Description

Chapter: 6 -Problem: 5 >> In Section 6.3, we listed four desirable characteristics of a broadcast channel. Which of these characteristics does slotted ALOHA have? Which of these characteristics does token passing have?
Answer Preview: Slotted Aloha 1 2 and 4 slott…

, Chapter: 6 -Problem: 23 >> Consider Figure 6.15. Suppose that all links arc loo Mbps. What is the maximum total aggregate throughput that can be achieved among the 9 hosts and 2 servers in this network? You can assume that any host or server can send to any other host or server. Why? Figure 6.15 Transcribed Image Text: 74-29-
Answer Preview: If all the 1192 nodes send …

, Chapter: 5 -Problem: 22 >> What are the purposes of the SNMP Get Request and Set Request messages?
Answer Preview: Get Request is a message sent from a managing serve…

, Chapter: 4 -Problem: 19 >> Consider the SDN Open Flow network shown in Figure 4.30. Suppose that the desired forwarding behavior for data-grams arriving at s2 is as follows:Any datgrams arriving on input port 1 from hosts h5 or h6 that are destined to host hi or h2 should be forward over output port 2:Any datagrams arriving on input port 2 from hosts hi or h2 that are destined to hosts h or h6 should be forwarded over outpu
Answer Preview: S2 Flow Table Match Action IngressPort 1 IP Src 103 IP Dst 101 Forw…

, Chapter: 3 -Problem: 18 >> True or false? Consider congestion control in TCP. When the timer expires at the sender, the value of ssthresh is set to one half of its previous value.
Answer Preview: False it is s…

, Chapter: 5 -Problem: 3 >> 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.
Answer Preview: A centralized routing algorithm computes the leastcost path between a source and destination by usi…

, Chapter: 5 -Problem: 15 >> Suppose you wanted to implement a new routing protocol in the SDN control plane. At which layer would you implement that protocol? Explain.
Answer Preview: I would implement a new routing protoc…

, Chapter: 3 -Problem: 19 >> 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 · RTTFE ÷ RTTBE + processing time, Justify this claim.
Answer Preview: Let X RTT FE Y RTT BE and ST Search time Consider the following timing d…

, Chapter: 9 -Problem: 12 >> How arc different RTP streams in different sessions identified by a receiver? How are different streams from within the same session identified?
Answer Preview: RTP streams in different sessions dif…

, Chapter: 3 -Problem: 31 >> Suppose that the fie measured Sample RTT values (see Section 3.5.3) are 106 ms, 120 ms, 140 ins, 90 ms, and 115 ms. Compute the Estimate–edRTT after each of these Sample RTT values is obtained, using a value of = 0.125 and assuming that the value of Estimated RTT was 100 ms just before the first of these five samples were obtained. Compute also the DevRTT after each sample is obtained, assuming a
Answer Preview: DevRTT 1 beta DevRTT beta SampleRTT EstimatedRTT EstimatedRTT 1alpha EstimatedRTT alpha …

, Chapter: 9 -Problem: 4 >> Recall the simple model for HTTP streaming shown in Figure 9.3. Suppose the client application buffer is infinite, the server sends at the constant rate x, and the video consumption rate is r with r < x. Also suppose playback begins immediately. Suppose that the user terminates the video early at time t = E. At the time of terminate, the server stops sending bits (if it hasn’t already sent all t
Answer Preview: a Buffer grows at rate x r At time E x rE bits are in buffer and …

, Chapter: 9 -Problem: 5 >> Streaming video systems can be classified into three categories. Name and briefly describe each of these categories.
Answer Preview: UDP Streaming With UDP streaming the server transmits video at a rate that matches the clients video …

, Chapter: 8 -Problem: 17 >> What does it mean to say that a nonce is a once-in-a-lifetime value? In whose lifetime?
Answer Preview: Once in a lifetimes means …

, Chapter: 7 -Problem: 2 >> Consider sender 2 in Figure 7.6. What is the sender's output to the channel (before it is added to the signal from sender 1). Z2i,m? Figure 7.6 Transcribed Image Text: Senders T 3510g no 150 299R INRITOnini d=-1 Data bits Demic Code Data bits d=1 Bilibid men SHINE SU powoppling Bobb 1 1 1 1 htlg-1
Answer Preview: Calculation of Sender 2 Output Sender 2 in Figure 76 is sending a data stream with …

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, Chapter: 2 -Problem: 2 >> SMS, iMessage. and WhatsApp are ail smartphone real-time messaging systems. After doing some research on the Internet, for each of these systems write one paragraph about the protocols they use. Then write a paragraph explaining how they differ.
Answer Preview: SMS Short Message Service is a technology that allows the sending and receiving of text messages bet…

, Chapter: 8 -Problem: 26 >> An IKE SA and an IPsec SA are the same thing. True or false?
Answer Preview: False An IK…

, Chapter: 4 -Problem: 12 >> Consider the topology shown in Figure 4.20. Denote the three subnets with hosts (starting clockwise at 12:00) as Networks A, D, and C. Denote the subnets without hosts as Networks D, E, and F.a. Assign network addresses to each of these six subnets, with the following constraints: All addresses must be allocated from 214.97.254/23: Subnet A should have enough addresses to support 250 interfaces: S
Answer Preview: From 2149725423 possible assignments are a Subnet A 2149725524 256 addresses Subnet B 21497254025 21…

, Chapter: 4 -Problem: 16 >> What is an essential different between RR and WFQ packet scheduling? Is there a case (Consider the WFQ weights) where RR and WFQ will behave exactly the same?
Answer Preview: With RR all service classes are treated equally ie no service clas…

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, Chapter: 6 -Problem: 7 >> In this problem, we explore some of the properties of the CRC. For the generator G (= 1001) given in Section 6.2.3. Answer the following questions.a. Why can it detect any single bit error in data D?b. Can the above G detect any odd number of bit errors? Why?
Answer Preview: a Without lo…

, Chapter: 5 -Problem: 19 >> Names four different types of ICMP messages
Answer Preview: Echo reply to ping type 0 code 0 …

, Chapter: 5 -Problem: 11 >> Consider Figure 5.7. Suppose there is another router w, connected to router y and z. The costs of all links are given as follows: c(x,v) 4, c(x,z) = 50, c(v,w) = 1, cz,w) = 1. c(v.z) = 3. Suppose that poisoned reverse is used in the distance-vector routing algorithm.a. When the distance vector routing is stabilized, router w, y, and z inform their distances to x to each other. What distance values
Answer Preview: a Router z Informs w D z x Informs y D z x6 Router w Informs y D w x Informs z D w x5 Router y I…

