COMPUTER COMMUNICATION NETWORK PDF
COMPUTER COMMUNICATION NETWORKS. Department of ECE, ACE. Page 2. Every layer clubs together all procedures, protocols, and methods which it. Communication and Computer Networks. Prerequisites. Before proceeding with this tutorial, you need a basic understanding of Computer. You should know the. PDF | On Jan 1, , D B Hoang and others published Computer Communication Networks—Lecture Notes.
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“No man but a blockhead ever wrote, except for money.” - Samuel Johnson. The textbook world is changing. On the one hand, open source. This book is concerned with post-computer communication networks and two of increasingly relying on digital computer technology, and data communication. Computer Networking: Principles, Protocols, and Practice was written by Dr. Olivier tween the communication devices is larger than one kilometer. There are.
Firewalls[ edit ] A firewall is a network device for controlling network security and access rules. Firewalls are typically configured to reject access requests from unrecognized sources while allowing actions from recognized ones. The vital role firewalls play in network security grows in parallel with the constant increase in cyber attacks. Message flows A-B in the presence of a router R , red flows are effective communication paths, black paths are across the actual network links.
A communication protocol is a set of rules for exchanging information over a network. In a protocol stack also see the OSI model , each protocol leverages the services of the protocol layer below it, until the lowest layer controls the hardware which sends information across the media. The use of protocol layering is today ubiquitous across the field of computer networking. This stack is used between the wireless router and the home user's personal computer when the user is surfing the web.
Communication protocols have various characteristics. They may be connection-oriented or connectionless , they may use circuit mode or packet switching , and they may use hierarchical addressing or flat addressing.
There are many communication protocols, a few of which are described below. The complete IEEE protocol suite provides a diverse set of networking capabilities. The protocols have a flat addressing scheme. They operate mostly at levels 1 and 2 of the OSI model. It is standardized by IEEE It offers connection-less as well as connection-oriented services over an inherently unreliable network traversed by data-gram transmission at the Internet protocol IP level. At its core, the protocol suite defines the addressing, identification, and routing specifications for Internet Protocol Version 4 IPv4 and for IPv6, the next generation of the protocol with a much enlarged addressing capability.
They were originally designed to transport circuit mode communications from a variety of different sources, primarily to support real-time, uncompressed, circuit-switched voice encoded in PCM Pulse-Code Modulation format. It uses asynchronous time-division multiplexing and encodes data into small, fixed-sized cells.
This differs from other protocols such as the Internet Protocol Suite or Ethernet that use variable sized packets or frames. ATM has similarity with both circuit and packet switched networking.
This makes it a good choice for a network that must handle both traditional high-throughput data traffic, and real-time, low-latency content such as voice and video.
ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before the actual data exchange begins. The negotiator communicates with peer negotiators of other agents for cooperation and negotiation.
Thus, it is responsible for planning cooperation and recovery from problematic situations, as well as conflict resolution during problem solving and resource sharing.
TaskProcessor is the module that actually executes the task of solving the problem assigned to that primary agent. It controls the execution of some base processes.
The domain specifier actually has knowledge of these controls. The four modules are realized as an event-driven problem solver that consists of a problem solving mechanism and corresponding knowledge base.
An event of a module is generated from the messages received from other modules. The module is then activated and a problem solving task begins execution. Group agent A model of a primary agent is shown in Fig. Primary agents communicate among themselves by messagepassing. The DomainKnowledge module is the main knowledge resource A large-scale problem is first decomposed into small independent problems that can finally be arranged in a hierarchical problem solving structure.
A group of primary agents, called an organization, is constructed in accordance with the hierarchical problem solving structure. Organizations are formed according to the task by an organizational agent, by collecting proper primary or other group agents.
An organizational agent has knowledge such as the organizational objective, memory, decision making capability and coordination strategies. Thus a group agent, shown in the box in Fig. Thus, a group agent forms the hierarchical structure for complex problem solving. An organizational agent OA administrates the elements of the MemberAgents of the group and plays the roles of both DomainKnowledge and Negotiator, as we have seen in case of the primary agent. An OA, in fact, has the same structure as a primary agent.
