Osi and Tci-ip Model

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OSI Model & TCP/IP

Chapter 2


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OSI LayersOSI Model

Data unit Layer Function

Host

layers

Data

7. Application Network process to application

6. PresentationData representation,encryption and decryption

5. Session Interhost communicationSegments

4. TransportEnd-to-end connections andreliability, Flow control

Medialayers

Packet 3. NetworkPath determination and logicaladdressing

Frame 2. Data Link Physical addressing

Bit 1. PhysicalMedia, signal and binarytransmission

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Going from layer 1 to 7: Please Do Not Throw Sausage PizzaAway

Going from layer 7 to 1: All People Seem To Need DataProcessing
http://en.wikipedia.org/wiki/Application_Layerhttp://en.wikipedia.org/wiki/Presentation_Layerhttp://en.wikipedia.org/wiki/Session_Layerhttp://en.wikipedia.org/wiki/Transport_Layerhttp://en.wikipedia.org/wiki/Network_Layerhttp://en.wikipedia.org/wiki/Logical_addresshttp://en.wikipedia.org/wiki/Logical_addresshttp://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Physical_Layerhttp://en.wikipedia.org/wiki/Physical_Layerhttp://en.wikipedia.org/wiki/Data_Link_Layerhttp://en.wikipedia.org/wiki/Logical_addresshttp://en.wikipedia.org/wiki/Logical_addresshttp://en.wikipedia.org/wiki/Network_Layerhttp://en.wikipedia.org/wiki/Transport_Layerhttp://en.wikipedia.org/wiki/Session_Layerhttp://en.wikipedia.org/wiki/Presentation_Layerhttp://en.wikipedia.org/wiki/Application_Layer


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Layer1: Physical Layer

The physical layer deals with the physicalcharacteristics of the transmission medium.

It defines the electrical, mechanical, procedural,and functional specifications for activating,

maintaining, and deactivating the physical linkbetween end systems.

Such characteristics as voltage levels, timing ofvoltage changes, physical data rates, maximum

transmission distances, physical connectors, andother similar attributes are defined by physicallayer specifications.

Examples :- EIA/TIA-232, RJ45, NRZ.

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Layer 2: Data Link Layer

The data link layer provides access to thenetworking media and physicaltransmission across the media and thisenables the data to locate its intendeddestination on a network.

The data link layer provides reliable transitof data across a physical link by using the

Media Access Control (MAC) addresses. The data link layer uses the MAC address

to define a hardware or data link address in

order for multiple stations to share the samemedium and still uni uel identif each 5


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Layer 2: Data Link Layer

Another is Logical Link Control (LLC).provides data transmission method indifferent network. It will re-package

date and add a new header. Concerned with network topology,

network access, error notification,ordered delivery of frames, and flowcontrol.

Examples :- Ethernet, Frame Relay,FDDI

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Layer 3: Network Layer

The Network Layer performs network routing functions,

perform fragmentation and reassembly,

report delivery errors.

The network layer also defines how tofragment a packet into smaller packets

to accommodate different media. Routers operate at Layer 3.

Protocols examples :- IP, IPX,

AppleTalk. 7


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Layer 4: Transport Layer

The Transport Layer provides transparenttransfer of data between end users,providing reliable data transfer services tothe upper layers.

The Transport Layer controls the reliabilityof a given link through flow control,segmentation/de-segmentation, and error

control. Layer 4 protocols include TCP

(Transmission Control Protocol) and UDP(User Datagram Protocol).

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Layer 5: Session Layer

The session layer defines how to start, control andend conversations (called sessions) betweenapplications.

This includes the control and management of

multiple bi-directional messages using dialoguecontrol.

It also synchronizes dialogue between two hosts'presentation layers and manages their data

exchange. The session layer offers provisions for efficient data

transfer.

Examples :- SQL, ASP(AppleTalk Session

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Layer 6: Presentation Layer

It is sometimes called the syntax layer.

The presentation layer ensures that the informationthat the application layer of one system sends outis readable by the application layer of anothersystem.

If necessary, the presentation layer translatesbetween multiple data formats by using a commonformat.

Provides encryption and compression of data.

Examples :- JPEG, MPEG, ASCII, EBCDIC, HTML.

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Layer 7: Application Layer

The application layer is the OSI layerthat is closest to the user.

It provides network services to the

users applications.

It differs from the other layers in that itdoes not provide services to any other

OSI layer, but rather, only toapplications outside the OSI model.

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Layer 7: Application Layer

Examples of such applications arespreadsheet programs, word processingprograms, and bank terminal programs.

