Wide Area Networks (WANs)
Objective 1.5: Compare and contrast transmission media and transceivers
● Introduction
○ Computer networking over time
■ Pareto Principle (80-20 rule) in early networking
● 80% of traffic stays within the LAN
● 20% of traffic goes out to the WAN
■ Pareto Principle (80-20 rule) in current networking
● 80% of traffic goes out to the WAN
● 20% of traffic stays within the LAN
● Fiber Optic Connections
○ Fiber Optic Connections
■ Backbone of hyper-connected lifestyles in homes and small offices
■ Various forms categorized by proximity to end user premises
○ Key Terms
■ FTTH (Fiber to the Home)
● Direct fiber optic connection to individual residences
● Highest speed and reliability due to entire connection being fiber
optic
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● Ideal for demanding users like home offices, gamers, and
streaming enthusiasts
■ FTTC (Fiber to the Curb/ Cabinet)
● Fiber optic cables run to curbside or nearby cabinet
● Uses traditional copper cable for the final connection
● Offers a balance between cost and performance
● Common in urban setups
■ FTTN (Fiber to the Node/Neighborhood)
● Extends fiber optic connection to a central point in an area
● Copper cables branch out from the node to individual locations
● Allows leveraging existing copper infrastructure for improved
speeds
■ FTTB (Fiber to the Building/Basement)
● Fiber optic cables reach building's main communication room or
basement
● Connection to individual units/offices within the building is usually
done through copper cabling
● Common in multi-dwelling units where high-speed fiber is brought
close to users but not directly into each unit
○ Speed and Reliability Comparison
■ Highest speed and reliability
● FTTH
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● FTTB
■ Slower but still faster than entirely copper-based networks
● FTTC
● FTTN
■ Marketers may use the term "fiber" even for slower connections like FTTC
or FTTN, so understanding the specific type is important for choosing the
best connection
● Cable (DOCSIS) Connections
○ DOCSIS Overview
■ A prevalent technology that brings high-speed internet through TV cable
lines
■ Uses (HFC) network
○ HFC (Hybrid Fiber Coaxial)
■ Network acts as a high-capacity highway for data transmission
■ Combines fiber optic and coaxial cables
● Fiber optic cables
○ Transmit data from service provider to distribution points
● Coaxial cables
○ Deliver data to homes/offices
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○ DOCSIS (Data Over Cable Service Interface Specification)
■ Standardizes data transmission over HFC networks for consistent, reliable,
high-speed internet access
■ Ensures cable modems speak the same language, regardless of location
or service provider
■ Frequency Ranges
● Upstream
○ Data that is sent out
○ 5-42 MHz
● Downstream
○ Data that is received
○ 50-860 MHz
■ Asynchronous Speeds
● Cable modems are usually asynchronous, providing high
download speeds but slower upload speeds
■ Advantages
● Utilizes existing cable TV infrastructure, making rollout
cost-effective and quick
● Offers higher speeds compared to DSL, a popular alternative in
the late 1990s and early 2000s
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○ DOCSIS Evolution
■ Evolved over versions (e.g., DOCSIS 1.0 to latest) for faster speeds (up to
1-5 Gbps), better performance, and improved security
■ Ensures safe and swift data transmission for activities like streaming,
video conferencing, and online gaming
● Digital Subscriber Line (DSL) Connections
○ Digital Subscriber Line (DSL)
■ A family of technologies that provide internet access by transmitting
digital data over the wires of a local telephone network
○ Types of DSL
■ Asymmetric DSL (ADSL)
● Different speeds for download and upload
○ Maximum download speed – about 8 Mbps
○ Upload speed – 1.544 Mbps
● Suitable for users who download more than they upload
■ Symmetric DSL (SDSL)
● Provides equal upload and download speeds
● Offers dedicated access but at a slower overall speed compared to
ADSL
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■ Very High Bit-Rate DSL (VDSL)
● Offers very high speeds
○ Downloads – up to 50 Mbps
○ Uploads around 10 Mbps
● Limited by distance from the DSLAM (Digital Subscriber Line
Access Multiplexer)
○ DSLAM (Digital Subscriber Line Access Multiplexer)
■ Point of presence that is owned by the telephone
company
■ Within 4,000 ft range for VDSL
■ 4,000 ft to 18,000 ft for ADSL
○ Popularity and Usage
■ DSL was popular in the late 1990s and early 2000s due to its affordability
and ability to provide high-speed data to small offices and home office
environments
■ ADSL was popular with home users and received significant funding from
telecommunication companies, leading to speed increases over time
