Communication networks leon garcia 2nd edition pdf

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Solution manual for communication networks 2nd edition lesforgesdessalles.info and random processes lesforgesdessalles.info» blog archive» leon garcia lesforgesdessalles.info» blog. Leon-Garcia, Widjaja, “Communication Networks: Fundamental Concepts and Key Architectures,” 2nd edition, McGraw Hill, ❑ ❑ News, updates. Welcome to the Leon-Garcia Supersite. Communication Networks, 1/e. Communication Networks, 2/e. Click on the appropriate cover above to open the Online.

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Search – will allow you to perform full-text searches of PDF document Alberto Leon-Garcia & Indra Widjaja vii. 1 Communication Networks and Services. 1. Alberto Leon-Garcia and Indra Widjaja: Communication Networks – Fundamental Concepts and Key architectures, 2nd Edition, Tata McGraw-Hill, Communication Networks Leon Garcia 2nd Edition PDF - Free download as PDF File .pdf), Text File .txt) or read online for free.

The network layer in connection-oriented networks performs routing on a per connection basis. Seller Inventory SKU How are disputes on working group documents resolved? The IP address of www. Goods or people arrive at train stations and are loaded for transport to specific places. The network layer in connectionless networks is more robust against failures.

What requirements are imposed on the network if the network is connection-oriented? We suppose that the game involves the interaction between a player and a server across a network. To support an interactive video game over a communications network, the network, whether connection-oriented or connectionless, must provide real-time delivery of the player's commands to the server, and of the server's responses to the player.

Communication Networks 2nd Edition Chapter 1 Solutions throughout the game with very little delay. In a connectionless network, user commands may be delivered to the other end with variable delay, out-of-sequence, or not at all. In-time delivery of commands cannot be assured. Repeat part a if the game involves several players located at different sites. The requirements on the network depend on how the game is implemented. In the centralized approach the players interact through a central server that processes the commands from all of the players, maintains a view of the state of the overall system, and issues appropriate responses to all the players.

Alternatively, the game could be implemented in a decentralized fashion, where each player receives commands from some or all of the players, maintains a local view of the system state, and transmits responses to some or all of the players. In the centralized approach, the network requirements are essentially the same as those in part a. In the decentralized approach, the real-time response requirement may apply only to a subset of players when they happen to be interacting with each other.

If players are located at different sites, the network could provide multicast capability so messages can be exchanged among the server and all the players. Repeat part b if one or more of the players is in motion, for example, kids in the back of the van during a summer trip.

If one or more players is in motion, then the network must also be able to locate each mobile player and then deliver and receive information to and from such player.

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Discuss the similarities between the following national transportation networks and a communications network. Is the transportation system more similar to a telephone network or to a packet network? Transportation networks are designed to transfer people and goods; communications networks are designed to transfer information. Like communication networks, all transportation systems involve links, in the form of roads, rails, or air corridors, and switching points, in the form of stations, airports, and highway interchanges.

Addressing and geographical names are used in transportation networks to identify destinations, and routing of various forms is required to direct goods to their destinations. Transportation resources, in the forms of cars or airplanes, are shared or "multiplexed" among various goods that traverse common parts of the network.

Communication Networks Leon Garcia 2nd Edition PDF | Computer Network | Telecommunications

Railroad network. Railroad network: Goods or people arrive at train stations and are loaded for transport to specific places. Tickets are purchased for a given destination, usually guaranteeing that there will be a place in a car from the starting station all the way to the destination station. This is similar to establishing a connection across a telephone network. Alternatively, a passenger may choose to purchase a ticket at each station along the way.

This corresponds more closely to a connectionless packet network model. Airline network. In this case passengers purchase tickets that guarantee a seat all the way to the destination, even if transfers are made at intermediate airports. This is similar to the establishment of connections across a telephone network. Highway system. Highway systems: Trucks or cars enter the highway without making reservations ahead of time and without informing any central authority of their destination or route.

This mode of operation corresponds closely to the operation of a connectionless packet network. Combination of a , b , and c. Combination of transportation systems: The combination of air, rail, and highway transportation systems can and are used jointly for the transfer of people and goods.