Some examples of application layerimplementations include

Hypertext Transfer Protocol (HTTP)

File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP)

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Introduction TCP/IP

The Internet Protocol Suite (commonlyknown as TCP/IP) is the setof communications protocols used for

the Internet and other similar networks. It is named from two of the most

important protocols in it:

the Transmission Control Protocol (TCP) and

the Internet Protocol (IP), which were the firsttwo networking protocols defined in thisstandard.

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TCP/IP Layers

OSI TCP/IP

Application LayerApplication Layer

TELNET, FTP, SMTP, POP3, SNMP,

NNTP, DNS,NIS, NFS, HTTP, ...Presentation Layer

Session Layer

Transport Layer Transport LayerTCP , UDP , ...

Network Layer Internet LayerIP , ICMP, ARP, RARP, ...

Data Link Layer Link LayerFDDI, Ethernet, ISDN, X.25,...

Physical Layer

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TCP/IP Some Protocol

Layer Protocol

Application

DNS, TFTP, TLS/SSL, FTP, Gopher, HTTP, IMAP, IRC, NNTP, POP3, SIP, SMTP, SMPP, SNMP, SSH, Telnet, Echo, RTP, PNRP, rlogin, ENRP

Routing protocols like BGP and RIP which run over TCP/UDP, mayalso be considered part of the Internet Layer.

Transport TCP, UDP, DCCP, SCTP, IL, RUDP, RSVP

Internet

IP (IPv4, IPv6), ICMP, IGMP, and ICMPv6

OSPF for IPv4 was initially considered IP layer protocol since itruns per IP-subnet, but has been placed on the Link since RFC2740.

