The purpose of this problem is to give you a better understanding as to the mechanisms of RSA. Write a function that receives as its parameters
Write a function that accepts a stream of ASCII characters and encrypts this input using a substitution cipher with the Cipher Block Chaining mode.
Write a procedure that computes the SHA-1 hash of a block of data. The procedure should have two parameters: a pointer to the input buffer and a
Write a program that encrypts its input by XORing it with a key stream. Find or write as good a random number generator as you can to generate the
Search the Internet for some court case involving copyright versus fair use and write a 1-page report summarizing your findings.
Rewrite the server of Fig. 6-6 as a true Web server using the GET command for HTTP 1.1. It should also accept the Host message. The server should
Numerous people have registered DNS names that consist of www.word.com, where word is a common word. For each of the following categories, list five
Some cybersquatters have registered domain names that are misspellings of common corporate sites, for example, www.microsfot.com. Make a list of at
Design and implement a chat system that allows multiple groups of users to chat. A chat coordinator resides at a well-known network address, uses UDP
One common function that all network protocols need is to manipulate messages. Recall that protocols manipulate messages by adding/striping headers.
The file server of Fig. 6-6 is far from perfect and could use a few improvements. Make the following modifications.(a) Give the client a third
Use the trace route (UNIX) or tracert (Windows) programs to trace the route from your computer to various universities on other continents. Make a
Write a function to do forwarding in an IP router. The procedure has one parameter, an IP address. It also has access to a global table consisting of
Write a program that simulates a computer network using discrete time. The first packet on each router queue makes one hop per time interval. Each
Write a program to simulate routing using flooding. Each packet should contain a counter that is decremented on each hop. When the counter gets to
Write a program to simulate the behavior of the CSMA/CD protocol over Ethernet when there are N stations ready to transmit while a frame is being
The goal of this lab exercise is to implement an error-detection mechanism using the standard CRC algorithm described in the text. Write two
Write a program to implement CDMA. Assume that the length of a chip sequence is eight and the number of stations transmitting is four. Your program
Multiplexing STS-1 multiple data streams, called tributaries, plays an important role in SONET. A 3:1 multiplexer multiplexes three input STS-1
Write a program that implements message flow from the top layer to the bottom layer of the 7-layer protocol model. Your program should include a
Search the Internet to find out some of the important peering points used for routing packets in the Internet at present.
The Internet is made up of a large number of networks. Their arrangement determines the topology of the Internet. A considerable amount of
Go to IETF’s Web site, www.ietf.org, to see what they are doing. Pick a project you like and write a half-page report on the problem and the
The ping program allows you to send a test packet to a given location and see how long it takes to get there and back. Try using ping to see how long
Find out what networks are used at your school or place of work. Describe the network types, topological, and switching methods used there.
Make a list of activities that you do every day in which computer networks are used. How would your life be altered if these networks were suddenly
Find the efficiency of the AMPS protocol in terms of simultaneous calls per megahertz of bandwidth. In other words, find the number of calls that can
Find the efficiency of the D-AMPS protocol in terms of simultaneous calls per megahertz of bandwidth. In other words, find the number of calls that
To which generation does each of the following cellular telephony systems belong?a. AMPSb. D-AMPSc. IS-95
Find the efficiency of the GSM protocol in terms of simultaneous calls per megahertz of bandwidth. In other words, find the number of calls that can
Find the efficiency of the IS-95 protocol in terms of simultaneous calls per megahertz of bandwidth. In other words, find the number of calls that
Write concurrent TCP client-server programs to simulate a simplified version of HTTP using only a nonpersistent connection. The client sends an HTTP
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
Do routers have IP addresses? If so, how many?
The DatagramPacket class has two constructors (see Table 25.11). Which constructor can be used as a sending packet?
Encrypt the message “this is an exercise” using additive cipher with key = 20. Ignore the space between words. Decrypt the message to get the
Use the additive cipher with k = 10 to encrypt the plaintext “book”. Then decrypt the message to get the original plaintext.
In real-time interactive audio/video, what will happen if a packet arrives at the receiver site after the scheduled playback time?
Explain why TCP, as a byte-oriented stream protocol, is not suitable for applications such as live or real-time multimedia streaming.
In Figure 28.26, can the Web server and media server run on different machines?
A program for encoding and decoding LZW compression.
Define a Response PDU (see Figure 27.18) using the syntax defined for structured data types in ASN.1.Figure 27.18
In SCTP, the state of a sender is as follows:a. The sending queue has chunks 18 to 23.b. The value of curTSN is 20.c. The value of the window size is
Define a GetRequest PDU (see Figure 27.18) using the syntax defined for structured data types in ASN.1.Figure 27.18
In a Kademlia network, the size of the identifier space is 1024. What is the height of the binary tree (the distance between the root and each leaf)?
