Dsl adsl and wi fi
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DSL – ADSL and Wi - Fi. DSL ADSL Protocols Security Wi-Fi Cable vs ADSL. DSL History. Dial Up too slow Pay for the connection time Telephone occupied VLSI advancements ( 1990 ) DSLAM ( DSL Access Multiplexer ) DSL modem cheaper Deployed over existing cable

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DSL – ADSL and Wi - Fi

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Dsl adsl and wi fi

DSL – ADSL and Wi - Fi

DSL

ADSL

Protocols

Security

Wi-Fi

Cable vs ADSL


Dsl history

DSL History

  • Dial Up too slow

  • Pay for the connection time

  • Telephone occupied

  • VLSI advancements ( 1990 )

    • DSLAM ( DSL Access Multiplexer )

    • DSL modem cheaper

  • Deployed over existing cable

    • Installing Fiber Optic Cable expensive

  • Competition in DSL drop prices


What is dsl

What is DSL ?

  • Digital Subscriber Line

  • Splitter ( Client )

  • Splitter ( Service Provider)

  • DSLAM

    • Fast Network Connection ( Fiber Optic )

    • Switch

      • PSTN (Public Switched Telephone Network )


Adsl frequencies

ADSL Frequencies


Dsl adsl and wi fi

ADSL

  • Asymetric Digital Subscriber Line

  • Asymetric -> Downstream != Upstream

  • 1 * Downstream = 4 * Upstream


How does it work

How does it work?

  • Upstream / Downstream bands

  • 25.875 kHz to 138 kHz Upstream

  • 138 kHz – 1104 kHz Downstream

  • 4.3125 kHz pieces ( 26 – 224 )

  • Acceptable signal-to-noise ratio

  • Distance – Electrical Noise

  • Splitter

    • DSLAM

    • PSTN


Dsl adsl and wi fi

DSL


Dslam

DSLAM


Dsl adsl and wi fi

xDSL

  • High Data Rate DSL (HDSL)

  • Symetric DSL (SDSL)

  • Asymetric DSL (ADSL)

  • Rate – Adaptive DSL (RADSL)

  • Very-high-bit-rate DSL (VDSL)

  • Very-high-bit-rate DSL2 (VDSL2)

  • Symetric High-speed DSL (G.SHDSL)

  • Powerline DSL (PDSL)


Speed dependencies

Speed Dependencies

  • ADSL – 5km, 128kbps / 8mbps

  • ADSL2 – 2.5km, 12mbps ( Framing – Err. Corr)

  • ADSL2+ - 1.5, 24mbps ( 2.2 MHz )


Protocols

Protocols

  • PPPoE

  • DHCP

  • Bridging

    • Transparent Bridging

    • Source Route Bridging


Pppoe

PPPoE

  • Point to Point Protocol over Ethernet

    • PPP -> Dial Up

  • Encapsulate PPP frames in Ethernet frames

  • Clasical connection

    • Username

    • Password

  • IP assaign -> Connection Open

    • Reuse of IP


Dsl adsl and wi fi

DHCP

  • Dynamic Host Configuration Protocol

  • Request and obtain internet address

  • DHCP client -> Query -> DHCP server

  • Immediately after Booting

  • IP address

  • Subnet Mask

  • DNS server ( Domain Name System Server )

  • Default Gateway info.


Dsl adsl and wi fi

DHCP


Network bridge

Network Bridge

  • Network Switch

  • Broadcast Message

  • Transparent Bridging

    • Forwarding Database

      • Recieved Frames Addresses

    • Broadcast Message

    • Store route in D.B.


Network bridge1

Network Bridge

  • Source Route Bridging

    • Single Route frames (SR)

      • Fixed destinations

    • All Route frames (AR)

      • Find routes

      • Broadcast frame -> All Ports

      • Register each step

      • Max. Hop Count

        • Diameter of Network Graph

        • Decrement by each Bridge

        • Hop Count = 0 -> Discard

      • First AR frame -> Best Route

      • Others Discarded


Adsl modem

ADSL MODEM

  • What is it?

  • Routing

  • Security

    • Firewall

    • NAT service

  • Wireless Connection


Adsl modem1

ADSL Modem


Wi fi

Wi-Fi

  • SSID (Service Set Identifier)

  • Broadcast SSID

  • Beacon packets

  • 100 ms

  • Same SSID -> Signal Strength

  • Lowest 1 Mbit/s


Wireless protocols

Wireless Protocols


Wireless security

Wireless Security

  • Access Control

    • MAC address check

    • Allow

    • Ban

  • WEP

  • WPA

  • 802.1x


Access control

Access Control


Wep w ired e qivalent p rivacy

WEP(WiredEqivalentPrivacy)

  • IEEE 802.11 standard

  • RC4

    • Stream Cipher

    • Block Cipher ?

  • RC4 for confidentiality

  • CRC-32 checksum for integrity


Wep w ired e qivalent p rivacy1

WEP(WiredEqivalentPrivacy)

  • 64 BIT WEP – 40 BIT Hex – 4 * 10 = 40

  • 128 BIT WEP – 104 BIT Hex – 4 * 26 = 104

  • 256 BIT WEP – 232 BIT Hex – 4 * 58 = 232

  • + 24 BIT Initialazition Vector (block of BIT exe S.C. Or B.C)

    • Stream Chiper

    • Block Cipher

  • =WEP key


Dsl adsl and wi fi

WEP


Wi fi protected access wpa

Wi-Fi Protected Access (WPA)

  • Key Recovery Attacks on WEP

    • Keys unknown but

    • Mathematical relation between keys known

  • TemporalKeyIntegrityProtocol ( TKIP )

    • Per-packet key mixing

    • a message integrity check and

    • re-keying mechanism

  • Every data packet -> unique encryption key.

  • Message Integrity Check

    • MAC address genereated


Dsl adsl and wi fi

TKIP


Dsl adsl and wi fi

WPA


802 1x

802.1x

  • Data – Link Layer

  • Closed Wireless Access Points

  • Detection -> Port on switch Unauthorized

  • Authenticator -> EAP Request -> Supplicant

  • Supplicant -> EAP Response -> Authenticator

  • Authenticator -> EAP Responce -> Authentication Server

  • EAP Logoff

  • Port Unauthorized


802 1x1

802.1x


802 1x2

802.1x


Cable vs adsl

Cable vs ADSL

  • SPEED

    • Cable upto 2 times faster than ADSL ( 3.0Mbps – 1.5Mbps)

      • Shared bandwidth

  • SHARING AND SECURITY

    • Cable modem -> Pay for each extra client

    • ADSL -> No Limitations

    • Both very secure


Cable vs adsl1

Cable vs ADSL

  • Price


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