Link ARP, RARP, OSPF (IPv4/IPv6), IS-IS, NDP

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http://en.wikipedia.org/wiki/Application_layerhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocolhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/File_Transfer_Protocolhttp://en.wikipedia.org/wiki/Gopher_(protocol)http://en.wikipedia.org/wiki/HyperText_Transfer_Protocolhttp://en.wikipedia.org/wiki/Internet_Message_Access_Protocolhttp://en.wikipedia.org/wiki/Internet_Relay_Chathttp://en.wikipedia.org/wiki/Network_News_Transfer_Protocolhttp://en.wikipedia.org/wiki/Post_Office_Protocolhttp://en.wikipedia.org/wiki/Post_Office_Protocolhttp://en.wikipedia.org/wiki/Session_Initiation_Protocolhttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://en.wikipedia.org/wiki/Short_message_peer-to-peer_protocolhttp://en.wikipedia.org/wiki/Simple_Network_Management_Protocolhttp://en.wikipedia.org/wiki/Secure_Shellhttp://en.wikipedia.org/wiki/Telnethttp://en.wikipedia.org/wiki/Echo_protocolhttp://en.wikipedia.org/wiki/Real-time_Transport_Protocolhttp://en.wikipedia.org/wiki/Peer_Name_Resolution_Protocolhttp://en.wikipedia.org/wiki/Rloginhttp://en.wikipedia.org/wiki/Rloginhttp://en.wikipedia.org/w/index.php?title=Endpoint_Handle_space_Redundancy_Protocol&action=edit&redlink=1http://en.wikipedia.org/wiki/Border_Gateway_Protocolhttp://en.wikipedia.org/wiki/Routing_Information_Protocolhttp://en.wikipedia.org/wiki/Transport_layerhttp://en.wikipedia.org/wiki/Transmission_Control_Protocolhttp://en.wikipedia.org/wiki/User_Datagram_Protocolhttp://en.wikipedia.org/wiki/Datagram_Congestion_Control_Protocolhttp://en.wikipedia.org/wiki/Stream_Control_Transmission_Protocolhttp://en.wikipedia.org/wiki/IL_Protocolhttp://en.wikipedia.org/wiki/Reliable_User_Datagram_Protocolhttp://en.wikipedia.org/wiki/Resource_reservation_protocolhttp://en.wikipedia.org/wiki/Internet_Layerhttp://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/IPv4http://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/Internet_Control_Message_Protocolhttp://en.wikipedia.org/wiki/Internet_Group_Management_Protocolhttp://en.wikipedia.org/wiki/ICMPv6http://en.wikipedia.org/wiki/Open_shortest_path_firsthttp://tools.ietf.org/html/rfc2740http://tools.ietf.org/html/rfc2740http://en.wikipedia.org/wiki/Link_Layerhttp://en.wikipedia.org/wiki/Address_Resolution_Protocolhttp://en.wikipedia.org/wiki/Reverse_Address_Resolution_Protocolhttp://en.wikipedia.org/wiki/Open_shortest_path_firsthttp://en.wikipedia.org/wiki/IS-IShttp://en.wikipedia.org/wiki/Neighbor_Discovery_Protocolhttp://en.wikipedia.org/wiki/Neighbor_Discovery_Protocolhttp://en.wikipedia.org/wiki/IS-IShttp://en.wikipedia.org/wiki/IS-IShttp://en.wikipedia.org/wiki/IS-IShttp://en.wikipedia.org/wiki/Open_shortest_path_firsthttp://en.wikipedia.org/wiki/Reverse_Address_Resolution_Protocolhttp://en.wikipedia.org/wiki/Address_Resolution_Protocolhttp://en.wikipedia.org/wiki/Link_Layerhttp://tools.ietf.org/html/rfc2740http://tools.ietf.org/html/rfc2740http://en.wikipedia.org/wiki/Open_shortest_path_firsthttp://en.wikipedia.org/wiki/ICMPv6http://en.wikipedia.org/wiki/Internet_Group_Management_Protocolhttp://en.wikipedia.org/wiki/Internet_Control_Message_Protocolhttp://en.wikipedia.org/wiki/IPv6http://en.wikipedia.org/wiki/IPv4http://en.wikipedia.org/wiki/Internet_Protocolhttp://en.wikipedia.org/wiki/Internet_Layerhttp://en.wikipedia.org/wiki/Resource_reservation_protocolhttp://en.wikipedia.org/wiki/Reliable_User_Datagram_Protocolhttp://en.wikipedia.org/wiki/IL_Protocolhttp://en.wikipedia.org/wiki/Stream_Control_Transmission_Protocolhttp://en.wikipedia.org/wiki/Datagram_Congestion_Control_Protocolhttp://en.wikipedia.org/wiki/User_Datagram_Protocolhttp://en.wikipedia.org/wiki/Transmission_Control_Protocolhttp://en.wikipedia.org/wiki/Transport_layerhttp://en.wikipedia.org/wiki/Routing_Information_Protocolhttp://en.wikipedia.org/wiki/Border_Gateway_Protocolhttp://en.wikipedia.org/w/index.php?title=Endpoint_Handle_space_Redundancy_Protocol&action=edit&redlink=1http://en.wikipedia.org/wiki/Rloginhttp://en.wikipedia.org/wiki/Rloginhttp://en.wikipedia.org/wiki/Peer_Name_Resolution_Protocolhttp://en.wikipedia.org/wiki/Real-time_Transport_Protocolhttp://en.wikipedia.org/wiki/Echo_protocolhttp://en.wikipedia.org/wiki/Telnethttp://en.wikipedia.org/wiki/Secure_Shellhttp://en.wikipedia.org/wiki/Simple_Network_Management_Protocolhttp://en.wikipedia.org/wiki/Short_message_peer-to-peer_protocolhttp://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocolhttp://en.wikipedia.org/wiki/Session_Initiation_Protocolhttp://en.wikipedia.org/wiki/Post_Office_Protocolhttp://en.wikipedia.org/wiki/Post_Office_Protocolhttp://en.wikipedia.org/wiki/Network_News_Transfer_Protocolhttp://en.wikipedia.org/wiki/Internet_Relay_Chathttp://en.wikipedia.org/wiki/Internet_Message_Access_Protocolhttp://en.wikipedia.org/wiki/HyperText_Transfer_Protocolhttp://en.wikipedia.org/wiki/Gopher_(protocol)http://en.wikipedia.org/wiki/File_Transfer_Protocolhttp://en.wikipedia.org/wiki/Transport_Layer_Securityhttp://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocolhttp://en.wikipedia.org/wiki/Domain_Name_Systemhttp://en.wikipedia.org/wiki/Application_layer


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Connecting Below Internet Level

Hub Center of star topology

In Ethernet, multiportrepeater or concentrator

Bridge Connects 2 networks of

same technologyextended LAN

Filters/forwards/floodsbased on MAC

Link layer - frames

Switch Connects 2+ networks

packet-switched network

Reduces collisions

Ethernet Ethernet

Hub

Bridge

Switch

Ethernet Ethernet

CISCOSYSTEMS

CISCOS YSTEMS CISCOS YSTEMS

T3 STS-N


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Connecting at the Internet Level

Router

Originally gateway

Forwards packets

based on network layerinfo (IP)

Separate broadcastdomains

In each domain, IPpacket encapsulated indomain-specific packet

Token-ring

CISCOSYST EMS

Ethernet

CISCOSYST EMS

Ethernet

CISCOSYST EMS

Router

Osi and Tci-ip Model

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