Podcast
Questions and Answers
What is the primary purpose of a WAN?
What is the primary purpose of a WAN?
- To interconnect multiple LANs over large distances (correct)
- To serve as a local connection for remote users
- To manage individual device communications
- To connect devices within the same geographic location
Who typically owns a WAN?
Who typically owns a WAN?
- Non-profit organizations
- A service provider (correct)
- An individual organization
- Local government authorities
Which statement describes the necessity of WANs?
Which statement describes the necessity of WANs?
- WANs are primarily used for connecting mobile devices.
- WANs are only useful for large organizations.
- WANs allow for isolated communication within LANs.
- WANs enable communication between geographically separated sites. (correct)
What must an organization do to utilize a WAN service?
What must an organization do to utilize a WAN service?
What is a characteristic of the Point-to-Point WAN topology?
What is a characteristic of the Point-to-Point WAN topology?
Which of the following is NOT a commonly cited reason for using WANs?
Which of the following is NOT a commonly cited reason for using WANs?
What type of connection typically represents a dedicated leased-line in WANs?
What type of connection typically represents a dedicated leased-line in WANs?
Why would organizations need WANs as they expand?
Why would organizations need WANs as they expand?
What type of connection do branch offices in nearby cities use for their WAN?
What type of connection do branch offices in nearby cities use for their WAN?
Which OSI layers are primarily focused on in WAN operations?
Which OSI layers are primarily focused on in WAN operations?
What must the WAN provide to remote sites as the company grows?
What must the WAN provide to remote sites as the company grows?
How has SPAN Engineering aimed to increase profitability in their network management?
How has SPAN Engineering aimed to increase profitability in their network management?
What kind of WAN connection must offices located in other countries utilize?
What kind of WAN connection must offices located in other countries utilize?
What is the primary function of the Data Service Unit (DSU)?
What is the primary function of the Data Service Unit (DSU)?
Which of the following accurately describes circuit-switched networks?
Which of the following accurately describes circuit-switched networks?
In circuit-switched technology, what must occur before users can communicate?
In circuit-switched technology, what must occur before users can communicate?
What is a characteristic of packet-switched networks?
What is a characteristic of packet-switched networks?
How does connectionless packet switching operate?
How does connectionless packet switching operate?
What is an example of circuit-switched technology?
What is an example of circuit-switched technology?
Which of the following is NOT a type of circuit-switched WAN technology?
Which of the following is NOT a type of circuit-switched WAN technology?
What does a core router or multilayer switch do?
What does a core router or multilayer switch do?
What is one disadvantage of the hub-and-spoke topology?
What is one disadvantage of the hub-and-spoke topology?
Which topology allows any site to communicate directly with any other site?
Which topology allows any site to communicate directly with any other site?
What is a critical disadvantage of implementing a full mesh topology?
What is a critical disadvantage of implementing a full mesh topology?
What is one characteristic of dual-homed topology?
What is one characteristic of dual-homed topology?
In terms of network efficiency, what do businesses typically focus on during economic downturns?
In terms of network efficiency, what do businesses typically focus on during economic downturns?
What is often expected from networks to justify large expenses?
What is often expected from networks to justify large expenses?
How does the dual-homed topology relate to load balancing?
How does the dual-homed topology relate to load balancing?
What does the hub-and-spoke topology facilitate among spoke sites?
What does the hub-and-spoke topology facilitate among spoke sites?
Which organization is NOT mentioned as responsible for defining and managing WAN access standards?
Which organization is NOT mentioned as responsible for defining and managing WAN access standards?
What does Layer 2 protocol primarily define?
What does Layer 2 protocol primarily define?
Which of the following best describes Customer Premises Equipment (CPE)?
Which of the following best describes Customer Premises Equipment (CPE)?
What is the primary role of Data Communications Equipment (DCE)?
What is the primary role of Data Communications Equipment (DCE)?
Which of the following is a key difference between WAN and LAN?
Which of the following is a key difference between WAN and LAN?
What does Data Terminal Equipment (DTE) refer to?
What does Data Terminal Equipment (DTE) refer to?
