[ONOS-3222] Implement toString method for each Packet class

Change-Id: I17d72338d4202117d08b3dca9463be35a87a0c1e
diff --git a/utils/misc/src/main/java/org/onlab/packet/LLC.java b/utils/misc/src/main/java/org/onlab/packet/LLC.java
index 78b4f3f..bd2739f 100644
--- a/utils/misc/src/main/java/org/onlab/packet/LLC.java
+++ b/utils/misc/src/main/java/org/onlab/packet/LLC.java
@@ -20,13 +20,12 @@
 
 import java.nio.ByteBuffer;
 
+import static com.google.common.base.MoreObjects.toStringHelper;
 import static org.onlab.packet.PacketUtils.*;
 
 /**
  * This class represents an Link Local Control header that is used in Ethernet
  * 802.3.
- *
- *
  */
 public class LLC extends BasePacket {
 
@@ -99,4 +98,13 @@
             return llc;
         };
     }
+
+    @Override
+    public String toString() {
+        return toStringHelper(getClass())
+                .add("dsap", Byte.toString(dsap))
+                .add("ssap", Byte.toString(ssap))
+                .add("ctrl", Byte.toString(ctrl))
+                .toString();
+    }
 }