Index: src/internet/model/tcp-socket-base.cc
===================================================================
--- src/internet/model/tcp-socket-base.cc	(revision 1027)
+++ src/internet/model/tcp-socket-base.cc	(working copy)
@@ -1928,19 +1928,16 @@
           m_errno = ERROR_SHUTDOWN;
           return false;
         }
-      // Stop sending if we need to wait for a larger Tx window (prevent silly window syndrome)
-      if (w < m_segmentSize && m_txBuffer.SizeFromSequence (m_nextTxSequence) > w)
-        {
-          break; // No more
-        }
+
+      if (w == 0) break;  // window empty
+
       // Nagle's algorithm (RFC896): Hold off sending if there is unacked data
-      // in the buffer and the amount of data to send is less than one segment
-      if (!m_noDelay && UnAckDataCount () > 0
-          && m_txBuffer.SizeFromSequence (m_nextTxSequence) < m_segmentSize)
-        {
-          NS_LOG_LOGIC ("Invoking Nagle's algorithm. Wait to send.");
-          break;
-        }
+      // in the buffer and the amount of data to send or the window size is 
+      // less than one segment 
+      if (m_txBuffer.SizeFromSequence (m_nextTxSequence) < m_segmentSize || w < m_segmentSize )
+        if (UnAckDataCount () > 0)
+           break;
+
       uint32_t s = std::min (w, m_segmentSize);  // Send no more than window
       uint32_t sz = SendDataPacket (m_nextTxSequence, s, withAck);
       nPacketsSent++;                             // Count sent this loop
@@ -1984,7 +1981,10 @@
 uint16_t
 TcpSocketBase::AdvertisedWindowSize ()
 {
-  return std::min (m_rxBuffer.MaxBufferSize () - m_rxBuffer.Size (), (uint32_t)m_maxWinSize);
+  uint16_t w = std::min (m_rxBuffer.MaxBufferSize () - m_rxBuffer.Size (), (uint32_t)m_maxWinSize);
+  // Clark's algorithm (RFC813): close window when the buffer space is smaller 
+  // than an MSS and smaller than its half capacity
+  return (w < m_segmentSize && w < m_rxBuffer.MaxBufferSize ()/2 ) ? 0 : w;
 }
 
 // Receipt of new packet, put into Rx buffer