diff --git a/gradle.properties b/gradle.properties
index 3b1c07f..baf5c51 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -1,3 +1,3 @@
 projectId               = jperf
 projectGroup            = biz.nellemann.jperf
-projectVersion          = 0.0.2
+projectVersion          = 0.0.3
diff --git a/src/main/java/biz/nellemann/jperf/Application.java b/src/main/java/biz/nellemann/jperf/Application.java
index 3748326..772180e 100644
--- a/src/main/java/biz/nellemann/jperf/Application.java
+++ b/src/main/java/biz/nellemann/jperf/Application.java
@@ -20,20 +20,24 @@ public class Application implements Callable<Integer> {
     final Logger log = LoggerFactory.getLogger(Application.class);
 
 
-    @CommandLine.Option(names = { "-c", "--connect" }, paramLabel = "SERVER", description = "run client and connect to remote server")
-    String remoteServer;
+    @CommandLine.ArgGroup(exclusive = true, multiplicity = "1")
+    RunMode runMode;
 
-    @CommandLine.Option(names = { "-s", "--server" }, description = "run server and wait for client")
-    boolean runServer = false;
+    static class RunMode {
+        @CommandLine.Option(names = { "-c", "--connect" }, required = true, description = "Connect to remote server", paramLabel = "HOST")
+        String remoteServer;
 
-    @CommandLine.Option(names = { "-l", "--pkt-size" }, paramLabel = "SIZE", description = "datagram size in bytes, max 65507 [default: ${DEFAULT-VALUE}]")
-    //int packetSize = 16384; // Min: 256  Max: 65507
+        @CommandLine.Option(names = { "-s", "--server" }, required = true, description = "Run server and wait for client")
+        boolean runServer = false;
+    }
+
+    @CommandLine.Option(names = { "-l", "--pkt-len" }, paramLabel = "SIZE", description = "Datagram size in bytes, max 65507 [default: ${DEFAULT-VALUE}]")
     int packetSize = 65507; // Min: 256  Max: 65507
 
-    @CommandLine.Option(names = { "-n", "--pkt-num" }, paramLabel = "NUM", description = "number of packets to send [default: ${DEFAULT-VALUE}]")
-    int packetCount = 5000;
+    @CommandLine.Option(names = { "-n", "--pkt-num" }, paramLabel = "NUM", description = "Number of packets to send [default: ${DEFAULT-VALUE}]")
+    int packetCount = 150_000;
 
-    @CommandLine.Option(names = { "-p", "--port" }, paramLabel = "PORT", description = "network port [default: ${DEFAULT-VALUE}]")
+    @CommandLine.Option(names = { "-p", "--port" }, paramLabel = "PORT", description = "Network port [default: ${DEFAULT-VALUE}]")
     int port = 4445;
 
 
@@ -41,12 +45,10 @@ public class Application implements Callable<Integer> {
     @Override
     public Integer call() throws Exception { // your business logic goes here...
 
-        if(runServer) {
+        if(runMode.runServer) {
             runServer();
-        }
-
-        if(remoteServer != null) {
-            runClient(remoteServer);
+        } else if(runMode.remoteServer != null) {
+            runClient(runMode.remoteServer);
         }
 
         return 0;
diff --git a/src/main/java/biz/nellemann/jperf/Datagram.java b/src/main/java/biz/nellemann/jperf/Datagram.java
index 4ddc014..12300c4 100644
--- a/src/main/java/biz/nellemann/jperf/Datagram.java
+++ b/src/main/java/biz/nellemann/jperf/Datagram.java
@@ -13,7 +13,7 @@ import org.slf4j.LoggerFactory;
  *
  * Datagram consists of the following
  * <p>
- * <------------------------- HEADER 32 bytes -------------->  <---------- DATA min 32 bytes -------->
+ * <------------------------- HEADER 32 bytes -------------->  <---------- DATA bytes min 32, max 65475 -------->
  *      _long      _int     _int       _long     _long
  *     8_bytes   4_bytes   4_bytes    8_bytes   8_bytes
  *    MAGIC-ID     TYPE    LENGTH     CUR_PKT    MAX_PKT
@@ -24,10 +24,7 @@ public class Datagram {
 
     final Logger log = LoggerFactory.getLogger(Datagram.class);
 
-    private final Random random = new Random();
-
     private final int HEADER_LENGTH = 32;
-
     private final byte[] MAGIC_ID = "jPerfTok".getBytes(StandardCharsets.UTF_8);    // Must be 8-bytes
 
     private final int type;
diff --git a/src/main/java/biz/nellemann/jperf/UdpClient.java b/src/main/java/biz/nellemann/jperf/UdpClient.java
index 8859e19..642929a 100644
--- a/src/main/java/biz/nellemann/jperf/UdpClient.java
+++ b/src/main/java/biz/nellemann/jperf/UdpClient.java
@@ -22,8 +22,6 @@ public class UdpClient {
     private final DatagramSocket socket;
 
     private byte[] buf = new byte[256];
-    private long packetsSent = 0;
-    private long bytesSent = 0;
 
     private int packetCount;
     private int packetSize;