Sketched out packet service and related abstractions.
diff --git a/core/api/src/main/java/org/onlab/onos/net/packet/Treatment.java b/core/api/src/main/java/org/onlab/onos/net/packet/Treatment.java
new file mode 100644
index 0000000..411ec38
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/net/packet/Treatment.java
@@ -0,0 +1,21 @@
+package org.onlab.onos.net.packet;
+
+import org.onlab.onos.net.PortNumber;
+
+/**
+ * Abstraction of different kinds of treatment that can be applied to an
+ * outbound packet.
+ */
+public interface Treatment {
+
+ // TODO: implement these later: modifications, group
+ // TODO: elsewhere provide factory methods for some default treatments
+
+ /**
+ * Returns the port number where the packet should be emitted.
+ *
+ * @return output port number
+ */
+ PortNumber output();
+
+}