Which component primarily interfaces with the local loop in a WAN environment?
Which component primarily interfaces with the local loop in a WAN environment?
Which of the following best describes a common terminology associated with WAN connections?
Which of the following best describes a common terminology associated with WAN connections?
A WAN is typically owned by an organization.
A WAN is typically owned by an organization.
Organizations must pay a fee to utilize WAN service provider networks.
Organizations must pay a fee to utilize WAN service provider networks.
WANs are only used for transmitting voice data.
WANs are only used for transmitting voice data.
Point-to-Point topology employs a circuit between multiple endpoints.
Point-to-Point topology employs a circuit between multiple endpoints.
Without WANs, LANs would be interconnected networks.
Without WANs, LANs would be interconnected networks.
T1/E1 lines are examples of dedicated leased-line connections typically used in WANs.
T1/E1 lines are examples of dedicated leased-line connections typically used in WANs.
Employees traveling for business do not need access to the corporate network via WANs.
Employees traveling for business do not need access to the corporate network via WANs.
One of the main purposes of WANs is to communicate between geographically separated sites.
One of the main purposes of WANs is to communicate between geographically separated sites.
The branch offices that are in nearby cities use public dedicated lines through their local service provider.
The branch offices that are in nearby cities use public dedicated lines through their local service provider.
Offices located in other countries utilize a secure private network for their WAN connection.
Offices located in other countries utilize a secure private network for their WAN connection.
WAN operations primarily focus on the physical and network layer of the OSI Model.
WAN operations primarily focus on the physical and network layer of the OSI Model.
Circuit switching requires a dedicated circuit established before communication can begin.
Circuit switching requires a dedicated circuit established before communication can begin.
Packet switching establishes a dedicated connection between nodes before data can be sent.
Packet switching establishes a dedicated connection between nodes before data can be sent.
To reduce operating expenses, SPAN Engineering needs to provide converged service and secure Internet WAN connectivity.
To reduce operating expenses, SPAN Engineering needs to provide converged service and secure Internet WAN connectivity.
The network requirements of a company can remain constant as the company grows over time.
The network requirements of a company can remain constant as the company grows over time.
The Integrated Services Digital Network (ISDN) is a commonly cited type of packet-switched WAN technology.
The Integrated Services Digital Network (ISDN) is a commonly cited type of packet-switched WAN technology.
Connectionless systems require full addressing information to be included in each packet.
Connectionless systems require full addressing information to be included in each packet.
Dialing a number to make a call exemplifies packet switching technology.
Dialing a number to make a call exemplifies packet switching technology.
The two most common types of circuit-switched WAN technologies are PSTN and ISDN.
The two most common types of circuit-switched WAN technologies are PSTN and ISDN.
The Data Service Unit (DSU) converts WAN frames into packet-switched formats.
The Data Service Unit (DSU) converts WAN frames into packet-switched formats.
A core router resides within the backbone of a WAN.
A core router resides within the backbone of a WAN.
WAN access standards are managed by organizations such as TIA/EIA and ISO.
WAN access standards are managed by organizations such as TIA/EIA and ISO.
Layer 1 protocols focus on how data is encapsulated for transmission.
Layer 1 protocols focus on how data is encapsulated for transmission.
Customer Premises Equipment (CPE) is found on the service provider's end of a WAN connection.
Customer Premises Equipment (CPE) is found on the service provider's end of a WAN connection.
Data Communications Equipment (DCE) consists of devices that connect customers to local loops.
Data Communications Equipment (DCE) consists of devices that connect customers to local loops.
Data Terminal Equipment (DTE) is responsible for transmitting data from a WAN to the internet.
Data Terminal Equipment (DTE) is responsible for transmitting data from a WAN to the internet.
A company needs to subscribe to a WAN service provider to use WAN services.
A company needs to subscribe to a WAN service provider to use WAN services.
DCE is often referred to as a type of customer device in the WAN.
DCE is often referred to as a type of customer device in the WAN.
WAN connections utilize both Layer 1 and Layer 2 protocols for data transmission.
WAN connections utilize both Layer 1 and Layer 2 protocols for data transmission.
