Classical IP Over ATM
The classical IP over ATM CLIP model RFC 2255 is an IETF specification whereby IP treats ATM as another subnetwork to which IP hosts and routers are attached. In the CLIP model multiple IP subnetworks are typically overlaid on top of an ATM network. The part of an ATM network that belongs to the same IP subnetwork is called a logical IP subnetwork LIS , as shown in Figure 10.2. All members IP end systems in the same LIS must use the same IP address prefix e.g., the same network number and...
Gigabit Ethernet
The IEEE 802.3z Gigabit Ethernet standard was completed in 1998 and established an Ethernet LAN that increased the transmission speed over that of Fast Ethernet by a factor of 10. The goal was to define new physical layers but to again retain the frame structure and procedures of the 10 Mbps IEEE 802.3 standard. The increase in speed by another factor of 10 put a focus on the limitations of the CSMA-CD MAC algorithm. For example, at a 1 Gbps speed, the transmission of a minimum size frame of 64...
Transmission Kdc
Each time the client wishes to access a particular server, it sends a request to the KDC along with the TGT and the server's name. The KDC decrypts the TGT to recover the session key. The KDC then returns a ticket to the client that allows access to the desired server. Public key systems require only one pair of keys per user, but they still face the problem of how the public keys are to be distributed. Because an imposter can advertise certain public keys as belonging to other parties, the...
Tcp 302
timing recovery 300, 335, 645 Burst error model 157, 166-67, 176-77, 293 Bursty 21, 22, 29, 313-14, 318, 322, 340-41, 347, 380, 382, 396, 450, 466, 503-04, 628, 638-39 Busy hour 233 C language programs 72-79, 160 Cable modem 143, 344 Cable television CATV 2, 31, 33, 42, 110, 140-43, 195, 253, 258 CAIDA 86, 93 Care-of address 589-90 Carried load 824 Carrier sensing 26, 359, 361, 427, 450 Carrier sensing multiple access CSMA 359-61, 365, 425, 428, 454 Carrier sensing multiple access with...
TCP Reliable Stream Service
The Transmission Control Protocol TCP provides a logical full-duplex two-way connection between two application layer processes across a datagram network. TCP provides these application processes with a connection-oriented, reliable, in-sequence, byte-stream service. TCP also provides flow control that allows receivers to control the rate at which the sender transmits information so that buffers do not overflow. TCP can also support multiple application processes in the same end system.6 Before...
X 1
where E Tm is the average delay experienced in each multiplexer. To apply the results from our M M 1 analysis, we need to make several assumptions. The most important assumption is that the service times that a packet experiences at different multiplexers are independent of each other. In fact, this assumption is untrue, since the service time is proportional to the packet length, and a packet has the same length as it traverses the network. Nevertheless, it has been found that this...
Properties of Analog Signals
Many signals that are found in nature can be represented as the sum of sinusoidal signals. For example, many speech sounds consist of the sum of a sinusoidal wave at some fundamental frequency and its harmonics. These analog signals have the form For example, Figure 12.22 shown later in the chapter contains the periodic waveform for the sound ae as in cat. As another example, suppose we are transmitting binary information at a rate of 8 kilobits second. A binary 1 is transmitted by sending a...
Fourier Series
Let x t represent a periodic signal with period T. The Fourier series resolves this signal into an infinite sum of sine and cosine terms where the coefficients an and bn represent the amplitude of the cosine and sine terms, respectively. The quantity n T represents the nth harmonic of the fundamental frequency f0 l T. The coefficient a0 is given by the time average of the signal over one period which is simply the time average of x t over one period. The coefficient an is obtained by...
Info Cwm
c. Find the one-dimensional sequence that results after zigzag scanning. 35. a. What impact does the speed of a CD-ROM drive have on the applications it can b. How does speed interact with total storage capacity 36. A DS-3 digital transmission system has a bit rate of 45 Mbps and is the first level of highspeed transmission available to users. a. How many PCM calls can be accommodated in one DS-3 line b. How many MPEG-1 or MPEG-2 television channels can be similarly accommodated 37. What...