, Chapter: 6 -Problem: 24 >> 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 23Consider Figure 6.15. Suppose that all links arc loo Mbps. What is the maximum total aggregate throughput that can be achieved among the 9 hosts and 2 servers in this network? You can assume that any host or server can
Answer Preview: Each departmental hub is a single collision domain that can have a maximum throughp…

, Chapter: 2 -Problem: 7 >> Referring to Figure 2.4, we see that none of the applications listed in Figure 2.4 requires both no data loss and timing. Can you conceive of an application that requires no data loss and that is also highly time-sensitive? Figure 2.4 Transcribed Image Text: Application Throughput Data Loss Time-Sen
Answer Preview: One such example is remote word p…

, Chapter: 5 -Problem: 10 >> Argue that for the distance-vector- algorithm in Figure 5.6, each value in the distance vector D(x) is non-increasing and will eventually stabilize in a finite number of steps.  Figure 5.6 Transcribed Image Text: Node x table cost to cost to cost to 20 1 2 0 1 y ? ? 3 1 0 Node y table cost to cost t
Answer Preview: At each step each updating of a nodes distance vectors is based on th…

, Chapter: 4 -Problem: 16 >> Consider the network setup in Figure 4.25. Suppose that the ISP instead assigns the router the address 24.34.112.235 and that the network address of the home network is 192.168.1/24.a. Assign addresses to all interfaces in the home network.b. Suppose each host has two ongoing TCP connections, all to port 80 at host 128.119.40.86, Provide the six corresponding entries in the NAT translation table.
Answer Preview: a Home addresses 19216811 19216812 19216813 with the router interface being 192…

, Chapter: 4 -Problem: 30 >> Compare and contrast the lPv4 and the 1Pv6 header fields. Do they have any fields in common?
Answer Preview: IPv6 has a fixed length header which does not include most of the options an IPv4 header ca…

, Chapter: 6 -Problem: 5 >> Consider the 5-bit generator, G = 10011, and suppose that D has the value 1010101010. What the value of R?
Answer Preview: If we divide 10011 into …

, Chapter: 5 -Problem: 19 >> In Figure 5.13, suppose that there is another stub network V that is a customer of ISP A. Suppose that B and C have a peering relationship, and A is a customer of both B and C. Suppose that A would like to have the traffic destined to W to come from B only, and the traffic destined to V from either B or C. How should A advertise its routes to B arid C? What AS routes does C receive? Figure 5.13
Answer Preview: A should advise to B tw…

, Chapter: 4 -Problem: 4 >> What is the role of the forwarding table within a router?
Answer Preview: The role of the forwarding table wi…

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, Chapter: 6 -Problem: 28 >> Consider the single switch VIAN in Figure 6.25, and assume an external router is connected to switch port 1. Assign IP addresses to the FE and CS hosts and router interface. Trace the steps taken at both the network layer and the link layer to transfer an IP data-gram from an FE host to a CS host. Figure 6.25 Transcribed
Answer Preview: The IP addresses for those three computers from left to right in EE department are 11111111 11111112 …

, Chapter: 6 -Problem: 15 >> What is the maximum number of VLANs that can be configured on a switch supporting the 802.1 Q protocol? Why?
Answer Preview: In 8021Q there i…

, Chapter: 9 -Problem: 6 >> In the VoIP example in Section 9.3, let h be the total number of header bytes added to each chunk including UDP and IP header. a. Assuming an IP datagram is emitted every 20 msecs, find the transmission rate in bits per second for the datagrams generated by one side of this application. b. What is a typical value of h when RTP is used?
Answer Preview: a bytes are sent every 20 mse…

, Chapter: 3 -Problem: 15 >> Consider the cross-country example shown in Figure 3.17. How big would the window size have to be for the channel utilization to be greater than 98 percent? Suppose that the size of a packet is 1,500 bytes. Including both header fields and data. Figure 3.17 Transcribed Image Text: Data packet Data
Answer Preview: It takes 12 microseconds or 0012 milli…

, Chapter: 4 -Problem: 2 >> We noted that network layer functionality can be broadly divided into data plane functionality and control plane functionality. What are the main functions of the data plane? Of the control plane?
Answer Preview: The main function of the data plane is packet forwarding which is to for…

, Chapter: 4 -Problem: 8 >> Consider a router that interconnects three subnets: Subnet 1, Subnet 2, and Subnet 3. Suppose all of the interfaces in each of these three subnets are required to have the prefix 223.1.17/24. Also suppose that Subnet 1 is required to support at least 60 interfaces, Subnet 2 is to support at least 90 interfaces, and Subnet 3 is to support at least 12 interfaces, Provide three network addresses (of
Answer Preview: 223117…

, Chapter: 6 -Problem: 25 >> Suppose that all the switches in Figure 6.15 are replaced by hubs. All links are 100 Mbps. Now answer the questions posed in problem P23. Data From Problem 6.23Consider Figure 6.15. Suppose that all links arc loo Mbps. What is the maximum total aggregate throughput that can be achieved among the 9 hosts and 2 servers in this network? You can assume that any host or server can send to any other hos
Answer Preview: All of the 11 end systems will l…

, Chapter: 4 -Problem: 2 >> 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 forwarded to two different output ports. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses a shared bus?b. Suppose the two packets are to be forwarded
Answer Preview: a No you can only transmit one packet at a time over a sha…

, Chapter: 6 -Problem: 2 >> Show (give an example other than the one in Figure 6.5) that two-dimensional parity checks can correct and detect a single bit error. Show (give an example of) a double-bit error that can be detected but not corrected. Figure 6.5 Transcribed Image Text: Row parity d1, j-1 d1,j d1,1 d2.j-1 d2.i d2,1
Answer Preview: Suppose we begin with the initial twodimensional par…

, Chapter: 4 -Problem: 31 >> It has been said that when IPv6 tunnels through IPv4 routers, lPv6 treats the IPv4 tunnels as link-layer protocols. Do you agree with this statement? Why or why not?
Answer Preview: Yes because the ent…