The Central Office (CO) connects customer equipment directly to the public telephone network.
The Central Office (CO) connects customer equipment directly to the public telephone network.
A CSU/DSU is necessary for digital-leased lines to maintain signal integrity.
A CSU/DSU is necessary for digital-leased lines to maintain signal integrity.
Broadband modems utilize lower frequencies than voiceband modems.
Broadband modems utilize lower frequencies than voiceband modems.
Dialup modems are modern WAN technology used primarily for high-speed internet access.
Dialup modems are modern WAN technology used primarily for high-speed internet access.
The local loop is the fiber cable connecting the Central Office to the customer premises.
The local loop is the fiber cable connecting the Central Office to the customer premises.
Toll networks consist of short-distance analog lines used for communication.
Toll networks consist of short-distance analog lines used for communication.
Access servers coordinate communications for both dial-in and dial-out users.
Access servers coordinate communications for both dial-in and dial-out users.
Customer Premises Equipment (CPE) includes devices used solely for service provider maintenance.
Customer Premises Equipment (CPE) includes devices used solely for service provider maintenance.
Match the following WAN purposes with their descriptions:
Match the following WAN purposes with their descriptions:
Match the following WAN topologies with their characteristics:
Match the following WAN topologies with their characteristics:
Match the following WAN connection types with their descriptions:
Match the following WAN connection types with their descriptions:
Match the following WAN technologies with their corresponding service:
Match the following WAN technologies with their corresponding service:
Match the following WAN operations with their primary focus areas:
Match the following WAN operations with their primary focus areas:
Match the following terms related to WAN with their definitions:
Match the following terms related to WAN with their definitions:
Match the following benefits of WANs with their related features:
Match the following benefits of WANs with their related features:
Match the following aspects of WAN ownership with their implications:
Match the following aspects of WAN ownership with their implications:
Match the following statements about SPAN Engineering with their implications:
Match the following statements about SPAN Engineering with their implications:
Match the following WAN characteristics with their definitions:
Match the following WAN characteristics with their definitions:
Match the following benefits of WAN with their impacts:
Match the following benefits of WAN with their impacts:
Match the following statements about WANs with their significance:
Match the following statements about WANs with their significance:
Match the following statements about WAN service providers with their roles:
Match the following statements about WAN service providers with their roles:
Match the following WAN topologies with their characteristics:
Match the following WAN topologies with their characteristics:
Match the following WAN topologies with their disadvantages:
Match the following WAN topologies with their disadvantages:
Match the following terms with their definitions in relation to WANs:
Match the following terms with their definitions in relation to WANs:
Match the following networking concepts to their implications for efficiency:
Match the following networking concepts to their implications for efficiency:
Match the following routing methods to their descriptions:
Match the following routing methods to their descriptions:
Match the following features with the appropriate topologies:
Match the following features with the appropriate topologies:
Match the following scenarios with the optimal WAN topology:
Match the following scenarios with the optimal WAN topology:
Match the purpose of WANs with their economic implications:
Match the purpose of WANs with their economic implications:
Match the following WAN components with their definitions:
Match the following WAN components with their definitions:
Match the following authorities with their responsibilities in WAN access standards:
Match the following authorities with their responsibilities in WAN access standards:
Match the following OSI layers with their relevance to WAN protocols:
Match the following OSI layers with their relevance to WAN protocols:
Match the following WAN terms with their descriptions:
Match the following WAN terms with their descriptions:
Match the following WAN topologies to their characteristics:
Match the following WAN topologies to their characteristics:
Match the following protocols with their functions in WAN communication:
Match the following protocols with their functions in WAN communication:
Match the following WAN characteristics with their descriptions:
Match the following WAN characteristics with their descriptions:
Match the following WAN connection types with their attributes:
Match the following WAN connection types with their attributes:
Match the following WAN components with their descriptions:
Match the following WAN components with their descriptions:
Match the WAN devices with their functions:
Match the WAN devices with their functions:
Match the following WAN technology terms with their definitions:
Match the following WAN technology terms with their definitions:
Match the following types of WAN connections with their characteristics:
Match the following types of WAN connections with their characteristics:
Match the following WAN characteristics with their corresponding technology:
Match the following WAN characteristics with their corresponding technology:
Match the following WAN connection types with their descriptions:
Match the following WAN connection types with their descriptions:
Match the following WAN service roles with their functions:
Match the following WAN service roles with their functions:
Match the following terminologies with their definitions in WAN:
Match the following terminologies with their definitions in WAN:
The company was required to implement a ______ in order for the remote sites to be able to access the data center.
