Part E: Standards Layered Standards Architectures TCP, IP, and TCP/IP Other Architectures.

Part E:Standards

Layered Standards Architectures

TCP, IP, and TCP/IP

Other Architectures

2Standards

Standards are rules of operation that most or all vendors follow

Open standards are created and owned by public standards organizations– No single vendor controls these standards

3Standards Are Layered

For Internet Access to a Webserver, standards are set at five layers– Application– Transport– Internet– Data Link– Physical

Together, these standards provide all that is needed for application programs on different hosts on different networks to work together

4Internet Standards

Application Layer Standards– Standards at the application layer specify how two

application programs communicate – For example, browser on user PC and webserver

application program on webserver

Browser

WebserverApplication

Program

5Internet Standards

HTTP (HyperText Transfer Protocol)– World Wide Web standard for browser-webserver

application program exchanges– Other applications (E-mail, etc.) have different

application standards

Browser

WebserverApplication

Program

HTTP

6Internet Standards

Transport Layer Protocols– Standards at the transport layer specify how two host

computers will work together, even if they are of different platform types (PCs, workstations, mainframes, and so forth)

– For instance, PC and non-PC webserver

PCPC or

Other Computer

7Internet Standards

The Transport Layer Gives Platform Independence– Two computers do not have to be of the same platform

type

A PC user does not even know what kind of computer the webserver is

PC?

8Internet Standards

HTTP Requires the Use of the TCP Transport Standard– Transmission Control Protocol– TCP messages are called TCP segments

TCP

9Internet Standards

Internet Layer Protocols– Standards at the internet layer specify how hosts and

routers will act to route packets end to end, from the source host to the destination host, across many single networks (subnets) connected by routers

Route

Single Network(Subnet)Host

Host

10Internet Standards

The Internet Protocol (IP) is the Main Protocol for Routing Packets Across the Internet– The IP in “TCP/IP”– IP messages are called packets– All internet layer messages are called packets

IP

Packet


Subnets– Single networks (LANs, WANs, point-to-point link) on

the Internet– A packet will pass through several subnets along its

route across the Internet

Subnet

Subnet

Subnet


Different Subnets Can Have Different Subnet Protocols– IP at the internet layer routes across different protocols

at the subnet layer

Point-to-Point SubnetProtocol 1

WAN SubnetProtocol 2

LAN Subnet Protocol 3

13Subnets Standards

Subnets are Single Networks on the Internet

Subnet Standards Divided into Two Layers

– Physical layer standards govern the transmission of individual bits within a subnet

– Data Link layer standards govern the transmission of messages within a subnet

Organize individual bits into structured messages


Data Link Layer Standards– Standards at the data link layer specify how to transmit

messages within a single network– Messages at the data link layer are called frames

10010001001

Data Link

Frame


Data Link Layer Standards– For accessing the Internet from home ...

– Point-to-Point Protocol (PPP) dominates

– Only used between home and ISP!

– Other subnets connecting routers are likely to use different subnet protocols!

ISPPPP ?


Physical Layer Standards– While the data link layer is concerned with the

organization and transmission of organized messages, standards at the physical layer specify how to transmit single bits one at a time

– Work bit by bit; no frame organization


Physical Layer Standards in Internet Access from Home– Telephone jack (RJ11)– Telephone wire– Serial port connection to external modem– Modem

SerialPort

External Modem TelephoneWire Wall Jack


Subnet Versus Internet Layer Standards– Internet layer provides routing across multiple subnets– Subnet layer standards (data link and physical) provide

for transmission within a single network

InternetLayer

Subnet Layer


Analogy for Subnet versus Internet– Take a vacation– Route from beginning to end (like internet layer)– For different parts, may travel by car, airplane, or boat

(like subnet layer)

InternetLayer

Subnet Layer

20Standards Organizations and Architectures

Architecture is a Design for Standards Creation

– Specifies what types of standards are needed (application, transport, etc.)

– After architecture is designed, individual standards of each type are created

– Analogy: architecture of house specifies what rooms will be needed and their relationships.

– After architecture is settled, individual rooms are designed


TCP/IP Standards– Created by the Internet Engineering Task Force (IETF)– Named after its two most widely known standards, TCP

and IP TCP/IP is the architecture, while TCP and IP are

individual standards However, these are not its only standards, even at

the transport and internet layers– IETF standards dominate in corporations at the

application, transport, and internet layers However, application, transport, and internet

standards from other architectures are still used


OSI Standards– Reference Model of Open Systems Interconnection

– Created by the International Telecommunications Union-Telecommunications Standards Sector (ITU-T)

– And the International Organization for Standardization (ISO)

– OSI standards dominate the data link and physical layers

Other architectures specify the use of OSI standards at these layers


5-Layer Hybrid TCP/IP-OSI Architecture– Most widely used architecture in organizations today– Used on the Internet

Application TCP/IP

Transport TCP/IP

Internet TCP/IP

Data Link OSI

Physical OSI


Recap: Accessing the WWW from Home

AppApp

TransTrans

IntInt

DLDL

PhyPhy

User PC

IntInt

DLDL

PhyPhy

Router

AppApp

TransTrans

IntInt

DLDL

PhyPhy

Webserver

HTTP

TCP

IP

PPP

Modem

IP

?

?

25TCP/IP versus OSI

Lowest Four Layers are Comparable in Functionality

TCP/IP OSI

Application ApplicationPresentationSession

Transport TransportInternet NetworkData Link (use OSI) Data LinkPhysical (use OSI) Physical

Box

26OSI Divides the Application Layer

OSI Session Layer– Sets up a connection between two application programs

on different machines– Manage streams of transactions (session); if there is a

break, can resume at the last roll-back point

Transactions

Box


OSI Presentation Layer– Handles presentation differences between the two

machines (how data are stored and represented)

– Two presentation layer processes select and use a common format for exchanging data

Application DataExchange in

Common Format

Box


OSI Application Layer

– Governs application-to-application communication freed from concerns about presentation format and transaction management

Box

Part E: Standards Layered Standards Architectures TCP, IP, and TCP/IP Other Architectures.

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Transcript of Part E: Standards Layered Standards Architectures TCP, IP, and TCP/IP Other Architectures.