1 / 33

DSL – ADSL and Wi - Fi

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

plato
Télécharger la présentation

DSL – ADSL and Wi - Fi

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. DSL – ADSL and Wi - Fi DSL ADSL Protocols Security Wi-Fi Cable vs ADSL

  2. 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

  3. What is DSL ? • Digital Subscriber Line • Splitter ( Client ) • Splitter ( Service Provider) • DSLAM • Fast Network Connection ( Fiber Optic ) • Switch • PSTN (Public Switched Telephone Network )

  4. ADSL Frequencies

  5. ADSL • Asymetric Digital Subscriber Line • Asymetric -> Downstream != Upstream • 1 * Downstream = 4 * Upstream

  6. 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

  7. DSL

  8. DSLAM

  9. 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)

  10. Speed Dependencies • ADSL – 5km, 128kbps / 8mbps • ADSL2 – 2.5km, 12mbps ( Framing – Err. Corr) • ADSL2+ - 1.5, 24mbps ( 2.2 MHz )

  11. Protocols • PPPoE • DHCP • Bridging • Transparent Bridging • Source Route Bridging

  12. 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

  13. 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.

  14. DHCP

  15. Network Bridge • Network Switch • Broadcast Message • Transparent Bridging • Forwarding Database • Recieved Frames Addresses • Broadcast Message • Store route in D.B.

  16. 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

  17. ADSL MODEM • What is it? • Routing • Security • Firewall • NAT service • Wireless Connection

  18. ADSL Modem

  19. Wi-Fi • SSID (Service Set Identifier) • Broadcast SSID • Beacon packets • 100 ms • Same SSID -> Signal Strength • Lowest 1 Mbit/s

  20. Wireless Protocols

  21. Wireless Security • Access Control • MAC address check • Allow • Ban • WEP • WPA • 802.1x

  22. Access Control

  23. WEP(WiredEqivalentPrivacy) • IEEE 802.11 standard • RC4 • Stream Cipher • Block Cipher ? • RC4 for confidentiality • CRC-32 checksum for integrity

  24. 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

  25. WEP

  26. 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

  27. TKIP

  28. WPA

  29. 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

  30. 802.1x

  31. 802.1x

  32. 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

  33. Cable vs ADSL • Price

More Related