diff --git a/common/logger/logger.go b/common/logger/logger.go
index e3d1e90..cb7229f 100644
--- a/common/logger/logger.go
+++ b/common/logger/logger.go
@@ -26,13 +26,14 @@
 	myLogger *log.Entry
 )
 
+// Setup logger
 func Setup(kafkaBroker string, level string) {
 
 	logger := log.New()
 	//logger.SetReportCaller(true)
 	myLogger = logger.WithField("topics", []string{"bbsim.log"})
 
-	var logLevel log.Level = log.DebugLevel
+	var logLevel = log.DebugLevel
 	switch level{
 		case "TRACE":
 			logLevel = log.TraceLevel
@@ -75,38 +76,47 @@
 	myLogger.WithField("kafkaBroker", kafkaBroker).Debug("Logger setup done")
 }
 
+// GetLogger return logger instance
 func GetLogger() *log.Entry {
 	return myLogger
 }
 
+// WithField logs message with specified field
 func WithField(key string, value interface{}) *log.Entry {
 	return myLogger.WithField(key, value)
 }
 
+// WithFields logs message with multiple fields
 func WithFields(fields log.Fields) *log.Entry {
 	return myLogger.WithFields(fields)
 }
 
+// Panic logs with log level panic
 func Panic(msg string, args ...interface{}) {
 	myLogger.Panicf(msg, args...)
 }
 
+// Fatal logs woth loge level fatal
 func Fatal(msg string, args ...interface{}) {
 	myLogger.Fatalf(msg, args...)
 }
 
+// Error logs with log level error
 func Error(msg string, args ...interface{}) {
 	myLogger.Errorf(msg, args...)
 }
 
+// Warn logs with log level warn
 func Warn(msg string, args ...interface{}) {
 	myLogger.Warnf(msg, args...)
 }
 
+// Info logs with log level info
 func Info(msg string, args ...interface{}) {
 	myLogger.Infof(msg, args...)
 }
 
+// Debug logs with log level debug
 func Debug(msg string, args ...interface{}) {
 	myLogger.Debugf(msg, args...)
 }
diff --git a/common/utils/utils.go b/common/utils/utils.go
index f36cae4..3bfd0de 100644
--- a/common/utils/utils.go
+++ b/common/utils/utils.go
@@ -17,20 +17,28 @@
 package utils
 
 import (
-	"fmt"
+	"strconv"
 
 	"gerrit.opencord.org/voltha-bbsim/common/logger"
-
 	"gerrit.opencord.org/voltha-bbsim/device"
 	log "github.com/sirupsen/logrus"
 )
 
-func OnuToSn(onu *device.Onu) string {
-	// FIXME
-	// see https://github.com/opencord/voltha/blob/master/voltha/adapters/openolt/openolt_device.py#L929-L943
-	return string(onu.SerialNumber.VendorId) + "00000" + fmt.Sprint(onu.IntfID) + "0" + fmt.Sprintf("%x", onu.OnuID-1)
+// ConvB2S converts byte array to string
+func ConvB2S(b []byte) string {
+	s := ""
+	for _, i := range b {
+		s = s + strconv.FormatInt(int64(i/16), 16) + strconv.FormatInt(int64(i%16), 16)
+	}
+	return s
 }
 
+// OnuToSn returns serial number in string format for given ONU
+func OnuToSn(onu *device.Onu) string {
+	return string(onu.SerialNumber.VendorId) + ConvB2S(onu.SerialNumber.VendorSpecific)
+}
+
+// LoggerWithOnu method logs ONU fields
 func LoggerWithOnu(onu *device.Onu) *log.Entry {
 
 	if onu == nil {
@@ -40,8 +48,8 @@
 
 	return logger.GetLogger().WithFields(log.Fields{
 		"serial_number": OnuToSn(onu),
-		"interfaceId":   onu.IntfID,
-		"onuId":         onu.OnuID,
-		"oltId":         onu.OltID,
+		"interfaceID":   onu.IntfID,
+		"onuID":         onu.OnuID,
+		"oltID":         onu.OltID,
 	})
 }