VOL-3121 -  Separated out logical ports from logical agent.

Similar to flows/groups/meters.
Also modified device_route tests to generate unique port IDs (`.OfpPort.PortNo`s) across all UNI ports withing each test, i.e. within an OLT.
Also replaced logicalPortsNo map & associated NNI vs UNI logic with root device checks.

Change-Id: Ib0cecbf7d4f8d509ce7c989b9ccf697c8b0d17d6
diff --git a/rw_core/core/device/agent.go b/rw_core/core/device/agent.go
index fe379d6..00a054e 100755
--- a/rw_core/core/device/agent.go
+++ b/rw_core/core/device/agent.go
@@ -378,7 +378,7 @@
 	}
 	updatedAllFlows := make([]*ofp.OfpFlowStats, 0)
 	if !dType.AcceptsAddRemoveFlowUpdates {
-		flowIDs := agent.flowLoader.List()
+		flowIDs := agent.flowLoader.ListIDs()
 		for flowID := range flowIDs {
 			if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 				updatedAllFlows = append(updatedAllFlows, flowHandle.GetReadOnly())
@@ -468,7 +468,7 @@
 	}
 	updatedAllGroups := make([]*ofp.OfpGroupEntry, 0)
 	if !dType.AcceptsAddRemoveFlowUpdates {
-		groupIDs := agent.groupLoader.List()
+		groupIDs := agent.groupLoader.ListIDs()
 		for groupID := range groupIDs {
 			if grpHandle, have := agent.groupLoader.Lock(groupID); have {
 				updatedAllGroups = append(updatedAllGroups, grpHandle.GetReadOnly())
@@ -579,7 +579,7 @@
 	}
 	updatedAllFlows := make([]*ofp.OfpFlowStats, 0)
 	if !dType.AcceptsAddRemoveFlowUpdates {
-		flowIDs := agent.flowLoader.List()
+		flowIDs := agent.flowLoader.ListIDs()
 		for flowID := range flowIDs {
 			if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 				updatedAllFlows = append(updatedAllFlows, flowHandle.GetReadOnly())
@@ -646,7 +646,7 @@
 	}
 	updatedAllGroups := make([]*ofp.OfpGroupEntry, 0)
 	if !dType.AcceptsAddRemoveFlowUpdates {
-		groupIDs := agent.groupLoader.List()
+		groupIDs := agent.groupLoader.ListIDs()
 		for groupID := range groupIDs {
 			if grpHandle, have := agent.groupLoader.Lock(groupID); have {
 				updatedAllGroups = append(updatedAllGroups, grpHandle.GetReadOnly())
@@ -721,7 +721,7 @@
 func (agent *Agent) filterOutFlows(ctx context.Context, uniPort uint32, flowMetadata *voltha.FlowMetadata) error {
 	var flowsToDelete []*ofp.OfpFlowStats
 	// If an existing flow has the uniPort as an InPort or OutPort or as a Tunnel ID then it needs to be removed
-	for flowID := range agent.flowLoader.List() {
+	for flowID := range agent.flowLoader.ListIDs() {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 			flow := flowHandle.GetReadOnly()
 			if flow != nil && (fu.GetInPort(flow) == uniPort || fu.GetOutPort(flow) == uniPort || fu.GetTunnelId(flow) == uint64(uniPort)) {
@@ -764,7 +764,7 @@
 	}
 	updatedAllFlows := make([]*ofp.OfpFlowStats, 0)
 	if !dType.AcceptsAddRemoveFlowUpdates {
-		flowIDs := agent.flowLoader.List()
+		flowIDs := agent.flowLoader.ListIDs()
 		for flowID := range flowIDs {
 			if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 				updatedAllFlows = append(updatedAllFlows, flowHandle.GetReadOnly())
@@ -853,7 +853,7 @@
 	}
 	updatedAllGroups := make([]*ofp.OfpGroupEntry, 0)
 	if !dType.AcceptsAddRemoveFlowUpdates {
-		groupIDs := agent.groupLoader.List()
+		groupIDs := agent.groupLoader.ListIDs()
 		for groupID := range groupIDs {
 			if grpHandle, have := agent.groupLoader.Lock(groupID); have {
 				updatedAllGroups = append(updatedAllGroups, grpHandle.GetReadOnly())
@@ -942,7 +942,7 @@
 func (agent *Agent) deleteAllFlows(ctx context.Context) error {
 	logger.Debugw("deleteAllFlows", log.Fields{"deviceId": agent.deviceID})
 
-	for flowID := range agent.flowLoader.List() {
+	for flowID := range agent.flowLoader.ListIDs() {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 			// Update the store and cache
 			if err := flowHandle.Delete(ctx); err != nil {
diff --git a/rw_core/core/device/agent_flow.go b/rw_core/core/device/agent_flow.go
index bb8fe08..58f9aa9 100644
--- a/rw_core/core/device/agent_flow.go
+++ b/rw_core/core/device/agent_flow.go
@@ -22,7 +22,7 @@
 
 // listDeviceFlows returns device flows
 func (agent *Agent) listDeviceFlows() map[uint64]*ofp.OfpFlowStats {
-	flowIDs := agent.flowLoader.List()
+	flowIDs := agent.flowLoader.ListIDs()
 	flows := make(map[uint64]*ofp.OfpFlowStats, len(flowIDs))
 	for flowID := range flowIDs {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
diff --git a/rw_core/core/device/agent_group.go b/rw_core/core/device/agent_group.go
index 18ac83a..cb9557c 100644
--- a/rw_core/core/device/agent_group.go
+++ b/rw_core/core/device/agent_group.go
@@ -22,7 +22,7 @@
 
 // listDeviceGroups returns logical device flow groups
 func (agent *Agent) listDeviceGroups() map[uint32]*ofp.OfpGroupEntry {
-	groupIDs := agent.groupLoader.List()
+	groupIDs := agent.groupLoader.ListIDs()
 	groups := make(map[uint32]*ofp.OfpGroupEntry, len(groupIDs))
 	for groupID := range groupIDs {
 		if groupHandle, have := agent.groupLoader.Lock(groupID); have {
diff --git a/rw_core/core/device/event/event.go b/rw_core/core/device/event/event.go
index c205564..16cd08b 100644
--- a/rw_core/core/device/event/event.go
+++ b/rw_core/core/device/event/event.go
@@ -18,11 +18,12 @@
 
 import (
 	"encoding/hex"
+	"sync"
+
 	"github.com/golang/protobuf/ptypes/empty"
 	"github.com/opencord/voltha-lib-go/v3/pkg/log"
 	"github.com/opencord/voltha-protos/v3/go/openflow_13"
 	"github.com/opencord/voltha-protos/v3/go/voltha"
-	"sync"
 )
 
 type Manager struct {
@@ -123,13 +124,17 @@
 	return nil
 }
 
-func (q *Manager) SendChangeEvent(deviceID string, portStatus *openflow_13.OfpPortStatus) {
-	// TODO: validate the type of portStatus parameter
-	//if _, ok := portStatus.(*openflow_13.OfpPortStatus); ok {
-	//}
-	event := openflow_13.ChangeEvent{Id: deviceID, Event: &openflow_13.ChangeEvent_PortStatus{PortStatus: portStatus}}
-	logger.Debugw("SendChangeEvent", log.Fields{"event": event})
-	q.changeEventQueue <- event
+func (q *Manager) SendChangeEvent(deviceID string, reason openflow_13.OfpPortReason, desc *openflow_13.OfpPort) {
+	logger.Debugw("SendChangeEvent", log.Fields{"device-id": deviceID, "reason": reason, "desc": desc})
+	q.changeEventQueue <- openflow_13.ChangeEvent{
+		Id: deviceID,
+		Event: &openflow_13.ChangeEvent_PortStatus{
+			PortStatus: &openflow_13.OfpPortStatus{
+				Reason: reason,
+				Desc:   desc,
+			},
+		},
+	}
 }
 
 // ReceiveChangeEvents receives change in events
diff --git a/rw_core/core/device/flow/loader.go b/rw_core/core/device/flow/loader.go
index b407a3b..25060ab 100644
--- a/rw_core/core/device/flow/loader.go
+++ b/rw_core/core/device/flow/loader.go
@@ -30,11 +30,10 @@
 
 // Loader hides all low-level locking & synchronization related to flow state updates
 type Loader struct {
+	dbProxy *model.Proxy
 	// this lock protects the flows map, it does not protect individual flows
 	lock  sync.RWMutex
 	flows map[uint64]*chunk
-
-	dbProxy *model.Proxy
 }
 
 // chunk keeps a flow and the lock for this flow
@@ -48,8 +47,8 @@
 
 func NewLoader(dbProxy *model.Proxy) *Loader {
 	return &Loader{
-		flows:   make(map[uint64]*chunk),
 		dbProxy: dbProxy,
+		flows:   make(map[uint64]*chunk),
 	}
 }
 
@@ -86,8 +85,6 @@
 		loader.lock.Unlock()
 
 		if err := loader.dbProxy.Set(ctx, fmt.Sprint(flow.Id), flow); err != nil {
-			logger.Errorw("failed-adding-flow-to-db", log.Fields{"flowID": flow.Id, "err": err})
-
 			// revert the map
 			loader.lock.Lock()
 			delete(loader.flows, flow.Id)
@@ -109,7 +106,7 @@
 	return &Handle{loader: loader, chunk: entry}, false, nil
 }
 
-// Lock acquires the lock for this flow, and returns a handle which can be used to access the meter until it's unlocked.
+// Lock acquires the lock for this flow, and returns a handle which can be used to access the flow until it's unlocked.
 // This handle ensures that the flow cannot be accessed if the lock is not held.
 // Returns false if the flow is not present.
 // TODO: consider accepting a ctx and aborting the lock attempt on cancellation
@@ -130,6 +127,8 @@
 	return &Handle{loader: loader, chunk: entry}, true
 }
 
+// Handle is allocated for each Lock() call, all modifications are made using it, and it is invalidated by Unlock()
+// This enforces correct Lock()-Usage()-Unlock() ordering.
 type Handle struct {
 	loader *Loader
 	chunk  *chunk
@@ -173,10 +172,10 @@
 	}
 }
 
-// List returns a snapshot of all the managed flow IDs
+// ListIDs returns a snapshot of all the managed flow IDs
 // TODO: iterating through flows safely is expensive now, since all flows are stored & locked separately
 //       should avoid this where possible
-func (loader *Loader) List() map[uint64]struct{} {
+func (loader *Loader) ListIDs() map[uint64]struct{} {
 	loader.lock.RLock()
 	defer loader.lock.RUnlock()
 	// copy the IDs so caller can safely iterate
diff --git a/rw_core/core/device/flow/loader_test.go b/rw_core/core/device/flow/loader_test.go
index b739272..8973f12 100644
--- a/rw_core/core/device/flow/loader_test.go
+++ b/rw_core/core/device/flow/loader_test.go
@@ -22,34 +22,43 @@
 	"os"
 	"regexp"
 	"strconv"
-	"strings"
 	"testing"
 )
 
 // TestLoadersIdentical ensures that the group, flow, and meter loaders always have an identical implementation.
 func TestLoadersIdentical(t *testing.T) {
+	types := []string{"flow", "group", "meter", "logical_port"}
+
 	identical := [][]string{
-		{"ofp\\.OfpFlowStats", "ofp\\.OfpGroupEntry", "ofp\\.OfpMeterEntry"},
-		{"\\.Id", "\\.Desc\\.GroupId", "\\.Config.MeterId"},
-		{"uint64", "uint32", "uint32"},
-		{"Flow", "Group", "Meter"},
-		{"flow", "group", "meter"},
+		{`ofp\.OfpFlowStats`, `ofp\.OfpGroupEntry`, `ofp\.OfpMeterEntry`, `voltha\.LogicalPort`},
+		{`\.Id`, `\.Desc\.GroupId`, `\.Config\.MeterId`, `\.OfpPort\.PortNo`},
+		{`uint64`, `uint32`, `uint32`, `uint32`},
+		{`Flow`, `Group`, `Meter`, `Port`},
+		{`flow`, `group`, `meter`, `port|logical_port`},
 	}
 
-	regexes := make([]*regexp.Regexp, len(identical))
+	regexes := make([][]*regexp.Regexp, len(identical[0]))
+	for i := range regexes {
+		regexes[i] = make([]*regexp.Regexp, len(identical))
+	}
 	for i, group := range identical {
-		regexes[i] = regexp.MustCompile(strings.Join(group, "|"))
+		for j, regexStr := range group {
+			// convert from column-wise to row-wise for convenience
+			regexes[j][i] = regexp.MustCompile(regexStr)
+		}
 	}
 
-	for i := 1; i < len(identical[0]); i++ {
-		if err := compare(regexes, "../"+identical[4][0]+"/loader.go", "../"+identical[4][i]+"/loader.go"); err != nil {
+	for i := 1; i < len(types); i++ {
+		if err := compare(regexes[0], regexes[i],
+			"../"+types[0]+"/loader.go",
+			"../"+types[i]+"/loader.go"); err != nil {
 			t.Error(err)
 			return
 		}
 	}
 }
 
