdC);
+
+  Ptr<Ipv4> ipv4A = nA->GetObject<Ipv4> ();
+  Ptr<Ipv4> ipv4B = nB->GetObject<Ipv4> ();
+  Ptr<Ipv4> ipv4C = nC->GetObject<Ipv4> ();
+  
+  int32_t ifIndexA = ipv4A->AddInterface (deviceA);
+  int32_t ifIndexC = ipv4C->AddInterface (deviceC);
+    
+  ipv4A->SetAddress (ifIndexA, Ipv4Address ("172.16.1.1"));
+  ipv4A->SetNetworkMask (ifIndexA, Ipv4Mask ("255.255.255.255"));
+  ipv4A->SetMetric (ifIndexA, 1);
+  ipv4A->SetUp (ifIndexA);
+
+  ipv4C->SetAddress (ifIndexC, Ipv4Address ("192.168.1.1"));
+  ipv4C->SetNetworkMask (ifIndexC, Ipv4Mask ("255.255.255.255"));
+  ipv4C->SetMetric (ifIndexC, 1);
+  ipv4C->SetUp (ifIndexC);
+ 
+  // Create static routes from A to C
+  // The ifIndex for this outbound route is 1; the first p2p link added
+  ipv4A->AddHostRouteTo (Ipv4Address ("192.168.1.1"), Ipv4Address ("10.1.1.2"), 1);
+  // The ifIndex we want on node B is 2; 0 corresponds to loopback, and 1 to the first point to point link
+  ipv4B->AddHostRouteTo (Ipv4Address ("192.168.1.1"), Ipv4Address ("10.1.1.6"), 2);
+
+  // Create the OnOff application to send UDP datagrams of size
+  // 210 bytes at a rate of 448 Kb/s
+  uint16_t port = 9;   // Discard port (RFC 863)
+  OnOffHelper onoff ("ns3::UdpSocketFactory", 
+    Address (InetSocketAddress (Ipv4Address("192.168.1.1"), port)));
+  onoff.SetAttribute ("OnTime", RandomVariableValue (ConstantVariable (1)));
+  onoff.SetAttribute ("OffTime", RandomVariableValue (ConstantVariable (0)));
+  onoff.SetAttribute ("DataRate", DataRateValue (DataRate (6000)));
+  ApplicationContainer apps = onoff.Install (nA);
+  apps.Start (Seconds (1.0));
+  apps.Stop (Seconds (10.0));
+
+  // Create a packet sink to receive these packets
+  PacketSinkHelper sink ("ns3::UdpSocketFactory",
+    Address (InetSocketAddress (Ipv4Address::GetAny (), port)));
+  apps = sink.Install (nC);
+  apps.Start (Seconds (1.0));
+  apps.Stop (Seconds (10.0));
+
+  std::ofstream ascii;
+  ascii.open ("static-routing-slash32.tr");
+  PointToPointHelper::EnablePcapAll ("static-routing-slash32");
+  PointToPointHelper::EnableAsciiAll (ascii);
+
+  Simulator::Run ();
+  Simulator::Destroy ();
+
+  return 0;
+}
--- a/examples/wscript	Wed Dec 10 21:11:05 2008 -0800
+++ b/examples/wscript	Thu Dec 11 12:43:11 2008 -0800
@@ -8,6 +8,18 @@
                                  ['core', 'simulator', 'mobility', 'wifi', 'point-to-point', 'internet-stack'])
     obj.source = 'mixed-wireless.cc'
 
+    obj = bld.create_ns3_program('dynamic-global-routing',
+                                 ['point-to-point', 'csma', 'internet-stack', 'global-routing'])
+    obj.source = 'dynamic-global-routing.cc'
+
+    obj = bld.create_ns3_program('static-routing-slash32',
+                                 ['point-to-point', 'internet-stack', 'global-routing'])
+    obj.source = 'static-routing-slash32.cc'
+
+    obj = bld.create_ns3_program('global-routing-slash32',
+                                 ['point-to-point', 'internet-stack', 'global-routing'])
+    obj.source = 'global-routing-slash32.cc'
+
     obj = bld.create_ns3_program('simple-global-routing',
                                  ['point-to-point', 'internet-stack', 'global-routing'])
     obj.source = 'simple-global-routing.cc'
--- a/src/routing/global-routing/global-router-interface.cc	Wed Dec 10 21:11:05 2008 -0800
+++ b/src/routing/global-routing/global-router-interface.cc	Thu Dec 11 12:43:11 2008 -0800
@@ -1277,6 +1277,11 @@
   NS_LOG_FUNCTION (nd << allowRecursion);
 
   Ptr<Channel> ch = nd->GetChannel();
+  if (!ch)
+    {
+      // It may be that this net device is a stub device, without a channel
+      return false;
+    }
   uint32_t nDevices = ch->GetNDevices();
   NS_ASSERT (nDevices);