diff --git a/device/device_olt.go b/device/device_olt.go
new file mode 100644
index 0000000..a01dda1
--- /dev/null
+++ b/device/device_olt.go
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package device
+
+type oltState int
+
+type Olt struct {
+	ID                 uint32
+	NumPonIntf         uint32
+	NumNniIntf         uint32
+	Mac                string
+	SerialNumber       string
+	Manufacture        string
+	Name               string
+	InternalState      oltState
+	OperState          string
+	Intfs              []intf
+	HeartbeatSignature uint32
+}
+
+type intf struct {
+	Type      string
+	IntfID    uint32
+	OperState string
+}
+
+const (
+	PRE_ENABLE oltState = iota
+	OLT_UP
+	PONIF_UP
+	ONU_DISCOVERED
+)
+
+func CreateOlt(oltid uint32, npon uint32, nnni uint32) *Olt {
+	olt := Olt{}
+	olt.ID = oltid
+	olt.NumPonIntf = npon
+	olt.NumNniIntf = nnni
+	olt.Name = "BBSIM OLT"
+	olt.InternalState = PRE_ENABLE
+	olt.OperState = "up"
+	olt.Intfs = make([]intf, olt.NumPonIntf+olt.NumNniIntf)
+	olt.HeartbeatSignature = oltid
+	for i := uint32(0); i < olt.NumNniIntf; i++ {
+		olt.Intfs[i].IntfID = i
+		olt.Intfs[i].OperState = "up"
+		olt.Intfs[i].Type = "nni"
+	}
+	for i := uint32(olt.NumNniIntf); i < olt.NumPonIntf+olt.NumNniIntf; i++ {
+		olt.Intfs[i].IntfID = i
+		olt.Intfs[i].OperState = "up"
+		olt.Intfs[i].Type = "pon"
+	}
+	return &olt
+}
diff --git a/device/device_onu.go b/device/device_onu.go
new file mode 100644
index 0000000..6d3df40
--- /dev/null
+++ b/device/device_onu.go
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package device
+
+import (
+	"fmt"
+	"log"
+	"gerrit.opencord.org/voltha-bbsim/protos"
+	"reflect"
+)
+
+type onuState int
+
+const (
+	ONU_PRE_ACTIVATED onuState = iota
+	ONU_ACTIVATED
+)
+
+type Onu struct {
+	InternalState onuState
+	IntfID        uint32
+	OperState     string
+	SerialNumber  *openolt.SerialNumber
+	OnuID         uint32
+}
+
+func createSN(oltid uint32, intfid uint32, onuid uint32) string {
+	sn := fmt.Sprintf("%X%X%02X", oltid, intfid, onuid)
+	return sn
+}
+
+func CreateOnus(oltid uint32, intfid uint32, nonus uint32, nnni uint32) []*Onu {
+	onus := []*Onu{}
+	for i := 0; i < int(nonus); i++ {
+		onu := Onu{}
+		onu.InternalState = ONU_PRE_ACTIVATED
+		onu.IntfID = intfid
+		onu.OperState = "up"
+		onu.SerialNumber = new(openolt.SerialNumber)
+		onu.SerialNumber.VendorId = []byte("NONE")
+		onu.SerialNumber.VendorSpecific = []byte(createSN(oltid, intfid, uint32(i))) //FIX
+		onus = append(onus, &onu)
+	}
+	return onus
+}
+
+func ValidateONU(targetonu openolt.Onu, regonus map[uint32][]*Onu) bool {
+	for _, onus := range regonus {
+		for _, onu := range onus {
+			if ValidateSN(*targetonu.SerialNumber, *onu.SerialNumber) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func ValidateSN(sn1 openolt.SerialNumber, sn2 openolt.SerialNumber) bool {
+	return reflect.DeepEqual(sn1.VendorId, sn2.VendorId) && reflect.DeepEqual(sn1.VendorSpecific, sn2.VendorSpecific)
+}
+
+func UpdateOnusOpStatus(ponif uint32, onus []*Onu, opstatus string) {
+	for i, onu := range onus {
+		onu.OperState = "up"
+		log.Printf("(PONIF:%d) ONU [%d] discovered.\n", ponif, i)
+	}
+}