■ DSL is still used in some remote areas, but cable modems and fiber optics
have become more common in larger city environments
○ Future Trends
■ Traditional copper phone lines, over which DSL operates, are being
phased out in favor of fiber optic connections and Voice over IP services
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● Satellite Connections
○ Satellite Internet Access
■ Method of utilizing communication satellites in space to connect users to
the internet
■ Ideal for remote areas where cable, cellular, or fiber is unavailable
○ Usage
■ Home Users
● Can use commercial services like HughesNet or Starlink
● Requires a satellite dish installed on the roof
■ Mobile Users
● Ideal for users on the go, like those in RVs, trucks, or traveling
internationally, providing internet access via satellite modems
○ Advantages
■ Availability
● Accessible in remote areas where other services are unavailable
■ Global Coverage
● Can be accessed almost anywhere with a clear line of sight to the
satellite
■ Decent Speed
● Provides relatively fast internet service, allowing activities like
streaming movies
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○ Drawbacks
■ Slower speed compared to fiber, microwave links, or cable modems
■ More expensive than other types of internet service
■ High latency due to geosynchronous satellites located around 22,000
miles above the earth
○ Recent Developments
■ Companies like SpaceX with Starlink are revolutionizing satellite internet
by deploying satellites in low earth orbit
● Reduces latency to around 25-35 milliseconds
■ Starlink's approach involves launching thousands of satellites at closer
distances (340 miles) to the earth
● Offers lower latency and higher speeds compared to traditional
geosynchronous satellites
○ Key Points
■ Satellite internet tends to be more expensive
■ Commonly used in remote or mobile environments
■ Opt for systems using low earth orbit for lower latency and higher speeds,
such as Starlink
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● Cellular Connections
○ Cellular Connections Overview
■ Includes smartphones, tablets, dedicated cellular modems, wireless
access points, and fixed cellular services
■ Encompasses a wide range of technologies, from 2G to 5G
○ Generations (G) of Cellular Technology
■ 1G (1980s)
● Frequency – 30 KHz
● Speed – 2 Kbps
● Voice calls-focused, with limited data capabilities
■ 2G (Late 1990s)
● Frequency – 1,800 MHz
● Speed – 14.4-64 Kbps (Similar to dial-up)
● Ran over digital network that used multiplexing
● Allowed data usage (low -speed) in addition to phone calls
○ SMS and text messaging
○ International roaming conference calls
■ 3G
● Frequency – 1.6-2 GHz
● Speed – 144 Kbps to 2 Mbps
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● Technologies:
○ WCDMA (Wideband Code Division Multiple Access)
■ Used by the UMTS (Universal Mobile Telephone
System) standard
■ Slowest (2 Mbps)
○ HSPA (High Speed Packet Access)
■ Referred to as 3.5G
■ Speed up to 14.4 Mbps
○ HSPA+ (High Speed Packet Access Evolution)
■ Referred to as 3.75G
■ Speed up to 50 Mbps
■ 4G
● Frequency – 2-8 GHz
● Speed – 100 Mbps to 1 Gbps
● Introduced MIMO (Multiple Input, Multiple Output) technology
● Often called 4G LTE (Long Term Evolution)
■ 5G (2019)
● Frequency –
● Speed – up to 10 Gbps
● Three Frequency Bands
○ Low Band
■ 600-850 MHz
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■ Speeds of 30-250 Mbps (low speed)
■ Long-range coverage
○ Mid Band
■ 2.5-3.7 GHz
■ Speeds of 100-900 Mbps
■ Good balance of coverage and speed
■ Most used
○ High Band
■ 25-39 GHz
■ Speeds in the gigabit range, but very short-range
coverage
○ Upward band means faster speed but decreasing coverage
area
■ Higher G means newer standard and faster speeds
○ Cellular Technologies
■ Determined by which area users live or which cellular provider users will
use in a particular country
■ GSM vs. CDMA
● GSM (Global System for Mobile Communications)
○ Converts voice to digital data
○ Uses time division for efficiency
○ More widely supported across the globe
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○ GSM phones use SIM cards
● CDMA (Code Division Multiple Access)
○ Uses code division to split channels
○ More flexible and powerful than GSM
○ Mostly used in 3G and beyond
○ CDMA phones are configured to the provider
■ Considerations for Cellular Devices
● Network Compatibility
○ Check the cellular technology (GSM or CDMA) supported
by your provider and region
● Modern smartphones support eSIMs for easy switching between
providers
● Microwave Connections
○ Microwave Link
■ Communication system that uses radio waves in the microwave frequency
band to transmit information between two fixed locations
■ Frequency range
● 300 MHz to 300 GHz