Configurationof the primary agent. Thus, a group agent accesses basic processes either via proper primary agents, or via group agents selected from the agent society, as shown in Fig. Various group agents are thereby defined by their respective OAs. Configuration We propose to design the flexible computer communication system with group agents, which would hold knowledge and various protocols as defined above.
The configuration of such a system is capable of changing, with little effort, through some negotiations among the different group agents. Thus, the flexible computer communication system, which needs to be autonomously reconfigurable to absorb small problems or perturbations, would be realizable. A complex task, which has to be accomplished by coordinating different basic processes, is done by negotiation and planning of different agents.
All this knowledge regarding with whom to communicate and what to negotiate is also embedded in those agents. Such knowledge is to be gathered from the of the group agent.
The ADIPS-Agent designer creates different agents using knowledge of the system designer, application programmer and the maintenance engineers. It is an agent-oriented language, with its own editor, interpreter and debugger.
CSE 222A: Computer Communication Networks
This repository is evolutionary in that new agents are added to the repository itself, so that efficient software reuse is possible. Once the agents are created and debugged, they are placed in the workspace. Depending on the complexity of the service requirement and the status of the underlying resources, the response may be very fast or a little slow. If we go back to Fig. Application example Of the different distributed processing applications, probably the most important and versatile would be multimedia applications, and probably in the very near future.
Files would be stored at one location, processed at another system, and flnally rendered somewhere else. As the constraints are different at different points, it is difficult to balance the whole system without proper coordination. Flexibility, as defined, is needed at every interface. In fact, it needs to be flexibly interpreted depending on the availability of system and communication resources. We have designed and implemented a flexible video conferencing tool using an agentoriented model described in the last section.
The block level model is shown in Fig. The RV conference agent is a group agent created for the application. Detailed discussion about the agent structure and task distribution is beyond the scope of this paper.
In the near future, it will be operational between the two distant universities of Japan, Tohoku University and Chiba Institute of Technology, using the Internet.
In this experimental project, we used existing software as much as possible. For controlling the base tasks by agents, control points were created and extended to the proper agents. The service parameters are flexibly changed in response to the system status. A simple illustration is shown in Fig. A moving picture of colored balls are displayed, as shown in Fig.
Dummy processes of different CPU requirements are run. As it crosses different levels, the motion picture changes from color to black and white, and then the frame rate is decremented for proper load balancing. Thus, instead of crashing the application due to lack of CPU resource on one side, or inefficiently reserving the resources on the other side, the application runs with graceful degradation and is restored to the initial level when possible resilience.
In the next step of the experiment, instead of processor load we would generate dummy packets in the LAN to increase the network traffic, and use our group agents to support graceful degradation. Once this ground-work is ready, we will run the system on the Internet during different traffic hours.
Discussion and conclusion In this paper, we have presented a direction towards building the next generation of computer communication systems. With the vast expansion of communication networks, various hardware and software vendors contributing without coordination, and on top of that occasional upgrades User and failures, the whole system of information networks becomes less friendly.
This flexible computing opens and encompasses various fields of research, depending on from what angle it is viewed. Our main goal is to use them under a single coordinated paradigm.
The Fig. Solid core cable is quite suitable for this purpose and for many home and small business network. It is also quite acceptable for use as patch cables. You might consider a stranded wire patch cable if you have a notebook computer you are constantly moving around. CAT 5 cable has four twisted pairs of wire for a total of eight individually insulated wires.
Each pair is color coded with one wire having solid color blue, orange, green, or brown twisted around a second wire with a white background and a stripe of the same color. The solid color may have white stripe in some cables. Cable colors are commonly described using the background color followed by the color of the stripe; e.
Make sure they are rated for Figure 3. RJ CAT 5 wiring. Also, there are RJ Connector plugs designed for both solid core wire and stranded wire. Others are designed specifically for one kind of wire or the other. Be sure you buy plugs appropriate for the wire you are going to use.
We normally use plugs designed to accommodate both kinds of wire. Network cabling tools 1. Modular Plug Crimp Tool You will need a modular crimp tool. This is very similar to the ones which have been used for many years for all kinds of telephone cable work and it Figure 3.