, Chapter: 5 -Problem: 16 >> What types of messages flow across an SDN controller’s northbound and southbound APIs? Who is the recipient of these messages sent from the controller across the southbound interface and who sends messages to the controller across the northbound interface?
Answer Preview: The following is a list of types of messages flow across a SDN controllers southbound from t…

, Chapter: 6 -Problem: 15 >> Consider Figure 6.33. Now we replace the router between subnets I and 2 with a switch SI, and label the router between subnets 2 and 3 as Rl. Figure 6.33a. Consider sending an IP data-gram from Host E to Host F. Will Host E ask router Rl to help forward the data-gram? Why? ¡n the Ethernet frame containing the IP data-gram, what are the source and destination IP and MAC addresses?b. Suppose E would
Answer Preview: a No E can check the subnet prefix of Host Fs IP address and then learn that F is on the same LAN Th…

, Chapter: 3 -Problem: 15 >> Suppose Host A sends two TCP segments back to back to Host B over a TCP connection. The first segment has sequence number 90: the second has sequence number I lo.a. How much data is in the first segment?b. Suppose that the first segment is lost but the second segment arrives at B. In the acknowledgment that Host B sends to Host A, what will be the acknowledgment number?
Answer Preview: a 20 …

, Chapter: 4 -Problem: 5 >> We said that a network layer’s service model “defines the characteristics of end-to-end transport of packets between sending and receiving hosts.” What is the service model of the Internet s network layer? What guarantees are made by the Internet’s service model regarding the host-to-host delivery of data-grams?
Answer Preview: The service model of the Internets network layer is bestef…

, Chapter: 5 -Problem: 13 >> 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.
Answer Preview: False A BGP router can choose not to add its own identity to the receive…

, Chapter: 5 -Problem: 17 >> Describe the purpose of two types of Open Flow messages (of your choosing) that are sent from a controlled device to the controller. Describe the purpose of two types of Open flow messages (of your choosing) that are send from the controller to a controlled device.
Answer Preview: Two types of messages from a controlled device to a controll…

, Chapter: 6 -Problem: 22 >> Suppose now that the leftmost router in Figure 6.33 is replaced by a switch. Hosts A, B, C, and D and the right router are all star-connected into this switch. Give the source and destination MAC addresses in the frame encapsulating this IP data-gram as the frame is transmitted (1,) from A to the switch, (ii) from the switch to the right router, (iii) from the right router to F. Also give the sour
Answer Preview: i From A to switch Source MAC address 000000000000 Destina…

, Chapter: 5 -Problem: 9 >> What is meant by an area in an OSPF autonomous system? Why was the concept of an area introduced?
Answer Preview: An area in an OSPF autonomous system is refers to a set o…

, Chapter: 4 -Problem: 17 >> Suppose Host A sends Host B a TCP segment encapsulated in an IP data- gram. When Host B receives the data-gram, how does the network layer in Host B know it should pass the segment (that is, the payload of the data-gram) to TCP rather than to UDP or to some other upper-layer protocol?
Answer Preview: The 8-bit protoco l field in t…

, Chapter: 3 -Problem: 28 >> Host A and 13 are directly connected with a 100 Mbps link. There is one TCF connection between the two hosts, and I-lost A is sending to Host B an enormous file over this connection. Host A can send its application data into its TCP socket at a rate as high as 120 Mbps hut Host B can read out of its TCP receive buffer at a maximum rate of 50 1Mbps. Describe the effect of TCP flow control.
Answer Preview: Since the link capacity is only 100 Mbps, so host As sending rate …

, Chapter: 4 -Problem: 21 >> Do routers have IP addresses? If so, how many?
Answer Preview: Yes. They …

, Chapter: 4 -Problem: 13 >> Use the whois service at the American Registry for Internet Numbers (http://www.arin.net/whois) to determine the IP address blocks for three universities. Can the whois services be used to determine with certainty the geographical location of a specific IP address? Use www.maxrnind.com to determine the locations of the Web servers at each of these universities.
Answer Preview: The IP address blocks of Polytechnic Institute of New York University are: NetRange: 128 238 0 0 - 1…

, Chapter: 8 -Problem: 20 >> 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 deleting a TCP segment? What does she need to do to succeed at the deletion attack? What effect will it have?(Wire shark screenshot reprinted by permission of the Wire shark Foundation.)
Answer Preview: Again we suppose that SSL does not provide sequence numbers Suppose that Trudy …

, Chapter: 8 -Problem: 22 >> Suppose an SSL session employs a block cipher with CBC. True or false: The server sends to the client the IV in the clear.
Answer Preview: True The IV is a…

, Chapter: 7 -Problem: 12 >> What are the differences between a master device in a Bluetooth network and a base station in an 802.11 network?
Answer Preview: Any ordinary Bluetooth node can be …

, Chapter: 7 -Problem: 22 >> What is the role of the anchor MSC in GSM networks?
Answer Preview: Anchor MSC is the MSC visited by the mobile when a call first begins anc…

, Chapter: 9 -Problem: 11 >> Consider the figure below (which is similar to Figure 9.3). A sender begins sending packetized audio periodically at t = 1. The first packet arrives at the receiver at t = 8. Figure 9.3a. What are the delays (from sender to receiver, ignoring any play out delays) of packets 2 through 8? Note that each vertical and horizontal line segment in the figure has a length of 1, 2, or 3 time units.b. If au
Answer Preview: a The delay of packet 2 is 7 slots The delay of pa…

, Chapter: 8 -Problem: 2 >> Internet entities (routers, switches, DNS servers, Web servers, user end systems, and so on) often need to communicate securely. Give three specific example pairs of Internet entities that may want secure communication.
Answer Preview: Users laptop …

, Chapter: 1 -Problem: 23 >> Consider Figure 1.19(a). Assume that we know the bottleneck link along the path from the server to the client is the first link with rate Rsbits/sec. Suppose we send a pair of packets back to back from the server to the client, and there is no other traffic on this path. Assume each packet of size L bits, and both links have the same propagation delay dprop.a. What is the packet inter-arrival time
Answer Preview: Lets call the first packet A and call the second packet B a If the bottleneck link is the first link …

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, Chapter: 7 -Problem: 17 >> What are three important differences between the 3G and 4G cellular architectures?
Answer Preview: In 3G architecture there are separate network components an…