The company was required to implement a ______ in order for the remote sites to be able to access the data center.
Offices located in other countries must use the ______ for their WAN connection.
Offices located in other countries must use the ______ for their WAN connection.
WAN operations focus primarily on the physical and ______ layer of the OSI Model.
WAN operations focus primarily on the physical and ______ layer of the OSI Model.
The cost of the network and its related ______ is a significant expense for the company.
The cost of the network and its related ______ is a significant expense for the company.
To meet new requirements, the network must provide the necessary ______ service and secure Internet WAN connectivity.
To meet new requirements, the network must provide the necessary ______ service and secure Internet WAN connectivity.
SPAN Engineering has developed a special process for converting household waste into ______.
SPAN Engineering has developed a special process for converting household waste into ______.
The initial structure of SPAN Engineering includes a small office with ______ employees.
The initial structure of SPAN Engineering includes a small office with ______ employees.
SPAN Engineering connects to the Internet using ______.
SPAN Engineering connects to the Internet using ______.
After five years, SPAN Engineering was contracted to design and implement a full-sized waste conversion ______.
After five years, SPAN Engineering was contracted to design and implement a full-sized waste conversion ______.
As of the latest update, SPAN Engineering occupies multiple ______ of an office building.
As of the latest update, SPAN Engineering occupies multiple ______ of an office building.
The company has expanded its operations by opening small ______ offices closer to project sites.
The company has expanded its operations by opening small ______ offices closer to project sites.
Now classified as a small to medium-sized business, SPAN Engineering has ______ employees.
Now classified as a small to medium-sized business, SPAN Engineering has ______ employees.
At this stage, SPAN Engineering has an in-house IT staff to support and maintain the ______.
At this stage, SPAN Engineering has an in-house IT staff to support and maintain the ______.
A disadvantage of the hub-and-spoke topology is that all communication has to go through the ______.
A disadvantage of the hub-and-spoke topology is that all communication has to go through the ______.
A full ______ topology allows any site to communicate directly with any other site.
A full ______ topology allows any site to communicate directly with any other site.
The dual-homed topology provides redundancy and ______ balancing.
The dual-homed topology provides redundancy and ______ balancing.
To justify large expenses, companies expect their networks to perform ______.
To justify large expenses, companies expect their networks to perform ______.
SPAN Engineering's network requirements change as the company grows from a small, local business into a global ______.
SPAN Engineering's network requirements change as the company grows from a small, local business into a global ______.
In slow economic times, businesses focus on increasing their ______ by improving network efficiency.
In slow economic times, businesses focus on increasing their ______ by improving network efficiency.
A single interface to the hub can be shared by all ______ circuits.
A single interface to the hub can be shared by all ______ circuits.
The large number of virtual circuits in a full mesh topology can be a ______ for configuration and maintenance.
The large number of virtual circuits in a full mesh topology can be a ______ for configuration and maintenance.
WAN access standards are defined and managed by recognized authorities such as TIA/EIA, ISO, and _____.
WAN access standards are defined and managed by recognized authorities such as TIA/EIA, ISO, and _____.
Layer 1 protocols describe how to provide electrical, mechanical, operational, and functional connects to the services of a communications service _____.
Layer 1 protocols describe how to provide electrical, mechanical, operational, and functional connects to the services of a communications service _____.
A primary difference between a WAN and a LAN is that a company must subscribe to an outside _____ service provider for WAN services.
A primary difference between a WAN and a LAN is that a company must subscribe to an outside _____ service provider for WAN services.
