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Flashcards in WAN Fundamentals Deck (17):

Leased line service delivers....

bits in both directions, at a predetermined speed, using full-duplex logic


Telco ...

installs a large network of cables and specialized switching devices to create its own computer network


To create a leased line...

a physical path must exist between the routers on the ends of the link; usually a large and complex network that gives the appearance of a cable between two routers


Telcos put their equipment in....

Central offices (COs) where they connect cables from COs to buildings where they expect to sell their services


Customer premises equipment includes:

router, serial interface card (within router?), CSU/DSU


CSU/DSU typically provides

the clock rate


The serial cables normally used between a router and external CSU/DSU are called

Data Terminal Equipment (DTE) cables; male cable


DCE cables are....

cables that are female and have the equivalent task of an Ethernet crossover cable


A leased line provides a ________ service

Layer 1


Two most popular DLL protocols for leased lines

High Level Data Link Control (HDLC) and Point to Point Protocol (PPP)
SN: Organizations create Layer 2 protocols for WAN links


Ethernet as a WAN technology basics

The customer connects to an Ethernet link using a router interface.
The fiber leaves the customer building and conncts to some nearby Service Provider location called a point of presence (POP) by using an Ethernet switch


Ethernet over MPLS (EoMPLS) provides:

A point-to-point connection between two customer devices
Behavior as if a fiber Ethernet link existed between the two devices
Simply two routers with a single Ethernet link between the two routers; uses Ethernet header and trailer over the WAN link


Main idea of WANs

give IP routers a way to forward IP packets from a LAN at one site, over the WAN, and to another LAN at another site.


What all three Internet access technologies have in common:

they use a pair of routers: one at the customer side of the WAN link and one at the ISP side.


Digital Subscriber LIne (DSL)

Creates a relatively short (miles long, not tens of miles) high speed WAN link between a telco customer and an ISP; utilizes the same single-pair telephone line used for a typical home phone line


In order to have DSL service:

You need DSL capable devices such as a DSL modem and the telco has to add DSL equipment at the CO; telco uses a DSL Access Multiplexer (DSLAM) to differentiate data between voice signals and Internet connections via a router


Cable Internet

utilizes cable TV cable (CATV) to send data; similar to DSL; both send data faster downstream than upstream; telephone line is replaced with coaxial cable from CATV company and uses a cable modem instead of a DSL