Attachment #867 for bug #702

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    &Ipv4GlobalRoutingHelper::RecomputeRoutingTables);
@end verbatim

There are two attributes that govern the behavior.  The first is 
Ipv4GlobalRouting::RandomEcmpRouting.  If set to true, packets are randomly
routed across equal-cost multipath routes.  If set to false (default), 
only one route is consistently used.  The second is 
Ipv4GlobalRouting::RespondToInterfaceEvents.  If set to true, dynamically 
recompute the global routes upon Interface notification events (up/down, 
or add/remove address).  If set to false (default), routing may break
unless the user manually calls RecomputeRoutingTables() after such events.
The default is set to false to preserve legacy ns-3 program behavior.

@subsection Global Routing Implementation

This section is for those readers who care about how this is implemented.






// This script exercises global routing code in a mixed point-to-point
// 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
//

//  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 be diverted to the n1-n2-n5-n6 path
//  At time 4s, re-enable the n1/n6 interface to up.  n1-n6 route restored.
//    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
//  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).  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 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
//  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 be diverted to the alternate path
//  At time 13s, call RecomputeRoutingTables() and traffic will
//    start flowing again on 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"

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 (false));

  // Allow the user to override any of the defaults and the above
  // Bind ()s at run-time, via command-line arguments
  CommandLine cmd;

  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> ();

  // 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 ();




 * The model assumes that all nodes on an ns-3 channel are reachable to
 * one another, regardless of whether the nodes can use the channel
 * successfully (in the case of wireless).  Therefore, this model
 * should typically be used only on wired topologies.  Layer-2 bridge
 * devices are supported.  API does not yet exist to control the subset 
 * of a topology to which this global static routing is applied.
 * 
 * If the topology changes during the simulation, by default, routing
 * will not adjust.  There are two ways to make it adjust.
 * - Set the attribute Ipv4GlobalRouting::RespondToInterfaceEvents to true 
 * - Manually call the sequence of GlobalRouteManager methods to delte global
 *   routes, build global routing database, and initialize routes.
 *   There is a helper method that encapsulates this 
 *   (Ipv4GlobalRoutingHelper::RecomputeRoutingTables())
 * 
 * \section api API and Usage
 * 
 * Users must include ns3/global-route-manager.h header file.  After the
 * IPv4 topology has been built and addresses assigned, users call
 * ns3::GlobalRouteManager::PopulateRoutingTables (), prior to the 
 * ns3::Simulator::Run() call.  
 *
 * There are two attributes of Ipv4GlobalRouting that govern behavior.
 * - Ipv4GlobalRouting::RandomEcmpRouting
 * - Ipv4GlobalRouting::RespondToInterfaceEvents  
 *
 * \section impl Implementation
 *

(-)a/src/routing/global-routing/ipv4-global-routing.cc (-5 / +49 lines)

Lines 17-22	Link Here

//

//

#include "ns3/log.h"

#include "ns3/log.h"

#include "ns3/simulator.h"

#include "ns3/object.h"

#include "ns3/object.h"

#include "ns3/packet.h"

#include "ns3/packet.h"

#include "ns3/net-device.h"

#include "ns3/net-device.h"

Lines 24-29	Link Here

#include "ns3/ipv4-routing-table-entry.h"

#include "ns3/ipv4-routing-table-entry.h"

#include "ns3/boolean.h"

#include "ns3/boolean.h"

#include "ipv4-global-routing.h"

#include "ipv4-global-routing.h"

#include "global-route-manager.h"

#include <vector>

#include <vector>

NS_LOG_COMPONENT_DEFINE ("Ipv4GlobalRouting");

NS_LOG_COMPONENT_DEFINE ("Ipv4GlobalRouting");

Lines 42-53	Link Here

                   BooleanValue(false),

                   BooleanValue(false),

                   MakeBooleanAccessor (&Ipv4GlobalRouting::m_randomEcmpRouting),

                   MakeBooleanAccessor (&Ipv4GlobalRouting::m_randomEcmpRouting),

                   MakeBooleanChecker ())

                   MakeBooleanChecker ())

    .AddAttribute ("RespondToInterfaceEvents",

                   "Set to true if you want to dynamically recompute the global routes upon Interface notification events (up/down, or add/remove address)",

                   BooleanValue(false),

                   MakeBooleanAccessor (&Ipv4GlobalRouting::m_respondToInterfaceEvents),

                   MakeBooleanChecker ())

  return tid;

  return tid;

Ipv4GlobalRouting::Ipv4GlobalRouting ()

Ipv4GlobalRouting::Ipv4GlobalRouting ()

