Section 11: Wide Area Networks (WANs)

Computer networking over time

• Pareto principle (80-20) in EARLY networking:

  • 80% of traffic stays within the LAN

  • 20% of traffic goes out to the WAN

• Pareto principle (80-20) in CURRENT networking

  • 80% of traffic goes out to the WAN

  • 20% of traffic stays within the LAN

Fiber Optic Connection

• Backbone of hyper-connected lifestyles in homes and small offices

• Various forms categorized by proximity to end user premises

Types of Fiber Connections (4)

• Fiber-to-the-Home

• Fiber to the Curb/ Cabinet

• Fiber to the Node/Neighborhood

• Fiber to the Building/Basement

Fiber-to-the-Home (FTTH)

• Direct fiber optic connection to individual residences

• Highest speed and reliability due to entire connection being fiber optic3

• Ideal for demanding users like home offices, gamers, and streaming enthusiasts

Fiber to the Curb/Cabinet (FTTC)

• 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

Fiber to the Node/Neighborhood (FTTN)

• Extends fiber optic connection to a central point in the area

• Copper cables branch out from the node to individual locations

• Allows leveraging existing copper infrastructure for improved speeds

Fiber to the Building/Basement (FTTB)

• 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

Fiber Speed and Reliability Comparison

• Highest speed and reliability

  • FTTH

  • FTTB

• Slower but faster than entirely copper-based networks

  • FTTC

  • FTTN

**** Marketers may use the term “fiber” for even slower connections like FTTC or FTTN, so understanding the specific type is important for choosing the best connection

DOCSIS Overview

• A prevalent technology that brings high-speed internet through TV-Cable lines

• Uses HFC network

Hybrid Fiber Coaxial (HFC)

• 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

Data Over Cable Service Interface Specification (DOCSIS)

• 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

DOCSIS Advantages

• Utilizes existing cable TV infrastructure, making rollout cost-effective and quick

• Offers higher speeds compared to a DSL, a popular alternative in the late 1990s and early 2000s

DOCSIS Evolution

• Evolved over versions (e.g. DOCSIS 1.0 to latest) for faster speeds (up to 1-5 Gbps)

  • Better performance

  • Improved security

• Safe and swift data transmission for activities such as

  • Streaming

  • Video confrencing

  • Online gaming

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 DSLs (3)

• ADSL

• SDSL

• VDSL

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

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

  • 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

DSL Popularity and Usage

• DSL was popular in the late 90s 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 telephone 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

DSL Future Trends

• Traditional copper phone lines, which DSL operates over, are being phased out in favor of fiber optic connections and Voice over IP services

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

Satellite 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 RVs, trucks, or traveling internationally, providing internet access via satellite modems

Satellite 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

Satellite Drawbacks

• Slower speeds 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

Satellite 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

Cellular Connections Overview

• Includes:

  • Smartphones

  • Tablets

  • Dedicated cellular modems

  • Wireless access points

  • Fixed cellular services

• Encompasses a wide range of technologies from 2G to 5G

Generations of Cellular Technology (5)

• 1G

• 2G

• 3G

• 4G

• 5G

*Higher G means newer standard and faster speeds

1G (1980s)

• Frequency - 30KHz

• Speed - 2 Kbps

• Voice calls-focused, 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

• 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 3.5 G

    • Speed up to 14.4 Mbps

  • HSPA+ (High Speed Packet Access Evolution)

    • Referred to as 3.75 G

    • 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)

• Speed - Up to 10 Gbps

• *3 Frequency Bands

  • Low Band

    • 600-850 MHz

    • 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

Cellular Technologies

• Determined by which area users live or which cellular providers 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

    • GSM phones use SIM cards

  • CDMA (Code Division Multiple Access)

    • Use code division to split channels

    • More flexible and powerful than GSM

    • Mostly used in 3G and beyond

    • CDMA phones are configured to the provider

• Consideration 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 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

  • UNH (Ultra High Frequency) range

  • SHF (Super High Frequency) range

  • EHF (Extremely High Frequency) range

• 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

Worldwide Interoperability for Microwave Access (WiMAX)

• Microwave connections were originally marketed as WiMAX

  • IEEE 802.16 standard for microwave access

  • Faster speeds than cellular and DSL services

  • Expensive

  • Complex installation

    • ISPs 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 due to 4G and 5G tech

• Still used for internal network connections in business parks or campuses

Leased Lines

• Fixed bandwidth that has symmetric data connection 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 telecommunications provider

Leased Line 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

    • Service Level Agreements (SLAs)

• 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 create WANs

Service Level Agreements (SLAs)

• Providers often offer SLAs with guaranteed uptimes

  exceeding 99.9%, ensuring swift repair and recovery

• High level of reliability

Leased Line Key Ideas

• 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

Multiprotocol Label Switching (MPLS)

• Technique that is leveraged by service providers to enhance network efficiency and flexibility

• 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 traffic 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

MPLS: Protocol Agnostic Nature

• MPLS can carry various types of data (e.g. Ethernet frames, ATM cells) but treats them all the same way

• This makes MPLS ideal for integrating diverse network types and services

MPLS: 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

MPLS: 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

MPLS: 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