An output interface in a switch is designed using the leaky bucket algorithm to send 8000 bytes/s (tick). If the following frames are received in
Alice uses the same key when she encrypts a message to be sent to Bob and when she decrypts a message received from Bob. Is this an example of
In SCTP, a SACK chunk reports the receipt of three out-of-order data chunks and five duplicate data chunks. What is the total size of the chunk in
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
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
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
Use the whois service at the American Registry for Internet Numbers (http://www.arin.net/whois) to determine the IP address blocks for three
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
Which of the following is not one of the five areas of network management defined by ISO?a. Faultb. Performancec. Personnel
Define an SNMP message (see Figure 27.19) using the syntax defined for structured data types in ASN.1.
Define a VarbindList (see Figure 27.19) using the syntax defined for structured data types in ASN.1.
In predictive coding, assume we have the following sample (xn). Show the encoded message sent if we use adaptive DM (ADM). Let y0 = 10, Δ1 = 4, M1 =
In DCT, is the value of T(m, n) in transform coding always between –1 and 1? Explain.
In transform coding, show that a receiver that receives an M matrix can create the original p matrix.
What is the main difference between live audio/video and real-time interactive audio/video?
Assume we devise a protocol with the packet size so large that it can carry all chunks of a live or real-time multimedia stream in one packet. Do we
In Internet telephony, explain how a call from Alice can be directed to Bob when he could be either in his office or at home?
Do you think H.323 is actually the same as SIP? What are the differences? Make a comparison between the two.
How many points can we have in a DHT with m = 10?
Repeat Example 29.2 in the text, but assume that node N12 needs to find the responsible node for key k7.
Explain the problems we encounter if we use IP addresses as the node identifiers in a DHT.
Explain two strategies used for storing an object in DHT-based network.
In Pastry, assume the address space is 16 and that b = 2. How many digits are in an address space? List some of the identifiers.
In a DHT-based network, assume m = 4. If the hash of a node identifier is 18, where is the location of the node in the DHT space?
In a Pastry network with m = 32 and b = 4, what is the size of the routing table and the leaf set?
In a DHT-based network, assume node 4 has a file with key 18. The closest next node to key 18 is node 20. Where is the file stored?a. In the direct
Show the outline of a routing table for Pastry with address space of 16 and b = 2. Give some possible entries for each cell in the routing table of
In a Chord network, we have node N5 and key k5. Is N5 the predecessor of k5? Is N5 the successor of k5?
In a Pastry network using DHT, in which m = 4 and b = 2, draw the identifier space with four nodes, N02, N11, N20, and N23, and three keys, k00, k12,
In the previous problem, answer the following questions:a. Show how node N02 responds to a query to find the responsible node for k24.b. Show how
In Kademlia, assume m = 4 and active nodes are N4, N7, and N12. Where is the key k3 stored in this system?
Using the routing tables in Figure 29.11 in the text, explain and show the route if node N0 receives a lookup message for the node responsible for
Using the binary tree in Figure 29.10 in the text, show the subtree for node N11.
In a Kademlia network with m = 4, we have five active nodes: N2, N3, N7, N10, and N12. Find the routing table for each active node (with only one
Rank the following applications based on their sensitivity to reliability:1. HTTP2. SNMP3. SMTP4. VoIP
Figure 30.13 shows a router using priority queuing at the input port.The arrival and required service times (transmission time is negligible) for 10
A program to simulate a token bucket.
Rank the following applications based on their sensitivity to delay:1. HTTP2. SNMP3. SMTP4. VoIP
To regulate its output flow, a router implements a weighted queueing scheme with three queues at the output port. The packets are classified and
Rank the following applications based on their sensitivity to jitter:1. HTTP2. SNMP3. SMTP4. VoIP
In Figure 30.3, assume the weight in each class is 4, 2, and 1. The packets in the top queue are labeled A, in the middle queue B, and in the bottom
Rank the following applications based on their sensitivity to bandwidth:1. HTTP2. SNMP3. SMTP4. VoIP
In a leaky bucket used to control liquid flow, how many gallons of liquid are left in the bucket if the output rate is 5 gal/min, there is an input
Which of the following applications are classified as CBR in ATM?a. HTTPb. SNMPc. SMTPd. VoIP
Assume fixed-sized packets arrive at a router with a rate of three packets per second. Show how the router can use the leaky bucket algorithm to send
Which of the following applications are classified as VBR-NRT in ATM?a. HTTPb. SNMPc. SMTPd. VoIP
Assume a router receives packets of size 400 bits every 100 ms, which means with the data rate of 4 kbps. Show how we can change the output data rate
Which of the following applications are classified as VBR-RT in ATM?a. HTTPb. SNMPc. SMTPd. VoIP
In a switch using the token bucket algorithm, tokens are added to the bucket at a rate of r = 5 tokens/second. The capacity of the token bucket is c
Which of the following applications are classified as UBR in ATM?a. HTTPb. SNMPc. SMTPd. VoIP
To understand how the token bucket algorithm can give credit to the sender that does not use its rate allocation for a while but wants to use it
Which of the following technique(s) is (are) used for scheduling?a. FIFO queuingb. Priority queuingc. Leaky Bucket
Which of the following technique(s) is (are) used for traffic shaping?a. Token bucketb. Priority queuingc. Leaky Bucket
A program to simulate a leaky bucket.
Assume an ISP uses three leaky buckets to regulate data received from three customers for transmitting to the Internet. The customers send fixed-size
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