diff --git a/src/engine_robust.cc b/src/engine_robust.cc
index 9f03bea5e..6b820f98a 100644
--- a/src/engine_robust.cc
+++ b/src/engine_robust.cc
@@ -13,6 +13,9 @@
 #include "./engine_robust.h"
 
 namespace engine {
+AllReduceRobust::AllReduceRobust(void) {
+  result_buffer_round = 1;
+}
 /*!
  * \brief perform in-place allreduce, on sendrecvbuf 
  *        this function is NOT thread-safe
@@ -23,18 +26,29 @@ namespace engine {
  */
 void AllReduceRobust::AllReduce(void *sendrecvbuf_,
                                 size_t type_nbytes,
-                                size_t count,           
+                                size_t count,
                                 ReduceFunction reducer) {
-  while (true) {
-    ReturnType ret = TryAllReduce(sendrecvbuf_, type_nbytes, count, reducer);
-    if (ret == kSuccess) return;
-    if (ret == kSockError) {
-      utils::Error("error occur during all reduce\n");
-    }
-    utils::LogPrintf("[%d] receive except signal, start reset link\n", rank);
-    TryResetLinks();
+  bool recovered = RecoverExec(sendrecvbuf_, type_nbytes * count, 0, seq_counter);
+  // now we are free to remove the last result, if any
+  if (resbuf.LastSeqNo() != -1 &&
+      (resbuf.LastSeqNo() % result_buffer_round != rank % result_buffer_round)) {
+    resbuf.DropLast();
   }
-  // TODO
+  void *temp = resbuf.AllocTemp(type_nbytes, count);
+  while (true) {
+    if (recovered) {
+      std::memcpy(temp, sendrecvbuf_, type_nbytes * count); break;
+    } else {
+      std::memcpy(temp, sendrecvbuf_, type_nbytes * count);
+      if (CheckAndRecover(TryAllReduce(temp, type_nbytes, count, reducer))) {
+        std::memcpy(sendrecvbuf_, temp, type_nbytes * count); break;
+      } else {
+        recovered = RecoverExec(sendrecvbuf_, type_nbytes * count, 0, seq_counter);
+      }
+    } 
+  }
+  resbuf.PushTemp(seq_counter, type_nbytes, count);
+  seq_counter += 1;
 }
 /*!
  * \brief broadcast data from root to all nodes
@@ -329,7 +343,6 @@ AllReduceRobust::TryDecideRouting(AllReduceRobust::RecoverType role,
   *p_recvlink = best_link;
   return kSuccess;
 }
-
 /*!
  * \brief try to finish the data recovery request,
  *        this function is used together with TryDecideRouting
@@ -417,7 +430,7 @@ AllReduceRobust::TryRecoverData(RecoverType role,
           if (req_in[i]) min_write = std::min(links[i].size_write, min_write);
         }
         utils::Assert(min_write <= links[pid].size_read, "boundary check");
-        if (!links[pid].ReadToRingBuffer(min_write)) return kSockError;        
+        if (!links[pid].ReadToRingBuffer(min_write)) return kSockError;    
       }
       for (int i = 0; i < nlink; ++i) {
         if (req_in[i] && selecter.CheckWrite(links[i].sock)) {
@@ -438,7 +451,7 @@ AllReduceRobust::TryRecoverData(RecoverType role,
 }
 /*!
  * \brief try to load check point
- *        
+ *
  *        This is a collaborative function called by all nodes
  *        only the nodes with requester set to true really needs to load the check point
  *        other nodes acts as collaborative roles to complete this request
@@ -448,8 +461,17 @@ AllReduceRobust::TryRecoverData(RecoverType role,
  * \sa ReturnType
  */
 AllReduceRobust::ReturnType AllReduceRobust::TryLoadCheckPoint(bool requester) {
-  
-  return kSuccess;
+  RecoverType role =  requester ? kRequestData : kHaveData;
+  size_t size = this->checked_model.length();
+  int recv_link;
+  std::vector<bool> req_in;
+  ReturnType succ = TryDecideRouting(role, &size, &recv_link, &req_in);
+  if (succ != kSuccess) return succ;
+  if (role == kRequestData) {
+    checked_model.resize(size);
+  }
+  utils::Check(size != 0, "zero size check point is not allowed");
+  return TryRecoverData(role, &checked_model[0], size, recv_link, req_in);
 }
 /*!