● UHF (Ultra High Frequency) range
● SHF (Super High Frequency) range
● EHF (Extremely High Frequency) range
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■ Commonly used in large college campuses and small businesses for
network connections
○ Line of Sight connection
■ Requires antennas to have a direct line of sight, limiting the distance to
around 40 miles (64 kilometers) due to the curvature of the earth
■ Requires professional installation with antennas mounted on the roof of
buildings
○ Originally marketed as WiMAX (Worldwide Interoperability for Microwave
Access)
■ IEEE 802.16 standard for microwave access
■ Offers faster speeds than cellular and DSL services
■ Expensive
■ Complex installation
● Internet service providers often place antennas on tall buildings
for better coverage
■ Wireless Fixed Location Service
● Requires larger antennas and radios compared to traditional
modems
■ WiMAX and microwave connections are losing popularity for consumer
internet due to the rise of 4G and 5G cellular technology
■ Still used for internal network connections in business parks or campuses
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● Leased Line Connections
○ Leased Lines
■ Fixed bandwidth that has symmetric data connections reserved for
subscribers' exclusive use
■ Premier choice for businesses and organizations that require a dedicated,
reliable, and high performance internet connection
■ Ideal solution for uncompromising communications infrastructure
■ Often referred to as Dedicated Leased Line
● Continuous connection between two points that are set up by a
telecommunications provider
○ Benefits
■ Symmetric Nature
● Upload and download speeds are identical
● Critical for businesses requiring high upload speeds
■ Bandwidth options
● 2 Mbps to 10 Gbps
● Allows tailored connectivity
■ Reliability
● Guarantees consistent speeds and high levels of service and
security
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● Service Level Agreements (SLAs)
○ Providers often offer SLAs with guaranteed uptimes
exceeding 99.9%, ensuring swift repair and recovery
○ Gives high level of availability
■ Security
● Fewer routers and switches reduce exposure to cyber attacks
● Ideal for handling sensitive information
■ Cost
● Generally more expensive than shared services like DSL or cable
● Justified by the benefits, especially for businesses with critical
communication needs
■ Applications
● Can be used to create wide area networks (WANs)
○ Primarily used by businesses where connectivity is a critical component of their
operational backbone
○ Offer unmatched speed, reliability, and security, making them a strategic
investment for businesses needing robust communication capabilities
● MPLS Connections
○ Multiprotocol Label Switching (MPLS)
■ Technique that is leveraged by service providers to enhance network
efficiency and flexibility
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■ Streamlines and speeds up data traffic flow
■ “Label Routing”
○ Label Switching
■ MPLS routers forward packets based on short path labels rather than
lengthy IP headers and routing tables
■ Label Assignment
● Ingress router assigns a short, fixed-length identifier (label) to the
packet
● The label encapsulates the packet's forwarding information
■ Label Switching
● Core routers in the MPLS network forward packets based on labels
● Routers use labels to look up forwarding tables and determine the
next hop
● Avoids complex route lookups
■ Label Removal
● Egress router (exit point of the MPLS network) removes the label
● The packet is forwarded based on its original IP header
○ MPLS operates like an expressway, getting on or off at certain points, not at every
router
○ Protocol Agnostic Nature
■ MPLS can carry various types of data (e.g., Ethernet frames, ATM cells)
because it treats them all the same way
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■ This versatility makes MPLS ideal for integrating diverse network types
and services
○ Quality of Service (QoS)
■ MPLS can enforce traffic engineering, allowing service providers to define
explicit paths for different types of traffic
■ Ensures optimal use of network resources and can prioritize high-priority
data packets
○ Reliability and Redundancy
■ Offers mechanisms for automatic and rapid rerouting of traffic in case of
link or node failure
■ Minimizes downtime and ensures continuous data flow, enhancing
service continuity and performance
○ End User Impact
■ Improves service quality, reliability, and performance for end users
■ Operates quietly behind the scenes but plays a crucial role in shaping
efficient, robust, and agile networks
■ Goes beyond traditional IP routing, offering more streamlined and
dynamic ways of handling data traffic using labeling