Network Architecture

1
Network Architecture Standards

• Unit 2, Chapter 3 4
• Why Standards?

2
Objectives

• Explain the importance of network architecture.
• Identify 802.x LAN standards as described by
  IEEE.
• Match the seven layers of the OSI model to
  network equipment and their role in
  cross-platform interoperability
• Describe the function of a network access PDU.
• Differentiate between connectionless and
  connection-oriented protocols.
• Describe selected basic functions of a protocol.

3
Architectures Standards

• Networks Architecture Principles in the design
  and implementation of a network
• Reduction in complexity, common solution
• Isolate network complexities from users
• Ability to connect different types of devices
• Management of the network
• Communications Standards Rules to establish
  compatibility among similar products
• View Points
• Vendor IBM, DEC, Microsoft, Novell
• Industry IEEE, ANSI, NIST

4
Vendor Technologies

• Systems Network Architecture (SNA)
• Digital Network Architecture (DNA)
• Burroughs Network Architecture (BNA)
• Novell (IPX/SPX - XNS)
• Banyan Virtual Integrated Network Services(Vines
  - XNS)

5
IEEE 802 StandardsInstitute of Electrical and
Electronics Engineers
6
International Telecommunications Union

• Most important telecommunications standards
  setting body
• V. Standards Connection of digital equipment to
  analog PSTN lines
• X. Standards Connection of digital equipment to
  digital lines
• Development of the Open System Interconnect Model
  with International Standards Organization
• Basis for interconnecting dissimilar systems

7
Open Systems Interconnect (OSI) Model
8
OSI Model Layers

• Application Layer (7)
• Where user works with at a terminal
• Presentation Layer (6)
• Code conversion data reformatting from
  application - network
• Session Layer (5)
• Establishing the communications rules(pacing,
  accounting)
• Turns communications on off
• Transport Layer (4)
• Identifies the actual address of recipient of the
  message
• Responsible for ensuring data is transmitted
  (retransmission)
• Network Layer (3)
• Routing message to recipient
• Establishes, maintains and terminates
  communications
• Data Link Layer (2)
• Establishing link between 2 points packing
  data, block transfers
• Physical Layer (1)
• Electrical components for the communication
• http//www.reskit.net/MCTFAQS/The20OSI20Model20
  as20explained20by20Laura.htm

9
More OSI

• X.25 standard for data transmission
• Used in packet switching networks
• 1st 3 OSI layers (physical, data link, network)
• Encapsulation process that surrounds the
  original data or requests with control characters
  for routing and error checking

10
Protocol Data Unit
11
Internet Architecture Principles

• Multiplexing
• Multiple Independent data streams on one physical
  communication line
• Survivability
• Message gets through no matter what
• Service Generality
• Useful for multiple purposes
• Diverse Network Technologies
• Accommodate previous network technologies
  (Arpanet, Satellite-based networks.)

12
TCP/IP

• Transmission Control Protocol / Internet Protocol
• Advanced Research Project Agency (ARPA)
• Arpanet
• TCP/IP 4 or 5 layers of OSI Model

13
OSI TCP/IP Models
  OSI Model OSI Model TCP/IP
L7 Application Application Application
L6 Presentation   Application
L5 Session   Application
L5 Session   Transport
L4 Transport   Transport
L3 Network   Internet
L2 Data Link   Internet
L2 Data link Data link Data link (Network interface)
L1 Physical Physical (Hardware)
14
Protocol Stack

• Protocol Set of rules used for communication
  between 2 points on a network
• What does the transportation header contain? Pg
  76

15
Protocol Examples
16
Protocol Functions

• Encapsulation control information (Where going?
  Is it right? Which protocols to use?)
• Fragmentation (Segmentation) Re-assembly
• Error Control using a check character to
  determine an error in the network access layer
• Synchronization
• Ordered Deliver (Sequencing)
• Addressing
• Multiplexing
• Transmission Services

17
Other Protocol Functions

• Connection Control
• Connection Oriented TCP
• Established and maintained before successful
  transmission
• Connectionless UDP
• Communication without establishing a connection
  (PING)
• Ordered Delivery
• Important to maintain order of packets
  connection oriented
• Flow Control Control data rate sent by
  transmitter

18
Other Protocol Functions

• Error Control Error Detection Error
  Correction
• Check Sum, retransmit
• Sequence Numbering, retransmit
• Addressing
• Network, Application
• Layer dependent
• Transmission Services
• Message priority

19
Protocols

• Transport
• Ensure messages are exchanged reliably
• Arrival of all data at the destination
• Presentation in the same order as sent
• Virtual Circuit Route between sender Receiver
• Data Link
• Communication Startup
• Character Identification
• PDU identification, how to process
• Error Control, what scheme to use
• Termination

20
Review Questions

• 1. Communications standards define what needs to
  be done but not how to do it.
• a. True
• b. False

21
Review Questions

• 2. Which field in a header tells the destination
  of a message or PDU?
• a. address
• b. flag
• c. byte
• d. none of the above

22
Review Questions

• 3. It is more difficult for a machine to process
  a code if all of the bits are of the same
  duration.
• a. True
• b. False

23
Review Questions

• 4. The combination of the first three layers of
  the OSI model is the standard for the
  ______________.
• a. X.25 standard for data transmission
• b. V. standard
• c. consolidated transmission standard
• d. Consolidated Transmission Protocol

24
Review Questions

• 5. When data or a request from one layer is
  passed down to another layer, the data are
  surrounded by control characters or other
  information. This process is called
  _____________.
• a. enclosure
• b. encapsulation
• c. isolation
• d. permutation

25
Review Questions

• 6. The process of reassembling a message a TCP/IP
  packetized stream of data that has been
  fragmented is called __________.
• a. reassembly
• b. reconstitution
• c. segmentation
• d. togetherness

26
Review Questions

• 7. It is much easier for a machine to process a
  code if ____________________.
• a. it is a true binary code
• b. all of the characters have the same number of
  bits
• c. all of the bits are the same duration
• d. all of the above

27
Review Questions

• 8. An example of a communications medium is
  ____________.
• a. a telephone
• b. a personal computer
• c. a teleprinter
• d. a copper wire

28
Review Questions

• 9. The PSTN is an example of a _____________.
• a. mesh network
• b. star network
• c. bus network
• d. ring network

29
Review Questions

• 10. The OSI layer responsible for establishing
  the communication rules between certain machines
  or applications is the ______________.
• a. network layer
• b. transport layer
• c. session layer
• d. data link layer

30
Homework

• Assignment Due Next Week
• Review
• Chapter 3, pp. 48-66
• Chapter 4, pp. 72-82
• Read
• Chapter 5, pp. 90-101
• Chapter 14, pp. 376-411
• Complete
• Assignment 2.1 Chapter 3 4 Multiple Choice
  Questions
• Assignment 2.2 Binary Exercise
• Assignment 2.3 Draw OSI Model (pg 57) by Hand