Please note that the content of this book primarily consists of articles
available from Wikipedia or other free sources online. One problem that
must be resolved when using a Transmission Control Protocol (TCP) is how
to deal with timeouts and retransmissions. The round-trip delay time or
round-trip time (RTT) is a big factor in helping to decide what to do in
each case. RTT may also be used to find the best possible route. In
telecommunications, the RTT is the length of time it takes for a signal
to be sent plus the length of time it takes for an acknowledgment of
that signal to be received. In the context of computer networks, the
signal is generally a data packet, and the RTT time is also known as the
ping time. An internet user can determine the RTT by using the ping
command. In space technology, the round-trip delay time or Round Trip
Light Time is the time light (and hence any signals) takes to go to the
spacecraft and to return.
