Free Powerpoint Templates Page 1 Internetworking Models.

Free Powerpoint Templates Page 1

Internetworking Models

http://www.powerpointstyles.com/


The Layered Approach

• A reference model is a conceptual blueprint of how communications should take place.

• It addresses all the processes required for effective communication and divides these processes into logical groupings called layers .

• When a communication system is designed in this manner, it’s known as layered architecture



Advantages of Reference Models

• Allows multiple-vendor development through standardization of network components

• Allows various types of network hardware and software to communicate

• Prevents changes in one layer from affecting other layers, so it does not hamper development



• OSI is the Open System Interconnection reference model for computer communication in a networking environment.

• The concept of a 7 layer model was provided by the work of Charles Bachman , Honeywell Information Services.

• Various aspects of OSI design evolved from the ARPANET.• Work on a layered model of network architecture was started in

the late 1970s based on a proposal developed by the International Standards Organization (ISO).

• Because of rapid prolification of TCP/IP protocol suite in 1990’s, OSI lagged behind.

• OSI protocols are still in existence and are used around the world.

The OSI Reference Model



Advice

Person

Sales

Take

Not

Do

Please

OSI Model Layers

Application

Presentation

Session

Transport

Network

Data Link

Physical

Layer - 7

Layer - 6

Layer - 5

Layer - 4

Layer - 3

Layer - 2

Layer - 1

Upper Layer or Software Layer

Lower Layer or Hardware Layer

Heart of OSI



Application LayerApplication Layer is responsible for providing Networking Services to user. It also known as Desktop Layer. Identification of Services is done using Port Numbers.

Ports are nothing but Socket i.e. Entry and Exit Point to the Layer

Total No. Ports 0 – 65535 Reserved Port 0---1023

Application

Presentation

Session

Transport

Network

Data Link

Physical

Application



Example of HTTP request

Client Web Server

http://www.zoomgroup.com



Example of HTTP request

Client Web Server

HTTP Request http:// www.zoomgroup.comWebpage

HTTP Request Listen on Port 80Sending HTTP ReplyWebpage

Received HTTP Reply http://www.zoomgroup.comWebpage



Example of FTP request

Client FTP Server

ftp://ftp.microsoft.com



Example of FTP request

FTP Request ftp://ftp.microsoft.com

FTP Request Listen on Port 21Sending FTP Reply

Received FTP Reply ftp://ftp.microsoft.com

Client FTP Server



Examples of Networking

ServicesService Port No.

HTTP 80

FTP 21

SMTP 25

TELNET 23

TFTP 69



Application

2180 25 6753 69

How data flows from Application Layer

Data

Presentation

Session

Transport

Network

Data Link

Physical



Presentation

Layer

Presentation Layer is responsible for converting data into standard format.

Examples : ASCII, EBCDIC, JPEG, MPEG,WAV, MP3

Following tasks are perform at Presentation layer :

Encoding – DecodingEncryption – DecryptionCompression – Decompression

Application

Presentation

Session

Transport

Network

Data Link

Physical

Presentation



How data flows from Presentation Layer

Data

DataApplication

Presentation

Session

Transport

Network

Data Link

Physical



Session Layer

Session Layer is responsible establishing, maintaining and terminating session. Session ID also works at Session Layer.

Examples :

RPC Remote Procedure Call SQL Structured Query languageNFS Network File System

Application

Presentation

Session

Transport

Network

Data Link

Physical

Session



How data flows from

Session Layer

Data

Data

Data

Application

Presentation

Session

Transport

Network

Data Link

Physical



Transport Layer

Transport Layer is responsible for end-to-end connectivity. It is also known as heart of OSI Layers. Following task are performed at Transport Layer : -

• Identifying Service

• Segmentation

• Sequencing & Reassembling

• Flow Control

• Error Correction

Application

Presentation

Session

Transport

Network

Data Link

Physical

Transport



Identifying Service

• Transmission Control Protocol

• Connection Oriented

• Acknowledgement

• Reliable

• Slower

• Port No. 6

• e.g. HTTP, FTP, SMTP

• User Datagram Protocol

• Connection Less

• No Acknowledgement

• Unreliable

• Faster

• Port No. 17

• e.g. DNS, DHCP, TFTP

TCP UDP



Connection Oriented (TCP)



Segmentation

Hello! How are you ?