Each transportation system is different in how it is organized and how transfers are accomplished. Nevertheless, it is possible to use these systems in combination to provide a higher degree of connectivity between sources and destinations of people and goods. We will see that the Internet plays a role similar to the combined transportation systems in that the Internet enables the transfer of information across multiple dissimilar networks that may differ in how they are organized and how they operate.

In the s, standard containers were developed for the transportation of goods. These standard containers could fit on a train car, on a truck, or in specially designed container ships. The standard size of the containers makes it possible to load and unload them much more quickly than using non-standard containers of different sizes.

Draw an analogy to packet switching communications networks. In your answer identify what might constitute a container and speculate on the advantages that may come from standard-size information containers. In a packet-switching communications network, the component that is analogous to the container is a constant-size packet preferably of short length that can be used for the transport of information. Transmission systems and networks of various types can be designed to transfer information of the given standardized size, much like trucks, trains, and ships can be designed to carry standard containers.

Packing and unpacking of fixed-size units is simpler than packing and unpacking of variable-length units. Consequently, it is simpler to schedule the transfer of packets across switches that use constant-size packets than across switches that make use of variable-length packets.

The requirements of world commerce led to the building of the Suez and Panama canals. What analogous situations might arise in communication networks? The Suez and Panama canals were built to provide a shorter path between geographical areas with major trade relationships.

The analogous situation arises in communication networks when the path between two areas in the network are too "long" either in terms of excessive delay or inadequate capacity to transfer the required volumes of traffic. The addition of network resources to provide shorter paths for lower delay or wider paths for higher capacity corresponds to the building of a canal. Two musicians located in different cities wish to have a jam session over a communications network.

Find the maximum possible distance between the musicians if they are to interact in real-time, in the sense of experiencing the same delay in hearing each other as if they were 10 meters apart. Assume that the network transmits the sound at the speed of light in cable, 2. Communication Networks 2nd Edition Chapter 1 Solutions The first step is to find the delay for the sound when the musicians are 10 meters apart: The propagation delay is the time that is required for the energy of a signal to propagate from one point to another.

Find the propagation delay for a signal traversing the following networks at the speed of light in cable 2. To find the propagation delay, divide distance by the speed of light in cable. Thus we have: How many bits are in transit during the propagation delay in the above cases, if bits are entering the above networks at the following transmission speeds: The number of bits in transit is obtained by multiplying the transmission rate R by the propagation delay: Distance m 10 Kbps 1 Mbps Mbps 10 Gbps 0.

Communication Networks 2nd Edition Chapter 1 Solutions In problem 14, how long does it take to send an L-byte file and to receive a 1-byte acknowledgment back? The total time required to send a file and receive an acknowledgment of its receipt is given by: The above equation shows that there are two main factors that determine total delay: Message and ACK transmission time, which depends on the message length and the transmission bit rate; 2.

Propagation delay, which depends solely on distance. When the propagation delay is small, message and ACK transmission times determine the total delay. On the other hand, when the bit rate becomes very large, the propagation delay provides a delay component that cannot be reduced no matter how fast the transmission rate becomes. The tables below show the two main components of the total delay in microseconds. The message transmission time is shown in red and the propagation delay is shown in blue.

The entries in the total delay tables are colored according to which delay component is dominant. Answer the following questions: Who was J.

Licklider, and what was his "Galactic Network" concept? In he envisioned a global network of computers where users could access data or programs from any site. Who coined the term packet? What who? Was packet voice proposed as an early application for Internet?

In the early development of TCP, work on packet voice in particular prompted the separation of TCP into two components: TCP and IP. IP was to provide addressing and forwarding; TCP provided special services such as recovery from packet losses important for packet voice. Communication Networks 2nd Edition Chapter 1 Solutions f. How many networks did the initial IP address provide for? The initial IP addressing scheme provided for networks. Use your web browser to access a search engine and retrieve the following presentation from the CM 97 conference: At what rate have processing, storage, and backbone technologies improved from to ?