  * \brief try to get the result of operation specified by seqno
@@ -458,17 +480,27 @@ AllReduceRobust::ReturnType AllReduceRobust::TryLoadCheckPoint(bool requester) {
  *        only the nodes with requester set to true really needs to get the result
  *        other nodes acts as collaborative roles to complete this request
  *
- * \param buf the buffer to store the result, this parameter is only use when current node is requester
- * \param size the total size of the buffer, this parameter is only use when current node is requester
+ * \param buf the buffer to store the result, this parameter is only used when current node is requester
+ * \param size the total size of the buffer, this parameter is only used when current node is requester
  * \param seqno sequence number of the operation, this is unique index of a operation in current iteration
  * \param requester whether current node is the requester
  * \return this function can return kSuccess/kSockError/kGetExcept, see ReturnType for details
  * \sa ReturnType
  */
 AllReduceRobust::ReturnType
-AllReduceRobust::TryGetResult(void *sendrecvbuf, size_t size, int seqno, bool requester) {
-  utils::Error("TryGetResult: not implemented");
-  return kSuccess;
+AllReduceRobust::TryGetResult(void *sendrecvbuf, size_t size, int seqno, bool requester) {  RecoverType role;
+  if (!requester) {
+    sendrecvbuf = resbuf.Query(seqno, &size);
+    role = sendrecvbuf != NULL ? kHaveData : kPassData;
+  } else {
+    role = kRequestData;
+  }
+  int recv_link;
+  std::vector<bool> req_in;
+  ReturnType succ = TryDecideRouting(role, &size, &recv_link, &req_in);
+  if (succ != kSuccess) return succ;
+  utils::Check(size != 0, "zero size check point is not allowed");  
+  return TryRecoverData(role, sendrecvbuf, size, recv_link, req_in);
 }
 /*!
  * \brief try to run recover execution for a request action described by flag and seqno,
diff --git a/src/engine_robust.h b/src/engine_robust.h
index be9cf0998..92febdd70 100644
--- a/src/engine_robust.h
+++ b/src/engine_robust.h
@@ -16,7 +16,8 @@
 namespace engine {
 /*! \brief implementation of fault tolerant all reduce engine */
 class AllReduceRobust : public AllReduceBase {
- public:  
+ public:
+  AllReduceRobust(void);
   virtual ~AllReduceRobust(void) {}
   /*!
    * \brief perform in-place allreduce, on sendrecvbuf 
@@ -178,6 +179,19 @@ class AllReduceRobust : public AllReduceBase {
       if (idx == seqno_.size() || seqno_[idx] != seqid) return NULL;
       *p_size = size_[idx];
       return BeginPtr(data_) + rptr_[idx];
+    } 
+    // drop last stored result
+    inline void DropLast(void) {
+      utils::Assert(seqno_.size() != 0, "there is nothing to be dropped");
+      seqno_.pop_back();
+      rptr_.pop_back();
+      size_.pop_back();
+      data_.resize(rptr_.back());
+    }
+    // the sequence number of last stored result
+    inline int LastSeqNo(void) const {
+      if (seqno_.size() == 0) return -1;
+      return seqno_.back();
     }
    private:
     // sequence number of each 
@@ -248,8 +262,8 @@ class AllReduceRobust : public AllReduceBase {
    *        only the nodes with requester set to true really needs to get the result
    *        other nodes acts as collaborative roles to complete this request
    *
-   * \param buf the buffer to store the result, this parameter is only use when current node is requester
-   * \param size the total size of the buffer, this parameter is only use when current node is requester
+   * \param buf the buffer to store the result, this parameter is only used when current node is requester
+   * \param size the total size of the buffer, this parameter is only used when current node is requester
    * \param seqno sequence number of the operation, this is unique index of a operation in current iteration
    * \param requester whether current node is the requester
    * \return this function can return kSuccess/kSockError/kGetExcept, see ReturnType for details
@@ -325,8 +339,13 @@ class AllReduceRobust : public AllReduceBase {
   // call sequence counter, records how many calls we made so far
   // from last call to CheckPoint, LoadCheckPoint
   int seq_counter;
+  // the round of result buffer, used to mode the result
+  int result_buffer_round;
   // result buffer
   ResultBuffer resbuf;
+  // last check point model
+  std::string checked_model;
+  
 };
 }  // namespace engine
 // implementation of inline template function