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UdpClient.DropMulticastGroup Method (IPAddress)

Leaves a multicast group.

Namespace:  System.Net.Sockets
Assembly:  System (in System.dll)

public void DropMulticastGroup(
	IPAddress multicastAddr


Type: System.Net.IPAddress

The IPAddress of the multicast group to leave.


The underlying Socket has been closed.


An error occurred when accessing the socket. See the Remarks section for more information.


The IP address is not compatible with the AddressFamily value that defines the addressing scheme of the socket.


multicastAddr is null.

The DropMulticastGroup method withdraws the UdpClient from the multicast group identified by the specified IPAddress. After calling the DropMulticastGroup method, the underlying Socket sends an Internet Group Management Protocol (IGMP) packet to the router, removing the router from the multicast group. After a UdpClient withdraws from the group, it will no longer be able to receive datagrams sent to that group.


If you receive a SocketException, use SocketException.ErrorCode to obtain the specific error code. Once you have obtained this code, you can refer to the Windows Sockets version 2 API error code documentation in MSDN for a detailed description of the error.

The following example demonstrates how to drop a multicast group by providing a multicast address.

      // Send data to ClientTarget.
      Console.WriteLine("\nThe ClientOriginator sent:\n");
      Send.OriginatorSendData(clientOriginator, m_ClientTargetdest);

      // Receive data from ClientTarget
      Ret = Receive.ReceiveUntilStop(clientOriginator);

      // Stop the ClientTarget thread

      // Abandon the multicast group.

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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