How does this rate compare to advances in telephony? What is Moore's Law? Microelectronic technologies improve by a factor of 4 every 3 years. What's the point of making predictions? To provide a vision and challenge for the future. What is the difficulty in anticipating trends that have exponential growth? The trouble with exponential growth is that "you can't see them coming! Who was Vannevar Bush and why is he famous? Vannevar Bush posited the "memex" in that in a sense provided the vision for the World Wide Web.

What is the size in bytes of each frame in this presentation? What is the size in bytes of the audio clip for a typical frame? What is the size of the video clip for a typical scene? The graphics-only presentation is approximately 1 MB; the graphics and audio presentation is 7 MB; the video presentation for kbps is 14MB.

The introduction of new communications services usually impacts other services through substitution. Describe how substitution takes place in the following cases. E-mail, facsimile, and postal mail. E-mail is used for most of the correspondence previously handled by postal mail.

Documents sent by facsimile are also transferred using E-mail as attachments. Hardcopies can be scanned for electronic transmission. E-mail, local, and long-distance phone service. E-mail is an inexpensive and convenient alternative for most of the communication in which real- time interaction is not essential.

Instant-messaging is faster than email and more closely approaches the real-time experience of the telephone. Communication Networks 2nd Edition Chapter 1 Solutions c.

Cell phone, local, and long-distance phone service. Cell phone is used for local or long distance calls mostly because users can be reached even if they are not in a specific location such as home or office.

Peer-to-peer file exchange and commercial CD recording. Peer-to-peer file exchange provides an easy means to access and share commercial recordings.

Individual songs rather than entire albums can be acquired. Users can readily arrange their personalized song mixes. Use your web browser to access news website and play a news video clip. Speculate about how the information is being transported over the Internet. How does the quality of the audio and video compare to that of broadcast or cable television? The video information is sent over the Internet, so a packet mode of information transfer is used.

The video signal is placed in a stream of packets that is sent from the video server to the PC. A steady stream of video information needs to be supplied to the video player application in the PC. For this reason the player first buffers a certain amount of video information in order to avoid running out of material to play out during periods when the packets encounter congestion and experience excessive delay.

The Internet is still subject to congestion and so packets are delayed and lost resulting in poor audio and video quality. Use your web browser to access the IETF web page currently at www.

Some RFCs standardize the results of community deliberations about statements of principle or conclusions about what is the best way to perform some operations or IETF process function. Such non-standards track specifications are not subject to the rules for Internet standardization.

What is an Internet Draft? During the development of a specification, draft versions of the document are made available for informal review and comment by placing them in the IETF's "Internet-Drafts" directory, which is replicated on a number of Internet hosts. This makes an evolving working document readily available to a wide audience, facilitating the process of review and revision.

A Proposed Standard specification is generally stable, has resolved known design choices, is believed to be well-understood, has received significant community review, and appears to enjoy enough community interest to be considered valuable. However, further experience might result in a change or even retraction of the specification before it advances.

A specification from which at least two independent and interoperable implementations from different code bases have been developed, and for which sufficient successful operational experience has been obtained, may be elevated to the "Draft Standard" level. Elevation to Draft Standard is a major advance in status, indicating a strong belief that the specification is mature and will be useful.

A Draft Standard may still require additional or more widespread field experience. A specification for which significant implementation and successful operational experience has been obtained may be elevated to the Internet Standard level.

An Internet Standard is characterized by a high degree of technical maturity and by a generally held belief that the specified protocol or service provides significant benefit to the Internet community. Which group in the IETF approves a certain specification for standards-track? A "standards action" -- entering a particular specification into, advancing it within, or removing it from, the standards track -- must be approved by the the Internet Engineering Steering Group IESG.

How are disputes on working group documents resolved? A person who disagrees with a Working Group recommendation shall always first discuss the matter with the Working Group's chair s , who may involve other members of the Working Group or the Working Group as a whole in the discussion.

If the disagreement cannot be resolved in this way, any of the parties involved may bring it to the attention of the Area Director s for the area in which the Working Group is chartered.

