diff --git a/core/utils.go b/core/utils.go
new file mode 100644
index 0000000..01ff500
--- /dev/null
+++ b/core/utils.go
@@ -0,0 +1,102 @@
+/*
+ * 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 core
+
+import (
+	"fmt"
+	"github.com/opencord/voltha-lib-go/v2/pkg/log"
+	"github.com/opencord/voltha-protos/v2/go/openolt"
+)
+
+var AttCtag map[uint32]uint32
+
+func init() {
+	_, _ = log.AddPackage(log.JSON, log.DebugLevel, nil)
+	AttCtag = make(map[uint32]uint32)
+}
+
+const (
+	vendorName = "ABCD"
+	// Number of bits for the physical UNI of the ONUs
+	bitsForUniID = 4
+	// Number of bits for the ONU ID
+	bitsForONUID = 8
+	//MaxOnusPerPon is Max number of ONUs on any PON port
+	MaxOnusPerPon = 1 << bitsForONUID
+)
+
+var vendorSpecificId = 1000
+
+func GenerateNextONUSerialNumber() *openolt.SerialNumber {
+
+	vi := []byte(vendorName)
+
+	vendorSpecificId += 1
+	vs := []byte(fmt.Sprint(vendorSpecificId))
+	// log.Infow("vendor-id-and-vendor-specific", log.Fields{"vi":vi, "vs":vs})
+	sn := &openolt.SerialNumber{VendorId: vi, VendorSpecific: vs}
+	// log.Infow("serial-num", log.Fields{"sn":sn})
+
+	return sn
+}
+
+//MkUniPortNum returns new UNIportNum based on intfID, inuID and uniID
+func MkUniPortNum(intfID, onuID, uniID uint32) uint32 {
+	var limit = int(onuID)
+	if limit > MaxOnusPerPon {
+		log.Warn("Warning: exceeded the MAX ONUS per PON")
+	}
+	return (intfID << (bitsForUniID + bitsForONUID)) | (onuID << bitsForUniID) | uniID
+}
+
+func GetAttCtag(ponIntf uint32) uint32 {
+	var currCtag uint32
+	var ok bool
+	if currCtag, ok = AttCtag[ponIntf]; !ok {
+		// Start with ctag 2
+		AttCtag[ponIntf] = 2
+		return AttCtag[ponIntf]
+	}
+	AttCtag[ponIntf] = currCtag + 1
+	return AttCtag[ponIntf]
+}
+
+func GetAttStag(ponIntf uint32) uint32 {
+	// start with stag 2
+	return ponIntf + 2
+}
+
+// TODO: More workflow support to be added here
+func GetCtag(workFlowName string, ponIntf uint32) uint32 {
+	switch workFlowName {
+	case "ATT":
+		return GetAttCtag(ponIntf)
+	default:
+		log.Errorw("unknown-workflowname", log.Fields{"workflow": workFlowName})
+	}
+	return 0
+}
+
+func GetStag(workFlowName string, ponIntf uint32) uint32 {
+	switch workFlowName {
+	case "ATT":
+		return GetAttStag(ponIntf)
+	default:
+		log.Errorw("unknown-workflowname", log.Fields{"workflow": workFlowName})
+	}
+	return 0
+}