Fast Ethernet
The IEEE 802.3u standard was approved in 1995 to provide Ethernet LANs operating at 100 Mbps. We refer to systems that operate under this standard as Fast Ethernet. To maintain compatibility with existing standards, the frame format, interfaces, and procedures have been kept the same. Recall that the performance of the CSMA-CD medium access control is sensitive to the ratio of the round-trip propagation delay and the frame transmission time. To obtain good performance, this ratio must be small....
Problems Pto
1. If a LIS has N members, how many VCCs are required by the LIS to support full connectivity 2. Suppose a department installs an ATM switch to interconnect a number of workstations and that classical IP over ATM is to be used. Explain how communications can be provided to workstations attached to an existing Ethernet LAN. 3. Explain how classical IP over ATM can be used to connect islands of ATM networks. Do these networks have to be confined to a local area 4. Discuss whether the ATM...
Nyquist Sampling Theorem
We now explain how the Nyquist sampling theorem comes about. Let x kT be the sequence of samples that result from the sampling of the analog signal x t . Consider a sequence of very narrow pulses S t kT that are spaced T seconds apart and whose amplitudes are modulated by the sample values x kT as shown in Figure 12.16. Signal theory enables us to show that y t has the spectrum in Figure 12.16, where the spectrum of x t is given by its Fourier transform The spectrum X f is defined for positive...
ExampleCommunicating with TCP
As an illustration of the use of the system calls and functions described above, let us show two application programs that communicate via TCP. The client prompts a user to type a line of text, sends it to the server, reads the data back from the server, and prints it out. The server acts as a simple echo server. After responding to a client, the server closes the connection and then waits for the next new connection. In this example each application client and server expects a fixed number of...
TokenRing and IEEE 8025 LAN Standard
Several versions of token-ring networks were developed in the 1970s and 1980s in token rings a number of stations are connected by point-to-point transmission links in a ring topology. Information flows in one direction along the ring from the source to the destination and back to the source. The key notion is that medium access control is provided via a small frame called a token that circulates around a ring-topology network. Only the station that has possession of the token is allowed to...
Emd0 Network Interface
The IP layer in the end-system hosts and in the routers work together to route packets from IP network sources to destinations. The IP layer in each host and router maintains a routing table that it uses to determine how to handle each IP packet. Consider the action of the originating host. If its routing table indicates that the destination host is directly connected to the originating host by a link or 3150 128 16 4 2, which gives 1001 0110 similarly 100 64 32 4 15 8 4 2 1 11 8 2 1. by a LAN,...
PNNI Signaling
The ATM Forum has developed the PNNI specification for use between private ATM switches private network node interface and between groups of private ATM switches private network-to-network interface as shown in Figure 9.24. The PNNI specification includes two types of protocols. 1. A routing protocol that provides for the selection of routes that can meet QoS requirements this routing protocol is discussed in the next section . 2. A complementary signaling protocol for the exchange of messages...
Problems Isb
a. Suppose that the data link control just transfers frames and does not implement error control. Find the probability that the message arrives without errors at station p. b. Suppose that error recovery is carried out end to end and that if there are any errors, the entire message is retransmitted. How many times does the message have to be retransmitted on average c. Suppose that the error recovery is carried out end to end on a packet by packet basis. What is the total number of packet...
Info Vsw
Finally, consider the World Wide Web WWW application that potentially includes the requirements of many of the previous applications. This application builds on a page of text and image information to include audio, video, and varying degrees of interactivity. The point-and-click nature of the application implies responsiveness requirements that have yet to be met by existing networks. In addition, the use of the Web for electronic commerce brings security concerns to the forefront. Together...
D 1
outgoing line. The frame travels along the ring over every point-to-point link and across every interface card. Each station examines the destination address in each passing frame to see whether it matches the station's own address. If not, the frame is forwarded to the next link after a few bits delay. If the frame is intended for the station, the frame is copied to a local buffer, several status bits in the frame are set, and the frame is forwarded along the ring. The sending station has the...
Consider The Synchronous Multiplexing In Fig 4.17. Explain How The Pointers In
1. A television transmission channel occupies a bandwidth of 6 MHz. a. How many two-way 30 kHz analog voice channels can be frequency-division multiplexed in a single television channel b. How many two-way 200 kHz GSM channels can be frequency-division multiplexed in a single television channel c. Discuss the trade-offs involved in converting existing television channels to cellular telephony channels 2. A cable sheath has an inner diameter of 2.5 cm. a. Estimate the number of wires that can be...