-func compare(regexes []*regexp.Regexp, fileNameA, fileNameB string) error {
+func compare(regexesA, regexesB []*regexp.Regexp, fileNameA, fileNameB string) error {
 	fileA, err := os.Open(fileNameA)
 	if err != nil {
 		return err
@@ -64,43 +73,63 @@
 
 	scannerA, scannerB := bufio.NewScanner(fileA), bufio.NewScanner(fileB)
 
-	spaceRegex := regexp.MustCompile(" +")
+	// treat any number of spaces as a single space
+	spaceRegex := regexp.MustCompile(` +`)
+	// extra lines are permitted before a "blank" line, or before a lock/unlock
+	spacerRegex := regexp.MustCompile(`^(?:[^a-z]*|.*Lock\(\)|.*Unlock\(\))$`)
+	// ignore import type differences
+	libGoImportRegex := regexp.MustCompile(`^.*github\.com/opencord/voltha-protos/.*$`)
 
-	line := 1
+	lineA, lineB := 1, 1
+linesLoop:
 	for {
-		if continueA, continueB := scannerA.Scan(), scannerB.Scan(); continueA != continueB {
-			if !continueA && continueB {
-				if err := scannerA.Err(); err != nil {
-					return err
+		if continueA, continueB := scannerA.Scan(), scannerB.Scan(); !continueA || !continueB {
+			// EOF
+			break linesLoop
+		}
+		textA, textB := scannerA.Text(), scannerB.Text()
+
+		// allow any number of "extra" lines just before a spacer line
+		for {
+			isSpacerA, isSpacerB := spacerRegex.MatchString(textA), spacerRegex.MatchString(textB)
+			if isSpacerA && !isSpacerB {
+				if !scannerB.Scan() {
+					// EOF
+					break linesLoop
 				}
-			}
-			if continueA && !continueB {
-				if err := scannerB.Err(); err != nil {
-					return err
+				lineB++
+				textB = scannerB.Text()
+				continue
+			} else if isSpacerB && !isSpacerA {
+				if !scannerA.Scan() {
+					// EOF
+					break linesLoop
 				}
+				lineA++
+				textA = scannerA.Text()
+				continue
 			}
-			return fmt.Errorf("line %d: files are not the same length", line)
-		} else if !continueA {
-			// EOF from both files
 			break
 		}
 
-		textA, textB := scannerA.Text(), scannerB.Text()
-
 		replacedA, replacedB := textA, textB
-		for i, regex := range regexes {
+		for i := range regexesA {
 			replacement := "{{type" + strconv.Itoa(i) + "}}"
-			replacedA, replacedB = regex.ReplaceAllString(replacedA, replacement), regex.ReplaceAllString(replacedB, replacement)
+			replacedA, replacedB = regexesA[i].ReplaceAllString(replacedA, replacement), regexesB[i].ReplaceAllString(replacedB, replacement)
 		}
 
 		// replace multiple spaces with single space
 		replacedA, replacedB = spaceRegex.ReplaceAllString(replacedA, " "), spaceRegex.ReplaceAllString(replacedB, " ")
 
-		if replacedA != replacedB {
-			return fmt.Errorf("line %d: files %s and %s do not match: \n\t%s\n\t%s\n\n\t%s\n\t%s", line, fileNameA, fileNameB, textA, textB, replacedA, replacedB)
+		// ignore voltha-protos import of ofp vs voltha
+		replacedA, replacedB = libGoImportRegex.ReplaceAllString(replacedA, "{{lib-go-import}}"), libGoImportRegex.ReplaceAllString(replacedB, "{{lib-go-import}}")
+
+		if replacedA != replacedB && textA != textB {
+			return fmt.Errorf("files which must be identical do not match: \n  %s:%d\n    %s\n  %s:%d\n    %s\n\n\t%s\n\t%s", fileNameA, lineA, textA, fileNameB, lineB, textB, replacedA, replacedB)
 		}
 
-		line++
+		lineA++
+		lineB++
 	}
 
 	if err := scannerA.Err(); err != nil {
diff --git a/rw_core/core/device/group/loader.go b/rw_core/core/device/group/loader.go
index 5b2890a..2edc29e 100644
--- a/rw_core/core/device/group/loader.go
+++ b/rw_core/core/device/group/loader.go
@@ -30,11 +30,10 @@
 
 // Loader hides all low-level locking & synchronization related to group state updates
 type Loader struct {
+	dbProxy *model.Proxy
 	// this lock protects the groups map, it does not protect individual groups
 	lock   sync.RWMutex
 	groups map[uint32]*chunk
-
-	dbProxy *model.Proxy
 }
 
 // chunk keeps a group and the lock for this group
@@ -48,8 +47,8 @@
 
 func NewLoader(dbProxy *model.Proxy) *Loader {
 	return &Loader{
-		groups:  make(map[uint32]*chunk),
 		dbProxy: dbProxy,
+		groups:  make(map[uint32]*chunk),
 	}
 }
 
@@ -86,8 +85,6 @@
 		loader.lock.Unlock()
 
 		if err := loader.dbProxy.Set(ctx, fmt.Sprint(group.Desc.GroupId), group); err != nil {
-			logger.Errorw("failed-adding-group-to-db", log.Fields{"groupID": group.Desc.GroupId, "err": err})
-
 			// revert the map
 			loader.lock.Lock()
 			delete(loader.groups, group.Desc.GroupId)
@@ -130,6 +127,8 @@
 	return &Handle{loader: loader, chunk: entry}, true
 }
 
+// Handle is allocated for each Lock() call, all modifications are made using it, and it is invalidated by Unlock()
+// This enforces correct Lock()-Usage()-Unlock() ordering.
 type Handle struct {
 	loader *Loader
 	chunk  *chunk
@@ -173,10 +172,10 @@
 	}
 }
 
-// List returns a snapshot of all the managed group IDs
+// ListIDs returns a snapshot of all the managed group IDs
 // TODO: iterating through groups safely is expensive now, since all groups are stored & locked separately
 //       should avoid this where possible
-func (loader *Loader) List() map[uint32]struct{} {
+func (loader *Loader) ListIDs() map[uint32]struct{} {
 	loader.lock.RLock()
 	defer loader.lock.RUnlock()
 	// copy the IDs so caller can safely iterate
diff --git a/rw_core/core/device/logical_agent.go b/rw_core/core/device/logical_agent.go
index f943106..c14750d 100644
--- a/rw_core/core/device/logical_agent.go
+++ b/rw_core/core/device/logical_agent.go
@@ -19,7 +19,6 @@
 import (
 	"context"
 	"encoding/hex"
-	"fmt"
 	"sync"
 	"time"
 
@@ -27,6 +26,7 @@
 	"github.com/opencord/voltha-go/db/model"
 	"github.com/opencord/voltha-go/rw_core/core/device/flow"
 	"github.com/opencord/voltha-go/rw_core/core/device/group"
+	"github.com/opencord/voltha-go/rw_core/core/device/logical_port"
 	"github.com/opencord/voltha-go/rw_core/core/device/meter"
 	fd "github.com/opencord/voltha-go/rw_core/flowdecomposition"
 	"github.com/opencord/voltha-go/rw_core/route"
@@ -42,26 +42,26 @@
 
 // LogicalAgent represent attributes of logical device agent
 type LogicalAgent struct {
-	logicalDeviceID    string
-	serialNumber       string
-	rootDeviceID       string
-	deviceMgr          *Manager
-	ldeviceMgr         *LogicalManager
-	ldProxy            *model.Proxy
-	stopped            bool
-	deviceRoutes       *route.DeviceRoutes
-	logicalPortsNo     map[uint32]bool //value is true for NNI port
-	lockLogicalPortsNo sync.RWMutex
-	flowDecomposer     *fd.FlowDecomposer
-	defaultTimeout     time.Duration
-	logicalDevice      *voltha.LogicalDevice
-	requestQueue       *coreutils.RequestQueue
-	startOnce          sync.Once
-	stopOnce           sync.Once
+	logicalDeviceID string
+	serialNumber    string
+	rootDeviceID    string
+	deviceMgr       *Manager
+	ldeviceMgr      *LogicalManager
+	ldProxy         *model.Proxy
+	stopped         bool
+	deviceRoutes    *route.DeviceRoutes
+	flowDecomposer  *fd.FlowDecomposer
+	defaultTimeout  time.Duration
+	logicalDevice   *voltha.LogicalDevice
+	requestQueue    *coreutils.RequestQueue
+	orderedEvents   orderedEvents
+	startOnce       sync.Once
+	stopOnce        sync.Once
 
 	flowLoader  *flow.Loader
 	meterLoader *meter.Loader
 	groupLoader *group.Loader
+	portLoader  *port.Loader
 }
 
 func newLogicalAgent(id string, sn string, deviceID string, ldeviceMgr *LogicalManager,
@@ -74,13 +74,13 @@
 		ldProxy:         ldProxy,
 		ldeviceMgr:      ldeviceMgr,
 		flowDecomposer:  fd.NewFlowDecomposer(deviceMgr),
-		logicalPortsNo:  make(map[uint32]bool),
 		defaultTimeout:  defaultTimeout,
 		requestQueue:    coreutils.NewRequestQueue(),
 
 		flowLoader:  flow.NewLoader(dbProxy.SubPath("logical_flows").Proxy(id)),
 		groupLoader: group.NewLoader(dbProxy.SubPath("logical_groups").Proxy(id)),
 		meterLoader: meter.NewLoader(dbProxy.SubPath("logical_meters").Proxy(id)),
+		portLoader:  port.NewLoader(dbProxy.SubPath("logical_ports").Proxy(id)),
 	}
 	agent.deviceRoutes = route.NewDeviceRoutes(agent.logicalDeviceID, agent.deviceMgr.getDevice)
 	return agent
@@ -134,7 +134,7 @@
 		}
 		logger.Debugw("logicaldevice-created", log.Fields{"logical-device-id": agent.logicalDeviceID, "root-id": ld.RootDeviceId})
 
-		agent.logicalDevice = proto.Clone(ld).(*voltha.LogicalDevice)
+		agent.logicalDevice = ld
 
 		// Setup the logicalports - internal processing, no need to propagate the client context
 		go func() {
@@ -158,14 +158,13 @@
 		agent.rootDeviceID = ld.RootDeviceId
 
 		// Update the last data
-		agent.logicalDevice = proto.Clone(ld).(*voltha.LogicalDevice)
+		agent.logicalDevice = ld
 
-		// Setup the local list of logical ports
-		agent.addLogicalPortsToMap(ld.Ports)
 		// load the flows, meters and groups from KV to cache
 		agent.flowLoader.Load(ctx)
 		agent.meterLoader.Load(ctx)
 		agent.groupLoader.Load(ctx)
+		agent.portLoader.Load(ctx)
 	}
 
 	// Setup the device routes. Building routes may fail if the pre-conditions are not satisfied (e.g. no PON ports present)
@@ -200,6 +199,8 @@
 		} else {
 			logger.Debugw("logicaldevice-removed", log.Fields{"logicaldeviceId": agent.logicalDeviceID})
 		}
+		// TODO: remove all entries from all loaders
+		// TODO: don't allow any more modifications to flows/groups/meters/ports or to any logical device field
 
 		agent.stopped = true
 
@@ -217,28 +218,6 @@
 	return proto.Clone(agent.logicalDevice).(*voltha.LogicalDevice), nil
 }
 
-// getLogicalDeviceWithoutLock returns a cloned logical device to a function that already holds the agent lock.
-func (agent *LogicalAgent) getLogicalDeviceWithoutLock() *voltha.LogicalDevice {
-	logger.Debug("getLogicalDeviceWithoutLock")
-	return proto.Clone(agent.logicalDevice).(*voltha.LogicalDevice)
-}
-
-//updateLogicalDeviceWithoutLock updates the model with the logical device.  It clones the logicaldevice before saving it
-func (agent *LogicalAgent) updateLogicalDeviceWithoutLock(ctx context.Context, logicalDevice *voltha.LogicalDevice) error {
-	if agent.stopped {
-		return fmt.Errorf("logical device agent stopped-%s", logicalDevice.Id)
-	}
-
-	updateCtx := context.WithValue(ctx, model.RequestTimestamp, time.Now().UnixNano())
-	if err := agent.ldProxy.Set(updateCtx, agent.logicalDeviceID, logicalDevice); err != nil {
-		logger.Errorw("failed-to-update-logical-devices-to-cluster-proxy", log.Fields{"error": err})
-		return err
-	}
-
-	agent.logicalDevice = logicalDevice
-	return nil
-}
-
 func (agent *LogicalAgent) addFlowsAndGroupsToDevices(deviceRules *fu.DeviceRules, flowMetadata *voltha.FlowMetadata) []coreutils.Response {
 	logger.Debugw("send-add-flows-to-device-manager", log.Fields{"logicalDeviceID": agent.logicalDeviceID, "deviceRules": deviceRules, "flowMetadata": flowMetadata})
 
diff --git a/rw_core/core/device/logical_agent_flow.go b/rw_core/core/device/logical_agent_flow.go
index b06b0f7..ff0f6e1 100644
--- a/rw_core/core/device/logical_agent_flow.go
+++ b/rw_core/core/device/logical_agent_flow.go
@@ -34,7 +34,7 @@
 