The Area Director s shall attempt to resolve the dispute. If the disagreement cannot be resolved by the Area Director s any of the parties involved may then appeal to the IESG as a whole.

The IESG shall then review the situation and attempt to resolve it in a manner of its own choosing.

The IAB shall then review the situation and attempt to resolve it in a manner of its own choosing. The IAB decision is final with respect to the question of whether or not the Internet standards procedures have been followed and with respect to all questions of technical merit.

Explain how the notion of layering and internetworking make the rapid growth of applications such as the World Wide Web possible. Internetworking allows many component networks each with different underlying technology and operation to work together and form one large network.

As new network technologies are introduced they can be readily incorporated into the Internet. This provides the ubiquitous connectivity for applications like WWW. The layering concept hides the specific underlying network technology from the upper layers and provides a common networking platform.

Using the communication service provided by the layers below, new applications can be introduced independently and at a rapid rate. TCP provides reliable connection-oriented transfer of a byte stream; UDP provides for best-effort connectionless transfer of individual messages. The IP addressing scheme is very scalable because of its hierarchical structure. The salient part of the above figure is that all of the higher layer protocols access the network interfaces through IP.

This is what provides the ability to operate over multiple networks. Once a network interface for IP is defined for a given network technology, then hosts connected using the given network technology can connect to the Internet. This allows the reach of the Internet to grow rapidly, leveraging multiple coexisting networks technologies. Thus investment in new network technologies extends the reach of the Internet.

What difference does it make to the network layer if the underlying data link layer provides a connection- oriented service versus a connectionless service? If the data link layer provides a connection-oriented service to the network layer, then the network layer must precede all transfer of information with a connection setup procedure.

If the connection- oriented service includes assurances that frames of information are transferred correctly and in sequence by the data link layer, the network layer can then assume that the packets it sends to its neighbor traverse an error-free pipe.

On the other hand, if the data link layer is connectionless, then each frame is sent independently through the data link, probably in unconfirmed manner without acknowledgments or retransmissions.

In this case the network layer cannot make assumptions about the sequencing or correctness of the packets it exchanges with its neighbors. The Ethernet local area network provides an example of connectionless transfer of data link frames. The transfer of frames using "Type 2" service in Logical Link Control discussed in Chapter 6 provides a connection-oriented data link control example. Suppose transmission channels become virtually error-free.

Is the data link layer still needed? The data link layer is still needed for framing the data and for flow control over the transmission channel. In a multiple access medium such as a LAN, the data link layer is required to coordinate access to the shared medium among the multiple users. Why is the transport layer not present inside the network? Some of the functions provided by the transport layer can be provided inside the networks, but other functions cannot. For example, the transport layer provides functions at the end-system to compensate for the limitations and impairments of the network layer, in order to meet requirements e.

QoS of the upper layer. To provide the reliable service required by some applications - that is, to compensate for the shortcomings of best effort service - TCP establishes connections and implements error control on an end-to-end basis.

Communication Networks Leon Garcia 2nd Edition PDF

One can imagine that a service provider could incorporate this error control function at the edge of its network. On the other hand, one of the main purposes of the transport layer is to allow multiple processes in the end systems to share a network service. This cannot be achieved inside the network.

Communication Networks 2nd Edition Chapter 2 Solutions 6. Which OSI layer is responsible for the following? The network layer is concerned with the selection of paths across the network. The transport layer is concerned with providing reliable service on an end-to-end basis across the network. The data link layer provides for the reliable transfer of information between adjacent nodes in a network. Should connection establishment be a confirmed service or an unconfirmed service?

What about data transfer in a connection-oriented service? Connection release? In general, the establishment of a connection needs to be confirmed before information transfer can commence across a connection.

Therefore connection establishment should be a confirmed service. A connection-oriented service is usually reliable so confirmation of data delivery is not necessary. In certain situations, however, it is possible that the transfer across a connection is not reliable; in this case confirmation of correct data transfer may be required. In general it is desirable that the release of a connection be confirmed by the parties involved. We will see in Chapter 8, section 5, that sometimes it is not easy to confirm that a connection has been closed.

