Chapter 9 Flashcards
(38 cards)
What is a common carrier?
A private company that sells or leases voice and data communication services to the public.
What is a local exchange carrier (LEC)?
A common carrier that provides local telephone services.
What is an interexchange carrier (IXC)?
A common carrier that provides long-distance services.
Who regulates common carriers in the U.S.?
The FCC regulates interstate and international; state PUCs handle intrastate.
What is MPLS?
A Layer 2.5 tech that adds a 4-byte label between Layer 2 and Layer 3 to help route packets efficiently.
How does MPLS work?
It adds a label with QoS info between the frame and IP packet for routing inside a carrier’s network.
How do dedicated-circuit services differ from packet-switched services?
Dedicated circuits are always-on and used only by one connection; packet-switched allows many to share the same network.
Why is a WAN with dedicated circuits harder to design?
Because contracts are fixed and changes are expensive; network design must be done carefully.
What is a ring architecture?
Each computer connects to two others in a loop; messages go around the ring.
What is a star architecture?
All computers connect to a central node that routes messages.
What is a mesh architecture?
Many devices are directly connected; offers multiple paths and better redundancy.
What is a T-1 line?
A digital circuit offering 1.544 Mbps, often used for both voice and data.
What is the speed of a T-3 circuit?
44.736 Mbps; can carry the equivalent of 28 T-1s.
What is SONET?
A U.S. optical standard for high-speed transmission; starts at 51.84 Mbps (OC-1).
How does SONET differ from SDH?
Both are nearly the same; SONET is U.S. standard, SDH is international; SONET offers more speeds.
What is packet switching?
A method where data is split into packets and sent over shared circuits; more efficient and flexible.
Where does packetizing happen?
At the PAD (packet assembly/disassembly device), which converts data into packets for the network.
What is frame relay?
A packet-switching tech that doesn’t perform error correction; offers CIR and MAR data rates.
What is CIR?
The guaranteed minimum data rate for a frame relay virtual circuit.
What is MAR?
The max data rate a frame relay circuit tries to deliver; packets over CIR may be discarded.
What is SMDS?
A connectionless, unreliable packet-switching service using 53-byte cells like ATM.
What are Ethernet services?
WAN services that use Ethernet and IP over fiber to simplify WAN design and reduce conversion.
What are the benefits of Ethernet services?
No protocol conversion, easier integration with LANs, high speed, and lower cost.
How is MPLS different from other WAN options?
It can work over any Layer 2 tech and supports multiple routing features.
