diff --git a/internal/multiplex/frameSorter.go b/internal/multiplex/frameSorter.go
index 0679673..236f3fe 100644
--- a/internal/multiplex/frameSorter.go
+++ b/internal/multiplex/frameSorter.go
@@ -86,6 +86,7 @@ func (fs *frameSorter) Close() error {
 // recvNewFrame is a forever running loop which receives frames unordered,
 // cache and order them and send them into sortedBufCh
 func (fs *frameSorter) recvNewFrame() {
+	// TODO: add timeout
 	defer log.Tracef("a recvNewFrame has returned gracefully")
 	for {
 		f := <-fs.newFrameCh
diff --git a/internal/multiplex/switchboard.go b/internal/multiplex/switchboard.go
index bec8c5f..8e02fb5 100644
--- a/internal/multiplex/switchboard.go
+++ b/internal/multiplex/switchboard.go
@@ -67,7 +67,8 @@ func (sb *switchboard) removeConn(connId uint32) {
 }
 
 // a pointer to connId is passed here so that the switchboard can reassign it
-func (sb *switchboard) send(data []byte, connId *uint32) (int, error) {
+func (sb *switchboard) send(data []byte, connId *uint32) (n int, err error) {
+	sb.Valve.rxWait(len(data))
 	sb.connsM.RLock()
 	defer sb.connsM.RUnlock()
 	if sb.strategy == UNIFORM_SPREAD {
@@ -76,13 +77,17 @@ func (sb *switchboard) send(data []byte, connId *uint32) (int, error) {
 		if !ok {
 			return 0, errBrokenSwitchboard
 		} else {
-			return conn.Write(data)
+			n, err = conn.Write(data)
+			sb.AddTx(int64(n))
+			return
 		}
 	} else {
 		var conn net.Conn
 		conn, ok := sb.conns[*connId]
 		if ok {
-			return conn.Write(data)
+			n, err = conn.Write(data)
+			sb.AddTx(int64(n))
+			return
 		} else {
 			// do not call assignRandomConn() here.
 			// we'll have to do connsM.RLock() after we get a new connId from assignRandomConn, in order to
@@ -99,7 +104,9 @@ func (sb *switchboard) send(data []byte, connId *uint32) (int, error) {
 			if !ok {
 				return 0, errBrokenSwitchboard
 			} else {
-				return conn.Write(data)
+				n, err = conn.Write(data)
+				sb.AddTx(int64(n))
+				return
 			}
 		}
 	}
diff --git a/internal/multiplex/switchboard_test.go b/internal/multiplex/switchboard_test.go
index 756cc83..49bc4cd 100644
--- a/internal/multiplex/switchboard_test.go
+++ b/internal/multiplex/switchboard_test.go
@@ -1,6 +1,7 @@
 package multiplex
 
 import (
+	"github.com/cbeuw/Cloak/internal/util"
 	"math/rand"
 	"testing"
 )
@@ -9,17 +10,13 @@ func BenchmarkSwitchboard_Send(b *testing.B) {
 	seshConfig := &SessionConfig{
 		Obfuscator: nil,
 		Valve:      nil,
-		UnitRead:   nil,
+		UnitRead:   util.ReadTLS,
 	}
 	sesh := MakeSession(0, seshConfig)
-	sbConfig := &switchboardConfig{
-		Valve:    UNLIMITED_VALVE,
-		strategy: FIXED_CONN_MAPPING,
-	}
-	sb := makeSwitchboard(sesh, sbConfig)
+
 	hole := newBlackHole()
-	sb.addConn(hole)
-	connId, err := sb.assignRandomConn()
+	sesh.sb.addConn(hole)
+	connId, err := sesh.sb.assignRandomConn()
 	if err != nil {
 		b.Error("failed to get a random conn", err)
 		return
@@ -28,7 +25,7 @@ func BenchmarkSwitchboard_Send(b *testing.B) {
 	rand.Read(data)
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
-		n, err := sb.send(data, &connId)
+		n, err := sesh.sb.send(data, &connId)
 		if err != nil {
 			b.Error(err)
 			return
@@ -36,3 +33,54 @@ func BenchmarkSwitchboard_Send(b *testing.B) {
 		b.SetBytes(int64(n))
 	}
 }
+
+func TestSwitchboard_TxCredit(t *testing.T) {
+	seshConfig := &SessionConfig{
+		Obfuscator: nil,
+		Valve:      MakeValve(1<<20, 1<<20),
+		UnitRead:   util.ReadTLS,
+	}
+	sesh := MakeSession(0, seshConfig)
+	hole := newBlackHole()
+	sesh.sb.addConn(hole)
+	connId, err := sesh.sb.assignRandomConn()
+	if err != nil {
+		t.Error("failed to get a random conn", err)
+		return
+	}
+	data := make([]byte, 1000)
+	rand.Read(data)
+
+	t.Run("FIXED CONN MAPPING", func(t *testing.T) {
+		*sesh.sb.Valve.(*LimitedValve).tx = 0
+		sesh.sb.strategy = FIXED_CONN_MAPPING
+		n, err := sesh.sb.send(data[:10], &connId)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if n != 10 {
+			t.Errorf("wanted to send %v, got %v", 10, n)
+			return
+		}
+		if *sesh.sb.Valve.(*LimitedValve).tx != 10 {
+			t.Error("tx credit didn't increase by 10")
+		}
+	})
+	t.Run("UNIFORM", func(t *testing.T) {
+		*sesh.sb.Valve.(*LimitedValve).tx = 0
+		sesh.sb.strategy = UNIFORM_SPREAD
+		n, err := sesh.sb.send(data[:10], &connId)
+		if err != nil {
+			t.Error(err)
+			return
+		}
+		if n != 10 {
+			t.Errorf("wanted to send %v, got %v", 10, n)
+			return
+		}
+		if *sesh.sb.Valve.(*LimitedValve).tx != 10 {
+			t.Error("tx credit didn't increase by 10")
+		}
+	})
+}