diff --git a/multiplexer/dialogue.go b/multiplexer/dialogue.go
index 7a29dd6..3c5c4d6 100644
--- a/multiplexer/dialogue.go
+++ b/multiplexer/dialogue.go
@@ -489,10 +489,12 @@ func (dg *dialogue) handleInDimssAckPacket(pkt *packet.DismissAckPacket) iodefin
 }
 
 func (dg *dialogue) handleInDataPacket(pkt packet.Packet) iodefine.IORet {
-	ok := dg.fsm.InStates(SESSIONED)
+	// we regard statuses which include sessioned, dismiss_half, dismiss_sent as normal statuses
+	// and status dismiss_recv should be optimized from client side.
+	ok := dg.fsm.InStates(SESSIONED, DISMISS_HALF, DISMISS_SENT, DISMISS_RECV)
 	if !ok {
-		dg.log.Debugf("data at non SESSIONED, clientID: %d, dialogueID: %d, packetID: %d",
-			dg.cn.ClientID(), dg.dialogueID, pkt.ID())
+		dg.log.Debugf("data at non normal status, clientID: %d, dialogueID: %d, packetID: %d, status: %s",
+			dg.cn.ClientID(), dg.dialogueID, pkt.ID(), dg.fsm.State())
 		if dg.failedCh != nil {
 			dg.failedCh <- pkt
 		}
diff --git a/multiplexer/dialogue_mgr.go b/multiplexer/dialogue_mgr.go
index e322caa..8eb79e6 100644
--- a/multiplexer/dialogue_mgr.go
+++ b/multiplexer/dialogue_mgr.go
@@ -360,12 +360,16 @@ func (dm *dialogueMgr) handlePkt(pkt packet.Packet) {
 		dm.mtx.RLock()
 		dg, ok := dm.dialogues[dialogueID]
 		if !ok {
-			dm.log.Errorf("clientID: %d, unable to find dialogueID: %d, packetID: %d, packetType: %s",
-				dm.cn.ClientID(), dialogueID, pkt.ID(), pkt.Type().String())
-			dm.mtx.RUnlock()
-			return
+			// maybe the dialogue is in negotiating
+			dg, ok = dm.negotiatingDialogues[dialogueID]
+			if !ok {
+				dm.log.Errorf("clientID: %d, unable to find dialogueID: %d, packetID: %d, packetType: %s",
+					dm.cn.ClientID(), dialogueID, pkt.ID(), pkt.Type().String())
+				dm.mtx.RUnlock()
+				return
+			}
 		}
-		dm.log.Tracef("write to dialogue, clientID: %d, dialogueID: %d, packetID: %d, packetType %s",
+		dm.log.Tracef("read to dialogue, clientID: %d, dialogueID: %d, packetID: %d, packetType %s",
 			dm.cn.ClientID(), dialogueID, pkt.ID(), pkt.Type().String())
 		dg.readInCh <- pkt
 		dm.mtx.RUnlock()
diff --git a/pkg/iodefine/iodefine.go b/pkg/iodefine/iodefine.go
index e8359a8..59fb36e 100644
--- a/pkg/iodefine/iodefine.go
+++ b/pkg/iodefine/iodefine.go
@@ -30,7 +30,8 @@ const (
 )
 
 var (
-	ErrIOTimeout = errors.New("io time out")
+	ErrIOTimeout    = errors.New("io time out")
+	ErrIOBufferFull = errors.New("io buffer full")
 )
 
 func ErrUseOfClosedNetwork(err error) bool {