diff --git a/src/engine_base.cc b/src/engine_base.cc
index 4e9a65229..3b08d1502 100644
--- a/src/engine_base.cc
+++ b/src/engine_base.cc
@@ -111,7 +111,11 @@ void AllReduceBase::Shutdown(void) {
   links.clear();
   utils::TCPSocket::Finalize();
 }
-// set the parameters for AllReduce
+/*!
+ * \brief set parameters to the engine 
+ * \param name parameter name
+ * \param val parameter value
+ */
 void AllReduceBase::SetParam(const char *name, const char *val) {
   if (!strcmp(name, "master_uri")) master_uri = val;
   if (!strcmp(name, "master_port")) master_port = atoi(val);
diff --git a/src/engine_base.h b/src/engine_base.h
index 0cc281cff..9e533fe27 100644
--- a/src/engine_base.h
+++ b/src/engine_base.h
@@ -39,7 +39,11 @@ class AllReduceBase : public IEngine {
   void Shutdown(void);
   // initialize the manager
   void Init(void);
-  /*! \brief set parameters to the sync manager */
+  /*!
+   * \brief set parameters to the engine 
+   * \param name parameter name
+   * \param val parameter value
+   */
   virtual void SetParam(const char *name, const char *val);
   /*! \brief get rank */
   virtual int GetRank(void) const {
diff --git a/src/engine_robust.cc b/src/engine_robust.cc
index 099e83934..9db11bc96 100644
--- a/src/engine_robust.cc
+++ b/src/engine_robust.cc
@@ -19,6 +19,13 @@ AllReduceRobust::AllReduceRobust(void) {
   result_buffer_round = 2;
   seq_counter = 0;
 }
+void AllReduceRobust::SetParam(const char *name, const char *val) {
+  AllReduceBase::SetParam(name, val);
+  if (!strcmp(name, "result_buffer_round")) result_buffer_round = atoi(val);
+  if (!strcmp(name, "result_replicate")) {
+    result_buffer_round = std::max(world_size / atoi(val), 1);
+  }
+}
 /*!
  * \brief perform in-place allreduce, on sendrecvbuf 
  *        this function is NOT thread-safe
@@ -32,7 +39,7 @@ void AllReduceRobust::AllReduce(void *sendrecvbuf_,
                                 size_t count,
                                 ReduceFunction reducer) {
   bool recovered = RecoverExec(sendrecvbuf_, type_nbytes * count, 0, seq_counter);
-  utils::LogPrintf("[%d] AllReduce recovered=%d\n", rank, recovered);
+  //utils::LogPrintf("[%d] AllReduce recovered=%d\n", rank, recovered);
   // now we are free to remove the last result, if any
   if (resbuf.LastSeqNo() != -1 &&
       (resbuf.LastSeqNo() % result_buffer_round != rank % result_buffer_round)) {
@@ -302,12 +309,15 @@ ShortestDist(const std::pair<bool, size_t> &node_value,
   int res = std::numeric_limits<int>::max();
   for (size_t i = 0; i < dist_in.size(); ++i) {
     if (i == out_index) continue;
-    if (dist_in[i].first < res) {
-      res = dist_in[i].first; size = dist_in[i].second;
+    if (dist_in[i].first == std::numeric_limits<int>::max()) continue;
+    if (dist_in[i].first + 1 < res) {
+      res = dist_in[i].first + 1;
+      size = dist_in[i].second;
     } 
   }
   // add one hop
-  return std::make_pair(res + 1, size);
+
+  return std::make_pair(res, size);
 }
 /*!
  * \brief message passing function, used to decide the
@@ -365,7 +375,8 @@ AllReduceRobust::TryDecideRouting(AllReduceRobust::RecoverType role,
       for (size_t i = 0; i < dist_in.size(); ++i) {
         if (dist_in[i].first != std::numeric_limits<int>::max()) {
           utils::Check(best_link == -2 || *p_size == dist_in[i].second,
-                       "AllReduce size inconsistent, size=%lu, reporting=%lu", *p_size, dist_in[i].second);
+                       "[%d] AllReduce size inconsistent, distin=%lu, size=%lu, reporting=%lu\n",
+                       rank, dist_in[i].first, *p_size, dist_in[i].second);
           if (best_link == -2 || dist_in[i].first < dist_in[best_link].first) {
             best_link = static_cast<int>(i);
             *p_size = dist_in[i].second;
@@ -416,7 +427,6 @@ AllReduceRobust::TryRecoverData(RecoverType role,
                                 size_t size,
                                 int recv_link,
                                 const std::vector<bool> &req_in) {
-  utils::LogPrintf("[%d] recv_link=%d\n", rank, recv_link);
   // no need to run recovery for zero size message
   if (links.size() == 0 || size == 0) return kSuccess;
   utils::Assert(req_in.size() == links.size(), "TryRecoverData");
@@ -432,6 +442,7 @@ AllReduceRobust::TryRecoverData(RecoverType role,
     // do not need to provide data or receive data, directly exit
     if (!req_data) return kSuccess;
   }
+  utils::LogPrintf("[%d] !!Need to pass data\n", rank);
   utils::Assert(recv_link >= 0 || role == kHaveData, "recv_link must be active");
   for (int i = 0; i < nlink; ++i) {
     links[i].ResetSize();
@@ -548,6 +559,7 @@ AllReduceRobust::TryGetResult(void *sendrecvbuf, size_t size, int seqno, bool re
   } else {
     role = kRequestData;
   }
+  utils::LogPrintf("[%d] role=%d\n", rank, role);
   int recv_link;
   std::vector<bool> req_in;
   ReturnType succ = TryDecideRouting(role, &size, &recv_link, &req_in);
diff --git a/src/engine_robust.h b/src/engine_robust.h
index 783b2deb7..7116764d8 100644
--- a/src/engine_robust.h
+++ b/src/engine_robust.h
@@ -20,6 +20,12 @@ class AllReduceRobust : public AllReduceBase {
  public:
   AllReduceRobust(void);
   virtual ~AllReduceRobust(void) {}
+  /*!
+   * \brief set parameters to the engine 
+   * \param name parameter name
+   * \param val parameter value
+   */
+  virtual void SetParam(const char *name, const char *val);
   /*!
    * \brief perform in-place allreduce, on sendrecvbuf 
    *        this function is NOT thread-safe
@@ -71,11 +77,11 @@ class AllReduceRobust : public AllReduceBase {
   /*! \brief type of roles each node can play during recovery */
   enum RecoverType {
     /*! \brief current node have data */
-    kHaveData,
+    kHaveData = 0,
     /*! \brief current node request data */
-    kRequestData,
+    kRequestData = 1,
     /*! \brief current node only helps to pass data around */
-    kPassData
+    kPassData = 2
   };
   /*!
    * \brief summary of actions proposed in all nodes
diff --git a/test/test.sh b/test/test.sh
index 9b27abb8b..78d267157 100755
--- a/test/test.sh
+++ b/test/test.sh
@@ -1,8 +1,8 @@
 #!/bin/bash
-if [ "$#" -ne 4 ];
+if [ "$#" -lt 4 ];
 then
     echo "Usage <nslave> <ndata> <config> <round_files_dir>"
     exit -1
 fi
 
-../submit_job_tcp.py $1 test_recover $2 $3 $4 $5
+../submit_job_tcp.py $1 test_recover "${@:2}"