Problems Ult
b. Give three examples of applications in which information can be represented in a lossy manner. 2. The probabilities for the letters in the English alphabet are given in Table 1.1. The space between letters constitutes one-sixth of the characters in a page. a. Design a Huffman code for the letters of the English alphabet and the space character. b. What is the average number of bits symbol c. Compare the answer of part b to the entropy. 3. Suppose an information source generates symbols from...
Signal Constellations and Telephone Modem Standards
Signal constellation diagrams of the type shown in Figure 3.33 and Figure 3.34 are used in the various signaling standards that have been adopted for use over telephone lines. For the purposes of data communications, most telephone channels have a usable bandwidth in the range f1 500 Hz to f2 2900 Hz. This implies W 2400 and hence a signaling rate of 1 T W 2400 pulses second. Table 3.4 lists some of the parameters that specify the ITU V.32bis and V.34bis modem standards that are in current use....
The Nyquist Signaling Rate
Let p t be the basic pulse that appears at the receiver after it has been sent over the combined transmitter filter, communication channel, and receiver filter. The first pulse is transmitted, centered at t 0. If the input bit was 1, then Ap t FIGURE 3.19 Digital baseband signal and baseband transmission system FIGURE 3.19 Digital baseband signal and baseband transmission system should be received if the input was 0, then Ap t should be received instead. For simplicity, we assume that the...
Channelization in Telephone Cellular Networks
In this section we given an overview of how FDMA, TDMA, and CDMA channelization techniques have been implemented in various telephone cellular networks. The Advanced Mobile Phone System AMPS , which was developed in the United States, is an example of a first-generation telephone cellular system. The system had an initial allocation of 40 MHz that was divided between two service providers A and B as shown in Figure 6.44. The allocation was later increased to 50 MHz as shown in the figure. AMPS...
Facsimile Coding Standards
Run-length coding forms the basis for the coding standards that have been developed for facsimile transmission. In facsimile a black and white image is scanned and converted into a rectangular array of dots called pixels. Each pixel corresponds to a measurement made at a given point in the document, and each pixel is assigned a value 0 for white or 1 for black according to the measured intensity. The International Telecommunications Union ITU standard defines several options for encoding...
Modems And Digital Modulation
In section 3.4 we considered digital transmission over channels that are low pass in nature. We now consider band-pass channels that do not pass the lower frequencies and instead pass power in some frequency range from f1 to 2, as shown in Figure 3.27. We assume that the bandwidth of the channel is W f2 f1 and discuss the use of modulation to transmit digital information over this type of channel. The basic function of the modulation is to produce a signal that contains the information sequence...
Tcp State Transition Diagram
A TCP connection goes through a series of states during its lifetime. Figure 8.28 shows the state transition diagram. Each state transition is indicated by an arrow, and the associated label indicates associated events and actions. Connection establishment begins in the CLOSED state and proceeds to the ESTABLISHED state. Connection termination goes from the ESTABLISHED state to the CLOSED state. The normal transitions for a client are indicated by thick solid lines, and the normal transitions...
RunLength Codes
In many applications one symbol occurs much more frequently than all other symbols, as shown in Figure 12.4. The sequence of symbols produced by such information sources consist of many consecutive occurrences of the frequent symbol, henceforth referred to as runs, separated by occurrences of the other symbols. For example, the files corresponding to certain types of documents will contain long strings of blank characters. Facsimile information provides another example of where the scanning...
Optical Fiber
The deployment of digital transmission systems using twisted pair and coaxial cable systems established the trend toward digitization of the telephone network during the 1960s and 1970s. These new digital systems provided significant economic advantages over previous analog systems. Optical fiber transmission systems, which were introduced in the 1970s, offered even greater advantages over copper-based digital transmission systems and resulted in a dramatic acceleration of the pace toward...
B Dic
FIGURE 5.22 Maximum window size in Selective Repeat ARQ FIGURE 5.22 Maximum window size in Selective Repeat ARQ Wait ARQ. Of course, this performance level is in exchange for significantly greater complexity. Example Transmission Control Protocol The Transmission Control Protocol TCP uses a form of Selective Repeat ARQ to provide end-to-end error control across a network. TCP is normally used over internets that use IP to transfer packets in connectionless mode. TCP must therefore contend with...