 // listLogicalDeviceFlows returns logical device flows
 func (agent *LogicalAgent) listLogicalDeviceFlows() map[uint64]*ofp.OfpFlowStats {
-	flowIDs := agent.flowLoader.List()
+	flowIDs := agent.flowLoader.ListIDs()
 	flows := make(map[uint64]*ofp.OfpFlowStats, len(flowIDs))
 	for flowID := range flowIDs {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
@@ -142,7 +142,7 @@
 			return changed, updated, err
 		}
 
-		groupIDs := agent.groupLoader.List()
+		groupIDs := agent.groupLoader.ListIDs()
 		groups := make(map[uint32]*ofp.OfpGroupEntry, len(groupIDs))
 		for groupID := range groupIDs {
 			if groupHandle, have := agent.groupLoader.Lock(groupID); have {
@@ -242,7 +242,7 @@
 	}
 
 	// search through all the flows
-	for flowID := range agent.flowLoader.List() {
+	for flowID := range agent.flowLoader.ListIDs() {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 			if flow := flowHandle.GetReadOnly(); fu.FlowMatchesMod(flow, mod) {
 				toDelete[flow.Id] = flow
@@ -283,7 +283,7 @@
 		}
 
 		groups := make(map[uint32]*ofp.OfpGroupEntry)
-		for groupID := range agent.groupLoader.List() {
+		for groupID := range agent.groupLoader.ListIDs() {
 			if groupHandle, have := agent.groupLoader.Lock(groupID); have {
 				groups[groupID] = groupHandle.GetReadOnly()
 				groupHandle.Unlock()
@@ -344,7 +344,7 @@
 	defer flowHandle.Unlock()
 
 	groups := make(map[uint32]*ofp.OfpGroupEntry)
-	for groupID := range agent.groupLoader.List() {
+	for groupID := range agent.groupLoader.ListIDs() {
 		if groupHandle, have := agent.groupLoader.Lock(groupID); have {
 			groups[groupID] = groupHandle.GetReadOnly()
 			groupHandle.Unlock()
@@ -419,7 +419,7 @@
 
 func (agent *LogicalAgent) deleteFlowsHavingMeter(ctx context.Context, meterID uint32) error {
 	logger.Infow("Delete-flows-matching-meter", log.Fields{"meter": meterID})
-	for flowID := range agent.flowLoader.List() {
+	for flowID := range agent.flowLoader.ListIDs() {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 			if flowMeterID := fu.GetMeterIdFromFlow(flowHandle.GetReadOnly()); flowMeterID != 0 && flowMeterID == meterID {
 				if err := flowHandle.Delete(ctx); err != nil {
@@ -438,7 +438,7 @@
 func (agent *LogicalAgent) deleteFlowsHavingGroup(ctx context.Context, groupID uint32) (map[uint64]*ofp.OfpFlowStats, error) {
 	logger.Infow("Delete-flows-matching-group", log.Fields{"groupID": groupID})
 	flowsRemoved := make(map[uint64]*ofp.OfpFlowStats)
-	for flowID := range agent.flowLoader.List() {
+	for flowID := range agent.flowLoader.ListIDs() {
 		if flowHandle, have := agent.flowLoader.Lock(flowID); have {
 			if flow := flowHandle.GetReadOnly(); fu.FlowHasOutGroup(flow, groupID) {
 				if err := flowHandle.Delete(ctx); err != nil {
diff --git a/rw_core/core/device/logical_agent_group.go b/rw_core/core/device/logical_agent_group.go
index bf2edbb..56f23bc 100644
--- a/rw_core/core/device/logical_agent_group.go
+++ b/rw_core/core/device/logical_agent_group.go
@@ -31,7 +31,7 @@
 
 // listLogicalDeviceGroups returns logical device flow groups
 func (agent *LogicalAgent) listLogicalDeviceGroups() map[uint32]*ofp.OfpGroupEntry {
-	groupIDs := agent.groupLoader.List()
+	groupIDs := agent.groupLoader.ListIDs()
 	groups := make(map[uint32]*ofp.OfpGroupEntry, len(groupIDs))
 	for groupID := range groupIDs {
 		if groupHandle, have := agent.groupLoader.Lock(groupID); have {
@@ -110,7 +110,7 @@
 
 	toDelete := map[uint32]struct{}{groupMod.GroupId: {}}
 	if groupMod.GroupId == uint32(ofp.OfpGroup_OFPG_ALL) {
-		toDelete = agent.groupLoader.List()
+		toDelete = agent.groupLoader.ListIDs()
 	}
 
 	for groupID := range toDelete {
diff --git a/rw_core/core/device/logical_agent_meter.go b/rw_core/core/device/logical_agent_meter.go
index dc44fda..991479a 100644
--- a/rw_core/core/device/logical_agent_meter.go
+++ b/rw_core/core/device/logical_agent_meter.go
@@ -29,7 +29,7 @@
 
 // listLogicalDeviceMeters returns logical device meters
 func (agent *LogicalAgent) listLogicalDeviceMeters() map[uint32]*ofp.OfpMeterEntry {
-	meterIDs := agent.meterLoader.List()
+	meterIDs := agent.meterLoader.ListIDs()
 	meters := make(map[uint32]*ofp.OfpMeterEntry, len(meterIDs))
 	for meterID := range meterIDs {
 		if meterHandle, have := agent.meterLoader.Lock(meterID); have {
diff --git a/rw_core/core/device/logical_agent_port.go b/rw_core/core/device/logical_agent_port.go
index 7229e05..ee4e77d 100644
--- a/rw_core/core/device/logical_agent_port.go
+++ b/rw_core/core/device/logical_agent_port.go
@@ -19,51 +19,46 @@
 import (
 	"context"
 	"fmt"
+	"sync"
 
-	"github.com/gogo/protobuf/proto"
 	coreutils "github.com/opencord/voltha-go/rw_core/utils"
 	fu "github.com/opencord/voltha-lib-go/v3/pkg/flows"
 	"github.com/opencord/voltha-lib-go/v3/pkg/log"
-	ic "github.com/opencord/voltha-protos/v3/go/inter_container"
 	ofp "github.com/opencord/voltha-protos/v3/go/openflow_13"
 	"github.com/opencord/voltha-protos/v3/go/voltha"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 )
 
-// ListLogicalDevicePorts returns logical device ports
-func (agent *LogicalAgent) ListLogicalDevicePorts(ctx context.Context) (*voltha.LogicalPorts, error) {
-	logger.Debug("ListLogicalDevicePorts")
-	logicalDevice, err := agent.GetLogicalDevice(ctx)
-	if err != nil {
-		return nil, err
+// listLogicalDevicePorts returns logical device ports
+func (agent *LogicalAgent) listLogicalDevicePorts() map[uint32]*voltha.LogicalPort {
+	logger.Debug("listLogicalDevicePorts")
+	portIDs := agent.portLoader.ListIDs()
+	ret := make(map[uint32]*voltha.LogicalPort, len(portIDs))
+	for portID := range portIDs {
+		if portHandle, have := agent.portLoader.Lock(portID); have {
+			ret[portID] = portHandle.GetReadOnly()
+			portHandle.Unlock()
+		}
 	}
-	if logicalDevice == nil {
-		return &voltha.LogicalPorts{}, nil
-	}
-	lPorts := make([]*voltha.LogicalPort, 0)
-	lPorts = append(lPorts, logicalDevice.Ports...)
-	return &voltha.LogicalPorts{Items: lPorts}, nil
+	return ret
 }
 
 func (agent *LogicalAgent) updateLogicalPort(ctx context.Context, device *voltha.Device, port *voltha.Port) error {
 	logger.Debugw("updateLogicalPort", log.Fields{"deviceId": device.Id, "port": port})
-	var err error
 	switch port.Type {
 	case voltha.Port_ETHERNET_NNI:
-		if _, err = agent.addNNILogicalPort(ctx, device, port); err != nil {
+		if err := agent.addNNILogicalPort(ctx, device, port); err != nil {
 			return err
 		}
-		agent.addLogicalPortToMap(port.PortNo, true)
 	case voltha.Port_ETHERNET_UNI:
-		if _, err = agent.addUNILogicalPort(ctx, device, port); err != nil {
+		if err := agent.addUNILogicalPort(ctx, device, port); err != nil {
 			return err
 		}
-		agent.addLogicalPortToMap(port.PortNo, false)
 	case voltha.Port_PON_OLT:
 		// Rebuilt the routes on Parent PON port addition
 		go func() {
-			if err = agent.buildRoutes(ctx); err != nil {
+			if err := agent.buildRoutes(ctx); err != nil {
 				// Not an error - temporary state
 				logger.Infow("failed-to-update-routes-after-adding-parent-pon-port", log.Fields{"device-id": device.Id, "port": port, "ports-count": len(device.Ports), "error": err})
 			}
@@ -72,7 +67,7 @@
 	case voltha.Port_PON_ONU:
 		// Add the routes corresponding to that child device
 		go func() {
-			if err = agent.updateAllRoutes(ctx, device); err != nil {
+			if err := agent.updateAllRoutes(ctx, device); err != nil {
 				// Not an error - temporary state
 				logger.Infow("failed-to-update-routes-after-adding-child-pon-port", log.Fields{"device-id": device.Id, "port": port, "ports-count": len(device.Ports), "error": err})
 			}
@@ -134,89 +129,77 @@
 	//Get UNI port number
 	for _, port := range device.Ports {
 		if port.Type == voltha.Port_ETHERNET_NNI {
-			if _, err = agent.addNNILogicalPort(ctx, device, port); err != nil {
+			if err = agent.addNNILogicalPort(ctx, device, port); err != nil {
 				logger.Errorw("error-adding-UNI-port", log.Fields{"error": err})
 			}
-			agent.addLogicalPortToMap(port.PortNo, true)
 		}
 	}
 	return err
 }
 
 // updatePortState updates the port state of the device
-func (agent *LogicalAgent) updatePortState(ctx context.Context, deviceID string, portNo uint32, operStatus voltha.OperStatus_Types) error {
+func (agent *LogicalAgent) updatePortState(ctx context.Context, portNo uint32, operStatus voltha.OperStatus_Types) error {
 	logger.Infow("updatePortState-start", log.Fields{"logicalDeviceId": agent.logicalDeviceID, "portNo": portNo, "state": operStatus})
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
+
+	portHandle, have := agent.portLoader.Lock(portNo)
+	if !have {
+		return status.Errorf(codes.NotFound, "port-%d-not-exist", portNo)
+	}
+	defer portHandle.Unlock()
+
+	newPort := clonePortSetState(portHandle.GetReadOnly(), operStatus)
+	if err := portHandle.Update(ctx, newPort); err != nil {
 		return err
 	}
-	defer agent.requestQueue.RequestComplete()
-	// Get the latest logical device info
-	original := agent.getLogicalDeviceWithoutLock()
-	updatedPorts := clonePorts(original.Ports)
-	for _, port := range updatedPorts {
-		if port.DeviceId == deviceID && port.DevicePortNo == portNo {
-			if operStatus == voltha.OperStatus_ACTIVE {
-				port.OfpPort.Config = port.OfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
-				port.OfpPort.State = uint32(ofp.OfpPortState_OFPPS_LIVE)
-			} else {
-				port.OfpPort.Config = port.OfpPort.Config | uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
-				port.OfpPort.State = uint32(ofp.OfpPortState_OFPPS_LINK_DOWN)
-			}
-			// Update the logical device
-			if err := agent.updateLogicalDevicePortsWithoutLock(ctx, original, updatedPorts); err != nil {
-				logger.Errorw("error-updating-logical-device", log.Fields{"error": err})
-				return err
-			}
-			return nil
-		}
-	}
-	return status.Errorf(codes.NotFound, "port-%d-not-exist", portNo)
+	agent.orderedEvents.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_MODIFY, newPort.OfpPort)
+	return nil
 }
 
 // updatePortsState updates the ports state related to the device
-func (agent *LogicalAgent) updatePortsState(ctx context.Context, device *voltha.Device, state voltha.OperStatus_Types) error {
+func (agent *LogicalAgent) updatePortsState(ctx context.Context, deviceID string, state voltha.OperStatus_Types) error {
 	logger.Infow("updatePortsState-start", log.Fields{"logicalDeviceId": agent.logicalDeviceID})
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return err
-	}
-	defer agent.requestQueue.RequestComplete()
-	// Get the latest logical device info
-	original := agent.getLogicalDeviceWithoutLock()
-	updatedPorts := clonePorts(original.Ports)
-	for _, port := range updatedPorts {
-		if port.DeviceId == device.Id {
-			if state == voltha.OperStatus_ACTIVE {
-				port.OfpPort.Config = port.OfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
-				port.OfpPort.State = uint32(ofp.OfpPortState_OFPPS_LIVE)
-			} else {
-				port.OfpPort.Config = port.OfpPort.Config | uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
-				port.OfpPort.State = uint32(ofp.OfpPortState_OFPPS_LINK_DOWN)
+
+	for portNo := range agent.portLoader.ListIDsForDevice(deviceID) {
+		if portHandle, have := agent.portLoader.Lock(portNo); have {
+			newPort := clonePortSetState(portHandle.GetReadOnly(), state)
+			if err := portHandle.Update(ctx, newPort); err != nil {
+				portHandle.Unlock()
+				return err
 			}
+			agent.orderedEvents.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_MODIFY, newPort.OfpPort)
+
+			portHandle.Unlock()
 		}
 	}
-	// Updating the logical device will trigger the poprt change events to be populated to the controller
-	if err := agent.updateLogicalDevicePortsWithoutLock(ctx, original, updatedPorts); err != nil {
-		logger.Warnw("logical-device-update-failed", log.Fields{"ldeviceId": agent.logicalDeviceID, "error": err})
-		return err
-	}
 	return nil
 }
 
