diff --git a/api/proto/common.go b/api/proto/common.go
index cda045114..94c921e87 100644
--- a/api/proto/common.go
+++ b/api/proto/common.go
@@ -34,11 +34,14 @@ const (
 	// TODO: add more types
 )
 
-// MessageCategoryBytes is the number of bytes message category takes
-const MessageCategoryBytes = 1
-
-// MessageTypeBytes is the number of bytes message type takes
-const MessageTypeBytes = 1
+const (
+	// ProtocolVersion is a constant defined as the version of the Harmony protocol
+	ProtocolVersion = 1
+	// MessageCategoryBytes is the number of bytes message category takes
+	MessageCategoryBytes = 1
+	// MessageTypeBytes is the number of bytes message type takes
+	MessageTypeBytes = 1
+)
 
 // GetMessageCategory gets the message category from the p2p message content
 func GetMessageCategory(message []byte) (MessageCategory, error) {
diff --git a/api/proto/node/pingpong.go b/api/proto/discovery/pingpong.go
similarity index 76%
rename from api/proto/node/pingpong.go
rename to api/proto/discovery/pingpong.go
index 9f340270f..9c645bf8d 100644
--- a/api/proto/node/pingpong.go
+++ b/api/proto/discovery/pingpong.go
@@ -1,5 +1,5 @@
 /*
-Package proto/node implements the communication protocol among nodes.
+Package proto/discovery implements the discovery ping/pong protocol among nodes.
 
 pingpong.go adds support of ping/pong messages.
 
@@ -8,7 +8,7 @@ pong: peer responds to ping messages, sending all pubkeys known by peer
 
 */
 
-package node
+package discovery
 
 import (
 	"bytes"
@@ -18,55 +18,20 @@ import (
 
 	"github.com/harmony-one/bls/ffi/go/bls"
 	"github.com/harmony-one/harmony/api/proto"
+	"github.com/harmony-one/harmony/api/proto/node"
 	"github.com/harmony-one/harmony/p2p"
-	peer "github.com/libp2p/go-libp2p-peer"
 )
 
-// RoleType defines the role of the node
-type RoleType int
-
-// Type of roles of a node
-const (
-	ValidatorRole RoleType = iota
-	ClientRole
-)
-
-func (r RoleType) String() string {
-	switch r {
-	case ValidatorRole:
-		return "Validator"
-	case ClientRole:
-		return "Client"
-	}
-	return "Unknown"
-}
-
-// Info refers to Peer struct in p2p/peer.go
-// this is basically a simplified version of Peer
-// for network transportation
-type Info struct {
-	IP          string
-	Port        string
-	PubKey      []byte
-	ValidatorID int
-	Role        RoleType
-	PeerID      peer.ID // Peerstore ID
-}
-
-func (info Info) String() string {
-	return fmt.Sprintf("Info:%v/%v=>%v/%v", info.IP, info.Port, info.ValidatorID, info.PeerID)
-}
-
 // PingMessageType defines the data structure of the Ping message
 type PingMessageType struct {
 	Version uint16 // version of the protocol
-	Node    Info
+	Node    node.Info
 }
 
 // PongMessageType defines the data structure of the Pong message
 type PongMessageType struct {
 	Version uint16 // version of the protocol
-	Peers   []Info
+	Peers   []node.Info
 	PubKeys [][]byte // list of publickKeys, has to be identical among all validators/leaders
 }
 
@@ -83,13 +48,13 @@ func (p PongMessageType) String() string {
 func NewPingMessage(peer p2p.Peer) *PingMessageType {
 	ping := new(PingMessageType)
 
-	ping.Version = ProtocolVersion
+	ping.Version = proto.ProtocolVersion
 	ping.Node.IP = peer.IP
 	ping.Node.Port = peer.Port
 	ping.Node.PeerID = peer.PeerID
 	ping.Node.ValidatorID = peer.ValidatorID
 	ping.Node.PubKey = peer.PubKey.Serialize()
-	ping.Node.Role = ValidatorRole
+	ping.Node.Role = node.ValidatorRole
 
 	return ping
 }
@@ -99,12 +64,12 @@ func NewPongMessage(peers []p2p.Peer, pubKeys []*bls.PublicKey) *PongMessageType
 	pong := new(PongMessageType)
 	pong.PubKeys = make([][]byte, 0)
 