Consequently, many protocols attempt to confirm the closing of a connection several times, and then give up and simply stop transmitting.

Does it make sense for a network to provide a confirmed, connectionless packet transfer service? Connectionless packet transfer is often unreliable, that is, packets may be lost or discarded inside a network.

Certain applications, for example, signaling in connection setup, require confirmation to acknowledge the receipt of packets. Explain how the notion of multiplexing can be applied at the data link, network, and transport layers. Draw a figure that shows the flow of PDUs in each multiplexing scheme. Transport Layer: Multiple application layers processes can share the service provided by UDP.

Multiple application layer processes also share the service provided by TCP. The packet transfer service provided by IP can be used by all transport layers operating in a machine.

Upon receiving an IP packet, a machine examines the protocol type field to determine which transport layer service to deliver the SDU to. We can also view all transport layer PDUs as sharing the IP packet transfer service between a source machine and a destination machine. Data Link Layer: We can also view packet flows that traverse a data link between two routers as sharing the link.

Give two features that the data link layer and transport layer have in common. Give two features in which they differ. Compare what can go wrong to the PDUs that are handled by these layers.

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Features they have in common: The data link layer involves the interaction of peer-to-peer processes that are connected directly. In general, the time that elapses in traversing a data link is much smaller than the time traversing a network, where packets can become trapped in temporary routing loops. Consequently, transport layer protocols must be able to deal with out-of-sequence PDUs and a much larger backlog of PDUs than data link layers.

Can a connection-oriented, reliable message transfer service be provided across a connectionless packet network? To provide a connection-oriented service, the transport layer can establish a logical connection across the connectionless packet network by setting up state information for example, packet sequence number at the end systems.

During the connection setup, the message is broken into separate packets, and each packet is assigned a sequence number. Using the sequence numbers, the end-system transport-layer entities can acknowledge received packets, determine and retransmit lost packets, delete duplicate packets, and rearrange out-of-order packets.

The original message is reassembled as packets arrive at the receiving end. For example, TCP provides a connection-oriented reliable transfer service over IP, a connectionless packet transfer service. Can a connectionless datagram transfer service be provided across a connection-oriented network? The connectionless datagram transfer service can be implemented by simply setting up a connection across the network each time a datagram needs to be transferred.

An internet path between two hosts involves a hop across network A, a packet-switching network, to a router and then another hop across packet-switching network B. Suppose that packet switching network A carries the packet between the first host and the router over a two-hop path involving one intermediate packet switch. Suppose also that the second network is an Ethernet LAN. Sketch the sequence of IP and non-IP packets and frames that are generated as an IP packet goes from host 1 to host 2.

This packet is encapsulated in a frame that traverses data link 1 to the packet switch. The packet is recovered and then forwarded inside a frame along data link 2. The data link at the router recovers the Network A packet, and the IP network interface at the router recovers the IP packet and determines that the next hop is on Network B. The router encapsulates the IP packet into an Ethernet frame, puts the host 2 Ethernet physical address in the frame and sends it to the LAN.

The Ethernet card on the host captures the frame and extracts the IP packet and passes it to the host. Does Ethernet provide connection-oriented or connectionless service? Ethernet provides connectionless transfer service of information frames.

How is it different? The transfer of frames in Ethernet occurs directly over a transmission medium and in this sense is similar to direct transmission over a wire. The sequence of frames into Ethernet arrive in the same order they are transmitted. However multiple stations can transmit in Ethernet which differs from direct transmission over a wire. Ethernet supports the transfer of frames among multiple end systems and in this sense is similar to a packet switching network.

Ethernet does not involve routing which is a feature of packet switching. Communication Networks 2nd Edition Chapter 2 Solutions Suppose that a group of workstations is connected to an Ethernet LAN. If the workstations communicate only with each other, does it make sense to use IP in the workstations?

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Should the workstations run TCP directly over Ethernet? How is addressing handled? Ethernet supports the exchange of frames between stations and can support the direct exchange of information. Using Ethernet without IP would result in an inflexible and difficult to manage system. Ethernet addresses are fixed and tables need to be changed whenever a machine is moved, while IP addresses are logical and can be changed whenever a machine is moved.

