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Services in a Converged
WAN
Accessing the WAN
Chapter 1
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
A WAN is a data communications network thatoperates beyond the geographic scope of a LAN.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Three major characteristics of WANs:
WANs generally connect devices that are separated by a broadergeographical area than can be served by a LAN.
WANs use the services of carriers, such as telephone companies,cable companies, satellite systems, and network providers.
WANs use serial connections of various types to provide access tobandwidth over large geographic areas.
People in the regional or branch offices of an organization need tobe able to communicate and share data with the central site.
Organizations often want to share information with otherorganizations across large distances.
Employees who travel on company business frequently need toaccess information that resides on their corporate networks.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
networks become complex and expensive to manage.
Because the network is a mixture of newer and older technologies,it can be difficult to support and maintain.
Outages and poor performance
Cisco Enterprise Architecture that has relevance to the differentstages of growth of a business.
designed to provide network plannerswith a roadmap for network growth asthe business moves through different
stages
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Enterprise Campus Architecture
A campus network is a building or group of buildingsconnected into one enterprise network that consists ofmany LANs. A campus is generally limited to a fixed
geographic area, but it can span several neighboringbuildings
methods to create a scalable network, while addressingthe needs of campus-style business operations.
The architecture is modular and can easily expand toinclude additional campus buildings or floors as theenterprise grows.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Enterprise Edge Architecture
voice, video, and data services outside the enterprise.
use Internet and partner resources, and provide
resources for its customers. This module often functions as a liaison between the
campus module and the other modules in the EnterpriseArchitecture.
Enterprise Branch Architecture
extend the applications and services to remote locationsand users
focuses on the technologies that are often implemented
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Describe the Key WAN TechnologyConcepts
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Customer Premises Equipment (CPE)-The devices and inside wiring locatedat the premises of the subscriber and connected with a telecommunicationchannel of a carrier.
Data Communications Equipment (DCE)- primarily provides an interface toconnect subscribers to a communication link on the WAN cloud.
Data Terminal Equipment (DTE)-The customer devices that pass the datafrom a customer network for transmission over the WAN.
Demarcation Point- separate customer equipment from service providerequipment. Physically, the demarcation point is the cabling junction box,located on the customer premises, that connects the CPE wiring to the local
loop. Local Loop- cable that connects the CPE at the subscriber site to the CO of
the service provider.
Central Office (CO)-A local service provider facility or building where localtelephone cables link to long-haul, all-digital, fiber-optic communicationslines through a system of switches and other equipment.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Modem-Modulates and demodulates the carrier signal
CSU/DSU- The CSU provides termination for the digital signal andensures connection integrity through error correction and linemonitoring. The DSU converts the T-carrier line frames into framesthat the LAN can interpret and vice versa.
Access server- Concentrates dial-in and dial-out usercommunications.
WAN switch- switch traffic such as Frame Relay, ATM, or X.25.PSTN switches used for circuit-switched connections, Integrated
Services Digital Network (ISDN) or analog dialup. Router-Provides internetworking and WAN access interface ports.
Core router- backbone of the WAN. able to support multipletelecommunications interfaces of the highest speed in use in theWAN core
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
A circuit-switchednetwork is one thatestablishes a dedicatedcircuit (or channel)between nodes and
terminals before theusers may communicate.
PSTN and ISDN are twotypes of circuit-switchingtechnology that may be
used to implement aWAN in an enterprisesetting.
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Describe the Key WAN TechnologyConcepts
packet switching splitstraffic data into packetsthat are routed over ashared network
Connectionless Connection-oriented
Frame RelayDataLink Connection
Identifiers (DLCIs).
Lower costs
More delay and jitter
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Select the Appropriate WAN Technology to meetECNM Requirements
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
permanent dedicated connections, leased from a carrier and arecalled leased lines.
provide a pre-established WAN communications path from thecustomer premises to a remote destination.
More expensive based on bandwidth and distance Advantages: removes latency or jitter
between the endpoints, Constantavailability
Disadvantages: capacity unused,
increases equipment costs,Any changes require a site visit bythe carrier.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Integrated Services Digital Network (ISDN) is a circuit-switching technology
64 kb/s bearer channels (B) for carrying voice or data
signaling, delta channel (D) for call setup and other purposes.
Basic Rate Interface (BRI)- provides two 64 kb/s B channels and a 16 kb/s Dchannel.
Primary Rate Interface (PRI)- 23 B channels with 64 kb/s and one D channelwith 64 kb/s in North America, 1.544 Mb/s. In Europe, Australia, and otherparts 30 B channels and one D channel, 2.048 Mb/s
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Select the Appropriate WAN Technology to meetECNM Requirements
Frame Relay
simpler protocol that works at the DataLink
no error or flow control, reducedlatency,
data rates up to 4 Mb/s Frame Relay VCs are identified by a
DLCI, which ensures bidirectionalcommunication from one DTE device toanother.
provides permanent, shared, medium-bandwidth connectivity that carries bothvoice and data traffic.
cost-effective connections betweenwidely scattered LANs.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Asynchronous Transfer Mode (ATM)
technology is capable of transferringvoice, video, and data throughprivate and public networks.
ATM cells fixed length of 53 bytes : 5byte ATM header followed by 48
bytes of ATM payload. voice and video traffic because of
less delay.
support link speeds of T1/E1 to OC-12 (622 Mb/s) and higher.
ATM offers both PVCs and SVCs,although PVCs are more commonwith WANs.
multiple VCs on a single leased-lineconnection to the network edge.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
DSL technology usesexisting twisted-pairtelephone lines totransport high-bandwidth data, and
provides IP servicesto subscribers.
Multiple DSLsubscriber lines aremultiplexed into a
single, high-capacitylink using a DSLaccess multiplexer(DSLAM) at theprovider location.
data rates of up to8.192 Mb/s.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
A VPN is an encrypted connection between privatenetworks over a public network such as the Internet.
uses virtual connections called VPN tunnels, which arerouted through the Internet from the private network of
the company to the remote site
VPN Benefits
Cost savings
Security
Scalability
Compatibility with broadband technology
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Site-to-site VPNs
connect entire networksto each other
Each site is equippedwith a VPN gateway,such as a router,firewall, VPNconcentrator, orsecurity appliance.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Remote-access VPNs
enable individual hoststo access a companynetwork securely overthe Internet.
VPN client softwareloaded or uses a web-based client.
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Describe How ECNM Provides IntegratedServices over an Enterprise Network
Reducedexpenses andadministration
Easy integrationwith existingnetworks
Enhanced
businessproductivity
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Summary
A WAN is defined as
A data communications network that operates beyond thegeographic scope of a LAN
WAN primarily operate on layer 1 & 2 of the OSI model
WAN technologies include
Leased line
ISDN
Frame relay
X.25
ATM
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Summary
Cisco Enterprise Architecture
This is an expansion of the hierarchical model that furtherdivides the enterprise network into
Physical areas
Logical areas
Functional areas
Selecting the appropriate WAN technology requiresconsidering some of the following:
WANs purpose
Geographic scope of WANTraffic requirements
If WAN uses a public or private infrastructure
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