Customer Premises Equipment (CPE) consists of devices and inside wiring located on the enterprise edge connecting to a _____
Customer Premises Equipment (CPE) consists of devices and inside wiring located on the enterprise edge connecting to a _____
Data Communications Equipment (DCE) is also called circuit-terminating equipment and primarily provides an interface to connect subscribers to a communication link on the _____ cloud.
Data Communications Equipment (DCE) is also called circuit-terminating equipment and primarily provides an interface to connect subscribers to a communication link on the _____ cloud.
Data Terminal Equipment (DTE) refers to the customer devices that pass the data from a customer network or host computer for transmission over the _____.
Data Terminal Equipment (DTE) refers to the customer devices that pass the data from a customer network or host computer for transmission over the _____.
Layer 2 protocols define how data is _____ and the mechanisms for transferring the resulting frames.
Layer 2 protocols define how data is _____ and the mechanisms for transferring the resulting frames.
DCE primarily provides an interface allowing connection to a communication link on the WAN _____ for data transmission.
DCE primarily provides an interface allowing connection to a communication link on the WAN _____ for data transmission.
The point established in a building to separate customer equipment from service provider equipment is called the ______.
The point established in a building to separate customer equipment from service provider equipment is called the ______.
The actual copper or fiber cable that connects the CPE to the CO of the service provider is referred to as the ______.
The actual copper or fiber cable that connects the CPE to the CO of the service provider is referred to as the ______.
The facility that connects the CPE to the provider network is known as the ______.
The facility that connects the CPE to the provider network is known as the ______.
The long-haul, all-digital communications lines within the WAN provider network are part of the ______ network.
The long-haul, all-digital communications lines within the WAN provider network are part of the ______ network.
A legacy WAN technology that converts digital signals into voice frequencies is called a ______ modem.
A legacy WAN technology that converts digital signals into voice frequencies is called a ______ modem.
A type of digital modem used with high-speed DSL or cable Internet service is known as a ______ modem.
A type of digital modem used with high-speed DSL or cable Internet service is known as a ______ modem.
Digital-leased lines require a ______ and a DSU for proper connectivity.
Digital-leased lines require a ______ and a DSU for proper connectivity.
The device that ensures connection integrity through error correction and line monitoring is the ______.
The device that ensures connection integrity through error correction and line monitoring is the ______.
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Study Notes
Purpose of WANs
- WANs (Wide Area Networks) connect multiple LANs (Local Area Networks) over large distances, enabling communication across geographically separated sites.
- Organizations pay service providers for WAN connectivity, which is essential for remote access and interoffice communication.
- WANs allow for data, voice, and video transmission between distant locations, preventing isolation of LANs.
WAN Topologies
- Point-to-Point Topology:
- Involves a dedicated leased-line connection (e.g., T1/E1).
- Utilizes a Data Service Unit (DSU) for signal conversion between LAN and WAN.
- Hub-and-Spoke Topology:
- A central hub connects multiple spoke sites, allowing shared access.
- Cost-effective but communication relies on the hub, which can lead to bottlenecks.
- Full Mesh Topology:
- Direct communication between all sites without dependence on a central hub.
- Higher complexity and maintenance due to numerous configurations required for virtual circuits.
- Dual-homed Topology:
- Offers redundancy and load balancing with increased costs.
- Requires advanced configurations and additional hardware like routers and switches.
WAN Operations
- Circuit Switching:
- Establishes a dedicated circuit before communication, common in traditional telephony (PSTN) and ISDN.
- Packet Switching:
- Breaks data into packets for transmission across shared networks without the need for a dedicated circuit.
- Includes connectionless systems requiring full addressing in each packet, exemplified by the Internet.
Evolving Networks
- Companies aim for optimal network performance to support growth and service delivery in competitive environments.
- Example of SPAN Engineering illustrates changing network requirements as the business expands from local to global presence.
- Needs a WAN for data center access, with dedicated lines for local branches and Internet for international connections.
WANs in the OSI Model
- Focus on the physical and data link layers, which govern network operations.
- Data Link Layer: Addresses physical addressing, flow control, and encapsulation.
