Open System Services NFS SCF Reference Manual

Glossary
Open System Services NFS SCF Reference Manual—522582-001
Glo ssary-11
Transmission Control Protocol over Internet Protocol
(TCP/IP)
on. TCP allows a process on one system to send a stream of data to a process on another.
It is connection-oriented; that is, before transmitting data, participants must establish a
connection.
Software implementing TCP usually resides on the operating system and uses the
Internet Protocol (IP) to transmit information across the Internet. It is possible to
terminate (shut down) one direction of flow across a TCP connection, leaving a one-way
(simplex) connection.
The Internet protocol suite is often referred to as TCP/IP because TCP is one of the two
most fundamental protocols. The TCP protocol is used by applications that require
reliable end-to-end data transfer. The TCP protocol is a byte-stream-oriented protocol
that includes no concept of packet boundaries; the only guarantee is that all of the data
sent will be received in the same order in which it was sent.
Transmission Control Protocol over Internet Protocol (TCP/IP). See Transmission
Control Protocol (TCP) and Internet Protocol (IP).
UDP. See User Datagram Protocol (UDP)
.
User Datagram Protocol (UDP). The Internet-standard protocol that allows an application
program on one system to send a datagram to an application program on another system.
UDP uses the Internet Protocol (IP) to deliver datagrams. Conceptually, the important
difference between UDP and IP is that UDP messages include a protocol port number,
allowing the sender to distinguish among multiple destinations (application programs)
on the remote system. In practice, UDP also includes a checksum over the data being
sent.
UDP provides unreliable datagram service. The integrity of the packets of data sent is
maintained; however, the delivery of the packet is not guaranteed. When a packet is
received, though, it is guaranteed to be exactly what was sent from the remote site. Also,
the ordering of datagrams is not guaranteed; it is possible to receive packets out of order
when using UDP.
XDR. See external data representation (XDR)
.