Glossary
98 (98)
EN/LZT 108 6492 R1
April 2003
UDP
Short for User Datagram Protocol, a connectionless protocol that, like TCP, runs on
top of IP networks. Unlike TCP/IP, UDP/IP provides very few error recovery services,
offering instead a direct way to send and receive datagrams over an IP network. It's
used primarily for broadcasting messages over a network.
Upstream
The direction of an upstream signal is from the user's computer to the ISP/service
provider (uploading).
VPI and VCI
A VPI (Virtual Path Identifier) is an 8-bit field while VCI (Virtual Channel
Identifier) is a 16-bit field in the ATM cell header. A VPI identifies a link formed by
a vritual path and a VCI identifies a channel within a vritual path. A unique and
separate VPI/VCI identifier is assigned in advance to indicate which type of cells
follow. Your ISP should supply you with the values.
WAN
Short for Wide Area Network, a computer network that spans a relatively large
geographical area. Typically, a WAN consists of two or more local-area networks
(LANs).
