CHAPTER 1 Computer Networks and the Internet 1 2 STUDY COMPANION FOR COMPUTER NETWORKING, THIRD EDITION Most Important Ideas and Concepts from Chapter 1 Nuts and bolts of computer networks. Computer networks consist of end systems, packet switches, and communication links. End systems—also called hosts—include desktop PCs, laptops, hand-held network devices (including cell phones, PDAs, and BlackBerries), sensors, and servers (such as Web and mail servers). Just as cities are interconnected by a network of roads and intersections, end systems of a computer network are interconnected by a network of communication links and packet switches. Communication links can be wired or wireless. Distributed applications. A computer …show more content…
Queuing delay and packet loss. Many packets can arrive at a packet switch roughly at the same time. If these packets need to be forwarded on the same outbound link, all but one will have to “queue,” that is, wait to be transmitted. This waiting introduces a queuing delay. Furthermore, if the queue of packets becomes very large, the packet switch’s buffer may become exhausted, causing packets to be dropped or “lost.” Queuing delay and packet loss can severely impact the performance of an application. Protocol layers. A typical computer network makes use of many protocols—easily hundreds. To deal with this complexity, the protocols are organized into layers. These protocol layers are arranged in a “stack.” For example, the Internet organizes its protocols into five layers—namely, from top to bottom: application layer, transport layer, network layer, link layer, and physical layer. The protocols of layer n use the services provided by the protocols at the layer n - 1 (the layer below). This abstract concept, 4 STUDY COMPANION FOR COMPUTER NETWORKING, THIRD EDITION often difficult to grasp at first, will become clearer as we delve into the different protocol layers. With the application-layer as the highest layer in the protocol stack, one can say that all other layers in the stack exist only to provide services to the application. Indeed this is the case, as applications are the raison d’être for computer networks. Without networked applications,
The fifth layer is the session layer this establishes a connection,this layer makes and sets up the connection using co ordinates and could terminate conversations links. the session layer produces services that make authentication after an interruption and not only that but it can reconnect.and as well as the transporting layer it can also have the TCP and the UDP can provide services for all most all applications.An application layer is an abstraction layer that specifies the shared protocols and interface methods used by hosts in a communications network. The application layer abstraction is used in both of the standard models of computer networking; the Internet Protocol Suite (TCP/IP) and the Open Systems Interconnection model (OSI model).Although both models use the same term for their respective highest level layer, the detailed definitions and purposes are different.In TCP/IP, the application layer contains the communications protocols and interface methods used in process-to-process communications
• “Application - The Application Layer is the layer that most network users are exposed to, and is the level at which human communication happens. HTTP, FTP, and SMTP are examples of the application layer protocols the Patton-Fuller will now be utilizing for communicating electronically” (Network Design, 2012).
The OSI (Open System Interconnection) model is a set of specifications that allow computers around the world to openly communicate. It is pivotal to understanding and developing computer to computer communications in a network. Each layer plays a role in the process of sending and receiving data. The application layer is the top layer (layer seven) it promotes communication between programs and lower-layer network services. The services at this layer allow the network to decipher a program's request and the program to decipher data sent from the network. The Application layer protocols, programs handles formatting, procedure, security, synchronization, and any other requirements with the network. The Presentation Layer (layer 6) acts as a translator. For instance these protocols decode the jpg/jpeg files sent within the Web server’s HTTP response. So, in the last step (the Application layer) we enter the Web address and it took us to the Web site. This step allows us to see the images and content of the site. The Session Layer (layer 5) regulates and controls the communication between two nodes on the network. It is an ongoing exchange of data between the two and keeps the connection between them for the duration. It keeps the communication secure, detects whether or not the communication has been cut off and if it has it determines where to restart the
The Application layer within the OSI reference model is where the application and the user communicates. In other words, the application layer is the ending of data that is transferred in visual form to the user. This layer provides the interface between the applications we use to communicate and the underlying network over which our messages are transmitted. The Application Layer functions are to provide the interface for application-specific protocols commonly used such as HyperText Transfer (HTTP), file transfer (FTP), Simple mail transfer (SMTP), Internet message Access (IMAP),
The internet layer is built up of four core protocols: IP, IGMP, ICMP and ARP. Internet protocol (IP) is responsible for routing, IP addressing and breakdown/reassembly of data packets, address resolution protocol (ARP) is responsible for mapping an IP address to a device on the local network, internet control message protocol (ICMP) provides diagnostic information and error reports on lost packets, internet group management protocol (IGMP) controls who receives IP datagrams in a single transmission. The transport layer is built up of two core protocols: TCP and UDP. Transmission control protocol (TCP) sequences and acknowledges packets sent and their recovery when lost in transmission allowing the computer to make and maintain network conversations where applications exchange data, defined as a connection-oriented protocol meaning the connection is maintained until the programs has finished exchanging data. User datagram protocol (UDP) This is used to transfer small amounts of data when the use of error correction isn’t needed increasing the speed of the transmission, common in multi-player video games as the user will not need to receive packets of past events in the game so the error correction featured in (TCP) would be
6. Why is Ethernet technology more appealing to users than the rest of the LAN technologies?
Host A will use application for the OS while allowing the PC to still communicate to other devices. Transport will control the data sent and received. The network will place IP addresses to the packets allowing data to be added to the MAC addresses and physical link between host and lines.
The two parts of the TCP/IP are the: Transport Layer Protocol and the Network Layer Protocol aka TCP and IP. TCP is what links the application layer to the network layer. It also helps by segmenting the data, by breaking them down
The two authors follow the story from the conception of the idea of "packet switching" in the early 1960s to the creation and development of the Internet. We see how one idea led to another and how the intelligent people around the circumstances influenced the developments.
When a CPU is composed of two or more processors, each one is referred to as a(n) ________.
The application layer: this layer allows different applications to communicate with each other’s. In order to exchange different data over the network connection, the protocols included in this layer set up the standards such as DNS, HTTP, FTP. The data coded in this layer will be encapsulated to transport layer for further packing.
A computer network is a network that consist of two or more computers that are able to share information between them or their users. There are a large variety of different networks and the advantages or disadvantages are strongly related to the type of network we choose.
All the computers, in the logically and physically networks have to follow the same rules known as Protocols such as TCP/IP, IPX/SPX and NETBEUI etc. Today, there are many computer networking technologies such as LAN, MAN, WAN, WLAN, ISDN, ATM, Frame Relay, X.25, Bluetooth,
Windows XP was introduced as a significant upgrade to Windows 98 and Windows Millennium. After Microsoft brought out MS-DOS in the 1980's it developed its futuristic operating system - Windows. Newer versions of this OS were developed over the years, including the out bringing of Windows NT (New Technology) which was aimed at business users and computer servers. After numerous incarnations of the Windows operating system, including Windows 95, 98 and the much criticized Windows Millennium, the XP system was released October 25, 2001.Windows XP has much in common with the singularities and also engineering of Windows 2000. In fundamentals XP was created to"bridge the two architectures
A given layer in the OSI model generally communicates with three other OSI layers: the layer directly above it, the layer directly below it, and its peer layer in other networked computer systems. The data link layer in System A, for example, communicates with the network layer of System A, the physical layer of System A, and the data link layer in System B. The following figure illustrates this example.