Nt1310 Unit 3

Layer 3: Network - The way that the data will be sent to the recipient device is determined in this layer. Logical protocols, routing and addressing are handled here.

In order to provide speed and reliability, large and enterprise-level networks today are typically constructed in multiple layers. They are the access layer, also called the network edge layer, the aggregation or distribution layer; and the network core layer. The access layer is usually a mesh of network switches, linked to other switches in the aggregation layer, which in turn is linked to the core.

The first protocol explain is TCP. Starting with the Layer 7, 6, and 5, the Application Layer is providing the payload (data and instructions). The web browser is an example of initiation of Layers 7,6,5 and the payload flow. The Transport

Communication protocols drive what type of computers and network processors are used in the network architecture.

The first three layers are part of the hardware. The first one, called Physical layer, defines the method of moving data between computers, so it is mostly the cabling and signal modulation. This is the physical channel through which the bits of data move. Network devices that operate at the physical layer include a repeater and a hub. The Data Link layer is the second layer and it has the NIC, which is the Network Interface Card. The NIC contains the Media Access Control (MAC) address, which is the unique physical identifier of each system. The recipient’s and sender’s Mac Address, together with the data and the frame check sequence (FCS) is contained in “envelopes” called frames, which are passed to the next layer. The Network layer is the third layer and it includes the routers. It is also the layer where the packets get created and addressed to go from one network to another using the Internet Protocol (IP). The IP packets include the destination IP address, the source IP address and the data. IP addresses work as the network interface identification and location addressing and are stored in the system software.

The designers of TCP / IP thought the higher level protocols should include details of the session and presentation layers. Just created an application layer that handles high-level protocols, issues of representation, encoding and dialog control. The TCP / IP model combines all aspects related to applications in a single layer and ensures that these data are properly packaged for the next layer. Then you will see a graph that associates these layers and see which is easier than it seems.

Describing the way of interaction between different applications and protocols on any network-aware devices is done by the OSI (Open System Interconnection) model. The OSI model characterizes seven layers that depict how applications running upon system mindful gadgets may correspond with one another. The model is nonexclusive and applies to all system sorts, not simply TCP/IP, and all media sorts, not simply Ethernet. It is consequently that any system specialist will garrulously toss around the term "Layer 4" and hope to be caught on.

The OSI reference model is a framework that is used to understand how information travels throughout a network. This model explains how packets travel through the various layers to another device on a network, even if the sender and destination have different types of network media. In the OSI reference model, there are seven numbered layers, each of which illustrates a particular network function.

The OSI data model originated in 1977 and this model contained the original seven layer protocol. The model has since been modified to be used with the changing protocols of the network whilst keeping the seven layers. The seven layer OSI model has been able to cope with the updates but there are duplications of operations which creates a redundancy in the model.

The OSI model shows how the hardware and software function together in order to enable communication between the computers. The OSI model is basically a framework of how the device operate on the network. Assume that user ‘A’ sends data to user ‘B’ through internet, the data has to travel the network to reach user B computer. During the data transfer, the data has to navigate through many intermediate nodes. To ensure the data transfer from user A to user B correctly and securely, so we need protocols to guide these data. These group of protocols are called communication model. OSI model is one of the communication model. Open System Interconnection (OSI) is made up of 7 layers, each layer has their own unique functions and protocols. Control is passed from one layer to another layer, start at application layer which is layer 7 to physical layer which is layer 1. The framework for the OSI model is design of network systems that

● Core Network is the internetworking of routers. ● Transport layer deals with communication between applications. ● The transport layer is not present because it provides additional functions to the core network to compensate for the limitation of the core network layer. ○ In the case of TCP/IP protocol, the Transport Layer provide more complex services such as flow control or connection­oriented data stream transfer to increase the reliability of the data as it is sent through the network. ● By keeping these layers separate, the transport layer is able to provide a uniform

In the second and third layer of osi model it is called data link and network link. Data link is packaging data into frames and transmitting those frames on the network and performing the error detection correction by uniquely identifying the network devices with an address, and handling the flow control. Data link layer has two sub layer which is called media access control which is know as the computer unique identifier to which the network is assigned The mac address comes with a 48 bit address that is assign to it devices network interface card/.Second sub layer is llc which stand for logic link control, which is know as the multiplex functions that is process of over media access control To provide a means of exchanging data between end users across a MAC-controlled

In this report, the OSI and TCP/IP models will be compared after going through a brief history and how the models were made. The report will bring the reader a greater understanding about the OSI and TCP model. The model shows the different layers for example for the OSI model it has the following layers: Application layer, Presentation layer, Session layer, Transport layer, Network layer, Data-Link layer and Physical layer. The similarities in the TCP model would be: the Application layer and the Transport layer. This is then compared for the differences to see which models layer has, that is different to the other.

Wireless networks consist of network nodes which makes use of radio communication for the wireless data transmissions. This execution is carried out at the physical layer of the OSI model.

1. Physical Layer: It is the lower most layer in OSI model, its purpose is transmission of data between the two system.