, Chapter: 8 -Problem: 4 >> Suppose that an intruder has an encrypted message as well as the decrypted version of that message. Can the intruder mount a cipher text-only attack, a known-plain text attack, or a chosen-plain text attack?
Answer Preview: In this case a known plaintext at…

, Chapter: 9 -Problem: 10 >> Compare the procedure described in Section 9.3 for estimating average delay with the procedure in Section 3.5 for estimating round-trip time. What do the procedures have in common? I-low are they different?
Answer Preview: The two procedures are very similar They both use the same formula thereby resulti…

, Chapter: 8 -Problem: 17 >> Figure 8.19 shows tie operations that Alice must perform with POP to provide confidentiality, authentication, and integrity. Diagram the corresponding operations that Bob mat perform on the package received from Alice. Figure 8.19 Transcribed Image Text: K?lm) Kg(m) K5() Ksl) Internet Kg () Ks Kg (K
Answer Preview: Figure Operations performed b…

, Chapter: 2 -Problem: 20 >> Look over your received e-mails, and examine the header of a message sent from a user with a .edu e-mail address. Is it possible to determine from the header the IP address of the host from which the message was sent? Do the same for a message sent from a Gmail account.
Answer Preview: You should be able to see the send…

, Chapter: 2 -Problem: 28 >> Install and compile the Python programs TCPClient and UDPClient on one host and TCPServer and UDPServer on another host.a. Suppose you run TCPClient before you run TCPServer. What happens’? Why?b. Suppose you run UDPClient before you run UDPServer, What happens? Why?c. What happens if you use different port numbers for the client and server sides?
Answer Preview: a If you run TCPClient first then the client will attempt to make a TCP connection with a nonexiste…

, Chapter: 9 -Problem: 1 >> Consider the figure below. Similar to our discussion of Figure 9.1. Suppose that video is encoded at a fixed bit rate, and thus each video block contains video frames that are to be played out over the same fixed amount of time, ˆ†. The server transmits the first video block at t0, the second block at t0+ ˆ†, the third block at t0+ 2ˆ†, and so on. Once the client begins play out, each block should
Answer Preview: a Client begins playout as soon as first block arrives at t1 and video blocks are to be played out o…

, Chapter: 1 -Problem: 2 >> The word protocol is often used to describe diplomatic relations. How does Wikipedia describe diplomatic protocol?
Answer Preview: From Wikipedia Diplomatic protocol is commonly described as a set of int…

, Chapter: 7 -Problem: 7 >> Suppose an 802.11 b station is configured to always reserve the channel with the RTS/CTS sequence. Suppose this station suddenly wants to transmit 1,000 bytes of data, and all other stations are idle at this time. As a function of SIFS and DIPS, and ignoring propagation delay and assuming no bit errors, calculate the time required to transmit the frame and receive the acknowledgment.
Answer Preview: A frame without data is 32 bytes long Assuming a transmission rate of 1…

, Chapter: 1 -Problem: 8 >> What are some of the physical media that Ethernet can run over?
Answer Preview: Today Ethernet most …

, Chapter: 9 -Problem: 8 >> Repeat parts (a) and (b) in Question P7 for the estimate of average delay deviation. Data From Problem  7Consider the procedure described in Section 9.3 for estimating average delay di. Suppose that u = 0.1. Let r1 – t1 be the most recent sample delay, let r2 – t2 be the next most recent sample delay, and so on. a. For a given audio application suppose four packets have arrived at the receiver wit
Answer Preview: a Denote v n for the estimate after the n t…

, Chapter: 9 -Problem: 6 >> List three disadvantages of UDP streaming.
Answer Preview: The three significant drawbacks of UDP Streaming are 1 Due to unpredictable and varying amount of a…

, Chapter: 7 -Problem: 7 >> Why are acknowledgments used in 802.11 but not in wired Ethernet.
Answer Preview: APs transmit beacon frames An APs b…

, Chapter: 9 -Problem: 10 >> Why is a packet that is received after its scheduled play out time considered lost?
Answer Preview: A packet that arrives after it…

, Chapter: 9 -Problem: 3 >> Recall the simple model for HTTP streaming shown in Figure 9.3. Suppose the buffer size is infinite but the server sends bits at variable rate x(t). Specifically, suppose (t) has the following saw-tooth shape. The rate is initially zero at time t = 0 and linearly climbs to H at time t = T. It then repeats this pattern again and again, as shown in the figure below.a. What is the server’s average
Answer Preview: a The servers average send rate is H2 b This part b is an odd question and will be removed from the …

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, Chapter: 1 -Problem: 21 >> 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 Rk1, Rk2, .. . , RkN. 1f the server can only use one path to send data to the client, what is the maximum throughput that the server can achieve? If the server can use all M paths to send data, what is the maxim
Answer Preview: If only use one path the m…

, Chapter: 3 -Problem: 4 >> a. Suppose you have the following 2 bytes: 01011100 and 01100101 What is the is complement of the sum of these 2 bytes?b. Suppose you have the following 2 bytes: 11011010 and 01100101. What is the is complement of the sum of these 2 bytes’?c. For the bytes in part (a), give an example where one bit is flipped in each of the 2 bytes and yet the is complement doesn’t change.
Answer Preview: a Adding the two bytes gives 11000001 T…

, Chapter: 1 -Problem: 32 >> Experiment with the Message Segmentation applet at the book’s Web site. Do the delays in the applet correspond to the delays in the previous problem? How do link propagation delays affect the overall end-to-end delay for packet switching (with message segmentation) and for message switching?
Answer Preview: Yes the delays in the applet corresp…

, Chapter: 3 -Problem: 12 >> Visit the Go-sack-N Java applet at the companion Web site.a. Have the source send five packets, and then pause the animation before any of the five packets reach the destination. Then kill the first packet and resume the animation. Describe what happens.b. Repeat the experiment, bin now let the first packet reach the destination and kill the first acknowledgment. Describe again what happens. c. Fi
Answer Preview: a The packet loss caused a time out after which all …

, Chapter: 7 -Problem: 15 >> What is the role of the RNC in the 3G cellular data network architecture? What role does the RNC play in the cellular voice network?
Answer Preview: UMTS t…

, Chapter: 3 -Problem: 3 >> UDP and TCP use Is complement for their check sums. Suppose you have the following three 8-bit bytes: 01010011, 01100110, 01110100. What is the Is complement of the sum of these 8-bit bytes? (That although UDP and TCP use 16-bit words in computing the checksum, for this problem you are being asked to consider s-bit sums.) Show all work. Why is it that UDP takes the Is complement of the sum; that i
Answer Preview: Wrap around if overflow Ones complement 1 1 0 1 0 0 0 1 To detect errors the receiver adds …

