diff --git a/clientside/os/frisbee.redux/client.c b/clientside/os/frisbee.redux/client.c
index 1bf1e5046fa90e4afd7ebec70d44006f5aa273dc..03d666b20520af83c5c9360e982e7b52d2ebd99d 100644
--- a/clientside/os/frisbee.redux/client.c
+++ b/clientside/os/frisbee.redux/client.c
@@ -22,6 +22,7 @@
  */
 
 #undef OLD_SCHOOL
+#undef PASSIVE
 
 /*
  * Frisbee client.
@@ -114,12 +115,17 @@ extern int	ImageUnzipQuit(void);
 /*
  * Chunk descriptor, one per MAXCHUNKSIZE*MAXBLOCKSIZE bytes of an image file.
  * For each chunk, record its state and the time at which it was last
- * requested by someone.  The time stamp is "only" 61 bits.  This could be a
- * problem if packets arrive more than 73,000 years apart.  But we'll take
+ * requested by someone.  The time stamp is "only" 60 bits.  This could be a
+ * problem if packets arrive more than 36,500 years apart.  But we'll take
  * our chances...
  */
 typedef struct {
+#ifdef PASSIVE
+	uint64_t lastreq:60;
+	uint64_t enroute:1;	/* we have seen a request but no data yet */
+#else
 	uint64_t lastreq:61;
+#endif
 	uint64_t ours:1;	/* last request was from us */
 	uint64_t seen:1;	/* chunk is either filling or been processed */
 	uint64_t done:1;	/* chunk has been fully processed */
@@ -152,6 +158,9 @@ Chunk_t		*Chunks;		/* Chunk descriptors */
 ChunkBuffer_t   *ChunkBuffer;		/* The cache */
 int		*ChunkRequestList;	/* Randomized chunk request order */
 int		TotalChunkCount;	/* Total number of chunks in file */
+#ifdef PASSIVE
+int		ChunksEnroute;		/* Total useful chunks enroute */
+#endif
 #ifdef CONDVARS_WORK
 static pthread_mutex_t	chunkbuf_mutex;
 static pthread_cond_t	chunkbuf_cond;
@@ -861,6 +870,21 @@ ClientRecvThread(void *arg)
 					pstamp.tv_sec, pstamp.tv_usec, 0, 0);
 #ifdef NEVENTS
 				needstamp = 1;
+#endif
+#ifdef PASSIVE
+				/*
+				 * If we timed-out with a en route counter
+				 * that has been keeping us from making our
+				 * own requests, then we are out of synch.
+				 * Just clear the enroute counters.
+				 */
+				if (ChunksEnroute >= maxreadahead) {
+					int i;
+					for (i = 0; i < TotalChunkCount; i++)
+						Chunks[i].enroute = 0;
+					ChunksEnroute = 0;
+					CLEVENT(1, EV_CLIENCLEAR, ChunksEnroute, 0, 0, 0);
+				}
 #endif
 				RequestChunk(1);
 				IdleCounter = idletimer;
@@ -926,6 +950,13 @@ ClientRecvThread(void *arg)
 			 */
 			(void) RequestStamp(p->msg.block.chunk,
 					    p->msg.block.block, 1, (void *)1);
+#ifdef PASSIVE
+			if (Chunks[p->msg.block.chunk].enroute) {
+				Chunks[p->msg.block.chunk].enroute = 0;
+				ChunksEnroute--;
+				CLEVENT(1, EV_CLIENROUTE, 0, ChunksEnroute, 0, 0);
+			}
+#endif
 			break;
 
 		case PKTSUBTYPE_REQUEST:
@@ -936,7 +967,7 @@ ClientRecvThread(void *arg)
 
 			if (RequestStamp(p->msg.request.chunk,
 					 p->msg.request.block,
-					 p->msg.request.count, 0))
+					 p->msg.request.count, 0)) {
 #ifndef OLD_SCHOOL
 				/*
 				 * XXX experimental: Also reset timer if
@@ -948,6 +979,22 @@ ClientRecvThread(void *arg)
 #else
 				;
 #endif
+#ifdef PASSIVE
+				/*
+				 * XXX experimental: If there is something
+				 * in the request we need, mark the chunk
+				 * as en route. If there are enough en route
+				 * packets when it comes time for us to make
+				 * a non-timeout driven request, then we
+				 * hold off making the request.
+				 */
+				if (!Chunks[p->msg.request.chunk].enroute) {
+					Chunks[p->msg.request.chunk].enroute = 1;
+					ChunksEnroute++;
+					CLEVENT(1, EV_CLIENROUTE, 1, ChunksEnroute, 0, 0);
+				}
+#endif
+			}
 			break;
 
 		case PKTSUBTYPE_PREQUEST:
@@ -1584,6 +1631,20 @@ GotBlock(Packet_t *p)
 		 */
 		Chunks[chunk].done = 1;
 