Suppose two Ethernet LANs are interconnected by a box that operates as follows. The box has a table that tells it the physical addresses of the machines in each LAN. The box listens to frame transmissions on each LAN. If a frame is destined to a station at the other LAN, the box retransmits the frame onto the other LAN, otherwise the box does nothing. Is the resulting network still a LAN? Does it belong in the data link layer or the network layer?

The resulting network is a local area network that has been extended. The extended LAN transfers frames, and so it still belongs in the data link layer.

Can the approach be extended to connect more than two LANs? If so, what problems arise as the number of LANs becomes large? As the number of LANs becomes large, the number of physical addresses stored in the bridge grows and becomes unmanageable.

Each time a machine is added the addresses in all the boxes need to be updated. Serious problems arise if boxes are connected so that loops can occur. Suppose all laptops in a large city are to communicate using radio transmissions from a high antenna tower. Is the data link layer or network layer more appropriate for this situation? The data link layer is concerned with the transfer of frames of information across a single hop.

Communication Networks Leon Garcia 2nd Edition PDF

The network layer involves the transfer of information across a network using multiple hops per path in general. The connection from a radio antenna to the laptops is direct, and thus a data link layer protocol is more suitable for this situation. Now suppose the city is covered by a large number of small antennas covering smaller areas. Which layer is more appropriate?

A number of areas each covered by small antennas can be interconnected using the "bridging" approach of problem 16, which remains in the data link layer.

However, the network layer may be more appropriate because it provides for the transfer of data in the form of packets across the communication network. A key aspect of this transfer is the routing of the packets from the source machine to the destination machine, typically traversing a number of transmission link and network nodes where routing is carried out.

Suppose that a host is connected to a connection-oriented packet-switching network and that it transmits a packet to a server along a path that traverses two packet switches. Suppose that each hop in the path involves a point-to-point link, that is, a wire. Show the sequence of network layer and data link layer PDUs that are generated as the packet travels from the host to the server.

When the host generates an IP packet for transfer to the server, the IP packet will be transferred using the network connection as follows. The packet may then be encapsulated into a frame that traverses data link 1 and arrives at switch 1. The connection ID in the packet is used to determine the outgoing port from switch 1. The connection ID may need to be mapped into a corresponding connection ID over data link 2. The packet is encapsulated into a frame that traverses data link 2.

The connection ID in the packet determines the outgoing port from switch 1 and the next connection ID. The packet is encapsulated into a frame that traverses data link 3.

The connection ID in the arriving packet indicates that this is the destination node. The IP packet is recovered. The connection-oriented network in this example could correspond to ATM or to frame relay. Suppose an application layer entity wants to send an L-byte message to its peer process, using an existing TCP connection. The TCP segment consists of the message plus 20 bytes of header. The segment is encapsulated into an IP packet that has an additional 20 bytes of header. The IP packet in turn goes inside an Ethernet frame that has 18 bytes of header and trailer.

The message overhead includes: Suppose that the TCP entity receives a 1. Calculate the amount of overhead incurred from segmenting the file into packet-sized units. Suppose a TCP entity receives a digital voice stream from the application layer. How much delay is incurred by the first byte in each block? Assume the stream is segmented as shown below, where the white cells represent data and the shaded cells represent the TCP header overhead. Assume zero processing delay due to data arrangement and segmenting.

How does the network layer in a connection-oriented packet-switching network differ from the network layer in a connectionless packet-switching network? The network layer in connection-oriented networks maintains state information about every connection. It can allocate resources at the switches through admission control. The network layer in connectionless networks has no knowledge of "connections", and instead deals independently with each packet.

The network layer in connection-oriented networks performs routing on a per connection basis. Each packet is routed based on a connection identifier of some sort and packets of the same connection have the same identifier value. In a connectionless network, routing is performed on per packet basis; each packet is routed independently based on information carried in the packet header, for example, the destination address.

In connection-oriented networks, the network layer forwarding table is set up by a signaling procedure during the connection establishment. In connectionless networks, the routers may execute a distributed algorithm to share network state information and dynamically calculate the routing table continuously.

