Datagram Support

The following are the datagram support commands:

• NCBDGRECV (receive datagram)
• NCBDGRECVBC (receive broadcast datagram)
• NCBDGSEND (send datagram)
• NCBDGSENDBC (send broadcast datagram)

Datagram support provides unreliable connectionless data transfer. The message is a single data frame whose size is limited to a MAC frame minus any headers. The protocol driver ensures that the message is transmitted to the network medium. The receiver does not generate a response to the sender to indicate that the datagram was received. Therefore, unreliable connectionless data transfer requires fewer system resources than reliable connection-oriented data transfer.

The NCBDGRECV and NCBDGSEND commands transfer a datagram to a specified NetBIOS name. If the specified name is a unique name, the datagram is received by the single process that registered the name. If the specified name is a group name, the datagram is received by all processes that registered the name. This process is shown in the following illustration.

The NCBDGSENDBC command broadcasts a datagram to all computers on the network. The datagram is received by all processes that have issued the NCBDGRECVBC command, as shown in the following illustration.