Appendix D: Glossary
MM701G and MM702G User Manual 153
traps
Autonomous, interrupt-driven, SNMP messages sent from a managed node to a
network management station to indicate that an event has occurred.
UAS
UnAvailable Seconds is the number of seconds during which the line is unavailable.
UBR
Unspecified Bit Rate is an ATM traffic type used for LAN traffic. When network
congestion occurs, the data is stored in a buffer until it can be sent.
UDP
User Datagram Protocol is a transport protocol used to map inbound traffic (from a
remote IP address) to an internal (LAN) IP address. Uses a protocol port number for
the destination at the remote location.
upstream traffic
Communications from a user to a service provider.
VCI
Virtual Channel Identifier is a 16-bit field addressing identifier in the header of an ATM
cell used to route cell traffic. It identifies a particular VC link for a given VP.
VCMUX
Virtual Channel Multiplexer-based encapsulation used for networks with large
numbers of virtual channels making it practical to carry a single protocol per virtual
channel.
VC
A Virtual Channel is a logical connection in the ATM network over which ATM cells are
transmitted.
VPI
Virtual Path Identifier is an 8-bit field addressing identifier in the header of an ATM
cell that is used to route cell traffic. It identifies a particular VP link.
VP
A Virtual Path is a group of VCs carried between two points. The VP provides a means
of bundling traffic traveling in the same direction. VPs are defined by a unique VPI
value.
WAN
Wide Area Network is a network consisting of nodes located across a large
geographical area. Also, the connection between a service provider and MM Modem.