Hello! How Are You ?


A B



Sequencing & Reassembling


Hello! How Are You ?


A B

You Hello! How ? Are

Hello! How AreYou ?

you Hello! How ? are



Sequencing & Reassembling


Hello!1/5

How2/5

Are3/5

You4/5

?5/5


A B


Hello!1/5

How2/5

Are3/5

You4/5

?5/5

Hello!1/5

How2/5

Are3/5

You4/5

?5/5




Error Correction


Hello!1/5

How2/5

Are3/5

You4/5

?5/5


Hello!1/5

Are3/5

You4/5

?5/5

Hello!1/5

Are3/5

You4/5

?5/5

Segment Missing

Hello!1/5

Are3/5

You4/5

?5/5

How2/5

How2/5

Hello! How are you ? Hello! How are you ?

A B



Flow Control -

Windowing

Sending 3-window

Received 3-window

Ack-Rec-3Sending5-window

Received 4-window

A B

Ack. Received-4

PC-A can send 4 Segment at a

time to PC-B



How data flows from

Transport Layer

Data

Data

Data

DataTHSegment

Application

Presentation

Session

Transport

Network

Data Link

Physical



Network Layer

Network Layer is responsible for providing best path to data to reach destination. Logical Addressing sits on this layer. Device working on Network Layer is Router.

It is divided into two parts

• Routed Protocols

e.g. IP, IPX, Apple Talk.

• Routing Protocols

e.g. RIP, IGRP, OSPF, EIGRP

Application

Presentation

Session

Transport

Network

Data Link

Physical

Network



Routed Protocols


192.168.1.1 192.168.1.2

A B

Segment

Segment

Source IP 192.168.1.1

Destination IP192.168.1.2

Source IP 192.168.1.1

Destination IP192.168.1.2

Segment




Routing Protocols

A

www.zoomgroup.com



How data flows from

Network Layer

Data

Data

Data

Segment

Segment

NH

e.g. Router

Packet

Application

Presentation

Session

Transport

Network

Data Link

Physical



Datalink Layer

Datalink Layer is divided into two Sub Layers :

• LLC – Logical Link ControlIt talks about Wan protocols e.g. PPP, HDLC, Frame-relay

• MAC – Media Access ControlIt talks about Physical Address. It is 48 bit Addressing i.e. 12 digit Hexadecimal No. It is also responsible for Error DetectionDevice working on Data Link Layer is Switch, Bridge, NIC.

Application

Presentation

Session

Transport

Network

Data Link

Physical

Data Link



Error Detection – CRC

Check


Packet

Packet

Source MAC 00-20-18-C0-07-71

Destination MAC00-20-18-C0-07-72

000003243422222896965543499323434349943446323111143333300000324342222289696554349932343434994344632311114Error Detected

192.168.1.100-20-18-C0-07-71

192.168.1.200-20-18-C0-07-72

A B



Error Detection – CRC

Check

Packet

Packet

Source MAC 00-20-18-C0-07-71


00000324342222289696554349932343434994344632311114202020000032434222228969655434993234343499434463231111420202

Source MAC 00-20-18-C0-07-71


Packet


192.168.1.100-20-18-C0-07-71

192.168.1.200-20-18-C0-07-72

A B



e.g. Switch

How data flows from Data Link Layer

Data

Data

Data

Segment

DH

Packet

DT

Application

Presentation

Session

Transport

Network

Data Link

Physical

PacketPacketFrame



Physical Layer

Physical Layer is responsible for electrical, mechanical or procedural checks. Data will be converted in Binary that is 0’s & 1’s. Data will be in the form of electrical pulses if it is Coaxial or Twisted Pair cable and in the form of Light if it is Fiber Optic Cable.

Devices working at Physical Layer are Hubs, Repeaters, Cables, Modems etc.

Application

Presentation

Session

Transport

Network

Data Link

PhysicalPhysical



Physical Layer Example

Frame

Frame

10101010101010101010101010101010

Frame


A B01010110101010101010101011010101101010101010101010010101101010101010101010110101011010101010101010100101011010101010101010101



How data flows from

Physical Layer

Data

Data

Data

Segment

Packet

Frame

Bits

e.g. Hub

Application

Presentation

Session

Transport

Network

Data Link

Physical



Segment

Packet

Frame

A B

Packet

Data

Data

Data

Bits

Data

Segment

Data Encapsulation & De-capsulation

Packet

Data

Data

Data

Application

Presentation

Session

Transport

Network

Data Link

Physical

Application

Presentation

Session

Transport

Network

Data Link

PhysicalBits

DH DT

NH

THSegment

Packet

DT PacketDH DTDH

NH Segment NH

TH Data TH

Frame Packet



TCP/IP reference model

• TCP/IP also has a network model.• TCP/IP was on the path of development when the OSI standard was

published and there was interaction between the designers of OSI and TCP/IP standards.