- Managed by standards organizations like TIA/EIA, ISO, and IEEE, ensuring compliance and interoperability.
Common WAN Terminology
- Customer Premises Equipment (CPE):
- Devices and wiring at the enterprise level connecting to the carrier’s network.
- Data Communications Equipment (DCE):
- Circuit-terminating devices that link local loops to WAN services, facilitating data transport.
- Data Terminal Equipment (DTE):
- Customer devices transmitting data over the WAN, connecting to DCE for local loop access.
WAN Cost Considerations
- As businesses grow, network costs rise, compelling organizations to seek reduction in operational expenses without sacrificing performance.
- Essential to provide converged services and secure WAN connectivity for remote access and data security.
Purpose of WANs
- WANs extend beyond the local coverage of LANs, interconnecting enterprise LANs to remote branches and telecommuter sites.
- Owned by service providers, WANs require organizations to pay for usage, unlike LANs, which are typically owned by the organization.
- WAN services facilitate the transport of data, voice, and video between remote sites, preventing LANs from being isolated networks.
Enhancements Through WANs
- Essential for businesses to communicate across geographically separated locations, including regional offices and clients.
- Enables employees traveling for business to access corporate networks.
- Consumers can interact with services, such as online banking, across the Internet due to WAN connectivity.
WAN Topologies
- Common WAN topologies include:
- Point-to-Point: Dedicated leased-line connections, like T1/E1 lines, providing direct links between two endpoints.
- Core Routers/Multilayer Switches: Centralized routers in the backbone of the WAN that facilitate data routing.
WAN Operations: Circuit Switching
- Circuit-switching establishes a dedicated circuit between nodes before communication begins, exemplified by phone calls via the PSTN and ISDN networks.
- Requires a connection to be created, limiting simultaneous communication channels.
WAN Operations: Packet Switching
- Packet switching divides data into packets sent over a shared network, allowing multiple communications without needing a dedicated connection.
- Utilizes connectionless systems, where addressing is included in each packet, as seen in Internet data transmission.
Case Study: SPAN Engineering
- A 20-year-old company with worldwide offices aims to cut network costs while ensuring secure WAN connectivity to remote sites.
- Demonstrates how growing operational needs lead to changes in network requirements.
WANs and OSI Model
- Primarily focused on the physical and data link layers of the OSI Model.
- Data link requirements include physical addressing, flow control, and encapsulation method protocols defined by bodies like TIA/EIA, ISO, and IEEE.
Common WAN Terminology
- Customer Premises Equipment (CPE): Devices and wiring at the enterprise edge connecting to the carrier.
- Data Communications Equipment (DCE): Equipment facilitating connection to a communication link on the WAN cloud.
- Data Terminal Equipment (DTE): Devices transmitting data from a local network to the WAN.
- Demarcation Point: Interface separating customer-owned equipment from service provider equipment.
- Local Loop: Last mile connection to the service provider's central office (CO).
- Toll Network: Fiber-optic lines within the WAN provider's network.
WAN Devices
- Dialup Modem: Converts digital signals for transmission over analog lines.
- Access Server: Manages communications for dialup users.
- Broadband Modem: Used for high-speed digital connections through DSL or cable.
- CSU/DSU: Required for digital-leased lines, providing termination and integrity checks for signals.
Purpose of WANs
- WANs enable communication between geographically separated local area networks (LANs).
- They interconnect enterprise LANs with remote sites, including branch locations and telecommuter access.
- WAN services are provided by service providers, contrasting with LANs, which are typically owned by organizations.
- Organizations incur costs to use WAN services for data, voice, and video transmission.
- WANs prevent LANs from being isolated networks, facilitating communication among offices and external entities.
WAN Topologies
- Point-to-Point: Direct, dedicated leased line connection (e.g., T1/E1) between two endpoints.
- Hub-and-Spoke: Central hub connects multiple sites, allowing shared communication through virtual circuits.
- Full Mesh: Allows direct communication between any sites, requiring numerous virtual circuits for management.
- Dual-homed: Provides network redundancy and load balancing, though at a higher cost and complexity of implementation.