+func clonePortSetState(oldPort *voltha.LogicalPort, state voltha.OperStatus_Types) *voltha.LogicalPort {
+	newPort := *oldPort // only clone the struct(s) that will be changed
+	newOfpPort := *oldPort.OfpPort
+	newPort.OfpPort = &newOfpPort
+
+	if state == voltha.OperStatus_ACTIVE {
+		newOfpPort.Config = newOfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
+		newOfpPort.State = uint32(ofp.OfpPortState_OFPPS_LIVE)
+	} else {
+		newOfpPort.Config = newOfpPort.Config | uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
+		newOfpPort.State = uint32(ofp.OfpPortState_OFPPS_LINK_DOWN)
+	}
+	return &newPort
+}
+
 // setupUNILogicalPorts creates a UNI port on the logical device that represents a child UNI interface
 func (agent *LogicalAgent) setupUNILogicalPorts(ctx context.Context, childDevice *voltha.Device) error {
 	logger.Infow("setupUNILogicalPort", log.Fields{"logicalDeviceId": agent.logicalDeviceID})
 	// Build the logical device based on information retrieved from the device adapter
 	var err error
-	var added bool
 	//Get UNI port number
 	for _, port := range childDevice.Ports {
 		if port.Type == voltha.Port_ETHERNET_UNI {
-			if added, err = agent.addUNILogicalPort(ctx, childDevice, port); err != nil {
+			if err = agent.addUNILogicalPort(ctx, childDevice, port); err != nil {
 				logger.Errorw("error-adding-UNI-port", log.Fields{"error": err})
 			}
-			if added {
-				agent.addLogicalPortToMap(port.PortNo, false)
-			}
 		}
 	}
 	return err
@@ -225,86 +208,52 @@
 // deleteAllLogicalPorts deletes all logical ports associated with this logical device
 func (agent *LogicalAgent) deleteAllLogicalPorts(ctx context.Context) error {
 	logger.Infow("updatePortsState-start", log.Fields{"logicalDeviceId": agent.logicalDeviceID})
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return err
-	}
-	defer agent.requestQueue.RequestComplete()
-	// Get the latest logical device info
-	cloned := agent.getLogicalDeviceWithoutLock()
 
-	if err := agent.updateLogicalDevicePortsWithoutLock(ctx, cloned, []*voltha.LogicalPort{}); err != nil {
-		logger.Warnw("logical-device-update-failed", log.Fields{"ldeviceId": agent.logicalDeviceID, "error": err})
-		return err
-	}
-	return nil
-}
-
-// deleteLogicalPort removes the logical port
-func (agent *LogicalAgent) deleteLogicalPort(ctx context.Context, lPort *voltha.LogicalPort) error {
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return err
-	}
-	defer agent.requestQueue.RequestComplete()
-
-	logicalDevice := agent.getLogicalDeviceWithoutLock()
-
-	index := -1
-	for i, logicalPort := range logicalDevice.Ports {
-		if logicalPort.Id == lPort.Id {
-			index = i
-			break
-		}
-	}
-	if index >= 0 {
-		clonedPorts := clonePorts(logicalDevice.Ports)
-		if index < len(clonedPorts)-1 {
-			copy(clonedPorts[index:], clonedPorts[index+1:])
-		}
-		clonedPorts[len(clonedPorts)-1] = nil
-		clonedPorts = clonedPorts[:len(clonedPorts)-1]
-		logger.Debugw("logical-port-deleted", log.Fields{"logicalDeviceId": agent.logicalDeviceID})
-		if err := agent.updateLogicalDevicePortsWithoutLock(ctx, logicalDevice, clonedPorts); err != nil {
-			logger.Errorw("logical-device-update-failed", log.Fields{"logicalDeviceId": agent.logicalDeviceID})
-			return err
-		}
-
-		// Remove the logical port from cache
-		agent.deleteLogicalPortsFromMap([]uint32{lPort.DevicePortNo})
-		// Reset the logical device routes
-		go func() {
-			if err := agent.buildRoutes(context.Background()); err != nil {
-				logger.Warnw("device-routes-not-ready", log.Fields{"logicalDeviceId": agent.logicalDeviceID, "error": err})
+	// for each port
+	for portID := range agent.portLoader.ListIDs() {
+		// TODO: can just call agent.deleteLogicalPort()?
+		if portHandle, have := agent.portLoader.Lock(portID); have {
+			oldPort := portHandle.GetReadOnly()
+			// delete
+			err := portHandle.Delete(ctx)
+			portHandle.Unlock()
+			if err != nil {
+				return err
 			}
-		}()
+			// and send event
+			agent.orderedEvents.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_DELETE, oldPort.OfpPort)
+		}
 	}
+
+	// Reset the logical device routes
+	go func() {
+		if err := agent.buildRoutes(context.Background()); err != nil {
+			logger.Warnw("device-routes-not-ready", log.Fields{"logicalDeviceId": agent.logicalDeviceID, "error": err})
+		}
+	}()
 	return nil
 }
 
 // deleteLogicalPorts removes the logical ports associated with that deviceId
 func (agent *LogicalAgent) deleteLogicalPorts(ctx context.Context, deviceID string) error {
 	logger.Debugw("deleting-logical-ports", log.Fields{"device-id": deviceID})
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return err
-	}
-	defer agent.requestQueue.RequestComplete()
 
-	logicalDevice := agent.getLogicalDeviceWithoutLock()
-	lPortstoKeep := []*voltha.LogicalPort{}
-	lPortsNoToDelete := []uint32{}
-	for _, logicalPort := range logicalDevice.Ports {
-		if logicalPort.DeviceId != deviceID {
-			lPortstoKeep = append(lPortstoKeep, logicalPort)
-		} else {
-			lPortsNoToDelete = append(lPortsNoToDelete, logicalPort.DevicePortNo)
+	// for each port
+	for portNo := range agent.portLoader.ListIDsForDevice(deviceID) {
+		if portHandle, have := agent.portLoader.Lock(portNo); have {
+			// if belongs to this device
+			if oldPort := portHandle.GetReadOnly(); oldPort.DeviceId == deviceID {
+				// delete
+				if err := portHandle.Delete(ctx); err != nil {
+					portHandle.Unlock()
+					return err
+				}
+				// and send event
+				agent.orderedEvents.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_DELETE, oldPort.OfpPort)
+			}
+			portHandle.Unlock()
 		}
 	}
-	logger.Debugw("deleted-logical-ports", log.Fields{"ports": lPortstoKeep})
-	if err := agent.updateLogicalDevicePortsWithoutLock(ctx, logicalDevice, lPortstoKeep); err != nil {
-		logger.Errorw("logical-device-update-failed", log.Fields{"logical-device-id": agent.logicalDeviceID})
-		return err
-	}
-	// Remove the port from the cached logical ports set
-	agent.deleteLogicalPortsFromMap(lPortsNoToDelete)
 
 	// Reset the logical device routes
 	go func() {
@@ -312,335 +261,286 @@
 			logger.Warnw("routes-not-ready", log.Fields{"logical-device-id": agent.logicalDeviceID, "error": err})
 		}
 	}()
-
 	return nil
 }
 
 // enableLogicalPort enables the logical port
-func (agent *LogicalAgent) enableLogicalPort(ctx context.Context, lPortID string) error {
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
+func (agent *LogicalAgent) enableLogicalPort(ctx context.Context, lPortNo uint32) error {
+	portHandle, have := agent.portLoader.Lock(lPortNo)
+	if !have {
+		return status.Errorf(codes.NotFound, "port-%d-not-exist", lPortNo)
+	}
+	defer portHandle.Unlock()
+
+	oldPort := portHandle.GetReadOnly()
+
+	newPort := *oldPort // only clone the struct(s) that will be changed
+	newOfpPort := *oldPort.OfpPort
+	newPort.OfpPort = &newOfpPort
+
+	newOfpPort.Config = newOfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
+	if err := portHandle.Update(ctx, &newPort); err != nil {
 		return err
 	}
-	defer agent.requestQueue.RequestComplete()
-
-	logicalDevice := agent.getLogicalDeviceWithoutLock()
-
-	index := -1
-	for i, logicalPort := range logicalDevice.Ports {
-		if logicalPort.Id == lPortID {
-			index = i
-			break
-		}
-	}
-	if index >= 0 {
-		clonedPorts := clonePorts(logicalDevice.Ports)
-		clonedPorts[index].OfpPort.Config = clonedPorts[index].OfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
-		return agent.updateLogicalDevicePortsWithoutLock(ctx, logicalDevice, clonedPorts)
-	}
-	return status.Errorf(codes.NotFound, "Port %s on Logical Device %s", lPortID, agent.logicalDeviceID)
-}
-
-// disableLogicalPort disabled the logical port
-func (agent *LogicalAgent) disableLogicalPort(ctx context.Context, lPortID string) error {
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return err
-	}
-	defer agent.requestQueue.RequestComplete()
-
-	// Get the most up to date logical device
-	logicalDevice := agent.getLogicalDeviceWithoutLock()
-	index := -1
-	for i, logicalPort := range logicalDevice.Ports {
-		if logicalPort.Id == lPortID {
-			index = i
-			break
-		}
-	}
-	if index >= 0 {
-		clonedPorts := clonePorts(logicalDevice.Ports)
-		clonedPorts[index].OfpPort.Config = (clonedPorts[index].OfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)) | uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
-		return agent.updateLogicalDevicePortsWithoutLock(ctx, logicalDevice, clonedPorts)
-	}
-	return status.Errorf(codes.NotFound, "Port %s on Logical Device %s", lPortID, agent.logicalDeviceID)
-}
-
-// addNNILogicalPort adds an NNI port to the logical device.  It returns a bool representing whether a port has been
-// added and an eror in case a valid error is encountered. If the port was successfully added it will return
-// (true, nil).   If the device is not in the correct state it will return (false, nil) as this is a valid
-// scenario. This also applies to the case where the port was already added.
-func (agent *LogicalAgent) addNNILogicalPort(ctx context.Context, device *voltha.Device, port *voltha.Port) (bool, error) {
-	logger.Debugw("addNNILogicalPort", log.Fields{"NNI": port})
-
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return false, err
-	}
-
-	defer agent.requestQueue.RequestComplete()
-	if agent.portExist(device, port) {
-		logger.Debugw("port-already-exist", log.Fields{"port": port})
-		return false, nil
-	}
-
-	// TODO: Change the port creation logic to include the port capability.  This will eliminate the port capability
-	// request that the Core makes following a port create event.
-	var portCap *ic.PortCapability
-	var err error
-	// First get the port capability
-	if portCap, err = agent.deviceMgr.getPortCapability(ctx, device.Id, port.PortNo); err != nil {
-		logger.Errorw("error-retrieving-port-capabilities", log.Fields{"error": err})
-		return false, err
-	}
-
-	portCap.Port.RootPort = true
-	lp := (proto.Clone(portCap.Port)).(*voltha.LogicalPort)
-	lp.DeviceId = device.Id
-	lp.Id = fmt.Sprintf("nni-%d", port.PortNo)
-	lp.OfpPort.PortNo = port.PortNo
-	lp.OfpPort.Name = lp.Id
-	lp.DevicePortNo = port.PortNo
-
-	ld := agent.getLogicalDeviceWithoutLock()
-
-	clonedPorts := clonePorts(ld.Ports)
-	if clonedPorts == nil {
-		clonedPorts = make([]*voltha.LogicalPort, 0)
-	}
-	clonedPorts = append(clonedPorts, lp)
-
-	if err = agent.addLogicalDevicePortsWithoutLock(ctx, ld, clonedPorts, lp, device); err != nil {
-		logger.Errorw("error-updating-logical-device", log.Fields{"error": err})
-		return false, err
-	}
-
-	return true, nil
-}
-
-func (agent *LogicalAgent) portExist(device *voltha.Device, port *voltha.Port) bool {
-	ldevice := agent.getLogicalDeviceWithoutLock()
-	for _, lPort := range ldevice.Ports {
-		if lPort.DeviceId == device.Id && lPort.DevicePortNo == port.PortNo {
-			return true
-		}
-	}
-	return false
-}
-
-// addUNILogicalPort adds an UNI port to the logical device.  It returns a bool representing whether a port has been
-// added and an eror in case a valid error is encountered. If the port was successfully added it will return
-// (true, nil).   If the device is not in the correct state it will return (false, nil) as this is a valid
-// scenario. This also applies to the case where the port was already added.
-func (agent *LogicalAgent) addUNILogicalPort(ctx context.Context, childDevice *voltha.Device, port *voltha.Port) (bool, error) {
-	logger.Debugw("addUNILogicalPort", log.Fields{"port": port})
-	if childDevice.AdminState != voltha.AdminState_ENABLED || childDevice.OperStatus != voltha.OperStatus_ACTIVE {
-		logger.Infow("device-not-ready", log.Fields{"deviceId": childDevice.Id, "admin": childDevice.AdminState, "oper": childDevice.OperStatus})
-		return false, nil
-	}
-	if err := agent.requestQueue.WaitForGreenLight(ctx); err != nil {
-		return false, err
-	}
-	defer agent.requestQueue.RequestComplete()
-
-	if agent.portExist(childDevice, port) {
-		logger.Debugw("port-already-exist", log.Fields{"port": port})
-		return false, nil
-	}
-
-	// TODO: Change the port creation logic to include the port capability.  This will eliminate the port capability
-	// request that the Core makes following a port create event.
-
-	var portCap *ic.PortCapability
-	var err error
-	// First get the port capability
-	if portCap, err = agent.deviceMgr.getPortCapability(ctx, childDevice.Id, port.PortNo); err != nil {
-		logger.Errorw("error-retrieving-port-capabilities", log.Fields{"error": err})
-		return false, err
-	}
-
-	// Get stored logical device
-	ldevice := agent.getLogicalDeviceWithoutLock()
-
-	logger.Debugw("adding-uni", log.Fields{"deviceId": childDevice.Id})
-	portCap.Port.RootPort = false
-	portCap.Port.Id = port.Label
-	portCap.Port.OfpPort.PortNo = port.PortNo
-	portCap.Port.DeviceId = childDevice.Id
-	portCap.Port.DevicePortNo = port.PortNo
-	clonedPorts := clonePorts(ldevice.Ports)
-	if clonedPorts == nil {
-		clonedPorts = make([]*voltha.LogicalPort, 0)
-	}
-	clonedPorts = append(clonedPorts, portCap.Port)
-
-	if err = agent.addLogicalDevicePortsWithoutLock(ctx, ldevice, clonedPorts, portCap.Port, childDevice); err != nil {
-		return false, err
-	}
-
-	return true, nil
-}
-
-func clonePorts(ports []*voltha.LogicalPort) []*voltha.LogicalPort {
-	return proto.Clone(&voltha.LogicalPorts{Items: ports}).(*voltha.LogicalPorts).Items
-}
-
-//updateLogicalDevicePortsWithoutLock updates the
-func (agent *LogicalAgent) updateLogicalDevicePortsWithoutLock(ctx context.Context, device *voltha.LogicalDevice, newPorts []*voltha.LogicalPort) error {
-	oldPorts := device.Ports
-	device.Ports = newPorts
-	if err := agent.updateLogicalDeviceWithoutLock(ctx, device); err != nil {
-		return err
-	}
-	agent.portUpdated(oldPorts, newPorts)
+	agent.orderedEvents.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_MODIFY, newPort.OfpPort)
 	return nil
 }
 
