DATA COMMUNICATION

NETWORK

By :-HARSHKUMAR MANILAL PATELLukhdhirji Engineering College1st ME Power SystemEnrollment No.:-130310737010

Network Architectures• Application Layer• Presentation Layer• Session Layer• Transport Layer• Network Layer• Data Link Layer• Physical Layer

Typical Network Topologies• Bus Network• Branching Network • Star Network• Ring Network

Content:-

Network Architectures • All electronic data communications equipment today use one

or more layer of the 7-layer OSI model.

• Each application may use one or all of the layers.

• The lowest level sa the simplest lavels,and they will use inalmost every application.

• The upper 4 lavels are more complex and are only use in moresophisticated systems.

• This that you may work with only the first three or four layersmost of time.

7 APPLICATION

6 PRESENTATION

5 SESSION

4 TRANSPORT

3 NETWORK

2 DATA LINK

1 PHYSICAL

The 7-layer OSI model

• This layer is the physical layer and it has the job of moving theelectrical signal from one point to another.

• This layer include the wire of cable through which data aresent.

• This layer also includes the electrical on-off pulse that movethrough the wire.

• This layer is only concerned with the physical medium oftransporting the signal from one point to another.

• This layer does not provide any error detection, error control,or sequencing of data.

• This layer include wire specifications and cable terminationspecifications.

1. The Physical Layer

• The data layer combines with the physical layer to make morereliable system in that it add error detection and errorrecovery methods.

• The rules for this layer are usually called protocols.

• This layer will include a means to start and stop the data flow,away to package each part of the data.

• A means of sequencing when data are sent and when they arereceived, a means to acknowledge that data have beenreceived.

• A means of providing timing that includes when the data arebeing sent and how long to wait if data have not arrived.

2. The Data Link Layer

• The primary function of the network layer is to provide adelivery mechanism for the transport layer.

• This use when the unit that is connected to the datacommunications system is part of a multiple-unit networkrather than one single unit connected to only one other singleunit.

• The network layer use a combination of hardware andsoftware.

• Provide protocols like the x.21.x.25, and x.75.

• This also use when one network must interface with othernetwork.

3. The Network Layer

• The transport layer provides connections from one network toanother.

• Also provides a means of keeping the upper layers fromknowing what the lower layers are doing.

• This is the layer that begins to be different in various type ofnetwork.

• With this possible to use a variety of different networksbecause they are fundamentally similar in first three layer.

• In this layer and upper layers, the syatem tend to become verycomplex and may have a variety of differences.

4. The Transport Layer

• The session layer establishes sessions between user,maintains the sessions between users, terminates thesessions between users.

• The major function of this layer also includes connections oftwo separate open systems.ISO 8326 and CCITT.X212 arestandards for the session layer.

• When one unit on one network requests data from a unit on asecond network, the session layer directs the transport layerto make proper connection.

• And regulate the flow of data smoothly interface theconnections and data flow between the two networks.

5. The Session Layer

• This layer transforms data information so that one networkcan pass information to or receive information from anothernetwork.

• The protocols for this layer are contained in ISO 8823 andCCITT X.226.

• This layer works closely with the session layer to make theconnection between system works smoothiy.

• This layer is vital if you want to have the networks open to thelargest number of different users.

6. The Presentation Layer

PLC2

PLC1

PLC4

PLC3

PLC6

PLC5

Shipping Receiving

OfficeNetwork

FactoryFloorNetwork

Quality ControlAccounting Process Engineering

Production Supervisor’s Computer

Maintenance Supervisor’s Computer

• This layer provides the functions of making all of the otherlayers compatible when users must interconnect betweenmultiple network.

• The protocols in the application layer provide this function.

7. The Application Layer

Typical Network Topologies

• Local area networks can be classified as baseband orbroadband networks.

• A baseband network is usually limited to equipment that isconnected over short distances.

• A broadband network depends on multiplexing techniques tosplit the network into multiple channels.

• Four Types Of network Topologies that are commonly use inindustrial data communications systems.

1. Bus

2. Branching

3. Star

4. Ring

Types Of Network Topologies

• This type of network is identified by one long spine with userdevices connected along the length of the network.

1. Bus Network

Bus Network

• Branching network is show in fig.

• The tree network is identified by one long spine and thebranches that flow from the spine.

• Each branch can also have branches.

2. Branching Network

Branching Network

• The star network is identified by a central node on thenetwork with all other branches of the network emanatingfrom the center node.

• The computer at the end of each branch can fail withoutharming data that are passed to other branches.

• If the computer that acts as the central node fails, the entairenetwork will become disabled.

3. Star Network

Star Network

• The ring network is identified by a main spine that is closed inthe shape of a ring.

• In both variations, data information flows in only onedirection around the ring.

• The first variation of this type of network shows the mainnetwork spine connected in a circle and each node is tap offthe main spine, much like the bus network.

• The second variation of the ring network shows each tap as anintegral part of the ring.

4. Ring Network

Ring Network

Thank You