In case of failure, the connection must be re-established in connection-oriented networks, whereas in connectionless networks, the packets are re-routed. The network layer in connectionless networks is more robust against failures. Connection-oriented Connectionless Maintain state information about every connection No knowledge of the "connection" Allocate resources to connections at switches No resource allocation Admission control No admission control Per connection routing Per packet routing Route packet based on identifier Route packet based on destination address.

Forwarding table specifies the output port and outgoing identifier value as function of the incoming identifier value Routing table specifies the output port depending on the destination address Forwarding table set up by signaling during connection establishment.

Router executes distributed algorithm to share network state information and dynamically calculate the routing table Connection must be re-established in cases of failure Packets are rerouted around failures, robust against failures Identify session layer and presentation layer functions in the HTTP protocol. Presentation layer functions: The request message and the response message headers include information about the content type of the documents e.

Session layer functions: Client sends the request for a file 2. Server replies with the file or error message if file is not found. Server closes the TCP connection after some timeout period.

Suppose we need a communication service to transmit real-time voice over the Internet. TCP is desirable in that it provides a connection for the transfer of a stream of information, which characterizes a digital voice stream. However, to provide reliable service TCP uses acknowledgments and retransmissions that result in packet delay and jitter that can not be tolerated by real-time traffic.

UDP provides connectionless service and delivers packets quickly. In case of packet loss, UDP does not provide retransmission, but some degree of packet loss can be tolerated by voice. Consider the end-to-end IP packet transfer examples in Figure 2. Sketch the sequences of IP packets and Ethernet and PPP frames that are generated by the three examples of packet transfers: Include all relevant header information in the sketch.

Workstation to Server: The server's NIC card recognizes that the frame is intended for its host, so it captures the frame and examines it.

The router examines frame and passes IP datagram to its IP entity which discover that the IP datagram is not for itself, but is to be routed on. The routing tables at the router show that the machine with address 2,2 is connected directly on the other side of the point-to-point link.

PC to Server: The routing table at the router shows that the machine with address 1,1 is connected in the other side of the Ethernet network. Suppose a user has two browser applications active at the same time, and suppose that the two applications are accessing the same server to retrieve HTTP documents at the same time.

How does the server tell the difference between the two applications? A client application generates an ephemeral port number for every TCP connection it sets up. An HTTP request connection is uniquely specified by the five parameters: The two applications in the above situations will have different ephemeral port s and will thus be distinguishable to the server.

Let T be the time that elapses from when a packet is sent from client to server to when the response is received. Find the rate at which HTTP exchanges can be made if the client cannot send an additional request until it receives a response for each request.

The client can send its request after the first two handshakes in part 1 which takes up T seconds. The request and response then take an additional T second. A new request can be initiated with an associated new TCP connection even while the previous TCP connection is being closes. What is the difference between a physical address, a network address, and a domain name? Textbook authors: Alberto Leon Garcia, Indra Widjaja. Communication Networks. ISBN Textbook and References. Communications Networks: Fundamental Concepts and Key Architectures, 2nd.

A PDF with a complete list of publications is available here. More recent topics from computer and communications networks and signal processing. The second edition expands on the success of the first edition by updating on technological changes in networks and responding to comprehensive market feedback. Fundamental Concepts and Key Architectures. McGraw Hill, , 2nd edition. Other Material. Widjaja, Communication Networks, 2nd edition. Stuber, Principles of Mobile Communication, 2nd edition, Kluwer.

Widjaja, Communication Networks, McGraw. Alberto Leon-Garcia. Welcome to the Leon- Garcia Supersite. Theres also a pdf ebook out there too. That makes. Communication Networks Hardcover. Alberto Leon-Garcia, Indra Widjaja: Jul 7, Flag for inappropriate content. Related titles. Jump to Page. Search inside document. Yasin Naman M. Marlon Calix. Sudesh Agrawal. Christopher Dorobek. Enrique San Vicente. Mohammed Ahsan Fawad. Victor Ali Menta.

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