Modular plug crimp tool works just fine for Ethernet cables. Some crimpers have cutters which can be used to cut the cable and individual wires, and possibly stripping the outer jacket. It is highly recommending for anyone who will make a lot of cables. Diagonal Cutters Figure 3. Figure 3. Each transmission line is a pair of twisted wires. One pair receives data signals and the other pair transmits data signals.
A much simplified schematic for one of these lines and its transmitter and receiver follows: The principal components of these pulses of energy are the potential difference between the wires and the current flowing near the surface of the wires. This energy can also be considered as residing in the magnetic field which surrounds the wires and the electric field between the wires.
In other words, an electromagnetic wave which is guided by, and travels down the wires. The main concern are the transient magnetic fields which surround the wires and the magnetic fields generated externally by the other transmission lines in the cable, other network cables, electric motors, fluorescent lights, telephone and electric lines, lightning, which may literally bury the Ethernet pulses, the conveyor of the information being sent down the line.
The twisted-pair Ethernet employs two principal means for combating noise.
The first is the use of balanced transmitters and receivers. A signal pulse actually consists of two simultaneous pulses relative to ground: The receiver detects the total difference between these two pules. Since a pulse of noise usually produces pulses of the same polarity on both lines, it is essentially canceled out at the receiver. Also, the magnetic field surrounding one wire from a signal pulse is a mirror of the one on the other wire.
At a very short distance from the two wires the magnetic fields are opposite and have a tendency to cancel the effect of each other out.
The second and the primary means of reducing cross-talk the term cross-talk came from the ability to overhear conversations on other lines on your phone between the pairs in the cable, is the double helix configuration produced by twisting the wires together. This configuration produces symmetrical dentinal noise signals in each wire. Ideally, their difference as detected at the receiver, is zero.
In actuality it is much reduced. Straight through and cross over cable Again, the wire with colored backgrounds may have white stripes and may be denoted that way in diagrams found elsewhere.
For example, the green wire may be labeled Green-White. The background color is always specified first.
Straight through and crossover cable wire scheme A Straight-through cable has identical ends, whereas a Crossover cable has different ends. Cable connector standard ordering It makes no functional difference which standard you use for a straight-through cable.
Your can start a crossover cable with either standard as long as the other end is the other standard. It makes no functional difference which end is which.
Despite what you may have read elsewhere, a A patch cable will work in a network with B wiring and B patch cable will work in a A network. Strip one end of the cable with the stripper or a knife and diags. If you are using the stripper, place the cable in the groove on the blade left side of the stripper and align the end of the cable with the right side of the stripper. If you turn it more, you will probably nick the wires. If you are using knife and diags, carefully slit the cable for about an inch or so and neatly trim around the circumference of the cable with diags to remove the jacket.
Inspect the wires for nicks. Cut off the end and start over if you see any. You may have to adjust the blade with the screw at the front stripper. Cable diameters and jacket thicknesses vary.
Spread and arrange the pairs roughly in the order of the desired cable end. Untwist the pairs and arrange the wires in the order of the desired cable end.
Flatten the end between your thumb and forefinger. Trim the ends of the wires so they are even with one another. Flatten again. There should be little or no space between the wires. Hold the RJ plug with the clip facing down or away from you. Push the wire firmly into the plug. Now, inspect before crimping and wasting the plug!
Looking through the bottom of the plug, the wire on the far-left side will have a white background. The wires should alternative light and dark from left to right. The furthest right wire is brown.
The wires should all end evenly at the front of the plug. The jacket should end just about where you see it in the diagram-right on the line. Hold the wire near the RJ plug with the clip down and firmly push it into the left side of the front of the Crimper it will only go in one way. Hold the wire in place and squeeze the crimper handles quite firmly. This is what will happen: Crimping Crimp it once. The crimper pushes two plungers down on the RJ plug. Test the crimp… if done properly an average person will not be able to pull the plug off the cable with his or her bare hands.