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, Chapter: 2 -Problem: 5 >> What information is used by a process running on one host to identify a process running on another host?
Answer Preview: The IP address of t…

, Chapter: 9 -Problem: 3 >> Suppose an analog audio signal is sampled 16,000 times per second, and each sample is quantized into one of 1024 levels. What would be the resulting bit rate of the PCM digital audio signal?
Answer Preview: Quantizing a sample into …

, Chapter: 1 -Problem: 16 >> Consider sending a packet from a source host to a destination host over a fixed route. List the delay components in the end-to-end delay. Which of these delays are constant and which are variable?
Answer Preview: The delay components are processing …

, Chapter: 7 -Problem: 14 >> Consider the chaining example discussed at the end of Section 7.7.2. Suppose a mobile user visits foreign networks A, B. and C, and that a correspondent begins a connection to the mobile user when it is resident in foreign network A. List the sequence of messages between foreign agents. and between foreign agents and the home agent as the mobile user moves from network A to network B to network C.
Answer Preview: First we note that chaining was discussed at the end of section 65 In the case of chaining using indirect routing through a home agent the following e…

, Chapter: 7 -Problem: 12 >> Suppose the correspondent in Figure 7.23 were mobile. Sketch the additional network-layer infrastructure that would be needed to route the data-gram from the original mobile user to the (now mobile) correspondent. Show the structure of the data-gram(s) between the original mobile user and the (now mobile) correspondent. as in Figure 7.24. Figure 7.23 Figure 7.24
Answer Preview: If the correspondent is mobile then any datagrams destined to the correspondent would ha…

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, Chapter: 4 -Problem: 28 >> What is meant by a “plug-and-play” or “zeroconf’ protocol?
Answer Preview: A plugandplay or zeroconf protoco…

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, Chapter: 1 -Problem: 6 >> List the available residential access technologies in your city. For each type of access, provide the advertised downstream rate, upstream rate, and monthly price.
Answer Preview: In most American ci…

, Chapter: 6 -Problem: 8 >> In Section 6.3, we provided an outline of the derivation of the efficiency of slotted ALOHA. In this problem we’ll complete the derivation.a. Recall that when there are N active nodes, the efficiency of slotted ALOHA is Np(1 – p)N - 1. Find the value of p that maximizes this expression.b. Using the value of p found in (a), find the efficiency of slotted ALOHA by letting N approach infinity. (1– 1/
Answer Preview: a b Ep Np1PN…

, Chapter: 2 -Problem: 15 >> List several popular messaging apps. Do they use the same protocols as SMS?
Answer Preview: A list of several popular m…

, Chapter: 5 -Problem: 18 >> What is the purpose of the service abstraction layer in the Open Daylight SDN control?
Answer Preview: The service abstraction layer allows internal network service applications to …

, Chapter: 1 -Problem: 19 >> (a) Visit the site www.traceroute.org and perform traceroutes from two different cities in France to the same destination host in the United States.How many links are the same in the two traceroutes? Is the transatlantic link the same?(b) Repeat (a) but this time choose one city in France and another city in Germany.(c) Pick a city in the United States, and perform trace routes to two hosts, each
Answer Preview: An example solution Traceroutes from two different cities in France to New York City in United State…

, Chapter: 5 -Problem: 23 >> What is the purpose of the SNMP trap message?
Answer Preview: A SNMP trap message is generated as a response to an event ha…

, Chapter: 1 -Problem: 20 >> Consider the throughput example corresponding to Figure 1.20(b). Now suppose that there are M client-server pairs rather than 10. Denote Rs, Rc, and R for the rates of the server links, client links, and network link. Assume all other links have abundant capacity and that there is no other traffic in the network besides the traffic generated by the M client-server pairs. Derive a general expressio
Answer Preview: Throu…

, Chapter: 1 -Problem: 14 >> Why will two ISPs at the same level of the hierarchy often peer with each other? How does an TXP earn money?
Answer Preview: If the two ISPs do not peer with each other then when they send …

, Chapter: 3 -Problem: 3 >> Consider a TCP connection between Host A and Host B. Suppose that the TCP segments traveling from Host A to Host B have source port number x and destination port number y. What are the source and destination port numbers for the segments traveling from 1-lost B to Host A?
Answer Preview: Source por…

, Chapter: 2 -Problem: 27 >> 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 choose at any time any of the N video versions and any of the N audio versions.a. If we create files so that the audio is mixed in with the video, so server sends only one media stream at given time, how m
Answer Preview: a N files under the assumption t…

, Chapter: 1 -Problem: 4 >> List six access technologies. Classify each one as home access, enterprise access, or wide-area wireless access.
Answer Preview: 1 Dialup modem over telephone line home 2 …

, Chapter: 4 -Problem: 3 >> 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?
Answer Preview: The key differences between routing and forwarding i…

, Chapter: 2 -Problem: 11 >> Why do HTTP, SMTP, and POP3 run on top of TCP rather than on UDP?
Answer Preview: The applications associated with th…

, Chapter: 3 -Problem: 22 >> Consider the GBN protocol with a sender window size of 4 and a sequence number range of 1,024. Suppose that at time î, the next in-order packet that the receiver is expecting has a sequence number of k. Assume that the medium does not reorder messages. Answer the following questions: a. What are the possible sets of sequence numbers inside the sender’s window at time t? Justify your answer. b. Wha
Answer Preview: a. Here we have a window size of N=3. Suppose the receiver has received packet k-1, and has ACKed th…

, Chapter: 4 -Problem: 34 >> What is meant by the ‘match plus action” operation of a router or switch? In the case of destination-based forwarding packet switch, what is matched and what is the action taken? In the case of an SDN, name three fields that can be matched, and three actions that can be taken.
Answer Preview: Match plus action means that a router or a switch tries to find a match betwe…

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, Chapter: 9 -Problem: 2 >> There are two types of redundancy in video. Describe them, and discuss how they can be exploited for efficient compression.
Answer Preview: Spatial Redundancy It is the redundancy within a given image Intuiti…

