8.1 - Dedicated-Circuit Networks Flashcards
______________ typically run long distances, connecting different offices in different cities or countries
Wide area networks (WANs)
______________ are private companies (e.g., AT&T, Bell Canada, Sprint, etc.) that provide communication services to the public
Common carriers
Common carriers are ________ oriented
profit
Common carriers’ primary products are services for voice and data transmissions, both over traditional __________ circuits and ___________ services
wired…cellular
A common carrier that provides local telephone services is commonly called a ______________ (LEC)
local exchange carrier
A common carrier that provides long-distance services is commonly called an ______________ (IXC)
interexchange carrier
With a dedicated-circuit network, the user leases circuits from the common carrier for his ______________
exclusive use
Dedicated-circuit networks is sometimes called ______________
private line services
The equipment of the basic architecture of a dedicated-circuit network may include ______________ or a channel service unit (CSU), and/or a data service unit (DSU)
multiplexers
A CSU/DSU is the WAN equivalent of a ______________ in a LAN
network interface card (NIC)
Three basic architectures used in dedicated-circuit networks
- Ring
- Star
- Mesh
A ______________ connects all computers in a closed loop with each computer linked to the next
ring architecture
Circuits of ring architecture are ______________ or half-duplex circuits — messages flow in both directions around the ring
full-duplex
A ______________ connects all computers to one central architecture that routes messages to the appropriate computer
star architecture
In a __________ architecture, every computer is connected to every other computer
full-mesh
A ______________ architecture is seldom used because of the extremely high cost (in circuit implementation)
full-mesh
______________ architecture (usually called just mesh architecture) many but not all computers are connected to each other
Partial-mesh
Most WANs use __________ topologies
partial-mesh
Two types of dedicated-circuit services in common use today:
- T-Carrier services
- Synchronous Optical Network (SONET)
______________ are the most commonly used form of dedicated-circuit services (esp in North America)
T-Carrier services
Costs are a fixed amount per month, regardless of how much or how little traffic flows through the circuit
T-Carrier Services
A ___________ (also called a DS1 circuit) provides a data rate of 1.544 Mbps
T1 circuit
Often used to transmit both data and voice; enables 24 simultaneous voice channels
T1 circuit
______________ allows transmission rate of 44.736 Mbps (equivalent to 28 T1 circuit capacity)
T3 circuit
The _____________________ is the American standard (ANSI) for high-speed dedicated-circuit services
synchronous optical network (SONET)
ITU-T recently standardized an almost identical service that easily interconnects with SONET under the name __________________________
synchronous digital hierarchy (SDH)