-	pong.Version = ProtocolVersion
-	pong.Peers = make([]Info, 0)
+	pong.Version = proto.ProtocolVersion
+	pong.Peers = make([]node.Info, 0)
 
 	var err error
 	for _, p := range peers {
-		n := Info{}
+		n := node.Info{}
 		n.IP = p.IP
 		n.Port = p.Port
 		n.ValidatorID = p.ValidatorID
@@ -144,7 +109,7 @@ func GetPingMessage(payload []byte) (*PingMessageType, error) {
 // GetPongMessage deserializes the Pong Message from a list of byte
 func GetPongMessage(payload []byte) (*PongMessageType, error) {
 	pong := new(PongMessageType)
-	pong.Peers = make([]Info, 0)
+	pong.Peers = make([]node.Info, 0)
 	pong.PubKeys = make([][]byte, 0)
 
 	r := bytes.NewBuffer(payload)
@@ -161,7 +126,7 @@ func GetPongMessage(payload []byte) (*PongMessageType, error) {
 // ConstructPingMessage contructs ping message from node to leader
 func (p PingMessageType) ConstructPingMessage() []byte {
 	byteBuffer := bytes.NewBuffer([]byte{byte(proto.Node)})
-	byteBuffer.WriteByte(byte(PING))
+	byteBuffer.WriteByte(byte(node.PING))
 
 	encoder := gob.NewEncoder(byteBuffer)
 	err := encoder.Encode(p)
@@ -175,7 +140,7 @@ func (p PingMessageType) ConstructPingMessage() []byte {
 // ConstructPongMessage contructs pong message from leader to node
 func (p PongMessageType) ConstructPongMessage() []byte {
 	byteBuffer := bytes.NewBuffer([]byte{byte(proto.Node)})
-	byteBuffer.WriteByte(byte(PONG))
+	byteBuffer.WriteByte(byte(node.PONG))
 
 	encoder := gob.NewEncoder(byteBuffer)
 	err := encoder.Encode(p)
diff --git a/api/proto/node/pingpong_test.go b/api/proto/discovery/pingpong_test.go
similarity index 96%
rename from api/proto/node/pingpong_test.go
rename to api/proto/discovery/pingpong_test.go
index cf3b629a6..61dea2d73 100644
--- a/api/proto/node/pingpong_test.go
+++ b/api/proto/discovery/pingpong_test.go
@@ -1,4 +1,4 @@
-package node
+package discovery
 
 import (
 	"fmt"
@@ -8,6 +8,7 @@ import (
 
 	"github.com/harmony-one/bls/ffi/go/bls"
 	"github.com/harmony-one/harmony/api/proto"
+	"github.com/harmony-one/harmony/api/proto/node"
 	"github.com/harmony-one/harmony/crypto/pki"
 	"github.com/harmony-one/harmony/p2p"
 )
@@ -55,7 +56,7 @@ func TestString(test *testing.T) {
 		test.Errorf("expect: %v, got: %v", e1, r1)
 	}
 
-	ping1.Node.Role = ClientRole
+	ping1.Node.Role = node.ClientRole
 
 	r3 := fmt.Sprintf("%v", *ping1)
 	if strings.Compare(r3, e3) != 0 {
diff --git a/api/proto/node/node.go b/api/proto/node/node.go
index 2c7b34120..ee46f888c 100644
--- a/api/proto/node/node.go
+++ b/api/proto/node/node.go
@@ -3,6 +3,7 @@ package node
 import (
 	"bytes"
 	"encoding/gob"
+	"fmt"
 	"log"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -10,16 +11,12 @@ import (
 	"github.com/harmony-one/harmony/core/types"
 
 	"github.com/harmony-one/harmony/api/proto"
+	peer "github.com/libp2p/go-libp2p-peer"
 )
 
 // MessageType is to indicate the specific type of message under Node category
 type MessageType byte
 
-// ProtocolVersion is a constant defined as the version of the Harmony protocol
-const (
-	ProtocolVersion = 1
-)
-
 // Constant of the top level Message Type exchanged among nodes
 const (
 	Transaction MessageType = iota
@@ -57,6 +54,41 @@ const (
 	Unlock
 )
 
+// RoleType defines the role of the node
+type RoleType int
+
+// Type of roles of a node
+const (
+	ValidatorRole RoleType = iota
+	ClientRole
+)
+
+func (r RoleType) String() string {
+	switch r {
+	case ValidatorRole:
+		return "Validator"
+	case ClientRole:
+		return "Client"
+	}
+	return "Unknown"
+}
+
+// Info refers to Peer struct in p2p/peer.go
+// this is basically a simplified version of Peer
+// for network transportation
+type Info struct {
+	IP          string
+	Port        string
+	PubKey      []byte
+	ValidatorID int
+	Role        RoleType
+	PeerID      peer.ID // Peerstore ID
+}
+
+func (info Info) String() string {
+	return fmt.Sprintf("Info:%v/%v=>%v/%v", info.IP, info.Port, info.ValidatorID, info.PeerID)
+}
+
 // BlockMessageType represents the type of messages used for Node/Block
 type BlockMessageType int
 
diff --git a/consensus/consensus.go b/consensus/consensus.go
index 0fc207191..0d36401c0 100644
--- a/consensus/consensus.go
+++ b/consensus/consensus.go
@@ -26,7 +26,7 @@ import (
 	"github.com/harmony-one/harmony/p2p/host"
 	"golang.org/x/crypto/sha3"
 
-	proto_node "github.com/harmony-one/harmony/api/proto/node"
+	proto_discovery "github.com/harmony-one/harmony/api/proto/discovery"
 )
 
