Easy To Remember Open Systems Interconnection (OSI)

Easy To Remember Open Systems Interconnection (OSI)

Funcions of OSI Layers
Wecan seefunctionsofOSI, TCP/IPModel, PDUs, ProtocolsandNetworklayerofthe OSI. Thereare twomodels that canbe usedtoexplain themechanism ofdata communication incomputer networks, namelyModelTCP/IPandOSImodels. Amultinationalentityestablishedin 1947namedthe InternationalStandards Organization(ISO) as anentitythat gave birth tothe standards ofinternational standards. ISOstandardsalsoissued acommunication networkthat coversall aspects oftheOSI model(OpenSystems Interconnection).

KeywordOpen SystemsInterconnection (OSI) [to easyremember you]
OpenSystems Interconnectionconsists ofsevenlayers:

7.Application
6.Presentation
5.session
4.transport
3.network
2.data link
1.Physical

OSI's objectiveistomake the standardrules of communicationthatcan beestablishedintercommunicationof different systemswithout the need forsignificant changes inhardwareandsoftware.

The seven layersare dividedinto 3sub-groups:
>Layer1, 2and 3is the NetworkSupportLayer(layers ofnetwork support)
>Layers5, 6and 7is the UserSupportLayer(layers of user support)
>Layer 4is theTransport LayerconnectsUserSuportSupportLayerandNetworkLayer

7.ApplicationFunction: is the layerin direct contact withusersand providenetwork services touser applications.
TCP/IPModel: Application
PDU: Data
Protocols:HTTP, SMTP, FTP, Telnet, SSH, DNS, DHCP, POP, IRC, SMB
NetworkDevice:-

6.Presentation
Funtion:Set the format ofthe data, organizedata representation, managedata security.
TCP/IPModel: Application
PDU: Data
Protocols: .Jpg,. Zip, ASCII,. Mp3
NetworkDevice: -

5.Session
Function:dutytocontrol thedialogue betweenthe nodes. A dialogueis aformalconversationin which twonodeshave agreedto exchangedata.Sessionlayerhas threesteps: (simplex, half duplex, fullsimplex) the establishment of relations, the transfer of data, termination.
TCP/IPModel:-
PDU:-
Protocols:-
NetworkDevice:-

4.Transport
Function:Thislayerprovides servicestransparentlyin terms oferror recovery andflow control. And ensuredata isgiven(on a layer abovethesessionlayer) intact,orderand withoutduplicationand error free.
TCP/IPModel: Transport
PDU: Segment
Protocols:TCP, UDP, PortNumber
NetworkDevice: Layer 4Switches

3.Network
Function: dutytodeterminethe network address, specifythe route to betaken duringthe trip.Maintain a queueof trafficon thenetwork.
TCP/IPModel:Internet
PDU: Package
Protocols: IP Addresses,PhysicalAddressing
NetworkDevice: Routers

2.DataLink
Function: dutytotransform thedata packets from thelayerabove ittosignaldata (and vice versa), which will be forwardedto thenetworkmedia.
TCP/IPModel:Network Access
PDU: Frames
Protocols: MACAddresses,PhysicalAddressing
NetworkDevice:Nics, Switches, Bridges

1.Physical
Function:definingthe characteristicsof themedia used.
TCP/IPModel:Network Access
PDU: Bits
Protocols:Media, Medium
NetworkDevice:Nics, Hubs, Cables, Wires, radiowaves.Easy To Remember Open Systems Interconnection (OSI)Keyword by LayerApplication Layer : network applications, services, programs, peer-to-peer applicationsPresentations Layer : file, compression, format and securitySession : -Transport : reliable (TCP), connection orianted, end-to-end delivery, flow controlNetwork : logical addressing IP, best path, path determinationData Link : media access, physical address, network access control, MAC frame

source : http://cnn.com, http://tipsbarudipercaya.blogspot.com, http://dailymotion.com