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Chapter 1
Introduction to WAN
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Objetives
Describe how the Enterprise Architectureprovides integrated services over an enterprisenetwork.
Describe key WAN technology concepts.
Select the appropriate WAN technology tomeet different enterprise business requirements.
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WAN Definition
Generally connect devices that are separated by abroad geographical area.
Use the services of carriers (telephone companies,cable companies, satellite systems, and network
providers)
Use serial connections of various types to provide
access to bandwidth.
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WAN Definition
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Growing Business Small Office Home
Office
Few employees LAN for sharing
peripherals andInternet
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Growing Business
Campus Network
Medium size (100+
employees) Multiple LANs
Limited to a fixed
geographic area In-house IT staff
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Growing Business
Headquarter andbranches
IT team and data center
Multiple LANs
WAN connection
Hierarchical modelneeds expansion
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Growing Business
Distributed network
Large size (1000+
employees) Multiple LANs
WAN connection
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Hierarchical Model
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Enterprise Architecture Expansion of the hierarchical model
Divides the enterprise network into:
Physical areas Logical areas
Functional areas
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Enterprise Architecture
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Enterprise Architecture:Campus
Connects the users, server farm and Enterpriseedge
Modular and allows enterprise grows
Include:
Access
Distribution
Core
Server Farm/ Data Center
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Enterprise Architecture:Enterprise Edge
Aggregates the connectivity from variousfunctional areas
Routes the traffic into the campus coresubmodule
Allows the networks to use resources
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Enterprise Architecture:External sites
Branch
Allows businesses to extend the applications andservices to remote locations
Data Center
Responsible for managing and maintaining thedata systems
Teleworker To telecommute is to leverage the network
resources of the enterprise from home
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Enterprise Architectures
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WAN Technologies
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WAN Physical Layer Terminology
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WAN Physical Layer Terminology
Customer Premises Equipment (CPE)
Equipment located at the subscribers premises andconnected with a telecom channel of a carrier.
Data Communications Equipment (DCE) Devices that put data on the local loop.
Provides an interface to connect subscribers to acommunication link on the WAN cloud.
Data Terminal Equipment (DTE)
Customer devices that pass the data from a customer fortransmission over the WAN.
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WAN Physical Layer Terminology
Demarcation Point
Separate customer equipment from serviceprovider equipment and its responsability-
Physically, is the cabling junction box.
Local Loop
Last-mile
Connects the CPE to the CO
Central Office (CO)
Local service provider facility
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WAN Physical Layer
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WAN Physical Layer Standards
EIA/TIA-232
Up to 64 kb/s on 25-pin D-connector (RS-232)
EIA/TIA-449/530
Up to 2 Mb/s on 36-pin D-connector (RS-422 / RS-423)
EIA/TIA612/613 (HSSI)
Up to 52 Mb/s on a 60-pin D-connector.
V-35
Up to 2.048 Mb/s using a 34-pin rectangular connector.
X.21
Synchronous digital communications /15-pin D-connector.
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WAN data link layer protocols
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WAN Switching technologies
A circuit-switched network establishes a dedicatedcircuit (or channel) between nodes and terminalsbefore the users may communicate.
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WAN Switching technologies
Packet switching splits traffic data into packets that
are routed over a shared network. Do not require a circuit to be established, and they
allow many pairs of nodes to communicate overthe same channel.
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WAN Technologies
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Leased Lines
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Leased Lines
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Circuit switching: Analog Dial-up
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Circuit switching: ISDN
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Packet switching: X.25
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Packet switching: Frame Relay
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Packet switching: ATM
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Internet Connection: DSL
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Internet Connection: Cable Modem
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Internet Connection: Broadband Wireless
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Internet Connection: VPN
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Internet Connection: VPN
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Internet Connection: MetroEthernet
Reduced expensesand administration
Easy integration withexisting networks
Enhanced businessproductivity
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Choosing WAN Connection
Purpose of the WAN
Geografic Scope
Traffic Requirements Type
Volumes
Quality
Security
Private or Public
Cost
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Choosing WAN Connection
Option Advantage Disadvantage
Leased line Most secure Expensive
Circuit Switching Less expensive Call setup
Packet Switching Less expensive Shared mediaCell Relay (ATM) Best for simulated
use of voice anddata
Overhead
Internet Least expensiveGlobally available
Least Secure
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Summary
The enterprise architecture is an expansion ofthe hierarchical model
WAN works over physical and Data LinkLayer
WAN technologies:
Leased lines
Circuit Switching
Packet Switching