+#ifdef PASSIVE
+		/*
+		 * If we know of enough chunks en route to keep us busy,
+		 * don't make a request here. Otherwise, if we were late
+		 * to the party, we might make a bunch of requests that
+		 * everyone else has already seen. For the greater good,
+		 * lets just ride the wave until we don't see any more
+		 * good stuff coming in.
+		 */
+		if (ChunksEnroute >= maxreadahead) {
+			CLEVENT(1, EV_CLIPASSIVE, ChunksEnroute, 0, 0, 0);
+			return 1;
+		}
+#endif
 		/*
 		 * Send off a request for a chunk we do not have yet. This
 		 * should be enough to ensure that there is more work to do
@@ -1764,7 +1825,13 @@ RequestChunk(int timedout)
 	/*
 	 * Scan our request list looking for candidates.
 	 */
-	k = (maxreadahead > emptybufs) ? emptybufs : maxreadahead;
+	k = maxreadahead;
+#ifdef PASSIVE
+	assert(maxreadahead > ChunksEnroute);
+	k -= ChunksEnroute;
+#endif
+	if (k > emptybufs)
+		k = emptybufs;
 	for (i = 0, j = 0; i < TotalChunkCount && j < k; i++) {
 		int chunk = ChunkRequestList[i];
 		
diff --git a/clientside/os/frisbee.redux/log.c b/clientside/os/frisbee.redux/log.c
index b055c24320e5b16534a7cb011042aaa2188fc6f3..112b2eb115f3253c0cc24a8ce129684a591fb8ba 100644
--- a/clientside/os/frisbee.redux/log.c
+++ b/clientside/os/frisbee.redux/log.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000-2013 University of Utah and the Flux Group.
+ * Copyright (c) 2000-2015 University of Utah and the Flux Group.
  * 
  * {{{EMULAB-LICENSE
  * 
@@ -188,7 +188,7 @@ FrisPwarning(const char *fmt, ...)
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 
-	FrisWarning("%s : %s", buf, strerror(errno));
+	FrisWarning("%s: %s", buf, strerror(errno));
 }
 
 void
@@ -201,5 +201,5 @@ FrisPfatal(const char *fmt, ...)
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 
-	FrisFatal("%s : %s", buf, strerror(errno));
+	FrisFatal("%s: %s", buf, strerror(errno));
 }
diff --git a/clientside/os/frisbee.redux/trace.c b/clientside/os/frisbee.redux/trace.c
index a5c12c12f82932710484dc67541192f922893e84..e98fe0a76134afd051a8072050757c44de6c9827 100644
--- a/clientside/os/frisbee.redux/trace.c
+++ b/clientside/os/frisbee.redux/trace.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2014 University of Utah and the Flux Group.
+ * Copyright (c) 2002-2015 University of Utah and the Flux Group.
  * 
  * {{{EMULAB-LICENSE
  * 
@@ -52,6 +52,7 @@ TraceInit(char *file)
 		fd = fopen(file, "a+");
 		if (fd == NULL)
 			FrisPfatal("Cannot open logfile %s", file);
+		FrisLog("Writing trace events to %s", file);
 	} else
 		fd = stderr;
 
@@ -502,6 +503,21 @@ TraceDump(int serverrel, int level)
 					inet_ntoa(ptr->srcip),
 					stamp.tv_sec, stamp.tv_usec/1000);
 				break;
+			case EV_CLIENROUTE:
+				fprintf(fd, "%s: chunk %s, %d total enroute\n",
+					inet_ntoa(ptr->srcip),
+					ptr->args[0] ? "enroute" : "arrived",
+					ptr->args[1]);
+				break;
+
+			case EV_CLIPASSIVE:
+				fprintf(fd, "%s: no request, %d chunks enroute\n",
+					inet_ntoa(ptr->srcip), ptr->args[0]);
+				break;
+			case EV_CLIENCLEAR:
+				fprintf(fd, "%s: idle with %d chunks enroute, cleared\n",
+					inet_ntoa(ptr->srcip), ptr->args[0]);
+				break;
 			}
 		}
 		if (++ptr == evend)
diff --git a/clientside/os/frisbee.redux/trace.h b/clientside/os/frisbee.redux/trace.h
index daf800bc9d2521a3c476e3bccaaffd3f624aa59c..44ec0d23975e26ad0e995150cc781e7a7fd5f3d2 100644
--- a/clientside/os/frisbee.redux/trace.h
+++ b/clientside/os/frisbee.redux/trace.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002-2012 University of Utah and the Flux Group.
+ * Copyright (c) 2002-2015 University of Utah and the Flux Group.
  * 
  * {{{EMULAB-LICENSE
  * 
@@ -116,8 +116,11 @@ if (evlogging >= (l)) { \
 #define EV_CLIDUBPROMO	45
 #define EV_CLIDCSTAT	46
 #define EV_CLIREDO	47
+#define EV_CLIENROUTE	48
+#define EV_CLIPASSIVE	49
+#define EV_CLIENCLEAR	50
 
-#define EV_MAX		47
+#define EV_MAX		50
 
 extern void ClientTraceInit(char *file);
 extern void ClientTraceReinit(char *file);