Game Development Reference
In-Depth Information
ledgement of receipt. If the sender does not get the acknowledgement after a cer-
tain period of time (the
timeout
), it will resend the packet. The sender will contin-
ue sending that packet until it finally receives an acknowledgement, as illustrated
in
Figure 12.3
.
Figure 12.3
In TCP, the sender keeps sending a packet until it receives an ac-
knowledgement.
It turns out that TCP guarantees not only that all packets will be received, but that
they will be received in the order they were sent. For example, suppose that three
packets are sent in the order A, B, and C. If packets A and C arrive, but B doesn't,
the receiver cannot process packet C until it gets packet B. So it has to wait for
packet B to be resent, and then once it finally is received, it'll be able to move on.
Depending onthe
packet loss
,orpercentage ofpackets that don'tmake itthrough,
this could really slow down the transmission of data, as shown in
Figure 12.4
.
Figure 12.4
TCP packets received out of order.
