UdpAnySourceMulticastClient.UnblockSource Method

Unblocks a source that was previously blocked by a call to the BlockSource method so that multicast packets originating from it can be received.

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


<SecuritySafeCriticalAttribute> _
Public Sub UnblockSource ( _
    sourceAddress As IPAddress _
public void UnblockSource(
    IPAddress sourceAddress



Exception Condition

The multicast group has not yet been joined.


The UdpAnySourceMulticastClient has been disposed.


An error occurred when attempting to access the socket. See the Remarks section for more information.


The UnblockSource method unblocks multicast packets originating from a specified source address so they can be received. The specified source address must have previously been blocked by a call to the BlockSource method.

The client must have completed a join to the multicast group.

The sourceAddress parameter may be either an IPv6 or IPv4 multicast address.

If the specified source address in the sourceAddress parameter was not previously blocked by a call to the BlockSource method, a SocketException is thrown with SocketError.AddressNotAvailable.

If there is a socket failure while performing the unblock source operation, a SocketException is thrown. The error received is specified as a member of the System.Net.Sockets.SocketError enumeration.

Version Information


Supported in: 5, 4

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1


For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.