• The TCP/IP model is not same as OSI model.• OSI is a seven-layered standard, but TCP/IP is a four layered

standard.• The OSI model has been very influential in the growth and

development of TCP/IP standard, and that is why much OSI terminology is applied to TCP/IP.



Application

Transport

Internet

Network Access

Comparing OSI with TCP/IP Layers

OSI Layers TCP/IP Layers

Application

Presentation

Session

Transport

Network

Data Link

Physical



Layer 4. Application Layer

• The top most layer of four layer TCP/IP model. Application layer is present on the top of the Transport layer. Application layer defines TCP/IP application protocols and how host programs interface with transport layer services to use the network.

• Application layer includes all the higher-level protocols like DNS (Domain Naming System), HTTP (Hypertext Transfer Protocol), Telnet, FTP (File Transfer Protocol), TFTP (Trivial File Transfer Protocol), SNMP (Simple Network Management Protocol), SMTP (Simple Mail Transfer Protocol) , DHCP (Dynamic Host Configuration Protocol), X Windows, RDP (Remote Desktop Protocol) etc.



Layer 3. Transport Layer

• Transport Layer is the third layer of the four layer TCP/IP model. The position of the Transport layer is between Application layer and Internet layer. The purpose of Transport layer is to permit devices on the source and destination hosts to carry on a conversation. Transport layer defines the level of service and status of the connection used when transporting data.

• The main protocols included at Transport layer are TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).



Layer 2. Internet Layer

• Internet Layer is the second layer of the four layer TCP/IP model. The position of Internet layer is between Network Access Layer and Transport Layer. Internet layer pack data into data packets known as IP datagrams, which contain source and destination address (logical address or IP address) information that is used to forward the datagrams between hosts and across networks. The Internet layer is also responsible for routing of IP datagrams.



Layer 1. Network Access Layer

• Network Access Layer is the first layer of the four layer TCP/IP model. • Network Access layer defines details of how data is physically sent

through the network, including how bits are electrically or optically signaled by hardware devices that interface directly with a network medium, such as coaxial cable, optical fiber, or twisted pair copper wire.



Cisco 3-layer Hierarchical Model



Core layer

• Responsible for transporting large amounts of traffic reliably and quickly. • Only purpose is to switch traffic as fast as possible (speed and latency are

factors). • Failure at the Core layer can affect every user, design for fault tolerance at

this level. • Design specifications

Don't Do at this layer – Don't use access lists, packet filtering, or VLAN Routing. – Don't support workgroup access here. – Don't expand (i.e. more routers), upgrade devices instead (faster with more

capacity). Do at this layer

– Design for high reliability (FDDI, Fast Ethernet with redundant links, or ATM). – Design for speed and low latency. – Use routing protocols with low convergence times.



Distribution layer

• Also called workgroup layer, this is the communication point between the access and core layers.

• Primary functions include routing, filtering, WAN access, and determining how packets can access the Core layer if necessary.

• Determines fastest/best path and sends request to the Core layer. Core layer will then quickly transport the request to the correct service.

• Place to implement network policies.

Distribution Layer Functions • Access lists, packet filtering, queuing. • Security and network policies such as address translation and fire-walling. • Re-distribution between routing protocols including static routing. • Routing between VLANs and other workgroup support functions. • Departmental or workgroup access. • Definition of broadcast and multicast domains. • Any media transitions that need to occur.



Access layer

• Controls local end user access to internetwork resources. • Also called desktop layer. • The resources most users need will be available locally. • Distribution layer handles traffic for remote services. • Continued use of access lists and filters. • Creation of separate collision domains (segmentation). • Workgroup connectivity at Distribution layer. • Technologies such as DDR and Ethernet switching are seen in the

Access layer. • Static routing is here




Free Powerpoint Templates Page 1 Internetworking Models.

Documents