-// addLogicalDevicePortsWithoutLock add the new ports to the logical device, update routes associated with those new
-// ports and send an add port event to the OF controller
-func (agent *LogicalAgent) addLogicalDevicePortsWithoutLock(ctx context.Context, lDevice *voltha.LogicalDevice, newPorts []*voltha.LogicalPort, lp *voltha.LogicalPort, device *voltha.Device) error {
-	oldPorts := lDevice.Ports
-	lDevice.Ports = newPorts
-	if err := agent.updateLogicalDeviceWithoutLock(ctx, lDevice); err != nil {
+// disableLogicalPort disabled the logical port
+func (agent *LogicalAgent) disableLogicalPort(ctx context.Context, lPortNo uint32) error {
+	portHandle, have := agent.portLoader.Lock(lPortNo)
+	if !have {
+		return status.Errorf(codes.NotFound, "port-%d-not-exist", lPortNo)
+	}
+	defer portHandle.Unlock()
+
+	oldPort := portHandle.GetReadOnly()
+
+	newPort := *oldPort // only clone the struct(s) that will be changed
+	newOfpPort := *oldPort.OfpPort
+	newPort.OfpPort = &newOfpPort
+
+	newOfpPort.Config = (newOfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)) | uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
+	if err := portHandle.Update(ctx, &newPort); err != nil {
 		return err
 	}
+	agent.orderedEvents.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_MODIFY, newPort.OfpPort)
+	return nil
+}
+
+// addNNILogicalPort adds an NNI port to the logical device.  It returns a bool representing whether a port has been
+// added and an error in case a valid error is encountered. If the port was successfully added it will return
+// (true, nil).   If the device is not in the correct state it will return (false, nil) as this is a valid
+// scenario. This also applies to the case where the port was already added.
+func (agent *LogicalAgent) addNNILogicalPort(ctx context.Context, device *voltha.Device, port *voltha.Port) error {
+	logger.Debugw("addNNILogicalPort", log.Fields{"NNI": port})
+
+	label := fmt.Sprintf("nni-%d", port.PortNo)
+	tmpPort := &voltha.LogicalPort{
+		RootPort:     true,
+		DeviceId:     device.Id,
+		Id:           label,
+		DevicePortNo: port.PortNo,
+		OfpPort: &voltha.OfpPort{
+			PortNo: port.PortNo,
+			Name:   label,
+		},
+		OfpPortStats: &ofp.OfpPortStats{},
+	}
+
+	portHandle, created, err := agent.portLoader.LockOrCreate(ctx, tmpPort)
+	if err != nil {
+		return err
+	}
+	defer portHandle.Unlock()
+
+	if !created {
+		logger.Debugw("port-already-exist", log.Fields{"port": port})
+		return nil
+	}
+
+	// TODO: VOL-3202 Change the port creation logic to include the port capability.  This will eliminate
+	//       the port capability request that the Core makes following a port create event.
+	// TODO: VOL-3202 the port lock should not be held while getPortCapability() runs (preferably not while *any*
+	//       external request runs), this is a temporary hack to avoid updating port state before the port is ready
+
+	// First get the port capability
+	portCap, err := agent.deviceMgr.getPortCapability(ctx, device.Id, port.PortNo)
+	if err != nil {
+		logger.Errorw("error-retrieving-port-capabilities", log.Fields{"error": err})
+		return err
+	}
+
+	newPort := portCap.Port
+	newPort.RootPort = true
+	newPort.DeviceId = device.Id
+	newPort.Id = label
+	newPort.DevicePortNo = port.PortNo
+	newPort.OfpPort.PortNo = port.PortNo
+	newPort.OfpPort.Name = label
+
+	// TODO: VOL-3202 shouldn't create tmp port then update, should prepare complete port first then LockOrCreate()
+	//      the use of context.Background() is required to ensure we don't get an inconsistent logical port state
+	//      while doing this, and can be removed later.
+	if err := portHandle.Update(ctx, newPort); err != nil {
+		if err := portHandle.Delete(context.Background()); err != nil {
+			return fmt.Errorf("unable-to-delete-%d: %s", port.PortNo, err)
+		}
+		return err
+	}
+
+	// ensure that no events will be sent until this one is
+	queuePosition := agent.orderedEvents.assignQueuePosition()
 
 	// Setup the routes for this device and then send the port update event to the OF Controller
 	go func() {
 		// First setup the routes
-		if err := agent.updateRoutes(context.Background(), device, lp, newPorts); err != nil {
+		if err := agent.updateRoutes(context.Background(), device, newPort, agent.listLogicalDevicePorts()); err != nil {
 			// This is not an error as we may not have enough logical ports to set up routes or some PON ports have not been
 			// created yet.
-			logger.Infow("routes-not-ready", log.Fields{"logical-device-id": agent.logicalDeviceID, "logical-port": lp.OfpPort.PortNo, "error": err})
+			logger.Infow("routes-not-ready", log.Fields{"logical-device-id": agent.logicalDeviceID, "logical-port": newPort.OfpPort.PortNo, "error": err})
 		}
 
-		// Send a port update event
-		agent.portUpdated(oldPorts, newPorts)
+		// send event, and allow any queued events to be sent as well
+		queuePosition.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_ADD, newPort.OfpPort)
 	}()
-
 	return nil
 }
 
-// diff go over two lists of logical ports and return what's new, what's changed and what's removed.
-func diff(oldList, newList []*voltha.LogicalPort) (newPorts, changedPorts, deletedPorts map[string]*voltha.LogicalPort) {
-	newPorts = make(map[string]*voltha.LogicalPort, len(newList))
-	changedPorts = make(map[string]*voltha.LogicalPort, len(oldList))
-	deletedPorts = make(map[string]*voltha.LogicalPort, len(oldList))
-
-	for _, n := range newList {
-		newPorts[n.Id] = n
+// addUNILogicalPort adds an UNI port to the logical device.  It returns a bool representing whether a port has been
+// added and an error in case a valid error is encountered. If the port was successfully added it will return
+// (true, nil).   If the device is not in the correct state it will return (false, nil) as this is a valid
+// scenario. This also applies to the case where the port was already added.
+func (agent *LogicalAgent) addUNILogicalPort(ctx context.Context, childDevice *voltha.Device, port *voltha.Port) error {
+	logger.Debugw("addUNILogicalPort", log.Fields{"port": port})
+	if childDevice.AdminState != voltha.AdminState_ENABLED || childDevice.OperStatus != voltha.OperStatus_ACTIVE {
+		logger.Infow("device-not-ready", log.Fields{"deviceId": childDevice.Id, "admin": childDevice.AdminState, "oper": childDevice.OperStatus})
+		return nil
 	}
 
-	for _, o := range oldList {
-		if n, have := newPorts[o.Id]; have {
-			delete(newPorts, o.Id) // not new
-			if !proto.Equal(n, o) {
-				changedPorts[n.Id] = n // changed
-			}
-		} else {
-			deletedPorts[o.Id] = o // deleted
+	tmpPort := &voltha.LogicalPort{
+		RootPort:     false,
+		DeviceId:     childDevice.Id,
+		Id:           port.Label,
+		DevicePortNo: port.PortNo,
+		OfpPort: &voltha.OfpPort{
+			PortNo: port.PortNo,
+		},
+		OfpPortStats: &ofp.OfpPortStats{},
+	}
+
+	portHandle, created, err := agent.portLoader.LockOrCreate(ctx, tmpPort)
+	if err != nil {
+		return err
+	}
+	defer portHandle.Unlock()
+
+	if !created {
+		logger.Debugw("port-already-exist", log.Fields{"port": port})
+		return nil
+	}
+
+	// TODO: VOL-3202 Change the port creation logic to include the port capability.  This will eliminate
+	//       the port capability request that the Core makes following a port create event.
+	// TODO: VOL-3202 the port lock should not be held while getPortCapability() runs (preferably not while *any*
+	//       external request runs), this is a temporary hack to avoid updating port state before the port is ready
+
+	// First get the port capability
+	portCap, err := agent.deviceMgr.getPortCapability(ctx, childDevice.Id, port.PortNo)
+	if err != nil {
+		logger.Errorw("error-retrieving-port-capabilities", log.Fields{"error": err})
+		return err
+	}
+
+	logger.Debugw("adding-uni", log.Fields{"deviceId": childDevice.Id})
+	newPort := portCap.Port
+	newPort.RootPort = false
+	newPort.DeviceId = childDevice.Id
+	newPort.Id = port.Label
+	newPort.DevicePortNo = port.PortNo
+	newPort.OfpPort.PortNo = port.PortNo
+
+	// TODO: VOL-3202 shouldn't create tmp port then update, should prepare complete port first then LockOrCreate()
+	//      the use of context.Background() is required to ensure we don't get an inconsistent logical port state
+	//      while doing this, and can be removed later.
+	if err := portHandle.Update(ctx, newPort); err != nil {
+		if err := portHandle.Delete(context.Background()); err != nil {
+			return fmt.Errorf("unable-to-delete-%d: %s", port.PortNo, err)
 		}
+		return err
 	}
 
-	return newPorts, changedPorts, deletedPorts
-}
+	// ensure that no events will be sent until this one is
+	queuePosition := agent.orderedEvents.assignQueuePosition()
 
-// portUpdated is invoked when a port is updated on the logical device
-func (agent *LogicalAgent) portUpdated(prevPorts, currPorts []*voltha.LogicalPort) interface{} {
-	// Get the difference between the two list
-	newPorts, changedPorts, deletedPorts := diff(prevPorts, currPorts)
-
-	// Send the port change events to the OF controller
-	for _, newP := range newPorts {
-		go agent.ldeviceMgr.SendChangeEvent(agent.logicalDeviceID,
-			&ofp.OfpPortStatus{Reason: ofp.OfpPortReason_OFPPR_ADD, Desc: newP.OfpPort})
-	}
-	for _, change := range changedPorts {
-		go agent.ldeviceMgr.SendChangeEvent(agent.logicalDeviceID,
-			&ofp.OfpPortStatus{Reason: ofp.OfpPortReason_OFPPR_MODIFY, Desc: change.OfpPort})
-	}
-	for _, del := range deletedPorts {
-		go agent.ldeviceMgr.SendChangeEvent(agent.logicalDeviceID,
-			&ofp.OfpPortStatus{Reason: ofp.OfpPortReason_OFPPR_DELETE, Desc: del.OfpPort})
-	}
-
+	// Setup the routes for this device and then send the port update event to the OF Controller
+	go func() {
+		// First setup the routes
+		if err := agent.updateRoutes(context.Background(), childDevice, newPort, agent.listLogicalDevicePorts()); err != nil {
+			// This is not an error as we may not have enough logical ports to set up routes or some PON ports have not been
+			// created yet.
+			logger.Infow("routes-not-ready", log.Fields{"logical-device-id": agent.logicalDeviceID, "logical-port": newPort.OfpPort.PortNo, "error": err})
+		}
+		// send event, and allow any queued events to be sent as well
+		queuePosition.send(agent, agent.logicalDeviceID, ofp.OfpPortReason_OFPPR_ADD, newPort.OfpPort)
+	}()
 	return nil
 }
 
