4.4 Connectionless RPCs With and Without a Delayed ACK

The following example illustrates the client sending an ACK packet.

Client sending an ACK packet

Figure 25: Client sending an ACK packet

There is no ACK sent between the RPCs with sequence numbers 0 and 1 because less than 2 seconds elapse between RPC 0's last response PDU and RPC 1's first request PDU.

The corresponding delay between sequence 1 and sequence 2 is larger than 2 seconds, so 2 seconds after the last response PDU of call 1, the client sends an ACK packet whose sequence number is 1. This does not affect the PDUs for call sequence 2.