part e: standards layered standards architectures tcp, ip, and tcp/ip other architectures
TRANSCRIPT
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
11Internet Standards
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
12Internet Standards
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
14Internet Standards
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
15Internet Standards
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 ?
16Internet Standards
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
17Internet Standards
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
18Internet Standards
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
19Internet Standards
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
21Standards Organizations and Architectures
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
22Standards Organizations and Architectures
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
23Internet Standards
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
24Internet Standards
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
27OSI Divides the Application Layer
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
28OSI Divides the Application Layer
OSI Application Layer
– Governs application-to-application communication freed from concerns about presentation format and transaction management
Box