-//GetWildcardInputPorts filters out the logical port number from the set of logical ports on the device and
-//returns their port numbers.  This function is invoked only during flow decomposition where the lock on the logical
-//device is already held.  Therefore it is safe to retrieve the logical device without lock.
-func (agent *LogicalAgent) GetWildcardInputPorts(excludePort ...uint32) []uint32 {
-	lPorts := make([]uint32, 0)
-	var exclPort uint32
-	if len(excludePort) == 1 {
-		exclPort = excludePort[0]
-	}
-	lDevice := agent.getLogicalDeviceWithoutLock()
-	for _, port := range lDevice.Ports {
-		if port.OfpPort.PortNo != exclPort {
-			lPorts = append(lPorts, port.OfpPort.PortNo)
-		}
-	}
-	return lPorts
+// send is a convenience to avoid calling both assignQueuePosition and qp.send
+func (e *orderedEvents) send(agent *LogicalAgent, deviceID string, reason ofp.OfpPortReason, desc *ofp.OfpPort) {
+	qp := e.assignQueuePosition()
+	go qp.send(agent, deviceID, reason, desc)
 }
 
-// helpers for agent.logicalPortsNo
+// TODO: shouldn't need to guarantee event ordering like this
+//       event ordering should really be protected by per-LogicalPort lock
+//       once routing uses on-demand calculation only, this should be changed
+// assignQueuePosition ensures that no events will be sent until this thread calls send() on the returned queuePosition
+func (e *orderedEvents) assignQueuePosition() queuePosition {
+	e.mutex.Lock()
+	defer e.mutex.Unlock()
 
-func (agent *LogicalAgent) addLogicalPortToMap(portNo uint32, nniPort bool) {
-	agent.lockLogicalPortsNo.Lock()
-	defer agent.lockLogicalPortsNo.Unlock()
-	if exist := agent.logicalPortsNo[portNo]; !exist {
-		agent.logicalPortsNo[portNo] = nniPort
+	prev := e.last
+	next := make(chan struct{})
+	e.last = next
+	return queuePosition{
+		prev: prev,
+		next: next,
 	}
 }
 
-func (agent *LogicalAgent) addLogicalPortsToMap(lps []*voltha.LogicalPort) {
-	agent.lockLogicalPortsNo.Lock()
-	defer agent.lockLogicalPortsNo.Unlock()
-	for _, lp := range lps {
-		if exist := agent.logicalPortsNo[lp.DevicePortNo]; !exist {
-			agent.logicalPortsNo[lp.DevicePortNo] = lp.RootPort
-		}
-	}
+// orderedEvents guarantees the order that events are sent, while allowing events to back up.
+type orderedEvents struct {
+	mutex sync.Mutex
+	last  <-chan struct{}
 }
 
-func (agent *LogicalAgent) deleteLogicalPortsFromMap(portsNo []uint32) {
-	agent.lockLogicalPortsNo.Lock()
-	defer agent.lockLogicalPortsNo.Unlock()
-	for _, pNo := range portsNo {
-		delete(agent.logicalPortsNo, pNo)
-	}
+type queuePosition struct {
+	prev <-chan struct{}
+	next chan<- struct{}
 }
 
+// send waits for its turn, then sends the event, then notifies the next in line
+func (qp queuePosition) send(agent *LogicalAgent, deviceID string, reason ofp.OfpPortReason, desc *ofp.OfpPort) {
+	if qp.prev != nil {
+		<-qp.prev // wait for turn
+	}
+	agent.ldeviceMgr.SendChangeEvent(deviceID, reason, desc)
+	close(qp.next) // notify next
+}
+
+// GetWildcardInputPorts filters out the logical port number from the set of logical ports on the device and
+// returns their port numbers.
+func (agent *LogicalAgent) GetWildcardInputPorts(excludePort uint32) map[uint32]struct{} {
+	portIDs := agent.portLoader.ListIDs()
+	delete(portIDs, excludePort)
+	return portIDs
+}
+
+// isNNIPort return true iff the specified port belongs to the parent (OLT) device
 func (agent *LogicalAgent) isNNIPort(portNo uint32) bool {
-	agent.lockLogicalPortsNo.RLock()
-	defer agent.lockLogicalPortsNo.RUnlock()
-	if exist := agent.logicalPortsNo[portNo]; exist {
-		return agent.logicalPortsNo[portNo]
+	portHandle, have := agent.portLoader.Lock(portNo)
+	if !have {
+		return false
 	}
-	return false
+	defer portHandle.Unlock()
+
+	// any root-device logical port is an NNI port
+	return portHandle.GetReadOnly().RootPort
 }
 
-func (agent *LogicalAgent) getFirstNNIPort() (uint32, error) {
-	agent.lockLogicalPortsNo.RLock()
-	defer agent.lockLogicalPortsNo.RUnlock()
-	for portNo, nni := range agent.logicalPortsNo {
-		if nni {
-			return portNo, nil
-		}
+// getAnyNNIPort returns an NNI port
+func (agent *LogicalAgent) getAnyNNIPort() (uint32, error) {
+	for portID := range agent.portLoader.ListIDsForDevice(agent.rootDeviceID) {
+		return portID, nil
 	}
 	return 0, status.Error(codes.NotFound, "No NNI port found")
 }
 
-//GetNNIPorts returns NNI ports.
-func (agent *LogicalAgent) GetNNIPorts() []uint32 {
-	agent.lockLogicalPortsNo.RLock()
-	defer agent.lockLogicalPortsNo.RUnlock()
-	nniPorts := make([]uint32, 0)
-	for portNo, nni := range agent.logicalPortsNo {
-		if nni {
-			nniPorts = append(nniPorts, portNo)
-		}
-	}
-	return nniPorts
+//GetNNIPorts returns all NNI ports
+func (agent *LogicalAgent) GetNNIPorts() map[uint32]struct{} {
+	return agent.portLoader.ListIDsForDevice(agent.rootDeviceID)
 }
 
 // getUNILogicalPortNo returns the UNI logical port number specified in the flow
diff --git a/rw_core/core/device/logical_agent_route.go b/rw_core/core/device/logical_agent_route.go
index fa96caf..dbf5e57 100644
--- a/rw_core/core/device/logical_agent_route.go
+++ b/rw_core/core/device/logical_agent_route.go
@@ -19,6 +19,7 @@
 import (
 	"context"
 	"fmt"
+
 	"github.com/opencord/voltha-go/rw_core/route"
 	"github.com/opencord/voltha-lib-go/v3/pkg/log"
 	ofp "github.com/opencord/voltha-protos/v3/go/openflow_13"
@@ -34,7 +35,7 @@
 
 	// Controller-bound flow
 	if egressPortNo != 0 && ((egressPortNo & 0x7fffffff) == uint32(ofp.OfpPortNo_OFPP_CONTROLLER)) {
-		logger.Debugw("controller-flow", log.Fields{"ingressPortNo": ingressPortNo, "egressPortNo": egressPortNo, "logicalPortsNo": agent.logicalPortsNo})
+		logger.Debugw("controller-flow", log.Fields{"ingressPortNo": ingressPortNo, "egressPortNo": egressPortNo})
 		if agent.isNNIPort(ingressPortNo) {
 			//This is a trap on the NNI Port
 			if agent.deviceRoutes.IsRoutesEmpty() {
@@ -55,7 +56,7 @@
 		}
 		// Treat it as if the output port is the first NNI of the OLT
 		var err error
-		if egressPortNo, err = agent.getFirstNNIPort(); err != nil {
+		if egressPortNo, err = agent.getAnyNNIPort(); err != nil {
 			logger.Warnw("no-nni-port", log.Fields{"error": err})
 			return nil, err
 		}
@@ -97,13 +98,7 @@
 	}
 	defer agent.requestQueue.RequestComplete()
 
-	if agent.deviceRoutes == nil {
-		agent.deviceRoutes = route.NewDeviceRoutes(agent.logicalDeviceID, agent.deviceMgr.getDevice)
-	}
-	// Get all the logical ports on that logical device
-	lDevice := agent.getLogicalDeviceWithoutLock()
-
-	if err := agent.deviceRoutes.ComputeRoutes(ctx, lDevice.Ports); err != nil {
+	if err := agent.deviceRoutes.ComputeRoutes(ctx, agent.listLogicalDevicePorts()); err != nil {
 		return err
 	}
 	if err := agent.deviceRoutes.Print(); err != nil {
@@ -113,7 +108,7 @@
 }
 
 //updateRoutes updates the device routes
-func (agent *LogicalAgent) updateRoutes(ctx context.Context, device *voltha.Device, lp *voltha.LogicalPort, lps []*voltha.LogicalPort) error {
+func (agent *LogicalAgent) updateRoutes(ctx context.Context, device *voltha.Device, lp *voltha.LogicalPort, lps map[uint32]*voltha.LogicalPort) error {
 	logger.Debugw("updateRoutes", log.Fields{"logical-device-id": agent.logicalDeviceID, "device-id": device.Id, "port:": lp})
 
 	if err := agent.deviceRoutes.AddPort(ctx, lp, device, lps); err != nil {
@@ -129,12 +124,7 @@
 func (agent *LogicalAgent) updateAllRoutes(ctx context.Context, device *voltha.Device) error {
 	logger.Debugw("updateAllRoutes", log.Fields{"logical-device-id": agent.logicalDeviceID, "device-id": device.Id, "ports-count": len(device.Ports)})
 
-	ld, err := agent.GetLogicalDevice(ctx)
-	if err != nil {
-		return err
-	}
-
-	if err := agent.deviceRoutes.AddAllPorts(ctx, device, ld.Ports); err != nil {
+	if err := agent.deviceRoutes.AddAllPorts(ctx, device, agent.listLogicalDevicePorts()); err != nil {
 		return err
 	}
 	if err := agent.deviceRoutes.Print(); err != nil {
diff --git a/rw_core/core/device/logical_agent_test.go b/rw_core/core/device/logical_agent_test.go
index 2e1b1d3..40c6b9c 100644
--- a/rw_core/core/device/logical_agent_test.go
+++ b/rw_core/core/device/logical_agent_test.go
@@ -40,328 +40,6 @@
 	"github.com/stretchr/testify/assert"
 )
 