Info Hoy
Note that both systems have delays that become arbitrarily large as the load approaches l, that is, as the arrival rate approaches the maximum packet transmission rate. However, the system with constant service times has half the average waiting time of the system with exponential service times. In general, the packet delay increases as systems become more random, that is, more variable in terms of packet arrivals and packet transmission times. Consider a statistical multiplexer that has a...
Transmission Efficiency of ARQ Protocols
In the previous sections we already introduced the performance differences between Stop-and-Wait, Go-Back-N, and Selective Repeat ARQ protocols. In this section we discuss performance results for these protocols and present a quantitative comparison of their transmission efficiency. We show that the delay-bandwidth product, the frame error rate, and the frame length are key parameters in determining system performance. For simplicity we focus here on the case where the information is...
Error Detection
In this section we discuss the idea of error detection in general terms, using the single parity check code as an example throughout the discussion. The basic idea in performing error detection is very simple. As illustrated in Figure 3.49, the information produced by an application is encoded so that the stream that is input into the communication channel satisfies a specific pattern or condition. The receiver checks the stream coming out of the communication channel to see whether the pattern...
Twisted Pair
The simplest guided transmission medium consists of two parallel insulated conducting e.g., copper wires. The signal is transmitted through one wire while a ground reference is transmitted through the other. This two-wire system is susceptible to crosstalk and noise. Crosstalk refers to the picking up of electrical signals from other adjacent wires. Because the wires are unshielded, there is attenuation for wireless media is proportional to n log10 d dB also a tendency to pick up noise, or...
Fddi
The Fiber Distributed Data Interface FDDI is a token-based LAN standard developed by the American National Standards Institute. FDDI uses a ring-topology network in which station interfaces are interconnected by optical fiber transmission links operating at 100 Mbps in a ring that spans up to 200 kilometers and accommodates up to 500 stations. FDDI has found application as a campus backbone network to interconnect various Ethernet LAN subnetworks. FDDI can operate over multimode or single-mode...
Info Sgu
FIGURE 7.39 Role of virtual paths in an ATM network FIGURE 7.39 Role of virtual paths in an ATM network the network at switch 1, share a common path up to switch 2, and are bundled together into a virtual path connection VPC that connects switch 1 to switch 2.5 This VPC happens to pass through an ATM cross-connect switch whose role in this example is to switch only virtual paths. The VPC that contains VCCs a, b, and c has been given virtual path identifier VPI 3 between switch 1 and the...
Problems Xbv
1. Suppose the size of an uncompressed text file is 1 megabyte. a. How long does it take to download the file over a 32 kilobit second modem b. How long does it take to download the file over a 1 megabit second modem c. Suppose data compression is applied to the text file. How much do the transmission times in parts a and b change 2. A scanner has a resolution of 600 x 600 pixels square inch. How many bits are produced by an 8-inch-x-10-inch image if scanning uses 8 bits pixel 24 bits pixel 3....
Internet Checksum
Several Internet protocols e.g., IP, TCP, UDP use check bits to detect errors. With IP a checksum is calculated for the contents of the header and included in a special field. Because the checksum must be recalculated at every router, the algorithm for the checksum was selected for its ease of implementation in software rather than for the strength of its error-detecting capabilities. The algorithm assumes that the header consists of a certain number, say, L, of 16-bit words, b0, b1 b2, , bL-1...
Applications AALs and ATM Service Categories
We saw in the previous section that AALs can be called upon to support a wide range of applications, from emulating a digital transmission line to transferring packet streams of various types. Table 9.3 lists features that characterize the requirements of various types of applications. Table 9.4 summarizes the capabilities of the various AALs. The application higher layer that operates over the AAL may require that information be transferred in the form of a stream or as discrete messages. The...
A3 MMl A BASIC MULTIPLEXER MODEL
In this section we develop the M M 1 K queueing system, shown in Figure A.9, as a basic model for a multiplexer. The interarrival times r in this system have mean E r 1 A as an exponential distribution. Let A t be the number of arrivals in the interval 0 to t then as indicated above A t has a Poisson distribution. The average packet length is E L bits per packet, and the transmission line has a speed of R bits second. So the average packet transmission time is E X E L R seconds. This...
