1. Network Architecture for Cyberspace
Joel Crichlow, ph.D

2. Network Architecture
Layers
Protocols
Standards
ISO/OSI Reference Model
International Organization for Standardization/Open Systems Interconnection
TCP/IP
Transmission Control Protocol/Internet Protocol

3. ISO/OSI

4. Physical Layer Digital-to-Analog Conversion
Analog-to-Digital Conversion
Modulation/Demodulation - modem
Transmission Media
Multiplexing
Circuit Switching and Packet Switching
Errors
Error correcting codes
Error detecting codes

5. Transmission Media Twisted pair Coaxial cable Optical fibers
Wireless Transmission

6. Multiplexing
Frequency Division Multiplexing (FDM)

7. Multiplexing Time Division Multiplexing (TDM) user 1 user 3 Channel 42
Channel 1
user 4
user 2

8. Circuit Switching and Packet Switching
Complete end-to-end path for exclusive use throughout the duration of session
Message Switching
Store-and-forward
Packet Switching

9. Data Link Layer Link management
Efficient and reliable transmission of information from one node (host or PSN) in the network to a neighboring node
Frames
Constructed from packets received from upper layer

10. Frames Flag – Begin, End Bit stuffing
For example, if the flag is , then no sequence of 6 ‘1’ bits is allowed, a ‘0’ bit is inserted (stuffed) after every sequence of five ‘1’ bits
FLC - kind of frame, sequence number and acknowledgement indication
CRC – polynomial code

11. Network Layer Connection Oriented Service Connectionless Service
Set up connection then transfer data
Connectionless Service
Transfer data without setting up connection
Acknowledged, Unacknowledged
Virtual Call
Virtual Circuit for all packets in right sequence
Datagram
Each packet handled independently
Routing
Flow Control

12. Routing number of hops distance (usually km) bandwidth traffic
Shortest Path
Best Route
number of hops
distance (usually km)
bandwidth
traffic
communication cost
Static Routing
Dynamic Routing

13. Distance vector Routing
Table at Router A
Route to
Preferred out line
Distance in hops A B 1 C 2 D G E F

14. Path vector routing Current path vector for router A
Route to Preferred outline Path
A A A
B B A-B
C B A-B-C
D G A-G-D
E E A-E
F E A-E-F
G G A-G

15. Dynamic routing Link State routing
Determine the delay along the link to neighbors
Send this information to all the other routers
Use this information to establish the shortest path to every other router

16. Flow control and congestion
Too much traffic can overwhelm the system
Finite bandwidth, finite memory
Processing overhead
Dropped packets
Re-sends

17. Transport Layer Process-to-Process Network-wide Addressing
Name Servers
Service
Connection oriented
Connectionless
Integrity of delivered messages
Flow control

18. Session Layer Application-oriented flavor
Different characteristics may determine different procedures
Distributed computation vs multimedia transfer
Session management
Multiple transport connections
Multiple sessions over single transport connection

19. Presentation Layer Data Integrity Data formats Conversions
Security and Privacy
Encryption

20. Application Layer
The User Layer
Useful
Open?
Friendly?

21. TCP/IP ISO/OSI? Five Layers TCP - Transmission Control Protocol
Connection Oriented
UDP – User Datagram Protocol
Connectionless
IP – Internet Protocol
Datagram service

22. Local Area Networks Range Topologies IEEE Standards Limited
Bus, Ring, Star, …
IEEE Standards
Widespread use M M M
Bus P P P P C C C
Ring C C C C C
Star C

23. Wireless Computing
Base Station
Adhoc Networks
WiFi
Bluetooth

24. WiFi
(a) WiFi with base station; (b) WiFi without base station

25. Bluetooth
Bluetooth topology: (a) 1 piconet, (b) A scatternet of 3 piconets

26. Conclusion We looked at: ISO/OSI Reference Model TCP/IP
Local Area Networks
Wireless Computing