-func TestLogicalDeviceAgent_diff_nochange_1(t *testing.T) {
-	currentLogicalPorts := []*voltha.LogicalPort{}
-	updatedLogicalPorts := []*voltha.LogicalPort{}
-	newPorts, changedPorts, deletedPorts := diff(currentLogicalPorts, updatedLogicalPorts)
-	assert.Equal(t, 0, len(newPorts))
-	assert.Equal(t, 0, len(changedPorts))
-	assert.Equal(t, 0, len(deletedPorts))
-}
-
-func TestLogicalDeviceAgent_diff_nochange_2(t *testing.T) {
-	currentLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1233",
-			DeviceId:     "d1234",
-			DevicePortNo: 3,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 3,
-				Name:   "port3",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	updatedLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1233",
-			DeviceId:     "d1234",
-			DevicePortNo: 3,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 3,
-				Name:   "port3",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	newPorts, changedPorts, deletedPorts := diff(currentLogicalPorts, updatedLogicalPorts)
-	assert.Equal(t, 0, len(newPorts))
-	assert.Equal(t, 0, len(changedPorts))
-	assert.Equal(t, 0, len(deletedPorts))
-}
-
-func TestLogicalDeviceAgent_diff_add(t *testing.T) {
-	currentLogicalPorts := []*voltha.LogicalPort{}
-	updatedLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	newPorts, changedPorts, deletedPorts := diff(currentLogicalPorts, updatedLogicalPorts)
-	assert.Equal(t, 2, len(newPorts))
-	assert.Equal(t, 0, len(changedPorts))
-	assert.Equal(t, 0, len(deletedPorts))
-	assert.Equal(t, updatedLogicalPorts[0], newPorts[updatedLogicalPorts[0].Id])
-	assert.Equal(t, updatedLogicalPorts[1], newPorts[updatedLogicalPorts[1].Id])
-}
-
-func TestLogicalDeviceAgent_diff_delete(t *testing.T) {
-	currentLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	updatedLogicalPorts := []*voltha.LogicalPort{}
-	newPorts, changedPorts, deletedPorts := diff(currentLogicalPorts, updatedLogicalPorts)
-	assert.Equal(t, 0, len(newPorts))
-	assert.Equal(t, 0, len(changedPorts))
-	assert.Equal(t, 1, len(deletedPorts))
-	assert.Equal(t, currentLogicalPorts[0], deletedPorts[currentLogicalPorts[0].Id])
-}
-
-func TestLogicalDeviceAgent_diff_changed(t *testing.T) {
-	currentLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1233",
-			DeviceId:     "d1234",
-			DevicePortNo: 3,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 3,
-				Name:   "port3",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	updatedLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 4,
-				State:  4,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 4,
-				State:  4,
-			},
-		},
-		{
-			Id:           "1233",
-			DeviceId:     "d1234",
-			DevicePortNo: 3,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 3,
-				Name:   "port3",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	newPorts, changedPorts, deletedPorts := diff(currentLogicalPorts, updatedLogicalPorts)
-	assert.Equal(t, 0, len(newPorts))
-	assert.Equal(t, 2, len(changedPorts))
-	assert.Equal(t, 0, len(deletedPorts))
-	assert.Equal(t, updatedLogicalPorts[0], changedPorts[updatedLogicalPorts[0].Id])
-	assert.Equal(t, updatedLogicalPorts[1], changedPorts[updatedLogicalPorts[1].Id])
-}
-
-func TestLogicalDeviceAgent_diff_mix(t *testing.T) {
-	currentLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 1,
-				State:  1,
-			},
-		},
-		{
-			Id:           "1233",
-			DeviceId:     "d1234",
-			DevicePortNo: 3,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 3,
-				Name:   "port3",
-				Config: 1,
-				State:  1,
-			},
-		},
-	}
-	updatedLogicalPorts := []*voltha.LogicalPort{
-		{
-			Id:           "1231",
-			DeviceId:     "d1234",
-			DevicePortNo: 1,
-			RootPort:     true,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 1,
-				Name:   "port1",
-				Config: 4,
-				State:  4,
-			},
-		},
-		{
-			Id:           "1232",
-			DeviceId:     "d1234",
-			DevicePortNo: 2,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 2,
-				Name:   "port2",
-				Config: 4,
-				State:  4,
-			},
-		},
-		{
-			Id:           "1234",
-			DeviceId:     "d1234",
-			DevicePortNo: 4,
-			RootPort:     false,
-			OfpPort: &ofp.OfpPort{
-				PortNo: 4,
-				Name:   "port4",
-				Config: 4,
-				State:  4,
-			},
-		},
-	}
-	newPorts, changedPorts, deletedPorts := diff(currentLogicalPorts, updatedLogicalPorts)
-	assert.Equal(t, 1, len(newPorts))
-	assert.Equal(t, 2, len(changedPorts))
-	assert.Equal(t, 1, len(deletedPorts))
-	assert.Equal(t, updatedLogicalPorts[0], changedPorts[updatedLogicalPorts[0].Id])
-	assert.Equal(t, updatedLogicalPorts[1], changedPorts[updatedLogicalPorts[1].Id])
-	assert.Equal(t, currentLogicalPorts[2], deletedPorts[currentLogicalPorts[2].Id])
-}
-
 type LDATest struct {
 	etcdServer       *mock_etcd.EtcdServer
 	deviceMgr        *Manager
@@ -442,7 +120,7 @@
 				DevicePortNo: 3,
 				RootPort:     false,
 				OfpPort: &ofp.OfpPort{
-					PortNo: 4,
+					PortNo: 3,
 					Name:   "port3",
 					Config: 4,
 					State:  4,
@@ -508,6 +186,16 @@
 	clonedLD.DatapathId = rand.Uint64()
 	lDeviceAgent := newLogicalAgent(clonedLD.Id, clonedLD.Id, clonedLD.RootDeviceId, lDeviceMgr, deviceMgr, lDeviceMgr.dbPath, lDeviceMgr.ldProxy, lDeviceMgr.defaultTimeout)
 	lDeviceAgent.logicalDevice = clonedLD
+	for _, port := range clonedLD.Ports {
+		handle, created, err := lDeviceAgent.portLoader.LockOrCreate(context.Background(), port)
+		if err != nil {
+			panic(err)
+		}
+		handle.Unlock()
+		if !created {
+			t.Errorf("port %d already exists", port.OfpPort.PortNo)
+		}
+	}
 	err := lDeviceAgent.ldProxy.Set(context.Background(), clonedLD.Id, clonedLD)
 	assert.Nil(t, err)
 	lDeviceMgr.addLogicalDeviceAgentToMap(lDeviceAgent)
@@ -522,7 +210,7 @@
 	// Change the state of the first port to FAILED
 	localWG.Add(1)
 	go func() {
-		err := ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[0].DeviceId, lda.logicalDevice.Ports[0].DevicePortNo, voltha.OperStatus_FAILED)
+		err := ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[0].DevicePortNo, voltha.OperStatus_FAILED)
 		assert.Nil(t, err)
 		localWG.Done()
 	}()
@@ -530,7 +218,7 @@
 	// Change the state of the second port to TESTING
 	localWG.Add(1)
 	go func() {
-		err := ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[1].DeviceId, lda.logicalDevice.Ports[1].DevicePortNo, voltha.OperStatus_TESTING)
+		err := ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[1].DevicePortNo, voltha.OperStatus_TESTING)
 		assert.Nil(t, err)
 		localWG.Done()
 	}()
@@ -538,9 +226,9 @@
 	// Change the state of the third port to UNKNOWN and then back to ACTIVE
 	localWG.Add(1)
 	go func() {
-		err := ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[2].DeviceId, lda.logicalDevice.Ports[2].DevicePortNo, voltha.OperStatus_UNKNOWN)
+		err := ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[2].DevicePortNo, voltha.OperStatus_UNKNOWN)
 		assert.Nil(t, err)
-		err = ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[2].DeviceId, lda.logicalDevice.Ports[2].DevicePortNo, voltha.OperStatus_ACTIVE)
+		err = ldAgent.updatePortState(context.Background(), lda.logicalDevice.Ports[2].DevicePortNo, voltha.OperStatus_ACTIVE)
 		assert.Nil(t, err)
 		localWG.Done()
 	}()
@@ -582,9 +270,11 @@
 	expectedChange.Ports[1].OfpPort.State = uint32(ofp.OfpPortState_OFPPS_LINK_DOWN)
 	expectedChange.Ports[2].OfpPort.Config = originalLogicalDevice.Ports[0].OfpPort.Config & ^uint32(ofp.OfpPortConfig_OFPPC_PORT_DOWN)
 	expectedChange.Ports[2].OfpPort.State = uint32(ofp.OfpPortState_OFPPS_LIVE)
-	updatedLogicalDevice, _ := ldAgent.GetLogicalDevice(context.Background())
-	assert.NotNil(t, updatedLogicalDevice)
-	assert.True(t, proto.Equal(expectedChange, updatedLogicalDevice))
+
+	updatedLogicalDevicePorts := ldAgent.listLogicalDevicePorts()
+	for _, p := range expectedChange.Ports {
+		assert.True(t, proto.Equal(p, updatedLogicalDevicePorts[p.DevicePortNo]))
+	}
 	globalWG.Done()
 }
 
diff --git a/rw_core/core/device/logical_manager.go b/rw_core/core/device/logical_manager.go
index d6ca4ce..b3f26da 100644
--- a/rw_core/core/device/logical_manager.go
+++ b/rw_core/core/device/logical_manager.go
@@ -20,6 +20,7 @@
 	"context"
 	"errors"
 	"io"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -260,6 +261,8 @@
 	}
 	// Device is child device
 	//	retrieve parent device using child device ID
+	// TODO: return (string, have) instead of *string
+	//       also: If not root device, just return device.parentID instead of loading the parent device.
 	if parentDevice := ldMgr.deviceMgr.getParentDevice(ctx, device); parentDevice != nil {
 		return &parentDevice.ParentId, nil
 	}
@@ -276,26 +279,6 @@
 	return ldMgr.getLogicalDeviceID(ctx, device)
 }
 
-func (ldMgr *LogicalManager) getLogicalPortID(ctx context.Context, device *voltha.Device) (*voltha.LogicalPortId, error) {
-	// Get the logical device where this device is attached
-	var lDeviceID *string
-	var err error
-	if lDeviceID, err = ldMgr.getLogicalDeviceID(ctx, device); err != nil {
-		return nil, err
-	}
-	var lDevice *voltha.LogicalDevice
-	if lDevice, err = ldMgr.GetLogicalDevice(ctx, &voltha.ID{Id: *lDeviceID}); err != nil {
-		return nil, err
-	}
-	// Go over list of ports
-	for _, port := range lDevice.Ports {
-		if port.DeviceId == device.Id {
-			return &voltha.LogicalPortId{Id: *lDeviceID, PortId: port.Id}, nil
-		}
-	}
-	return nil, status.Errorf(codes.NotFound, "%s", device.Id)
-}
-
 // ListLogicalDeviceFlows returns the flows of logical device
 func (ldMgr *LogicalManager) ListLogicalDeviceFlows(ctx context.Context, id *voltha.ID) (*openflow_13.Flows, error) {
 	logger.Debugw("ListLogicalDeviceFlows", log.Fields{"logicaldeviceid": id.Id})
@@ -333,22 +316,29 @@
 // ListLogicalDevicePorts returns logical device ports
 func (ldMgr *LogicalManager) ListLogicalDevicePorts(ctx context.Context, id *voltha.ID) (*voltha.LogicalPorts, error) {
 	logger.Debugw("ListLogicalDevicePorts", log.Fields{"logicaldeviceid": id.Id})
-	if agent := ldMgr.getLogicalDeviceAgent(ctx, id.Id); agent != nil {
-		return agent.ListLogicalDevicePorts(ctx)
+	agent := ldMgr.getLogicalDeviceAgent(ctx, id.Id)
+	if agent == nil {
+		return nil, status.Errorf(codes.NotFound, "%s", id.Id)
 	}
-	return nil, status.Errorf(codes.NotFound, "%s", id.Id)
+
+	ports := agent.listLogicalDevicePorts()
+	ctr, ret := 0, make([]*voltha.LogicalPort, len(ports))
+	for _, port := range ports {
+		ret[ctr] = port
+		ctr++
+	}
+	return &voltha.LogicalPorts{Items: ret}, nil
 }
 
 // GetLogicalDevicePort returns logical device port details
 func (ldMgr *LogicalManager) GetLogicalDevicePort(ctx context.Context, lPortID *voltha.LogicalPortId) (*voltha.LogicalPort, error) {
-	// Get the logical device where this device is attached
-	var err error
-	var lDevice *voltha.LogicalDevice
-	if lDevice, err = ldMgr.GetLogicalDevice(ctx, &voltha.ID{Id: lPortID.Id}); err != nil {
-		return nil, err
+	// Get the logical device where this port is attached
+	agent := ldMgr.getLogicalDeviceAgent(ctx, lPortID.Id)
+	if agent == nil {
+		return nil, status.Errorf(codes.NotFound, "%s", lPortID.Id)
 	}
-	// Go over list of ports
-	for _, port := range lDevice.Ports {
+
+	for _, port := range agent.listLogicalDevicePorts() {
 		if port.Id == lPortID.PortId {
 			return port, nil
 		}
@@ -373,30 +363,6 @@
 	return nil
 }
 
-// deleteLogicalPort removes the logical port associated with a device
-func (ldMgr *LogicalManager) deleteLogicalPort(ctx context.Context, lPortID *voltha.LogicalPortId) error {
-	logger.Debugw("deleting-logical-port", log.Fields{"LDeviceId": lPortID.Id})
-	// Get logical port
-	var logicalPort *voltha.LogicalPort
-	var err error
-	if logicalPort, err = ldMgr.GetLogicalDevicePort(ctx, lPortID); err != nil {
-		logger.Debugw("no-logical-device-port-present", log.Fields{"logicalPortId": lPortID.PortId})
-		return err
-	}
-	// Sanity check
-	if logicalPort.RootPort {
-		return errors.New("device-root")
-	}
-	if agent := ldMgr.getLogicalDeviceAgent(ctx, lPortID.Id); agent != nil {
-		if err := agent.deleteLogicalPort(ctx, logicalPort); err != nil {
-			logger.Warnw("deleting-logicalport-failed", log.Fields{"LDeviceId": lPortID.Id, "error": err})
-		}
-	}
-
-	logger.Debug("deleting-logical-port-ends")
-	return nil
-}
-
 // deleteLogicalPort removes the logical port associated with a child device
 func (ldMgr *LogicalManager) deleteLogicalPorts(ctx context.Context, deviceID string) error {
 	logger.Debugw("deleting-logical-ports", log.Fields{"device-id": deviceID})
@@ -469,7 +435,7 @@
 		return err
 	}
 	if agent := ldMgr.getLogicalDeviceAgent(ctx, *ldID); agent != nil {
-		if err := agent.updatePortState(ctx, deviceID, portNo, state); err != nil {
+		if err := agent.updatePortState(ctx, portNo, state); err != nil {
 			return err
 		}
 	}
@@ -487,7 +453,7 @@
 		return err
 	}
 	if agent := ldMgr.getLogicalDeviceAgent(ctx, *ldID); agent != nil {
-		if err := agent.updatePortsState(ctx, device, state); err != nil {
+		if err := agent.updatePortsState(ctx, device.Id, state); err != nil {
 			return err
 		}
 	}
@@ -547,7 +513,11 @@
 	if agent == nil {
 		return nil, status.Errorf(codes.NotFound, "%s", id.Id)
 	}
-	return &empty.Empty{}, agent.enableLogicalPort(ctx, id.PortId)
+	portNo, err := strconv.ParseUint(id.PortId, 10, 32)
+	if err != nil {
+		return nil, status.Errorf(codes.InvalidArgument, "failed to parse %s as a number", id.PortId)
+	}
+	return &empty.Empty{}, agent.enableLogicalPort(ctx, uint32(portNo))
 }
 
