Pertemuan 1
WAN
1
Discussion Topics
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Introduction to WANs
Introduction to routers in a WAN
Router LANs and WANs
Role of routers in a WAN
Academy approach to hands-on labs
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Introduction to WANs
• A WAN is a data communications network
that spans a large geographic area such
as a state, province, or country.
WAN Devices
The following devices are used in WANs:
•Routers offer many services, including internetworking and WAN
interface ports.
•Modems include interface voice-grade services, channel service
units/digital service units (CSU/DSUs) that interface T1/E1 services, and
Terminal Adapters/Network Termination 1 (TA/NT1s) that interface
Integrated Services Digital Network (ISDN) services.
•Communication servers concentrate dial in and dial out user
communication.
WAN Services
Data Link Encapsulations
WAN data link protocols describe how frames are carried between systems on a
single data link. They include protocols designed to operate over dedicated pointto-point, multipoint, and multi-access switched services such as Frame Relay. WAN
standards are defined and managed by a number of recognized authorities,
including the following agencies:
•International Telecommunication Union-Telecommunication Standardization
Sector (ITU-T), formerly the Consultative Committee for International Telegraph
and Telephone (CCITT)
•International Organization for Standardization (ISO)
•Internet Engineering Task Force (IETF)
•Electronic Industries Association (EIA)
Routers Connected by WAN
Technologies
Internal Configuration
Components
RAM
RAM has the following characteristics and functions:
•Stores routing tables
•Holds ARP cache
•Holds fast-switching cache
•Performs packet buffering as shared RAM
•Maintains packet-hold queues
•Provides temporary memory for the configuration file of a
router while the router is powered on
•Loses content when a router is powered down or restarted
NVRAM , FLASH MEMORY
NVRAM has the following characteristics and functions:
•Provides storage for the startup configuration file
•Retains content when a router is powered down or restarted
Flash memory has the following characteristics and functions:
•Holds the IOS image
•Allows software to be updated without removing and replacing chips on
the processor
•Retains content when a router is powered down or restarted
•Can store multiple versions of IOS software
•Is a type of electrically erasable programmable read-only memory
(EEPROM)
ROM , INTERFACE
ROM has the following characteristics and functions:
•Maintains instructions for power-on self test (POST) diagnostics
•Stores bootstrap program and basic operating system software
•Requires replacing pluggable chips on the motherboard for software
upgrades
Interfaces have the following characteristics and functions:
•Connect routers to a network for packet entry and exit
•Can be on the motherboard or on a separate module
Path Determination
Internetwork Routers
• Any internetwork must include the following:
– Consistent end-to-end addressing
– Addresses that represent network topologies
– Best path selection
– Dynamic or static routing
– Switching
Academy Approach to Labs
• In the academy lab, all the networks will
be connected with serial or Ethernet
cables and the students can see and
physically touch all the equipment.
• Devices that make up the WAN cloud are
simulated by the connection between the
back-to-back DTE-DCE cables.