Introduction to WAN
Accessing the WAN – Chapter 1
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Objectives
ƒ Introduction to WAN
ƒ WAN technology concepts
ƒ Internet connection options
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The purpose and function of WANs
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The Hierarchical Design Model
Access layer - Grants user access to network devices.
Distribution layer - aggregates WAN connections at the
edge of the campus and provides policy-based connectivity.
Core layer - high-speed backbone that is designed to switch
packets as fast as possible.
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The Enterprise Architecture
Different businesses
need different types of
networks.
Some examples
of the modules:
Enterprise Campus Architecture
Enterprise Branch Architecture
Enterprise Data Center Architecture
Enterprise Teleworker Architecture
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Describe the Key WAN Technology
Concepts
WAN operations focus primarily on Layer 1 and Layer 2.
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WAN Physical Layer Terminology
ƒ Customer Premises
Equipment
ƒ Data
Communications
Equipment
ƒ Data Terminal
Equipment
ƒ Demarcation Point
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WAN Physical Layer Standards
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WAN Data Link Layer Standards
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WAN Frame Encapsulation Formats
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Circuit Switching
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Packet Switching
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Various options for connecting subscribers to the WAN
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Leased line
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VPN Technology
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Factors to consider when selecting a WAN
connection
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Factors to consider when selecting a WAN
connection (cont.)
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Summary
ƒ A WAN is defined as
A data communications network that operates beyond the
geographic scope of a LAN
ƒ WAN primarily operate on layer 1 & 2 of the OSI model
ƒ WAN technologies include
–Leased line
–ISDN
–Frame relay
–X.25
–ATM
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Summary
ƒ Cisco Enterprise Architecture
–This is an expansion of the hierarchical model that further
divides the enterprise network into
•Physical areas
•Logical areas
•Functional areas
ƒ Selecting the appropriate WAN technology requires
considering some of the following:
–WAN’s purpose
–Geographic scope of WAN
–Traffic requirements
–If WAN uses a public or private infrastructure
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