 // DisableLogicalDevicePort disables logical device port
@@ -557,7 +527,11 @@
 	if agent == nil {
 		return nil, status.Errorf(codes.NotFound, "%s", id.Id)
 	}
-	return &empty.Empty{}, agent.disableLogicalPort(ctx, id.PortId)
+	portNo, err := strconv.ParseUint(id.PortId, 10, 32)
+	if err != nil {
+		return nil, status.Errorf(codes.InvalidArgument, "failed to parse %s as a number", id.PortId)
+	}
+	return &empty.Empty{}, agent.disableLogicalPort(ctx, uint32(portNo))
 }
 
 func (ldMgr *LogicalManager) packetIn(ctx context.Context, logicalDeviceID string, port uint32, transactionID string, packet []byte) error {
diff --git a/rw_core/core/device/logical_port/common.go b/rw_core/core/device/logical_port/common.go
new file mode 100644
index 0000000..85e6af2
--- /dev/null
+++ b/rw_core/core/device/logical_port/common.go
@@ -0,0 +1,33 @@
+/*
+ * Copyright 2020-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 Common Logger initialization
+package port
+
+import (
+	"github.com/opencord/voltha-lib-go/v3/pkg/log"
+)
+
+var logger log.Logger
+
+func init() {
+	// Setup this package so that it's log level can be modified at run time
+	var err error
+	logger, err = log.AddPackage(log.JSON, log.ErrorLevel, log.Fields{"pkg": "port"})
+	if err != nil {
+		panic(err)
+	}
+}
diff --git a/rw_core/core/device/logical_port/loader.go b/rw_core/core/device/logical_port/loader.go
new file mode 100644
index 0000000..ab6713e
--- /dev/null
+++ b/rw_core/core/device/logical_port/loader.go
@@ -0,0 +1,223 @@
+/*
+ * 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 port
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/opencord/voltha-go/db/model"
+	"github.com/opencord/voltha-lib-go/v3/pkg/log"
+	"github.com/opencord/voltha-protos/v3/go/voltha"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// Loader hides all low-level locking & synchronization related to port state updates
+type Loader struct {
+	dbProxy *model.Proxy
+	// this lock protects the ports map, it does not protect individual ports
+	lock         sync.RWMutex
+	ports        map[uint32]*chunk
+	deviceLookup map[string]map[uint32]struct{}
+}
+
+// chunk keeps a port and the lock for this port
+type chunk struct {
+	// this lock is used to synchronize all access to the port, and also to the "deleted" variable
+	lock    sync.Mutex
+	deleted bool
+
+	port *voltha.LogicalPort
+}
+
+func NewLoader(dbProxy *model.Proxy) *Loader {
+	return &Loader{
+		dbProxy:      dbProxy,
+		ports:        make(map[uint32]*chunk),
+		deviceLookup: make(map[string]map[uint32]struct{}),
+	}
+}
+
+// Load queries existing ports from the kv,
+// and should only be called once when first created.
+func (loader *Loader) Load(ctx context.Context) {
+	loader.lock.Lock()
+	defer loader.lock.Unlock()
+
+	var ports []*voltha.LogicalPort
+	if err := loader.dbProxy.List(ctx, &ports); err != nil {
+		logger.Errorw("failed-to-list-ports-from-cluster-data-proxy", log.Fields{"error": err})
+		return
+	}
+	for _, port := range ports {
+		loader.ports[port.OfpPort.PortNo] = &chunk{port: port}
+		loader.addLookup(port.DeviceId, port.OfpPort.PortNo)
+	}
+}
+
+// LockOrCreate locks this port if it exists, or creates a new port if it does not.
+// In the case of port creation, the provided "port" must not be modified afterwards.
+func (loader *Loader) LockOrCreate(ctx context.Context, port *voltha.LogicalPort) (*Handle, bool, error) {
+	// try to use read lock instead of full lock if possible
+	if handle, have := loader.Lock(port.OfpPort.PortNo); have {
+		return handle, false, nil
+	}
+
+	loader.lock.Lock()
+	entry, have := loader.ports[port.OfpPort.PortNo]
+	if !have {
+		entry := &chunk{port: port}
+		loader.ports[port.OfpPort.PortNo] = entry
+		loader.addLookup(port.DeviceId, port.OfpPort.PortNo)
+		entry.lock.Lock()
+		loader.lock.Unlock()
+
+		if err := loader.dbProxy.Set(ctx, fmt.Sprint(port.OfpPort.PortNo), port); err != nil {
+			// revert the map
+			loader.lock.Lock()
+			delete(loader.ports, port.OfpPort.PortNo)
+			loader.removeLookup(port.DeviceId, port.OfpPort.PortNo)
+			loader.lock.Unlock()
+
+			entry.deleted = true
+			entry.lock.Unlock()
+			return nil, false, err
+		}
+		return &Handle{loader: loader, chunk: entry}, true, nil
+	}
+	loader.lock.Unlock()
+
+	entry.lock.Lock()
+	if entry.deleted {
+		entry.lock.Unlock()
+		return loader.LockOrCreate(ctx, port)
+	}
+	return &Handle{loader: loader, chunk: entry}, false, nil
+}
+
+// Lock acquires the lock for this port, and returns a handle which can be used to access the port until it's unlocked.
+// This handle ensures that the port cannot be accessed if the lock is not held.
+// Returns false if the port is not present.
+// TODO: consider accepting a ctx and aborting the lock attempt on cancellation
+func (loader *Loader) Lock(id uint32) (*Handle, bool) {
+	loader.lock.RLock()
+	entry, have := loader.ports[id]
+	loader.lock.RUnlock()
+
+	if !have {
+		return nil, false
+	}
+
+	entry.lock.Lock()
+	if entry.deleted {
+		entry.lock.Unlock()
+		return loader.Lock(id)
+	}
+	return &Handle{loader: loader, chunk: entry}, true
+}
+
+// Handle is allocated for each Lock() call, all modifications are made using it, and it is invalidated by Unlock()
+// This enforces correct Lock()-Usage()-Unlock() ordering.
+type Handle struct {
+	loader *Loader
+	chunk  *chunk
+}
+
+// GetReadOnly returns an *voltha.LogicalPort which MUST NOT be modified externally, but which is safe to keep indefinitely
+func (h *Handle) GetReadOnly() *voltha.LogicalPort {
+	return h.chunk.port
+}
+
+// Update updates an existing port in the kv.
+// The provided "port" must not be modified afterwards.
+func (h *Handle) Update(ctx context.Context, port *voltha.LogicalPort) error {
+	if err := h.loader.dbProxy.Set(ctx, fmt.Sprint(port.OfpPort.PortNo), port); err != nil {
+		return status.Errorf(codes.Internal, "failed-update-port-%v: %s", port.OfpPort.PortNo, err)
+	}
+	h.chunk.port = port
+	return nil
+}
+
+// Delete removes the device from the kv
+func (h *Handle) Delete(ctx context.Context) error {
+	if err := h.loader.dbProxy.Remove(ctx, fmt.Sprint(h.chunk.port.OfpPort.PortNo)); err != nil {
+		return fmt.Errorf("couldnt-delete-port-from-store-%v", h.chunk.port.OfpPort.PortNo)
+	}
+	h.chunk.deleted = true
+
+	h.loader.lock.Lock()
+	delete(h.loader.ports, h.chunk.port.OfpPort.PortNo)
+	h.loader.removeLookup(h.chunk.port.DeviceId, h.chunk.port.OfpPort.PortNo)
+	h.loader.lock.Unlock()
+
+	h.Unlock()
+	return nil
+}
+
+// Unlock releases the lock on the port
+func (h *Handle) Unlock() {
+	if h.chunk != nil {
+		h.chunk.lock.Unlock()
+		h.chunk = nil // attempting to access the port through this handle in future will panic
+	}
+}
+
+// ListIDs returns a snapshot of all the managed port IDs
+// TODO: iterating through ports safely is expensive now, since all ports are stored & locked separately
+//       should avoid this where possible
+func (loader *Loader) ListIDs() map[uint32]struct{} {
+	loader.lock.RLock()
+	defer loader.lock.RUnlock()
+	// copy the IDs so caller can safely iterate
+	ret := make(map[uint32]struct{}, len(loader.ports))
+	for id := range loader.ports {
+		ret[id] = struct{}{}
+	}
+	return ret
+}
+
+// ListIDsForDevice lists ports belonging to the specified device
+func (loader *Loader) ListIDsForDevice(deviceID string) map[uint32]struct{} {
+	loader.lock.RLock()
+	defer loader.lock.RUnlock()
+	// copy the IDs so caller can safely iterate
+	devicePorts := loader.deviceLookup[deviceID]
+	ret := make(map[uint32]struct{}, len(devicePorts))
+	for id := range devicePorts {
+		ret[id] = struct{}{}
+	}
+	return ret
+}
+
+func (loader *Loader) addLookup(deviceID string, portNo uint32) {
+	if devicePorts, have := loader.deviceLookup[deviceID]; have {
+		devicePorts[portNo] = struct{}{}
+	} else {
+		loader.deviceLookup[deviceID] = map[uint32]struct{}{portNo: {}}
+	}
+}
+
+func (loader *Loader) removeLookup(deviceID string, portNo uint32) {
+	if devicePorts, have := loader.deviceLookup[deviceID]; have {
+		delete(devicePorts, portNo)
+		if len(devicePorts) == 0 {
+			delete(loader.deviceLookup, deviceID)
+		}
+	}
+}
diff --git a/rw_core/core/device/manager.go b/rw_core/core/device/manager.go
index c7af54a..d12cee9 100755
--- a/rw_core/core/device/manager.go
+++ b/rw_core/core/device/manager.go
@@ -1168,23 +1168,6 @@
 	return nil
 }
 
-// DeleteLogicalPort removes the logical port associated with a device
-func (dMgr *Manager) DeleteLogicalPort(ctx context.Context, device *voltha.Device) error {
-	logger.Info("deleteLogicalPort")
-	var err error
-	// Get the logical port associated with this device
-	var lPortID *voltha.LogicalPortId
-	if lPortID, err = dMgr.logicalDeviceMgr.getLogicalPortID(ctx, device); err != nil {
-		logger.Warnw("getLogical-port-error", log.Fields{"deviceId": device.Id, "error": err})
-		return err
-	}
-	if err = dMgr.logicalDeviceMgr.deleteLogicalPort(ctx, lPortID); err != nil {
-		logger.Warnw("deleteLogical-port-error", log.Fields{"deviceId": device.Id})
-		return err
-	}
-	return nil
-}
-
 // DeleteLogicalPorts removes the logical ports associated with that deviceId
 func (dMgr *Manager) DeleteLogicalPorts(ctx context.Context, cDevice *voltha.Device) error {
 	logger.Debugw("delete-all-logical-ports", log.Fields{"device-id": cDevice.Id})
diff --git a/rw_core/core/device/meter/loader.go b/rw_core/core/device/meter/loader.go
index daae9ae..c597006 100644
--- a/rw_core/core/device/meter/loader.go
+++ b/rw_core/core/device/meter/loader.go
@@ -30,11 +30,10 @@
 
 // Loader hides all low-level locking & synchronization related to meter state updates
 type Loader struct {
+	dbProxy *model.Proxy
 	// this lock protects the meters map, it does not protect individual meters
 	lock   sync.RWMutex
 	meters map[uint32]*chunk
-
-	dbProxy *model.Proxy
 }
 
 // chunk keeps a meter and the lock for this meter
@@ -48,8 +47,8 @@
 
 func NewLoader(dbProxy *model.Proxy) *Loader {
 	return &Loader{
-		meters:  make(map[uint32]*chunk),
 		dbProxy: dbProxy,
+		meters:  make(map[uint32]*chunk),
 	}
 }
 
@@ -86,8 +85,6 @@
 		loader.lock.Unlock()
 
 		if err := loader.dbProxy.Set(ctx, fmt.Sprint(meter.Config.MeterId), meter); err != nil {
-			logger.Errorw("failed-adding-meter-to-db", log.Fields{"meterID": meter.Config.MeterId, "err": err})
-
 			// revert the map
 			loader.lock.Lock()
 			delete(loader.meters, meter.Config.MeterId)
@@ -130,6 +127,8 @@
 	return &Handle{loader: loader, chunk: entry}, true
 }
 
+// Handle is allocated for each Lock() call, all modifications are made using it, and it is invalidated by Unlock()
+// This enforces correct Lock()-Usage()-Unlock() ordering.
 type Handle struct {
 	loader *Loader
 	chunk  *chunk
@@ -173,10 +172,10 @@
 	}
 }
 
-// List returns a snapshot of all the managed meter IDs
+// ListIDs returns a snapshot of all the managed meter IDs
 // TODO: iterating through meters safely is expensive now, since all meters are stored & locked separately
 //       should avoid this where possible
-func (loader *Loader) List() map[uint32]struct{} {
+func (loader *Loader) ListIDs() map[uint32]struct{} {
 	loader.lock.RLock()
 	defer loader.lock.RUnlock()
 	// copy the IDs so caller can safely iterate