: m_randomEcmpRouting (false)

: m_randomEcmpRouting (false),

  m_respondToInterfaceEvents (false)

  NS_LOG_FUNCTION_NOARGS ();

  NS_LOG_FUNCTION_NOARGS ();

Lines 486-501	Link Here

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void

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void

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Ipv4GlobalRouting::NotifyInterfaceUp (uint32_t i)

496

Ipv4GlobalRouting::NotifyInterfaceUp (uint32_t i)

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{}

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  NS_LOG_FUNCTION (this << i);

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  if (m_respondToInterfaceEvents && Simulator::Now ().GetSeconds () > 0)  // avoid startup events

500

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      GlobalRouteManager::DeleteGlobalRoutes ();

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      GlobalRouteManager::BuildGlobalRoutingDatabase ();

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      GlobalRouteManager::InitializeRoutes ();

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void

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void

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Ipv4GlobalRouting::NotifyInterfaceDown (uint32_t i)

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Ipv4GlobalRouting::NotifyInterfaceDown (uint32_t i)

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{}

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  NS_LOG_FUNCTION (this << i);

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  if (m_respondToInterfaceEvents && Simulator::Now ().GetSeconds () > 0)  // avoid startup events

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      GlobalRouteManager::DeleteGlobalRoutes ();

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      GlobalRouteManager::BuildGlobalRoutingDatabase ();

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      GlobalRouteManager::InitializeRoutes ();

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void

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void

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Ipv4GlobalRouting::NotifyAddAddress (uint32_t interface, Ipv4InterfaceAddress address)

520

Ipv4GlobalRouting::NotifyAddAddress (uint32_t interface, Ipv4InterfaceAddress address)

495

{}

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  NS_LOG_FUNCTION (this << interface << address);

523

  if (m_respondToInterfaceEvents && Simulator::Now ().GetSeconds () > 0)  // avoid startup events

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      GlobalRouteManager::DeleteGlobalRoutes ();

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      GlobalRouteManager::BuildGlobalRoutingDatabase ();

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      GlobalRouteManager::InitializeRoutes ();

528

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void

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void

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Ipv4GlobalRouting::NotifyRemoveAddress (uint32_t interface, Ipv4InterfaceAddress address)

532

Ipv4GlobalRouting::NotifyRemoveAddress (uint32_t interface, Ipv4InterfaceAddress address)

498

{}

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  NS_LOG_FUNCTION (this << interface << address);

535

  if (m_respondToInterfaceEvents && Simulator::Now ().GetSeconds () > 0)  // avoid startup events

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      GlobalRouteManager::DeleteGlobalRoutes ();

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      GlobalRouteManager::BuildGlobalRoutingDatabase ();

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      GlobalRouteManager::InitializeRoutes ();

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void

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void

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Ipv4GlobalRouting::SetIpv4 (Ptr<Ipv4> ipv4)

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Ipv4GlobalRouting::SetIpv4 (Ptr<Ipv4> ipv4)

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(-)a/src/routing/global-routing/ipv4-global-routing.h (+3 lines)

Lines 81-86	Link Here

  Ipv4GlobalRouting ();

  Ipv4GlobalRouting ();

  virtual ~Ipv4GlobalRouting ();

  virtual ~Ipv4GlobalRouting ();

  // These methods inherited from base class

  virtual Ptr<Ipv4Route> RouteOutput (Ptr<Packet> p, const Ipv4Header &header, Ptr<NetDevice> oif, Socket::SocketErrno &sockerr);

  virtual Ptr<Ipv4Route> RouteOutput (Ptr<Packet> p, const Ipv4Header &header, Ptr<NetDevice> oif, Socket::SocketErrno &sockerr);

  virtual bool RouteInput  (Ptr<const Packet> p, const Ipv4Header &header, Ptr<const NetDevice> idev,

  virtual bool RouteInput  (Ptr<const Packet> p, const Ipv4Header &header, Ptr<const NetDevice> idev,

Lines 215-220	Link Here

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private:

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private:

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  /// Set to true if packets are randomly routed among ECMP; set to false for using only one route consistently

217

  /// Set to true if packets are randomly routed among ECMP; set to false for using only one route consistently

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  bool m_randomEcmpRouting;

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  bool m_randomEcmpRouting;

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  /// Set to true if this interface should respond to interface events by globallly recomputing routes

220

  bool m_respondToInterfaceEvents;

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  /// A uniform random number generator for randomly routing packets among ECMP

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  /// A uniform random number generator for randomly routing packets among ECMP

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  UniformVariable m_rand;

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  UniformVariable m_rand;

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