, Chapter: 7 -Problem: 3 >> Suppose that the receiver in Figure 7.6 wanted to receive the data being sent by sender 2. Show (by calculation) that the receiver is indeed able to recover sender 2€™s data from the aggregate channel signal by using sender 2€™s code. Figure 7.6 Transcribed Image Text: Senders suoresgusio hedis d =
Answer Preview: d d 11 11 1…

, Chapter: 1 -Problem: 1 >> What is the difference between a host and an end system? List several different types of end systems. Is a Web server an end system?
Answer Preview: There is no difference Throughout this t…

, Chapter: 2 -Problem: 10 >> What is meant by a handshaking protocol?
Answer Preview: A protocol uses handshaking if the two …

, Chapter: 7 -Problem: 10 >> Consider the following idealized LTE scenario. The downstream channel (see Figure 7.21) is slotted in time, across F frequencies. There are four nodes, A, B, C, and D, reachable from the base station at rates of 10 Mbps, 5 Mbps, 2.5 Mbps, and 1 Mbps, respectively, on the downstream channel. These rates assume that the base station utilizes all time slots available on all F frequencies to send to j
Answer Preview: a 10 Mbps if it only transmits to node A This solution is not fair since only A is getting served By …

, Chapter: 9 -Problem: 14 >> a. Consider an audio conference call in Skype with N > 2 participants. Suppose each participant generates a constant stream of rate r bps. How many bits per second will the call initiator need to send? How many bits per second will eh of the other N – 1 participants need to send? What is the total send rate, aggregated over all participants?b. Repeat part (a) for a Skype video conference call usin
Answer Preview: a Each of the other N 1 participants sends a single audio stream of rate r bps to t…

, Chapter: 8 -Problem: 21 >> What is the purpose of the random nonces in the SSL handshake?
Answer Preview: The purpose of the …

, Chapter: 8 -Problem: 16 >> What is the purpose of Nonce in an end-point authentication protocol?
Answer Preview: The purpose …

, Chapter: 8 -Problem: 24 >> Consider sending a stream of packets from Host A to Host B using IPsec. Typically, a new SA will be established for each packet sent in the stream. True or false?
Answer Preview: False Typically an IPse…

, Chapter: 9 -Problem: 7 >> Consider the procedure described in Section 9.3 for estimating average delay di. Suppose that u = 0.1. Let r1 – t1 be the most recent sample delay, let r2 – t2 be the next most recent sample delay, and so on. a. For a given audio application suppose four packets have arrived at the receiver with sample delays r4 – t4, r3 – t3, r2 – t2, and r1 – t1. Express the estimate of delay d in terms of the f
Answer Preview: a Denote d n for the estimate after the nth sam…

, Chapter: 7 -Problem: 5 >> Describe the role of the beacon frames in 802.11.
Answer Preview: APs transmit beacon frames An APs b…

, Chapter: 2 -Problem: 1 >> List five non-proprietary Internet applications and the application-layer protocols that they use.
Answer Preview: The Web HTTP file tra…

, Chapter: 7 -Problem: 11 >> In Section 7.5, one proposed solution that allowed mobile users to maintain their IP addresses as they moved among foreign networks was to have a foreign network advertise a highly specific route to the mobile user and use the existing routing infrastructure to propagate this information throughout the network. We identified scalability as one concern. Suppose that when a mobile user moves from on
Answer Preview: a No All the routers might not be able to route the datagram immediately This is becau…

, Chapter: 7 -Problem: 4 >> For the two-sender, two-receiver example, give an example of two CDMA codes containing 1 and 21 values that do not allow the two receivers to extract the original transmitted bits from the two CDMA senders.
Answer Preview: Sender 1 …

, Chapter: 9 -Problem: 7 >> With HTTP streaming, are the TCP receive buffer and the client’s application buffer the same thing? If not, how do they interact?
Answer Preview: No On the client side the c…

, Chapter: 4 -Problem: 20 >> When a large data-gram is fragmented into multiple smaller data-grams, where are these smaller data-grams reassembled into a single larger data-gram?
Answer Preview: The reassembly of …

, Chapter: 3 -Problem: 5 >> Why is it that voice and video traffic is often sent over TCP rather than UDP in today’s Internet?
Answer Preview: Since most firewalls are c…

, Chapter: 3 -Problem: 27 >> Host A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through byte 126. Suppose Host A then sends two segments to Host B back-to-back. The first and second segments contain 80 and 40 bytes of data, respectively. In the first segment, the sequence number is 127, the source port number is 302, and the destination port number is 80. Host B sends an
Answer Preview: a. In the second segment from Host A to B, the sequence number is 20…

, Chapter: 8 -Problem: 19 >> Suppose that Bob receives a POP message from Alice. How does Bob know for sure that Alice created the message (rather than, say, Trudy)? Does PGP use a MAC for message integrity?
Answer Preview: Alice provides a digital sign…

, Chapter: 1 -Problem: 34 >> Skype offers a service that allows you to make a phone call from a PC to an ordinary phone. This means that the voice call must pass through both the Internet and through a telephone network. Discuss how this might be done.
Answer Preview: The circuitswitched telephone networks and the Internet are …

, Chapter: 5 -Problem: 20 >> What two types of ICMP messages are received at the sending host executing the Trace route program?
Answer Preview: ICMP warning messag…

, Chapter: 8 -Problem: 22 >> The following true/false questions pertain to Figure 8.28.a. When a host in 172.16.1/24 sends a data-gram to an Amazon.con, server, the router Rl will encrypt the data-gram using IPsec.b. When a host in 172. 16. 1/24 sends a data-gram to a host in 172. 16.2/24, the rouler R I will change the source and destination address of the IP data-grarn.c. Suppose a host in 172.16.1/24 initiates a TCP connec
Answer Preview: a Fal…

, Chapter: 9 -Problem: 11 >> Section 9.3 describes two FEC schemes. Briefly summarize them. Both schemes increase the transmission rate of the stream by adding overhead. Does interleaving also increase the transmission rate?
Answer Preview: First scheme send a redundant encoded chunk after every n …

, Chapter: 9 -Problem: 1 >> Reconstruct Table 9.1 for when Victor Video is watching a 4 Mbps video, Facebook Frank is looking at a new 100 Kbyte image every 20 seconds, and Martha Music is listening to 200 kbps audio stream. Table 9.1 Transcribed Image Text: Bytes transferred in 67 min Bit rate 80 Mbytes 160 kbps 128 kbps Face
Answer Preview: Bit rate Bytes transferred …

