1. Protocols and the TCP/IP Suite
Lecture 12

2. Overview Requirement of Protocol Why Layered Approach is Adopted
Key Features of a Protocol
Simple Protocol Architecture
Addressing
TCP/IP and OSI model
General Networking Terminology

3. The Need For Protocol Architecture
To transfer data several tasks must be performed:
1.) the source must activate communications path or inform network of destination
2.) the source must make sure that destination is prepared to receive data
3.) the file transfer application on source must confirm file management program at destination is prepared to accept and store file
4.) a format translation function may need to be performed if the formats on systems are different

4. Functions of Protocol Architecture
breaks logic into subtask modules which are implemented separately
modules are arranged in a vertical stack
each layer in the stack performs a subset of functions
relies on next lower layer for primitive functions
changes in one layer should not require changes in other layers

5. Key Features of a Protocol
A protocol is a set of rules or conventions that allow peer layers to communicate.
The key features of a protocol are:
Syntax
format of data blocks
Semantics
control information for coordination and error handling
Timing
speed matching and sequencing

6. examples of applications include file transfer and electronic mail
A Simple Protocol
agents involved:
applications
computers
networks
examples of applications include file transfer and electronic mail
these execute on computers that support multiple simultaneous applications

7. Communication Layers
communication tasks are organized into three relatively independent layers:
Network access layer
concerned with the exchange of data
Transport layer
provides reliable data transfer
Application layer
Contains logic to support applications

8. Network Access Layer
covers the exchange of data between an end system and the network that it is attached to
concerned with issues like :
destination address provision
invoking specific services like priority
access to & routing data across a network for two end systems attached to the same network

9. Transport Layer concerned with providing reliable delivery of data
common layer shared by all applications
essentially independent of the nature of the applications

10. Application Layer
contains the logic needed to support user applications
separate module is needed for each type of application

11. Protocol Architecture and Networks

12. Protocols in a Simplified Architecture

14. Addressing Two levels of addressing are needed:
each computer on the network has a unique network address
each application has an address that is unique with that computer (SAPs)

15. Protocol Data Unit (PDU)
the combination of data and control information is a protocol data unit (PDU)
typically control information is contained in a PDU header
control information is used by the peer transport protocol at computer B
headers may include:
source port, destination port, sequence number, and error-detection code

16. Network Access Protocol
after receiving segment from transport layer, the network access protocol must request transmission over the network
the network access protocol creates a network access PDU (packet) with control information
header includes:
source computer address
destination computer address
facilities requests

17. TCP/IP Protocol Architecture
Result of protocol research and development conducted on ARPANET
Referred to as TCP/IP protocol suite
TCP/IP comprises a large collection of protocols that are Internet standards

18. TCP/IP Layers and Example Protocols

19. Physical Layer
covers the physical interface between computer and network
concerned with issues like:
characteristics of transmission medium
nature of the signals
data rates

20. Network Access Layer
covers the exchange of data between an end system and the network that it is attached to
concerned with issues like :
destination address provision
invoking specific services like priority
access to & routing data across a network for two end systems attached to the same network

21. Internet Layer
implements procedures needed to allow data to travel across multiple interconnected networks
uses the Internet Protocol (IP) to provide routing function
implemented in end systems and routers

22. Host-to-Host (Transport) Layer
concerned with providing reliable delivery of data
common layer shared by all applications
most commonly used protocol is the Transmission Control Protocol (TCP)

23. Operation of TCP/IP

24. TCP/IP Address Requirements
Two levels of addressing are needed:
each host on a subnetwork must have a unique global internet address
each process with a host must have an address (known as a port) that is unique within the host

25. TCP/IP Addressing

26. Operation of TCP/IP

27. Transmission Control Protocol (TCP)
TCP is the transport layer protocol for most applications
TCP provides a reliable connection for transfer of data between applications
A TCP segment is the basic protocol unit
TCP tracks segments between entities for duration of each connection

28. TCP Header

29. User Datagram Protocol(UDP)
alternative to TCP
does not guarantee delivery, preservation of sequence, or protection against duplication
adds port addressing capability to IP
used with Simple Network Management Protocol (SNMP)

30. UDP Header

31. IPv6 Provides enhancements over existing IP
Designed to accommodate higher speeds and the mix of graphic and video data
Driving force was the need for more addresses due to growth of the Internet
IPv6 includes 128-bit source and destination address fields

32. IPv6 Header

33. TCP/IP Protocols

34. Standardized Protocol Architectures

35. Layer Specific Standards

36. Protocol specification
OSI Standardization
framework for standardization was motivator
lower layers are concerned with greater levels of details
each layer provides services to the next higher layer
three key elements:
Protocol specification
Service definition
Addressing

37. Primitive Types REQUEST
A primitive issued by a service user to invoke some service and to pass the parameters needed to specify fully the requested service
INDICATION
A primitive issued by a service provider either to:
indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters, or
notify the service user of a provider-initiated action
RESPONSE
A primitive issued by a service user to acknowledge or complete some procedure previously invoked by an indication to that user
CONFIRM
A primitive issued by a service provider to acknowledge or complete some procedure previously invoked by a request by the service user

38. Service Primitives and Parameters
define services between adjacent layers using:
primitives to specify function performed
parameters to pass data and control information

39. Internet Applications
Applications that operate on top of TCP include:
SMTP
FTP
SSH
TCP

40. Multimedia Terminology

41. Multimedia Terminology
audio generally encompasses sounds that are produced by a human, telephony and related voice communications technology
image supports the communication of individual pictures, charts, or drawings
video service carries sequences of pictures in time
text is information that can be entered via a keyboard and is directly readable and printable

42. Multimedia Applications

43. Domains of Multimedia Systems and Example Applications

44. Elastic and Inelastic Traffic
can adjust to delay and throughput changes across an internet
-traditional “data” style TCP/IP traffic
does not easily adapt to changes in delay and throughput
-“real-time” traffic such as voice and video
Inelastic Traffic

45. Multimedia Technologies

47. Internetworking Terms
End System (ES) – device used to support end-user applications or services
Intermediate System (IS) – device used to connect two networks
Bridge – an IS used to connect two LANs that use similar LAN protocols
Router - an IS used to connect two networks that may or may not be similar

48. Functions of a Router Provide a link between networks
Provide for the routing and delivery of data between processes on end systems attached to different networks
Provide these functions in such a way as not to require modifications of the networking architecture of any of the attached subnetworks

49. Network Differences Routers Must Accommodate
Addressing schemes
Different schemes for assigning addresses
Maximum packet sizes
Different maximum packet sizes requires segmentation
Interfaces
Differing hardware and software interfaces
Reliability
Network may provide unreliable service

50. Summary Why we need protocols for communication
Benefits of adopting layered approach
From simple to featured protocol example
Addressing schemes
Standards Comparison (TCP/IP Vs. OSI)
Functionality of and important device on the basis of studied protocol