Bug 1812 - example/stats wifi program manual is erroneous

src/flow-monitor/model/ipv4-flow-probe.cc

@@ -359,7 +359,10 @@ Ipv4FlowProbe::DropLogger (const Ipv4Header &ipHeader, Ptr<const Packet> ipPaylo
           myReason = DROP_FRAGMENT_TIMEOUT;
           NS_LOG_DEBUG ("DROP_FRAGMENT_TIMEOUT");
           break;
-
+        case Ipv4L3Protocol::DROP_MTU_TOO_LITTLE:
+          myReason = DROP_MTU_TOO_LITTLE;
+          NS_LOG_DEBUG ("DROP_MTU_TOO_LITTLE");
+          break;
         default:
           myReason = DROP_INVALID_REASON;
           NS_FATAL_ERROR ("Unexpected drop reason code " << reason);

src/flow-monitor/model/ipv4-flow-probe.h

@@ -69,6 +69,7 @@ public:
     DROP_INTERFACE_DOWN,   /**< Interface is down so can not send packet */
     DROP_ROUTE_ERROR,   /**< Route error */
     DROP_FRAGMENT_TIMEOUT, /**< Fragment timeout exceeded */
+    DROP_MTU_TOO_LITTLE, /**< MTU (or PMTU) lower than minimum */
 
     DROP_INVALID_REASON, /**< Fallback reason (no known reason) */
   };

src/internet/model/ipv4-l3-protocol.cc

@@ -748,6 +748,15 @@ Ipv4L3Protocol::SendRealOut (Ptr<Ipv4Route> route,
   Ptr<Ipv4Interface> outInterface = GetInterface (interface);
   NS_LOG_LOGIC ("Send via NetDevice ifIndex " << outDev->GetIfIndex () << " ipv4InterfaceIndex " << interface);
 
+  // RFC 791, pg.25:
+  //  Every internet module must be able to forward a datagram of 68
+  //   octets without further fragmentation.  This is because an internet
+  //   header may be up to 60 octets, and the minimum fragment is 8 octets.
+  if (outInterface->GetDevice ()->GetMtu () < 68)
+    {
+      m_dropTrace (ipHeader, packet, DROP_MTU_TOO_LITTLE, m_node->GetObject<Ipv4> (), interface);
+    }
+
   if (!route->GetGateway ().IsEqual (Ipv4Address ("0.0.0.0")))
     {
       if (outInterface->IsUp ())

src/internet/model/ipv4-l3-protocol.h

@@ -98,8 +98,9 @@ public:
     DROP_BAD_CHECKSUM,   /**< Bad checksum */
     DROP_INTERFACE_DOWN,   /**< Interface is down so can not send packet */
     DROP_ROUTE_ERROR,   /**< Route error */
-    DROP_FRAGMENT_TIMEOUT /**< Fragment timeout exceeded */
-  };
+    DROP_FRAGMENT_TIMEOUT, /**< Fragment timeout exceeded */
+    DROP_MTU_TOO_LITTLE, /**< MTU (or PMTU) lower than minimum */
+ };
 
   /**
    * \brief Set node associated with this stack.

src/internet/model/ipv6-l3-protocol.cc

@@ -888,6 +888,11 @@ void Ipv6L3Protocol::SendRealOut (Ptr<Ipv6Route> route, Ptr<Packet> packet, Ipv6
       targetMtu = dev->GetMtu ();
     }
 
+  if (targetMtu<1280)
+    {
+      m_dropTrace (ipHeader, packet, DROP_MTU_TOO_LITTLE, m_node->GetObject<Ipv6> (), interface);
+    }
+
   if (packet->GetSize () > targetMtu + 40) /* 40 => size of IPv6 header */
     {
       // Router => drop

src/internet/model/ipv6-l3-protocol.h

@@ -81,6 +81,7 @@ public:
     DROP_INTERFACE_DOWN, /**< Interface is down so can not send packet */
     DROP_ROUTE_ERROR, /**< Route error */
     DROP_UNKNOWN_PROTOCOL, /**< Unknown L4 protocol */
+    DROP_MTU_TOO_LITTLE, /**< MTU (or PMTU) lower than minimum */
   };
 
   /**

src/stats/doc/statistics.rst

@@ -242,7 +242,7 @@ To see what the example program, applications, and stat framework are doing in d
   
 .. sourcecode:: bash
 
-  $ export NS_LOG=StatFramework:WiFiDistanceExperiment:WiFiDistanceApps
+  $ export NS_LOG=WiFiDistanceExperiment:WiFiDistanceApps
 
 Note that this slows down the simulation extraordinarily.