Tcp Connection Termination
TCP provides for a graceful close that involves the independent termination of each direction of the connection. A termination is initiated when an application tells TCP that it has no more data to send. The TCP entity completes transmission of its data and, upon receiving acknowledgment from the receiver, issues a segment with the FIN bit set. Upon receiving a FIN segment, a TCP entity informs its application that the other entity has terminated its transmission of data. For example, in Figure...
Info Ojk
TABLE 5.1 Efficiency of Stop-and-Wait ARQ in the absence of errors delays correspond to distances of about 1500 km, 15,000 km, and 150,000 km links that could correspond roughly to moderate distance, intercontinental, and satellite links, respectively. We consider four values of bit rate 30,000 bps for an ordinary telephone modem, 1.5 Mbps for a high-speed telephone line, 45 Mbps for high-speed access lines, and 2.4 Gbps for a high-speed backbone line. For the case of an ordinary telephone...
Info Ftt
1 bit 7 bits 1 bit 7 bits I G Individual or group access C R Command or response frame 1 bit 7 bits 1 bit 7 bits I G Individual or group access C R Command or response frame three-bit sequence numbering is used. The control field is two bytes long when extended sequence numbering is used. The LLC PDU is encapsulated in IEEE MAC frames as shown in Figure 6.15. The MAC adds both a header and a trailer. Note the accumulation of header overhead After TCP and IP have added their minimum of 20 bytes...
Info Ngd
consists of an n x n array of crosspoints. Each input switch has one line connecting it to each of k intermediate stage N n x N n switches. Each intermediate switch in turn has one line connecting it to each of the N n switches in the third stage. The latter switches are k x n. In effect each set of n input lines shares k possible paths to any one of the switches at the last stage that is, the first path goes through the first intermediate switch, the second path goes through the second...
Info Dgf
.1 2 3 4 5 6 7 8 9 11 12 13 14 15 16 17 18 19 T n A _'_'_'_'_10 n_'_'_'_'_'_'_'_' FIGURE 12.21 A smooth signal and its successive differences FIGURE 12.22 Sample waveform of ae sound as in cat Figure 12.23 gives an example of an image where, in smooth portions of the picture, neighboring samples tend to have the same values. Long-term dependencies can also be observed when images contain periodic patterns. The compression techniques discussed in this section attempt to exploit the redundancies...
Problems Vwx
1. Suppose that a certain information source produces symbols from a ternary alphabet A, B, C . Suppose also that the source produces As three times as frequently as Bs and Bs twice as frequently as Cs. Can you break the following ciphertext 2. Suppose that a certain information source produces symbols from a ternary alphabet A, B, C . Suppose that it is known that As always occur in pairs. Suppose that it is also known that an encryption scheme takes blocks of four symbols and permutes their...
TokenPassing Rings
Polling can be implemented in a distributed fashion on networks with a ring topology. As shown in Figure 6.30, such ring networks consist of station interfaces that are connected by point-to-point digital transmission lines. Each interface acts like a repeater in a digital transmission line but has some additional functions. An interface in the listen mode reproduces each bit that is received at its input at its output after some constant delay, ideally in the order of one bit time. This delay...
Info Emc
system that requires its packets to be delivered to the destination within a certain time constraint. Routers that see these packets will have to process them according to their request. Hosts that do not support flows are required to set this field to 0. Payload length The payload length indicates the length of the data excluding header . With 16 bits allocated to this field, the payload length is limited to 65,535 bytes. As we explain below, it is possible to send larger payloads by using the...
Problems Jpz
1. Explain how a network that operates internally with virtual circuits can provide connectionless service. Comment on the delay performance of the service. Can you identify inefficiencies in this approach virtual channel identifier VCI virtual-circuit connection VCC virtual-circuit identifier VCI virtual-circuit packet switching virtual path virtual path identifier VPI weighted fair queueing 2. Is it possible for a network to offer best-effort virtual-circuit service What features would such a...
Ip Forwarding Architectures
1 Pure destination-based forwarding lookup based on IP address a Overlay model b Peer model a Overlay model b Peer model typically required implementation in software or firmware. Category 2 can be further classified into the overlay model and the peer model. In the overlay model, ATM switches are not aware of IP addresses and IP routing protocols. This model overlays an IP network onto an ATM network, essentially creating two network infrastructures with two addressing schemes and two routing...