diff --git a/src/network-workloads/model-net-synthetic.c b/src/network-workloads/model-net-synthetic.c
index 89913d88e46066c870e1011ef125c38b9ec8849b..a747535ff7a2d0fdb19b5896c82e9bf6350d0d8e 100644
--- a/src/network-workloads/model-net-synthetic.c
+++ b/src/network-workloads/model-net-synthetic.c
@@ -163,7 +163,10 @@ static void handle_kickoff_rev_event(
     if(m->incremented_flag)
         return;
 
-	model_net_event_rc(net_id, lp, PAYLOAD_SZ);
+    if(b->c1)
+        tw_rand_reverse_unif(lp->rng);
+	
+    model_net_event_rc(net_id, lp, PAYLOAD_SZ);
 	ns->msg_sent_count--;
     tw_rand_reverse_unif(lp->rng);
 }	
@@ -194,16 +197,14 @@ static void handle_kickoff_event(
     m_remote->svr_event_type = REMOTE;
 
     assert(net_id == DRAGONFLY); /* only supported for dragonfly model right now. */
-
     ns->start_ts = tw_now(lp);
-    
-   codes_mapping_get_lp_info(lp->gid, group_name, &group_index, lp_type_name, &lp_type_index, anno, &rep_id, &offset);
-   
-   int local_id = codes_mapping_get_lp_relative_id(lp->gid, 0, 0);
+    codes_mapping_get_lp_info(lp->gid, group_name, &group_index, lp_type_name, &lp_type_index, anno, &rep_id, &offset);
+    int local_id = codes_mapping_get_lp_relative_id(lp->gid, 0, 0);
 
    /* in case of uniform random traffic, send to a random destination. */
    if(traffic == UNIFORM)
    {
+    b->c1 = 1;
    	local_dest = tw_rand_integer(lp->rng, 0, num_nodes - 1);
    }
    else if(traffic == NEAREST_GROUP)
@@ -367,7 +368,7 @@ int main(
 
     /* 5 days of simulation time */
     g_tw_ts_end = s_to_ns(5 * 24 * 60 * 60);
-    //model_net_enable_sampling(8000, 10000);
+    model_net_enable_sampling(8000, 16000);
 
     if(net_id != DRAGONFLY)
     {
diff --git a/src/networks/model-net/dragonfly.c b/src/networks/model-net/dragonfly.c
index 0bf5743c62cee96474a45ead84054292911a9887..1797839befd3d6fc72631d98a47e0e1f3090f754 100644
--- a/src/networks/model-net/dragonfly.c
+++ b/src/networks/model-net/dragonfly.c
@@ -80,6 +80,9 @@ FILE * dragonfly_log = NULL;
 int sample_bytes_written = 0;
 int sample_rtr_bytes_written = 0;
 
+char cn_sample_file[MAX_NAME_LENGTH];
+char router_sample_file[MAX_NAME_LENGTH];
+
 typedef struct terminal_message_list terminal_message_list;
 struct terminal_message_list {
     terminal_message msg;
@@ -521,6 +524,11 @@ static void dragonfly_read_config(const char * anno, dragonfly_param *params){
     configuration_get_value_double(&config, "PARAMS", "router_delay", anno,
             &p->router_delay);
 
+    configuration_get_value(&config, "PARAMS", "cn_sample_file", anno, cn_sample_file,
+            MAX_NAME_LENGTH);
+    configuration_get_value(&config, "PARAMS", "rt_sample_file", anno, router_sample_file,
+            MAX_NAME_LENGTH);
+    
     char routing_str[MAX_NAME_LENGTH];
     configuration_get_value(&config, "PARAMS", "routing", anno, routing_str,
             MAX_NAME_LENGTH);
@@ -1983,13 +1991,17 @@ void dragonfly_rsample_fin(router_state * s,
                 p->radix, p->radix);
         fclose(fp);
     }
-    char file_name[64];
-    sprintf(file_name, "dragonfly-router-sampling-%ld.bin", g_tw_mynode); 
+    char cn_fn[MAX_NAME_LENGTH];
+    if(strcmp(router_sample_file, "") == 0)
+        sprintf(cn_fn, "dragonfly-router-sampling-%ld.bin", g_tw_mynode); 
+    else
+        sprintf(cn_fn, "%s-%ld.bin", router_sample_file, g_tw_mynode);
+    
     int i = 0;
     int j = 0;
 
     int size_sample = sizeof(tw_lpid) + p->radix * (sizeof(int64_t) + sizeof(tw_stime)) + sizeof(tw_stime);
-    FILE * fp = fopen(file_name, "a");
+    FILE * fp = fopen(cn_fn, "wa");
     fseek(fp, sample_rtr_bytes_written, SEEK_SET);
 
     for(; i < s->op_arr_size; i++)
@@ -2132,16 +2144,18 @@ void dragonfly_sample_fin(terminal_state * s,
                 "data size per sample \t finished hops \t time to finish chunks \t busy time \t sample end time");
         fclose(fp);
     }
-    char file_name[64];
-    sprintf(file_name, "dragonfly-cn-sampling-%ld.bin", g_tw_mynode);
+    char rt_fn[MAX_NAME_LENGTH];
+    if(strncmp(router_sample_file, "", 10) == 0)
+        sprintf(rt_fn, "dragonfly-cn-sampling-%ld.bin", g_tw_mynode); 
+    else
+        sprintf(rt_fn, "%s-%ld.bin", cn_sample_file, g_tw_mynode);
 
-    FILE * fp = fopen(file_name, "a");
+    FILE * fp = fopen(rt_fn, "wa");
     fseek(fp, sample_bytes_written, SEEK_SET);
     fwrite(s->sample_stat, sizeof(struct dfly_cn_sample), s->op_arr_size, fp);
     fclose(fp);
 
     sample_bytes_written += (s->op_arr_size * sizeof(struct dfly_cn_sample));
-    //printf("\n Bytes written %ld ", sample_bytes_written);
 }
 
 void terminal_buf_update_rc(terminal_state * s,
diff --git a/tests/conf/modelnet-test-dragonfly.conf b/tests/conf/modelnet-test-dragonfly.conf
index 7c754a9283ed53095e6f9941a11906429a7a9556..ae49e1c14b7b02216e4ccc686ca7b27f7cff3c8c 100644
--- a/tests/conf/modelnet-test-dragonfly.conf
+++ b/tests/conf/modelnet-test-dragonfly.conf
@@ -25,4 +25,6 @@ PARAMS
    cn_bandwidth="5.25";
    message_size="368";
    routing="nonminimal";
+   cn_sample_file = "dragonfly-sample-ur";
+   rt_sample_file = "dragonfly-router-ur";
 }