Evolving Networks
- Businesses aim to enhance profitability by improving network efficiency, reducing operational expenses.
- Network demands change dramatically as companies scale, necessitating robust and secure WAN connectivity.
- Example: SPAN Engineering transitions from a local business to a global enterprise requiring extensive WAN solutions.
WAN Operations
- Focus on the physical and data link layers of the OSI Model, addressing physical addressing, flow control, and encapsulation.
- WAN standards governed by organizations like TIA/EIA, ISO, and IEEE ensure compatibility and functionality of services.
- Layer 1 protocols focus on the physical connections with service providers, while Layer 2 protocols handle data encapsulation and frame transfer.
Common WAN Terminology
- Customer Premises Equipment (CPE): Devices and wiring at the enterprise edge connecting to a carrier.
- Data Communications Equipment (DCE): Circuit-terminating equipment that connects subscribers to the WAN.
- Data Terminal Equipment (DTE): Customer devices that send data over the WAN, interfacing with the DCE.
- Demarcation Point: The boundary separating customer equipment from service provider equipment.
- Local Loop: The last mile connection wiring between CPE and the service provider's central office (CO).
WAN Devices
- Dialup Modem: Converts digital signals to voice frequencies for transmission over public telephone lines.
- Access Server: Manages dial-up connections for both incoming and outgoing communications.
- Broadband Modem: Used for high-speed DSL or cable internet, operating at higher frequencies than voiceband modems.
- CSU/DSU: Essential for digital leased lines, ensuring signal integrity and connection monitoring.
WAN Topologies
- Transparent Connections: Establishes a direct physical link between two endpoints for customer networks.
- Hub-and-Spoke Topology: Useful for private network connections among sites; the hub shares an interface with all spoke circuits, allowing interconnections via virtual circuits.
- Full Mesh Topology: Enables direct communication between any two sites, reducing reliance on a hub; however, requires extensive virtual circuit configuration and maintenance.
- Dual-Homed Topology: Offers redundancy and load balancing, requiring more investment in hardware like routers and switches, and involves complex configurations.
Purpose of WANs & Evolving Networks
- Economic Considerations: Companies aim to boost profits by improving network efficiency, demanding optimal performance, and diverse service delivery.
- Company Example - SPAN Engineering: Evolves from a small firm (15 employees) to a global enterprise, illustrating changing network needs as business scales.
SPAN Engineering's Growth Stages
- Initial Stage: Small office with a single LAN, supporting VoIP and shared peripherals; utilizes DSL for internet connectivity and external IT support.
- Expansion Stage: Five years later, the firm grows to hundreds of employees, spans multiple office floors, and develops an in-house IT team.
- Branch Networks: After six more years, SPAN opens offices closer to project sites, requiring WAN for access to central databases, employing dedicated lines in local areas and internet connections abroad.
- Distributed Network: After 20 years, the company has numerous global offices and faces high networking costs, necessitating cost-reduction strategies while requiring secure WAN connectivity.
WAN Operations
- Functional Areas: Focus on physical and data link layers of OSI Model involving addressing, flow control, and encapsulation.
- Standards: Established by TIA/EIA, ISO, and IEEE to manage WAN access.
Common WAN Terminology
- Customer Premises Equipment (CPE): Devices and wiring on the enterprise edge connecting to carriers.
- Data Communications Equipment (DCE): Circuit-terminating equipment that interfaces subscribers with communication links.
- Data Terminal Equipment (DTE): Customer devices transmitting data for WAN access.
- Demarcation Point: Separates customer equipment from service provider equipment within a building.
- Local Loop: Connects CPE to the central office (CO) of the service provider, often referred to as the "last mile."
- Toll Network: Consists of long-haul, high-capacity digital telecommunications lines within the WAN provider's network.
WAN Devices
- Dialup Modem: Converts digital signals for transmission over traditional phone lines, considered legacy technology.
- Access Server: Manages dial-up connections and user communications.
- Broadband Modem: Used for high-speed internet connections, operates on broadband frequencies.
- CSU/DSU: Necessary for digital leased lines, providing termination and ensuring integrity through error correction and monitoring.
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