4.01-1. Packet scheduling (a). Consider the pattern of red and green packet arrivals to arouter's output port queue, shown below. Suppose each packet takes one time slot to betransmitted, and can only begin transmission at the beginning of a time slot after its arrival.Indicate the sequence of departing packet numbers (at t = 1, 2, 3, 4, 5, 6, 7) under FCFSscheduling. Give your answer as 7 ordered digits (each corresponding to the packet number ofa departing packet), with a single space between each digit, and no spaces before the first orafter the last digit, e.g., in a form like 7 6 5 4 3 2 1).[Note: You can find more examples of problems similar to this here B.)arrivalspacketin servicedepartures2340???? ? ? ? ?267-w45 4.01-2. Packet scheduling (b). Consider the same pattern of red and green packet arrivals to arouter's output port queue, shown below. Suppose each packet takes one time slot to betransmitted, and can only begin transmission at the beginning of a time slot after its arrival.Indicate the sequence of departing packet numbers (at t = 1, 2, 3, 4, 5, 6, 7) under priorityscheduling (where red packets have priority over green packets). Give your answer as 7ordered digits (each corresponding to the packet number of a departing packet), with a singlespace between each digit, and no spaces before the first or after the last digit, e.g., in a formlike 7 6 5 4 3 2 1).[Note: You can find more examples of problems similar to this here B.)arrivalspacketin servicedepartures1 234015???????IN6734 5 6

4.01-1. Packet scheduling (a). Consider the pattern of red and green packet arrivals to a router's output port queue, shown below. Suppose each packet takes one time slot to be transmitted, and can only begin transmission at the beginning of a time slot after its arrival. Indicate the sequence of departing packet numbers (at t = 1, 2, 3, 4, 5, 6, 7) under FCFS scheduling. Give your answer as 7 ordered digits (each corresponding to the packet number of a departing packet), with a single space between each digit, and no spaces before the first or after the last digit, e.g., in a form like 7 6 5 4 3 2 1). [Note: You can find more examples of problems similar to this here B.) arrivals 1 234 51 67

4.01-1. Packet scheduling (a). Consider the pattern of red and green packet arrivals to a router's output port queue, shown below. Suppose each packet takes one time slot to be transmitted, and can only begin transmission at the beginning of a time slot after its arrival. Indicate the sequence of departing packet numbers (at t = 1, 2, 3, 4, 5, 6, 7) under FCFS scheduling. Give your answer as 7 ordered digits (each corresponding to the packet number of a departing packet), with a single space between each digit, and no spaces before the first or after the last digit, e.g., in a form like 7 6 5 4 3 2 1). [Note: You can find more examples of problems similar to this here B.) arrivals 1 234 51 67