, Chapter: 4 -Problem: 35 >> Name three header fields in an LP data-gram that can be “matched” in Open- Flow 1.0 generalized forwarding. What are three IP data-gram header fields that cannot be ‘matched” in Open Flow?
Answer Preview: Three example header fields in an IP datagram that can b…

, Chapter: 2 -Problem: 31 >> We have seen that Internet TCP sockets treat the data being sent as a byte stream but UDP sockets recognize message boundaries. What are one advantage arid one disadvantage of byte-oriented API versus having the API explicitly recognize and preserve application-defined message boundaries?
Answer Preview: For an application such as remote login telnet and ssh a bytestream oriented protocol …

, Chapter: 1 -Problem: 3 >> Why are standards important for protocols?
Answer Preview: Standards are importan…

, Chapter: 4 -Problem: 19 >> Recall that we the Internet checksum being used in both transport-layer segment (in UDP and TCP headers, Figures 3.7 and 3.29 respectively) and in network-layer data-grarns (IP header, Figure 4.16). Now consider a transport layer segment encapsulated in an IP data-gram. Are the check-sums in the segment header and data-gram header computed over any common bytes in the IP data-gram? Explain your an
Answer Preview: No IP header checksum only compu…

, Chapter: 3 -Problem: 6 >> Is ¡t possible for an application to enjoy reliable data transfer even when the application runs over UDP If so, how?
Answer Preview: Yes The application developer can …

, Chapter: 6 -Problem: 3 >> Suppose the information portion of a packet (D in Figure 6.3) contains 10 bytes consisting of the 8-bit unsigned binary ASCII representation of string €œNetworking.€ Compute the Internet checksum for this data.Figure 6.3 Transcribed Image Text: Datagram Datagram H, all bits in D' OK Detected error
Answer Preview: 01001100 01101001 0110111001101011 10111010 1101…

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, Chapter: 4 -Problem: 3 >> In Section 4.2. We noted that the maximum queuing delay is (n - I) D if the switching fabric is n times faster than the input line rates. Suppose that all packets are of the same length, n packets arrive at the same time to the n input ports, and all n packets want to be forwarded to different output port: What is the maximum delay for a packet for the (a) Memory, (b) Bus, (c) Crossbar switching f
Answer Preview: a. (…

, Chapter: 4 -Problem: 33 >> What is the difference between a forwarding table that we encountered in destination-based forwarding in Section 4.1 and Open Flow’s flow table that we encountered in Section 4 · 4?
Answer Preview: Each entry in the forwarding table of a destinationbased forwarding contains only an IP header fie…

, Chapter: 8 -Problem: 23 >> 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 duplicate copy of one of the data-grams sent from R I Lo R2. Will R2 decrypt the duplicate data-gram and forward it into the branch-office network? If not, describe in detail how R2 detects the duplicate d
Answer Preview: If Trudy does not bother to change the seque…

, Chapter: 5 -Problem: 7 >> Why are different inter-AS and intra-AS protocols used in the Internet?
Answer Preview: Policy Among ASs policy issues dominate It may well be important that traffic originating in a given …

, Chapter: 2 -Problem: 32 >> What is the Apache Web server? How much does it cost? What functional ity does it currently have? You may want to look at Wikipedia to answer this question.
Answer Preview: To create a web server we need to run web server soft…

, Chapter: 4 -Problem: 9 >> Suppose that an arriving packet matches two or more entries in a router’s forwarding table. With traditional destination-based forwarding, what rule does a router apply to determine which of these rules should be applied to determine the output port to which the arriving packet should be switched?
Answer Preview: A router uses longest prefix matching to determine which link …

, Chapter: 2 -Problem: 30 >> Can you configure your browser to open multiple simultaneous connections to a Web site? What are the advantages and disadvantages of having a large number of simultaneous TCP connections?
Answer Preview: Yes you can configure many browsers to open multiple simultaneous …

, Chapter: 5 -Problem: 2 >> What is meant by a control plane that is based on logically centralized control? In such cases, are the data plane and the control plane implemented within the same device or in separate devices? Explain.
Answer Preview: Logically centralized control means that a logically central routing controller computes and dis…

, Chapter: 2 -Problem: 25 >> Besides network-related considerations such as delay, loss, and bandwidth performance, there are other important factors that go into designing a CON server selection strategy. What are they?
Answer Preview: Other than networkrelated factors there are some important factors to conside…

, Chapter: 5 -Problem: 1 >> 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?
Answer Preview: Perrouter control means that a routing algorithm runs in each and every router both forwarding an…

, Chapter: 1 -Problem: 15 >> Some content providers have created their own networks. Describe Google’s network. What motivates content providers to create these networks?
Answer Preview: Googles private network connects together all its data centers big and small …

, Chapter: 4 -Problem: 6 >> In Section 4.2, we saw that a router typically consists of input ports. Output ports, a switching fabric and a routing processor Which of these are implemented in hardware and which are implemented in software? Why? Returning to the notion of the network layer’s data plane and control plane, which are implemented in hardware and which are implemented in software? Why?
Answer Preview: Input port switching fabric and output ports are implemented in hardware because their datagram…

, Chapter: 3 -Problem: 11 >> Consider the rt2.2 receiver in Figure 3.14, and the creation of a new packet in the se1f-ansition (i.e., the transition from the state back to itself) in the Waifor-0-from-below arid the Wait-for-I-from-below states: sndpkt = make_pkt (ACK, 1, checksurn) and sndpkt = make_ pkt (ACK, 0, checkum). Would the protocol work correctly if this action were removed from the self-transition in the Wait-for-
Answer Preview: If the sending of this message were removed the sending …

, Chapter: 4 -Problem: 24 >> Suppose there are three routers between a source host and a destination host. Ignoring fragmentation, an IP data-gram sent from the source host to the destination host will travel over how many interfaces? How many forwarding tables will be indexed to move the data-gram from the source to the destination?
Answer Preview: 8 inte…

, Chapter: 1 -Problem: 13 >> (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 average queuing delay for the ,N packets?(b) Now suppose that N such packets arrive to the link every LN/R seconds. What is the average queuing delay of a packet?
Answer Preview: a The queuing delay is 0 for the first transmitted …