 // Consensus is the main struct with all states and data related to consensus process.
@@ -412,7 +412,7 @@ func (consensus *Consensus) RemovePeers(peers []p2p.Peer) int {
 		// Or the shard won't be able to reach consensus if public keys are mismatch
 
 		validators := consensus.GetValidatorPeers()
-		pong := proto_node.NewPongMessage(validators, consensus.PublicKeys)
+		pong := proto_discovery.NewPongMessage(validators, consensus.PublicKeys)
 		buffer := pong.ConstructPongMessage()
 
 		host.BroadcastMessageFromLeader(consensus.host, validators, buffer, consensus.OfflinePeers)
diff --git a/node/node.go b/node/node.go
index a01ba8c5a..6abb31507 100644
--- a/node/node.go
+++ b/node/node.go
@@ -22,6 +22,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/harmony-one/harmony/api/client"
 	clientService "github.com/harmony-one/harmony/api/client/service"
+	proto_discovery "github.com/harmony-one/harmony/api/proto/discovery"
 	proto_node "github.com/harmony-one/harmony/api/proto/node"
 	"github.com/harmony-one/harmony/api/services/explorer"
 	"github.com/harmony-one/harmony/api/services/syncing"
@@ -432,7 +433,7 @@ func (node *Node) JoinShard(leader p2p.Peer) {
 	for {
 		select {
 		case <-tick.C:
-			ping := proto_node.NewPingMessage(node.SelfPeer)
+			ping := proto_discovery.NewPingMessage(node.SelfPeer)
 			if node.Client != nil { // assume this is the client node
 				ping.Node.Role = proto_node.ClientRole
 			}
diff --git a/node/node_handler.go b/node/node_handler.go
index 085b379fa..b1e52d762 100644
--- a/node/node_handler.go
+++ b/node/node_handler.go
@@ -10,6 +10,7 @@ import (
 	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/harmony-one/bls/ffi/go/bls"
 	"github.com/harmony-one/harmony/api/proto"
+	proto_discovery "github.com/harmony-one/harmony/api/proto/discovery"
 	proto_identity "github.com/harmony-one/harmony/api/proto/identity"
 	proto_node "github.com/harmony-one/harmony/api/proto/node"
 	"github.com/harmony-one/harmony/core/types"
@@ -288,7 +289,7 @@ func (node *Node) AddNewBlock(newBlock *types.Block) {
 }
 
 func (node *Node) pingMessageHandler(msgPayload []byte) int {
-	ping, err := proto_node.GetPingMessage(msgPayload)
+	ping, err := proto_discovery.GetPingMessage(msgPayload)
 	if err != nil {
 		utils.GetLogInstance().Error("Can't get Ping Message")
 		return -1
@@ -318,7 +319,7 @@ func (node *Node) pingMessageHandler(msgPayload []byte) int {
 	node.AddPeers([]*p2p.Peer{peer})
 
 	peers := node.Consensus.GetValidatorPeers()
-	pong := proto_node.NewPongMessage(peers, node.Consensus.PublicKeys)
+	pong := proto_discovery.NewPongMessage(peers, node.Consensus.PublicKeys)
 	buffer := pong.ConstructPongMessage()
 
 	// Send a Pong message directly to the sender
@@ -339,7 +340,7 @@ func (node *Node) pingMessageHandler(msgPayload []byte) int {
 }
 
 func (node *Node) pongMessageHandler(msgPayload []byte) int {
-	pong, err := proto_node.GetPongMessage(msgPayload)
+	pong, err := proto_discovery.GetPongMessage(msgPayload)
 	if err != nil {
 		utils.GetLogInstance().Error("Can't get Pong Message")
 		return -1
diff --git a/node/node_test.go b/node/node_test.go
index 538a0833f..26a08cb3d 100644
--- a/node/node_test.go
+++ b/node/node_test.go
@@ -6,7 +6,7 @@ import (
 	"testing"
 	"time"
 
-	proto_node "github.com/harmony-one/harmony/api/proto/node"
+	proto_discovery "github.com/harmony-one/harmony/api/proto/discovery"
 	"github.com/harmony-one/harmony/consensus"
 	"github.com/harmony-one/harmony/crypto/pki"
 	"github.com/harmony-one/harmony/internal/utils"
@@ -114,7 +114,7 @@ func sendPingMessage(node *Node, leader p2p.Peer) {
 		PubKey: pubKey1,
 	}
 
-	ping1 := proto_node.NewPingMessage(p1)
+	ping1 := proto_discovery.NewPingMessage(p1)
 	buf1 := ping1.ConstructPingMessage()
 
 	fmt.Println("waiting for 5 seconds ...")
@@ -138,7 +138,7 @@ func sendPongMessage(node *Node, leader p2p.Peer) {
 		PubKey: pubKey2,
 	}
 
-	pong1 := proto_node.NewPongMessage([]p2p.Peer{p1, p2}, nil)
+	pong1 := proto_discovery.NewPongMessage([]p2p.Peer{p1, p2}, nil)
 	buf1 := pong1.ConstructPongMessage()
 
 	fmt.Println("waiting for 10 seconds ...")