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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TCP congestion control example. Consider the figure below, where a TCP sender sends 8 TCP segments at t = 1, 2, 3, 4, 5, 6, 7, 8. Suppose the initial value of the sequence number is 0 and every segment sent to the receiver each contains 100 bytes. The delay between the sender and receiver is 5 time units, and so the first segment arrives at the receiver at t = 6. The ACKs sent by the receiver at t = 6, 7, 8, 10, 11, 12 are shown. The TCP segments (if any) sent by the sender at t = 11, 13, 15, 16, 17, 18 are not shown. The segment sent at t=4 is lost, as is the ACK segment sent at t=7. TCP sender t=1 T t=2 t=3 t=4+ t=5- t=6+ t=11 t=12 t=13 t=14 t=15 t=16 t=17 t=18 I data segment data segment data segment data segment data segment data segment data segment data segment ACK ACK ACK ACK ACK ACK Ty A A V V htt TCP receiver t=6 t=7 t=8 t=9 t=10 t=11 t=12 t=13 What does the sender do at t=17? You can assume for this question that no timeouts have occurred.
4.2-2. Packet scheduling (FCFS). Consider the pattern of red and green packet arrivals to a router's output port queue, shown below. Suppose each packet takes one time slot to be transmitted, and can only begin transmission (at the earliest) at the beginning of a time slot after its arrival. Indicate the sequence of departing packet numbers (at t=1, 2, 3, 4, 5, 6, 7) under FCFS scheduling. Match each time unit (t=1, t=2, t=3 ....) with the number of the packet that was transmitted and thus "departs" at that time unit. arrivals packet in service departures 1 23 ??????? m At t= 1, the number of the packet that finishes transmission is: At t=4, the number of the packet that finishes transmission is: [Choose ] [Choose ] packet 1 At t=2, the number of the packet that packet 4 finishes transmission is: packet 5 packet 6 packet 3 At t=3, the number of the packet that No packet leaves at this time. finishes transmission is: packet 2 At t=5, the …
Consider an IP packet with a length of 4,500bytes that includes a 20-byteIPv4 header ans 40-byte TCP header. The packet is forwarded to an IPv4 router that supports a Maximum Transmission Unit (MTU) of 600bytes. Assume that the length of the IP header in all the outgoing fragments of this packet is 20bytes. Assume that the fragmentation offset value stored in the first fragment is 0. The fragmentation offset value stored in the third fragment is
Consider the following scenario in which host A is sending a file to host B over a TCP connection. Assuming that the sequence number of the first data byte sent by A is 0 and every segment always includes 1000 bytes of data, excluding the TCP header. At some point of time, bytes up to 6400 have been written into the sender’s buffer. Bytes up to 4999 have been sent out but the segment which contains bytes 2000~2999 has not arrived at host B yet. At the receiver’s side, all bytes up to 3999 have been received except for bytes 2000~2999. Bytes up to 499 have been read from the buffer by the application. Assume that the maximum size of the sender’s buffer is large enough. Consider the sliding window algorithm in TCP and answer the following questions. 1) What are the values for LastByteAcked, LastByteSent, and LastByteWritten? 2) What are the values for LastByteRead, NextByteExpected, and LastByteRcvd? 3) Assuming that the maximum size of the receiver’s buffer is 4000 byte, what would…
Consider a simple protocol for transferring files over a link. After some initial negotiation, A sends data packets of size 1 KB to B; B then replies with an acknowledgment. A always waits for each ACK before sending the next data packet; this is known as stop-and-wait. Packets that are overdue are presumed lost and are retransmitted. (a) In the absence of any packet losses or duplications, explain why it is not necessary to include any "sequence number" data in the packet headers. (b) Suppose that the link can lose occasional packets, but that packets that do arrive always arrive in the order sent. Is a 2-bit sequence number (that is, N mod 4) enough for A and B to detect and resend any lost packets? Is a 1-bit sequence number enough? (c) Now suppose that the link can deliver out of order and that sometimes a packet can be delivered as much as 1 minute after subsequent packets. How does this change the sequence number requirements?
In a bit-oriented link-layer protocol, the start and end of a frame are each marked by a flag, which is a sequence of exactly 6 consecutive 1 bits. Bit stuffing is used during the rest of the frame: after sending 5 consecutive 1 bits, a 0 is added. The bits below contain an example frame, with the leftmost bit received first. The content of the frame is a sequence of bytes, sent most significant bit first. Put the values of the first four bytes of the frame content, in order, in the four answer boxes below. You may enter the values in either decimal (e.g. 76, 123) or hexadecimal (e.g. 2a, f7). 00101011111010001111110011100111110000111101111101010110100010010011111101101100100 57−240−123−229
Compare GBN, SR, and TCP (no delayed ACK). Assume that the timeout values for all three protocols are sufficiently long such that 5 consecutive data segments and their corresponding ACKs can be received (if not lost in the channel) by the receiving host (Host B) and the sending host (Host A) respectively. Suppose Host A sends 5 data segments to Host B, and the 3rd segment (sent from A) is lost. In the end, all 5 data segments have been correctly received by Host B. How many segments has Host A sent in total and how many ACKs has Host B sent in total? What are their sequence numbers? Answer this question for all three protocols. The previous expert did the wrong question and the answer was incorrect. The 3rd packet is lost not the 2nd packet
as a possible congestion control mechanism in a subnet using virtual circuits internally, a router could refrain from acknowledging a received packet until (1) it knows its last transmission along the virtual circuit was received successfully and (2) it has a free buffer. for simplicity, assume that the routers use a stop-and-wait protocol and that each virtual circuit has one buffer dedicated to it for each direction of traffic. if it takes 7 sec to transmit a packet (data or acknowledgement) and there are n routers on the path, what is the rate at which packets are delivered to the destination host? assume that transmission errors are rare and that the host-router connection is infinitely fast.
1. What is the difference between packet fragmentation (i.e., at network layer) and frame frag- mentation (i.e., at link layer) in terms of purpose? 2. Suppose that host A is connected to a router R1, R1 is connected to another router, R2, and R2 is connected to host B. Suppose that a TCP message that contains 800 bytes of data and 20 bytes of TCP header is passed to the IP function at host A for delivery to B. Show the Total length, DF, MF, and Fragment offset fields of the IP header in each packet transmitted over the three links. (Assume that link A-R1 can support a maximum frame size of 1024 bytes including a 14-byte frame header, link R1-R2 can support a maximum frame size of 512 bytes, including an 8-byte frame header, and link R2-B can support a maximum frame size of 432 bytes including a 12-byte frame header.) (*hint: the Fragment offset field is denominated by 8-bytes, not bytes) 3. What is the purpose of the path MTU discovery process (see textbook Figure 5-42) and why does…
2. Consider a slotted TDM hierarchical network in which there are 8 computers sharing a 10 Mbps channel to a router R1, sending packets to R1 which must all be forwarded by R1 over an outgoing link (called the MAN link), as shown in Figure 1. Computers A-H always have packets waiting to be sent, so no timeslot on the shared LAN is idle. Ignore the propagation delay on the LAN. The MAN link outgoing from R1 is a 100 Mbps link. The network layer protocol in use has a PDU with exactly 40 bytes of header and exactly 200 bytes of payload (SDU). The DLC layer protocol in use on the LAN has a PDU with exactly 40 bytes of header and 20 bytes of trailer. The DLC layer protocol in use on the outgoing link from R1 has a PDU with 40 bytes of header and no trailer. The physical layer does not impose any bit overhead in either channel. Use 1 Mbps = 1000000 bps. B D E F G H R1 R2 Figure 1 (a) What is the transmission delay of a bit for Computer A? (b) What is the transmission delay of a DLC PDU for…
A workstation uses the HTTP protocol to download a large file from a web server. No proxy server is used. One router's queue is full when one of the web server's packets arrives.Select the four best statements to describe this situationa. The router stores the packet until such time that it can be sent.b. Further packets sent by the server are transmitted at a higher rate to compensate for the lost packet.c. The router sends an ICMP link congested message to the server.d. The packet must be retransmitted.e. Router configuration and network behavior could be improved by configuring FQ or WFQ.f. Further packets sent by the server are transmitted at a lower rate to reduce the load on the congested link.g. Router configuration and network behavior could be improved by configuring RED or WRED.h. A tail drop will happen.
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 223.10.128/24. Also suppose that Subnet 1 is required to support at least 50 interfaces, Subnet 2 is to support at least 100 interfaces, and Subnet 3 is to support at least 12 interfaces. Provide three network addresses (of the form a.b.c.d/x) that satisfy these constraints.