Weidmuller GPRS Alarm Unit - Manual (Page 93)

Glossary
9-91
T
• TCP
The Transmission Control Protocol (TCP) is a reliable, connection-
oriented transfer protocol in computer networks. It is part of the
TCP/IP protocol family. TCP provides a virtual channel between
two computers (more exactly: the end points (sockets) of two
applications on these computers). Data can be transferred on this
channel in both directions. In the most cases, TCP is based on the
IP protocol.
U
• UDP
The User Datagram Protocol (UDP) is a minimum network protocol
without connection. It is part of the transport layer of the TCP/IP
protocol family and is - in contrast to TCP - not designed for
reliability. UDP has the main objective to extend the connection to
the end system established by the IP layer by a user interface
(ports). The quality of the underlying services, in particular, the
reliability of the transfer, however, is not increased by the UDP.
• Upload
Upload is a technical term from the field of IT. During an upload,
data are transferred from a computer to a remote station (e.g.
network computer, Internet). The upload is thus the opposite to the
download.
V
• VPN
A Virtual Private Network (VPN) is a computer network that uses a
public network (for example, the Internet) to transfer private data.
Subscribers to a VPN can exchange data in the same way as in an
internal LAN. The connection of the networks is provided by a
tunnel between VPN client and VPN server. In the most cases, the
tunnel is secured, but an unsecured clear-text tunnel is also a VPN.
IP VPNs use the Internet for transferring IP packets independently
of the transmission network, which - in contrast to direct remote
access to an internal network (direct dialling, for example, via ISDN,
GSM...) - provides significantly more flexibility and is more cost-
effective.