diff -r -U4 rp-l2tp-0.4/dgram.c rp-l2tp-0.4+pppcfgprio/dgram.c
--- rp-l2tp-0.4/dgram.c	2003-01-11 05:29:03.000000000 +0000
+++ rp-l2tp-0.4+pppcfgprio/dgram.c	2009-11-08 15:34:31.000000000 +0000
@@ -1015,8 +1015,9 @@
 {
     int r;
     unsigned char *real_buf = (unsigned char *) buf - 8;
     l2tp_tunnel *tunnel = ses->tunnel;
+    unsigned int protocol;
 
     /* Drop frame if tunnel and/or session in wrong state */
     if (!tunnel ||
 	tunnel->state != TUNNEL_ESTABLISHED ||
@@ -1030,9 +1031,17 @@
 	tunnel->ack_handler = NULL;
 	tunnel_send_ZLB(tunnel);
     }
 
-    real_buf[0] = 0;
+    /* Get protocol */
+    if (buf[0] & 0x01) {
+        /* Compressed protcol field */
+        protocol = buf[0];
+    } else {
+        protocol = ((unsigned int) buf[0]) * 256 + buf[1];
+    }
+
+    real_buf[0] = (protocol < 0x8000) ? 0 : PRIORITY_BIT;
     real_buf[1] = 2;
     real_buf[2] = (tunnel->assigned_id >> 8);
     real_buf[3] = tunnel->assigned_id & 0xFF;
     real_buf[4] = ses->assigned_id >> 8;
diff -r -U4 rp-l2tp-0.4/tunnel.c rp-l2tp-0.4+pppcfgprio/tunnel.c
--- rp-l2tp-0.4/tunnel.c	2004-07-01 15:58:56.000000000 +0100
+++ rp-l2tp-0.4+pppcfgprio/tunnel.c	2009-11-08 15:35:26.000000000 +0000
@@ -196,26 +196,49 @@
 static void
 tunnel_enqueue_dgram(l2tp_tunnel *tunnel,
 		     l2tp_dgram  *dgram)
 {
-    dgram->next = NULL;
-    if (tunnel->xmit_queue_tail) {
-	tunnel->xmit_queue_tail->next = dgram;
-	tunnel->xmit_queue_tail = dgram;
+    if ((dgram->bits & (TYPE_BIT|PRIORITY_BIT)) == 0) {
+	dgram->next = NULL;
+	if (tunnel->xmit_queue_tail) {
+	    tunnel->xmit_queue_tail->next = dgram;
+	    tunnel->xmit_queue_tail = dgram;
+	} else {
+	    tunnel->xmit_queue_head = dgram;
+	    tunnel->xmit_queue_tail = dgram;
+	}
     } else {
-	tunnel->xmit_queue_head = dgram;
-	tunnel->xmit_queue_tail = dgram;
+	dgram->next = NULL;
+	if (tunnel->xmit_queue_head) {
+	    l2tp_dgram *prev, *tmp;
+
+	    prev = NULL;
+	    tmp = tunnel->xmit_queue_head;
+	    while (tmp != NULL && (tmp->bits & (TYPE_BIT|PRIORITY_BIT)) != 0) {
+		prev = tmp;
+		tmp = tmp->next;
+	    }
+	    dgram->next = tmp;
+	    if (prev == NULL)
+		tunnel->xmit_queue_head = dgram;
+	    else
+		prev->next = dgram;
+	} else {
+	    tunnel->xmit_queue_head = dgram;
+	    tunnel->xmit_queue_tail = dgram;
+	}
     }
     if (!tunnel->xmit_new_dgrams) {
 	tunnel->xmit_new_dgrams = dgram;
     }
 
     dgram->Ns = tunnel->Ns;
     tunnel->Ns++;
-    DBG(l2tp_db(DBG_FLOW, "tunnel_enqueue_dgram(%s, %s) %s\n",
+    DBG(l2tp_db(DBG_FLOW, "tunnel_enqueue_dgram(%s, %s) %s %d\n",
 	   l2tp_debug_tunnel_to_str(tunnel),
 	   l2tp_debug_message_type_to_str(dgram->msg_type),
-	   tunnel_flow_control_stats(tunnel)));
+	   tunnel_flow_control_stats(tunnel),
+	   (dgram->bits & (TYPE_BIT|PRIORITY_BIT)) == 0 ? 0 : 1));
 
 }
 
 /**********************************************************************