下列范例使用 UdpClient，在通訊端口11000傳送UDP 資料包至多點(diǎn)傳送位址群組 224.268.100.2。它傳送命令列上指定的信息字串。

[C#] 
using System; 
using System.Net; 
using System.Net.Sockets; 
using System.Text; 
public class UDPMulticastSender { 

private static IPAddress GroupAddress = 
IPAddress.Parse("224.168.100.2"); 
private static int GroupPort = 11000; 

private static void Send( String message) { 
UdpClient sender = new UdpClient(); 
IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort); 

try { 
Console.WriteLine("Sending datagram : {0}", message); 
byte[] bytes = Encoding.ASCII.GetBytes(message); 

sender.Send(bytes, bytes.Length, groupEP); 

sender.Close(); 

} catch (Exception e) { 
Console.WriteLine(e.ToString()); 
} 

} 

public static int Main(String[] args) { 
Send(args[0]); 

return 0; 
} 
} 

下列范例使用 UdpClient，在通訊端口 11000 監(jiān)聽廣播到多點(diǎn)傳送位址群組 224.168.100.2 的 UDP 資料包还蹲。它接收信息字串，并將信息寫入主控臺(tái) (Console)耙考。

[C#] 
using System; 
using System.Net; 
using System.Net.Sockets; 
using System.Text; 
public class UDPMulticastListener { 

private static readonly IPAddress GroupAddress = 
IPAddress.Parse("224.168.100.2"); 
private const int GroupPort = 11000; 

private static void StartListener() { 
bool done = false; 

UdpClient listener = new UdpClient(); 
IPEndPoint groupEP = new IPEndPoint(GroupAddress,GroupPort); 

try { 
listener.JoinMulticastGroup(GroupAddress); 
listener.Connect(groupEP); 

while (!done) { 
Console.WriteLine("Waiting for broadcast"); 
byte[] bytes = listener.Receive( ref groupEP); 

Console.WriteLine("Received broadcast from {0} :/n {1}/n", 
groupEP.ToString(), 
Encoding.ASCII.GetString(bytes,0,bytes.Length)); 
} 

listener.Close(); 

} catch (Exception e) { 
Console.WriteLine(e.ToString()); 
} 

} 

public static int Main(String[] args) { 
StartListener(); 

return 0; 
} 
}