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(a) Suppose N packets arrive simultaneously to a link at which no packets are currently being transmitted or queued. Each packet is of length L and the link has transmission rate R. What is the... Consider an overlay network with N active peers, with each pair of peers haying an active TCP connection. Additionally, suppose that the TCP connection. pass through a total of M routers. How many... Consider Figure 1.19(b). Now suppose that there are M paths between the server and the client. Nu two paths share any link. Path k (k = 1,...,M) consists of N links with transmission rates R k 1 , R... Consider a DASH system for which there are W video versions (at N different rates and qualities) and N audio versions (at N different rates and qualities). Suppose we want to allow the player to... How big is the MAC address space? The IPv4 address space? Tue IP6 address space? Consider the procedure described in Section 9.3 for estimating average delay d i . Suppose that u = 0.1. Let r 1 t 1 be the most recent sample delay, let r 2 t 2 be the next most recent sample... Consider the example in Figure 8.28. Suppose Trudy is a woman-in-the middle. Who can insert data-grams into the stream of data-gram going from Rl and R2. As part of a reply attack, Trudy sends a... In Section 8.6. 1, it is shown that without sequence numbers, Trudy (a woman- in-the middle) can wreak havoc in an SSL session by interchanging TCP segments. Can Trudy do something similar by... Names four different types of ICMP messages True or false: When a BGP router receives an advertised path from its neigh bor, it must add its own identity to the received path and then send that new path on to all of its neighbors. Explain. What is the count to infinity problem in distance vector routing? Compare and contrast the properties of a centralized and a distributed routing algorithm. Give an example of a routing protocol that takes a centralized and a decentralized approach. What is ment by a control plane that is based on per-router control? In such cases, when we say the network control and data planes are implemented monolithically, what do we mean? We made a distinction between the forwarding function and the routing function performed in the network layer. What are the key differences between routing and forwarding? In the discussion of TCP splitting in the sidebar in Section 3.7, it was claimed that the response time with TCP splitting is approximately 4 RTT FE RTT BE + processing time, Justify this claim. Suppose the three departmental switches in Figure 6. 15 are replaced by hubs. All links are 100 Mbps. Now answer the questions posed in problem P23. Figure 6.15 Data From Problem 23 Consider Figure... Suppose two packets arrive to two different input ports of a router at exactly the same time. Also suppose there are no other packets anywhere in the router. a. Suppose the two packets are to be... What are the advantages of fiber optics over copper as a transmission medium? Is there any downside of using fiber optics over copper? Consider two network entities. A and B. which are connected by a perfect hi-directional channel (i.e., any message sent will he received correctly: the channel will not corrupt, lose, or re-order... A 100-byte IP packet is transmitted over a local loop using ADSL protocol stack. How many ATM cells will be transmitted? Briefly describe their contents. Suppose that A, B, and C are simultaneously transmitting 0 bits, using a CDMA system with the chip sequences of Fig. 2-28(a). What is the resulting chip sequence? Figure 2-28(a) A = (-1-1 -1 +1 +1-1... A CDMA receiver gets the following chips: (1 +1 3 +1 1 3 +1 +1). Assuming the chip sequences defined in Fig. 2-28(a), which stations transmitted, and which bits did each one send? Figure 2-28(a) A =... Six stations, A through F, communicate using the MACA protocol. Is it possible for two transmissions to take place simultaneously? Explain your answer. What is the baud rate of classic 10-Mbps Ethernet? Give an example to show that the RTS/CTS in the 802.11 protocol is a little different than in the MACA protocol. A wireless LAN with one AP has 10 client stations. Four stations have data rates of 6 Mbps, four stations have data rates of 18 Mbps, and the last two stations have data rates of 54 Mbps. What is the... A token bucket scheme is used for traffic shaping. A new token is put into the bucket every 5 sec. Each token is good for one short packet, which contains 48 bytes of data. What is the maximum... In IP, the checksum covers only the header and not the data. Why do you suppose this design was chosen? Primitives of transport service assume asymmetry between the two end points during connection establishment, one end (server) executes LISTEN while the other end (client) executes CONNECT. However,... One criteria for deciding whether to have a server active all the time or have it start on demand using a process server is how frequently the service provided is used. Can you think of any other... Write an HTML page that includes a link to the email address username@DomainName. com. What happens when a user clicks this link? John wants to have an original domain name and uses a randomized program to generate a secondary domain name for him. He wants to register this domain name in