And that quite simply, besides lower cost, is the primary advantage of twisted-pair cables over the older thin wire, coaxial cables. In fact, the ease of installation and the modular RJ plug is the main reason coaxial cable is no longer widely used for small Ethernet. It could stretch the cable and change its characteristics. Look at the side of the plug and see if it looks like the diagram and give it a fairly firm tug to make sure it is crimped well. Prepare the other end of the cable so it has the desired end and crimp.
If both ends of the cable are within reach, hold them next to each other and with RJ clips facing away. Look through the bottom of the plugs. If the plugs are wired correctly, and they are identical, it is a straight-through cable. If they are wired correctly and they are different, it is a crossover cable.
Try to avoid running cables parallel to power cables. If you bundle a group of cables together with cable ties zip ties , do not over-clinch them. Keep cables away from devices which can introduce noise into them. Do not use a stapler to secure UTP cables. Use telephone wire hangers, which are available at most hardware stores.
Give the reason why it is not advisable to bend UTP cables more than four times the diameter of the cable. Why is it not advisable to run UTP cable outside of a building? In order to do well in the labs, we need to understand the basic set-up of the lab.
You will be using the PC as a terminal to talk to the routers. One of them has RJ connectors and the other has serial connectors. Ethernet ports are pre-connected to the RJ patch panel. Serial ports are pre-connected to the serial patch panel. The ports are labeled on their left. You will find the console cable as a UTP cable with one of its ends connected through a small devices to a serial port on the PC. Cisco routers support different modes of operation.
Cisco routers use many other modes, but let us keep it simple for now. Connect the PC to R1. Question mark lists commands that can be used in a certain context. You only need to type enough of a command to differentiate it from all other commands.
Type the following commands: The prompt ends with router-config? Go into configuration mode and type the following commands: Type these commands: Now you can configure interface Ethernet0. This command will bring them up.
Now type the following command: Again type this command: Cisco commands are not case-sensitive. Determine which mode you operate in when you first access the router. The command used to save changes made in the running configuration to start-up configuration is: List the interfaces on three routers of your choice. Be sure to indicate the router number. Which of the condition s are possible for an interface: Figure 5.
In this kind of protocols we require an addressing scheme and sub netting. Addressing scheme will be used to determine the network to which a host belongs and to identifying that host on that particular network.
All hosts on an internetwork use the services of a routed protocol. It makes possible for routers to build and maintain routing tables. Although dynamic routing protocols are flexible and adjust to network changes, they do have associated network traffic which competes for network bandwidth with the user data traffic. Configuring Static Routes Static routes specify a fixed route for a certain destination network. They need to be configured on any router that needs to reach a network that it is not directly connected to.
The IOS command used to configure static routes is ip route. The syntax is: Multiple networks may be combined such that the destination- address and subnet-mask combination matches all hosts on those networks. Adding a static route to an Ethernet or other broadcast interface for example, ip route 0. This configuration is not generally recommended.
When the next hop of a static route points to an interface, the router considers each of the hosts within the range of the route to be directly connected through that interface, and therefore it will send ARP requests to any destination addresses that route through the static route.
If unspecified the default value is 1. Connect the network as shown in the network diagram. Configure appropriate ip addresses and clock rates if needed on the router interfaces as specified in the network diagram.
For R1, enter the following static routes ip route On R2 enter: On R3 enter: After that verify the static routes by entering the following commands in the privilege mode: Run the command show IP route and write its output. What is the default administrative distance of static route?
Write the IP route command to modify the same. Create a loop back interface on R3 and assign an IP address Now add static routes to each of the other routers to reach this interface.
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Verify your work by pinging the newly created interface from routers R1 and R2 respectively. Figure 6.On R3 enter: The largest cost component is f or installation and Following t hese simple ideas will help ensure that testing labor. Write down these ways. It discusses the problem of modeling the performance of local area networks under file transfer.
Description Computer- Communication Networks presents a collection of articles the focus of which is on the field of modeling, analysis, design, and performance optimization. Data link Reliable data transfer. Address ranges for 1Pv4 networks Classful addresses. Other computers connected that year were on the campuses of Stanford. This stack is used between the wireless router and the home user's personal computer when the user is surfing the web.