VOL-1077 added NNI port and management port distinction

Change-Id: Ie24e05aa927661bb9a227d04e565018ce5523cd6
diff --git a/ponsim/v2/core/ponsim_device.go b/ponsim/v2/core/ponsim_device.go
index 13cae92..3fc52a5 100644
--- a/ponsim/v2/core/ponsim_device.go
+++ b/ponsim/v2/core/ponsim_device.go
@@ -111,7 +111,9 @@
 		forwarded := 0
 		links := o.links[int(egressPort)]
 
-		o.Counter.CountTxFrame(int(egressPort), len(common.GetEthernetLayer(egressFrame).Payload))
+		if int(egressPort) <= 2 && int(egressPort) > 0 {
+			o.Counter.CountTxFrame(int(egressPort), len(common.GetEthernetLayer(egressFrame).Payload))
+		}
 
 		for _, link := range links {
 			forwarded += 1