the com generic domain. The domain name... Besides bandwidth and latency, what other parameter is needed to give a good characterization of the quality of service offered by a network used for (i) Digitized voice traffic? (ii) Video traffic?... Alice is using the public-key authentication protocol of Fig. 8-43 to authenticate communication with Bob. However, when sending message 7, Alice forgot to encrypt R B . Trudy now knows the value of... Explain the difference between an Internet draft and a proposed standard. If the bandwidth of the channel is 5 Kbps, how long does it take to send a frame of 100,000 bits out of this device? An analog signal has a bandwidth of 20 KHz. If we sample this signal and send it through a 30 Kbps channel, what is the SNRdB? We need a three-stage time-space-time switch with N = 100. We use 10 TSIs at the first and third stages and 4 crossbars at the middle stage. a. Draw the configuration diagram. b. Calculate the total... Repeat Problem 8-12 if we use 6 crossbars at the middle stage. Problem 8-12 We need a three-stage space-division switch with N = 100. We use 10 crossbars at the first and third stages and 4 crossbars... Check to see if the following set of chips can belong to an orthogonal system. [+1, +1] and [+1, 1] In the previous problem we tried to find the number of bits to be added to a dataword to correct a single-bit error. If we need to correct more than one bit, the number of redundant bits increases.... Using the following specifications, draw a finite state machine with three states (I, II, and III), five events, and six actions: a. If the machine is in state I, two events can occur. If event 1... Using the following specifications, draw a finite state machine with three states (I, II, and III), six events, and four actions: a. If the machine is in state I, two events can occur. If event 1... Show how STS-9s can be multiplexed to create an STS-36. Is there any extra overhead involved in this type of multiplexing? What is the minimum number of cells resulting from an input packet in the AAL5 layer? What is the maximum number of cells resulting from an input packet? A program to simulate the calculation of Adler checksum. Write and test a program to simulate the flow diagram of CSMA/CA in Figure 12.15. Figure 12.15 Flow diagram of CSMA/CA Station has a frame to send K = 0 Legend K: Number of attempts T: Backoff time... Which is better, a low reuse factor or a high reuse factor? Explain your answer. What is the maximum number of simultaneous calls in each cell in a GSM, assuming no analog control channels? What is the maximum number of callers in each cell in an IS-95 system? What is the size of the address space in each of the following systems? a. A system in which each address is only 16 bits. b. A system in which each address is made of six hexadecimal digits. c. A... Rewrite the following IP addresses using binary notation: a. 110.11.5.88 b. 12.74.16.18 c. 201.24.44.32 Rewrite the following IP addresses using dotted-decimal notation: a. 01011110 10110000 01110101 00010101 b. 10001001 10001110 11010000 00110001 c. 01010111 10000100 00110111 00001111 If a label in a connection-oriented service is 8 bits, how many virtual circuits can be established at the same time? In Figure 18.10, assume that the link between R1 and R2 is upgraded to 170 kbps and the link between the source host and R1 is now downgraded to 140 kbps. What is the throughput between the source... Which of the following cannot be a mask in CIDR? a. 255.225.0.0 b. 255.192.0.0 c. 255.255.255.6 Assume we have an internet with an 8-bit address space. The addresses are equally divided between four networks (N 0 to N 3 ). The internetwork communication is done through a router with four... Assume we have an internet with a 12-bit address space. The addresses are equally divided between eight networks (N 0 to N 7 ). The internetwork communication is done through a router with eight... Assume we have an internet with a 9-bit address space. The addresses are divided between three networks (N 0 to N 2 ), with 64, 192, and 256 addresses respectively. The internetwork communication is... Can router R1 in Figure 18.35 receive a packet with destination address 140.24.7.194? What will happen to the packet if this occurs? Figure 18.35 Figure 18.35 Longest mask matching 140.24.7.0/26... In Figure 19.4, show how the sum, wrapped sum, and checksum can be calculated when each word (16 bits) is created instead of waiting for the whole packet to be created. Figure 19.4 Example of... In Figure 19.4, show how the sum, wrapped sum, and checksum can be calculated when the words are given in decimal numbers (the way the words are stored in a computer memory). Figure 19.4 Example of... Briefly describe how we can defeat the following security attacks: a. Packet sniffing b. Packet modification c. IP spoofing Explain when each of the following attributes can be used in BGP: a. LOCAL-PREF b. AS-PATH c. NEXT-HOP Can a router combine the advertisement of a link and a network in a single link-state update? Explain what type of OSPF link state is advertised in each of the following cases: a. A router needs to advertise the existence of another router at the end of a point-to-point link. b. A router... In computer science, when we encounter an algorithm, we often need to ask about the