From 0eae63b29a9b54e6f00c17b9682a37733796bfe7 Mon Sep 17 00:00:00 2001
From: nvt-se <nvt-se>
Date: Fri, 19 Mar 2010 16:55:29 +0000
Subject: [PATCH] Set a higher start ETX. Avoiding adding a neighbor after a
 failed packet transmission.

---
 core/net/neighbor-info.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/core/net/neighbor-info.c b/core/net/neighbor-info.c
index 298fa9420..1bf37acae 100644
--- a/core/net/neighbor-info.c
+++ b/core/net/neighbor-info.c
@@ -28,7 +28,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: neighbor-info.c,v 1.3 2010/03/17 15:08:46 nvt-se Exp $
+ * $Id: neighbor-info.c,v 1.4 2010/03/19 16:55:29 nvt-se Exp $
  */
 /**
  * \file
@@ -56,7 +56,7 @@
 
 #define ETX_SCALE		100
 #define ETX_ALPHA		60
-#define ETX_FIRST_GUESS		1
+#define ETX_FIRST_GUESS		(ETX_LIMIT - 1)
 #define ETX_COLLISION_PENALTY	5
 #define ETX_NO_ACK_PENALTY	(ETX_LIMIT + 1)
 /*---------------------------------------------------------------------------*/
@@ -77,6 +77,7 @@ update_etx(const rimeaddr_t *dest, int packet_etx)
     recorded_etx = *etxp;
   }
 
+  /* Update the EWMA of the ETX for the neighbor. */
   new_etx = (ETX_SCALE / 2 + ETX_ALPHA * recorded_etx +
 		 (ETX_SCALE - ETX_ALPHA) * packet_etx) / ETX_SCALE;
   PRINTF("neighbor-info: ETX changed from %d to %d (packet ETX = %d)\n", 
@@ -85,7 +86,7 @@ update_etx(const rimeaddr_t *dest, int packet_etx)
   if(new_etx > ETX_LIMIT) {
     neighbor_attr_remove_neighbor(dest);
     subscriber_callback(dest, 0, new_etx);
-  } else {
+  } else if(neighbor_attr_has_neighbor(dest)) {
     neighbor_attr_set_data(&etx, dest, &new_etx);
     if(new_etx != recorded_etx && subscriber_callback != NULL) {
       subscriber_callback(dest, 1, new_etx);