PDF of this tutorialADM
add-drop multiplexer
ANSI
American National Standards Institute
ATM
asynchronous transfer mode; a form of fast short packet switching and multiplexing
AU
administrative unit; a managed entity within the SDH structure
BISDN
broadband integrated services digital network
CCITT
Comité Consultif International Telegraphique et Telephonique; in English, Consultative Committee on International Telegraphy and Telephony; predecessor of ITU–TS11
DCC
data communications channel; the main management channel inside SDH
DCS
digital cross-connect system; an electronic multiport switch for digital traffic
DXC
digital cross-connect; see DCS
ETSI
European Telecommunications Standards Institute
FDDI
fiber distributed data interface; a short range 100 Mbps interface used between large computing nodes
IDLC
integrated digital loop carrier; a North American system for connecting an exchange/central office to subscribers over a large area via fiber
IP
Internet protocol; a component of protocol for many computer links including the Internet
LAN
local-area network; a linked group of computers
MAN
metropolitan-area network; an area network for public broadband traffic
NNI
network node interface; a defined interface between nodes in the public network
PDH
plesiochronous digital hierarchy; the widely deployed transmission system which predates SDH
POH
path overhead; a group of management communications facilities in SDH
SDH
synchronous digital hierarchy
SOH
section overhead; a group of management communications facilities in SDH
SONET
synchronous optical network; the North American variant of SDH
STM
synchronous transport module; the basic unit of transmission in SDH
TU
tributary unit; the basic unit of payload together with its management overheads and synchronisation data
TUG
tributary unit group; a managed group of TU
UNI
user-network interface; a defined interface between the user and the public network
VC
virtual container; the basic unit of payload together with its management overheads