complexity of that algorithm (how many computations we need to do). To find the complexity of Dijkstras algorithm,... Why do you think we need only one RIP update message, but several OSPF update messages? At any moment, a RIP message may arrive at a router that runs RIP as the routing protocol. Does it mean that the RIP process should be running all the time? Is the path-vector routing algorithm closer to the distance-vector routing algorithm or to the link-state routing algorithm? Explain. Exactly describe why we cannot use the CIDR notation for the following blocks in Table 21.1: a. AD HOC block with the range 224.0.2.0 to 224.0.255.255. b. The first reserved block with the range... Write a program to simulate the distance-vector algorithm (Table 20.1). for (y = 1 to N) { if (y is a neighbor) D[y] = c[myself][y] else 10 D[y] = 0 11 } send vector {D[1], D[2], ..., D[N]} to all... Define which of the following addresses are multicast addresses: a. 224.8.70.14 b. 226.17.3.53 c. 240.3.6.25 Define the group of each of the following multicast addresses (local network control block, internetwork control block, SSM block, Glop block, or administratively scoped block): a. 224.0.1.7 b.... A multicast router is connected to four networks. The interest of each network is shown below. What is the group list that should be advertised by the router? a. N1: {G1, G2, G3} b. N2: {G1, G3} c.... Assume that m is much less than n and that router R is connected to n networks in which only m of these networks are interested in receiving packets related to group G. How can router R manage to... Does RPB actually create a shortest path tree? Explain. What are the leaves of the tree? Does RPM actually create a shortest path tree? Explain. What are the leaves of the tree? List three steps that a DVMRP router uses to create a source-based tree. Which phase is responsible for creating the part of the tree from the source to the current router? Which phase is responsible... Explain why an MOSPF router can create the shortest path with the source as the root in one step, but DVMRP needs three steps to do so. Explain why PIM is called Protocol Independent Multicast. Which version of PIM uses the first and the third steps of DVMRP? What are these two steps? Router A sends a unicast RIP update packet to router B that says 134.23.0.0/16 is 7 hops away. Network B sends an update packet to router A that says 13.23.0.0/16 is 4 hops away. If these two routers... Find the interface identifier if the physical address of the EUI is (F5-A9-23-AA-07-14-7A-23) 16 using the format we defined for Ethernet addresses. An organization is assigned the block 2000:1110:1287/48. What is the IPv6 address of an interface in the third subnet if the IEEE physical address of the computer is (F5-A9-23-14-7A-D2) 16 . A sender sends a series of packets to the same destination using 5-bit sequence numbers. If the sequence numbers start with 0, what is the sequence number of the 100th packet? Using 5-bit sequence numbers, what is the maximum size of the send and receive windows for each of the following protocols? a. Stop-and-Wait b. Go-Back-N c. Selective-Repeat Create a scenario similar to Figure 23.22 in which the sender sends three packets. The first and second packets arrive and are acknowledged. The third packet is delayed and resent. The duplicate... Redraw Figure 23.35 if the sender sends 5 packets (0, 1, 2, 3, and 4). Packets 0, 1, and 2 are received in order and acknowledged, one by one. Packet 3 is delayed and received after packet 4. Assume we need to design a Go-Back-N sliding-window protocol for a network in which the bandwidth is 100 Mbps and the average distance between the sender and receiver is 10,000 km. Assume the average... Some of the application programs can use the services of two transport-layer protocols (UDP or TCP). When a packet arrives at the destination, how can the computer find which transport layer is... In TCP, how do we define the sequence number of a segment (in each direction)? Consider two cases: the first segment and other segments. In TCP, we have two consecutive segments. Assume the sequence number of the first segment is 101. What is the sequence number of the next segment in each of the following cases? a. The first segment... For a clearer view of Nagles algorithm, let us repeat the previous problem, but let the server transport layer acknowledge a segment when there is a previous segment that has not been acknowledged... Assume a TCP server expects to receive byte 2001, but it receives a segment with sequence number 2200. What is the reaction of the TCP server to this event? Can you justify the reaction? You know that the domain name of a computer is aBusiness.com. Write a statement in Java to create an InetAddress object associated with that computer. Why do you think that Java provides no constructors for the InetAddress class? You know that the IP address of a computer is 23.14.76.44. Write a statement in Java to create an InetAddress object associated with this address. Why do you think that Java uses an instance of a class instead of just an integer to represent an IP address? A port number in the TCP/IP protocol suite is an unsigned 16-bit integer. How can we represent a port number in Java using a 32-bit integer?
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