1. DSL ADSL Protocols Security Wi-Fi Cable vs ADSL
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)
ADSL , 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
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 Wireless Connection 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 WEP WPA 802.1x MAC address check
Allow
Ban
WEP
WPA
802.1x

22. Access Control

23. WEP(Wired Eqivalent Privacy)
IEEE standard
RC4
Stream Cipher
Block Cipher ?
RC4 for confidentiality
CRC-32 checksum for integrity

24. WEP(Wired Eqivalent Privacy)
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
Temporal Key Integrity Protocol ( 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 SHARING AND SECURITY
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