, Chapter: 4 -Problem: 12 >> Describe how packet loss can occur at output ports. Can this loss he pre vented by increasing the switch fabric speed?
Answer Preview: Assuming input and output line speeds are the same packet loss can still occ…

, Chapter: 8 -Problem: 29 >> Stateful packet filters maintain two data structures. Name them and briefly describe what they do.
Answer Preview: Filter table and connecti…

, Chapter: 3 -Problem: 16 >> Suppose an application uses rdt. 3.0 as its transport layer protocol. As the stop-and-wait protocol has very low channel utilization (shown in the cross- country example), the designers of this application let the receiver keep sending back a number (more than two) of alternating ACK 0 and ACK 1 even if the corresponding data have not arrived at the receiver. Would this application design increase
Answer Preview: Yes This actually causes the sender to send a number of pip…

, Chapter: 7 -Problem: 14 >> What is the role of the “core network” in the 3G cellular data architecture?
Answer Preview: Opportunistic Scheduling refers to matching the physical …

, Chapter: 4 -Problem: 10 >> Three types of switching fabrics are discussed in Section 4.2. List and briefly describe each type. Which if any, can send multiple packets across the fabric in parallel?
Answer Preview: Switching via memory switching via a bus s…

, Chapter: 2 -Problem: 24 >> CDNs typically adopt one of two different server placement philosophies. Name and briefly describe them.
Answer Preview: One server placement philosophy is called Enter Deep which e…

, Chapter: 5 -Problem: 8 >> True or false: When an OSPF route sends its link state information, it is sent only to those nodes directly attached neighbors. Explain.
Answer Preview: False With OSPF a router broadcasts its linkstate information to all other ro…

, Chapter: 8 -Problem: 5 >> Consider an 8-block cipher. How many possible input blocks does this cipher have? How many possible mappings are there? If we view each mapping as a key, then how many possible keys does this cipher have?
Answer Preview: An 8block cipher has 2 8 possible …

, Chapter: 4 -Problem: 27 >> What is meant by the term “route aggregation”? Why is it useful for a router to perform route aggregation?
Answer Preview: Route aggregation means that an ISP uses a single pr…

, Chapter: 8 -Problem: 20 >> In the SSL record, there is a field for SSL sequence numbers. True or false?
Answer Preview: False SS…

, Chapter: 9 -Problem: 8 >> Consider the simple model for HTTP? Streaming. Suppose the server sends bits at a constant rate of 2 Mbps and playback begins when 8 million bits have been received. What is the initial buffering delay tp?
Answer Preview: The initi…

, Chapter: 9 -Problem: 2 >> Recall the simple model for HTTP streaming shown in Figure 9.3. Recall that B denotes the size of the client's application buffer, and Q denotes the number of bits that must be buffered before the client application begins play out. Also r denotes the video consumption rate. Assume that the server sends bits at a constant rate x whenever the client buffer is not full. a. Suppose that x < r. As dis
Answer Preview: a During a playout period the buffer starts with Q bi…

, Chapter: 3 -Problem: 50 >> Consider a simplified TCP’s AIMD algorithm where the congestion window size is measured in number of segments, not in bytes. In additive increase, the congestion window size increases by one segment in each RTT. In multiplicative decrease, the congestion window size decreases by half (if the result is not an integer, round down to the nearest integer). Suppose that two TCP connections, C1 and C2,
Answer Preview: a The key difference between C1 and C2 is that C1s RTT is only half of that of C2 Thus C1 adjusts its window size after 50 msec but C2 adjusts its window size after 100 msec Assume that whenever a los…

, Chapter: 1 -Problem: 22 >> Consider Figure 1. 1 (b). Suppose that each link between the server and the client has a packet loss probability p, and the packet loss probabilities for these links are independent. What is the probability that a packet (sent by the server) is successfully received by the receiver? If a packet is lost in the path from the server to the client, then the server will re-transmit the packet. On avera
Answer Preview: Probability of successfully receiving a packet is p s 1p N The number of …

, Chapter: 1 -Problem: 4 >> Consider the circuit-switched network in Figure 1.13. Recall that there are 4 circuits on each link. Label the four switches A, B, C, and D, going in the clockwise direction.a. What is the maximum number of simultaneous connections that can be in progress at any one time in this network?b. Suppose that all connections are between switches A and C. What is the maximum number of simultaneous connect
Answer Preview: a Between the switch in the upper left and the switch in the upper righ…

, Chapter: 5 -Problem: 20 >> Suppose ASs X and Z are not directly connected but instead are connected by AS Y. Further suppose that X has a peering agreement with Y, and that Y has a peering agreement with Z. Finally, suppose that Z wants to transit all of Y’s traffic but does not want to transit X’s traffic. Does BGP allow Z to implement this policy?
Answer Preview: Since Z wants to transit Ys traffic Z will send route advertisements to Y In th…

, Chapter: 9 -Problem: 9 >> For the VoIP example in Section 9.3, we introduced an online procedure (exponential moving average) for estimating delay. In this problem we will examine an alternative procedure. Let ti be the timestamp of the ith packet received; let ri be the time at which the ith packet is received. Let dn be our estimate of average delay after receiving the nth packet. After the first packet is received, we s
Answer Preview: a r1 t1 r2 t2 rn1tn1 n1dn1 Substituting this into the expression for dn g…

, Chapter: 5 -Problem: 5 >> What is the “count to infinity” problem in distance vector routing?
Answer Preview: The counttoinfinity problem refers to a problem of distance vector r…

, Chapter: 3 -Problem: 9 >> In our rdt protocols, why did we need to introduce sequence numbers?
Answer Preview: Sequence numbers are req…

, Chapter: 3 -Problem: 38 >> In our description of TCP in Figure 3.53. the value of the threshold. ssthresh, is set as ssthresh=cwnd/2 in several places and ssthresh value is referred to as being set to half the window size when a loss event occurred. Must the rate at which the sender is sending when the loss event occurred be approximately equal to cwnd segments per RTT? Explain your answer. If your answer is no. can you sug
Answer Preview: Yes …

, Chapter: 2 -Problem: 29 >> Suppose that in UDPClient.py, after we create the socket, we add the line: clientSocket.bind((‘‘, 5432)). Will it become necessary to change UDPServer.py? What are the port numbers for the sockets in UDP Client and UDPServer? What were they before making this change?
Answer Preview: In the original program UDPClient does not specify a port number when it creat…

, Chapter: 6 -Problem: 13 >>