4.2-2b Packet scheduling (PRI). Consider again the same pattern of red and green packet arrivals to a router's output port queue, as shown above (in question 4.2-2a). Indicate the sequence of departing packet numbers (at t = 1, 2, 3, 4, 5, 6, 7) under Priority scheduling, where red packets have priority over green packets. 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. At t=1, the number of the packet that finishes transmission is: [Choose] [Choose ] packet 6 packet 5 At t-3, the number of the packet that No packet departs at this time unit. finishes transmission is: packet 2 At t=4, the number of the packet that packet 4 finishes transmission is: packet 1 At t=2, the number of the packet that finishes transmission is: At t=5, the number of the packet that finishes transmission is: At t=6, the number of the packet that finishes transmission is: At t-7, the number of the packet that finishes transmission is: packet 3 [Chovat [Choose ] [Choose ]

4.2-2b Packet scheduling (PRI). Consider again the same pattern of red and green packet arrivals to a router's output port queue, as shown above (in question 4.2-2a). Indicate the sequence of departing packet numbers (at t = 1, 2, 3, 4, 5, 6, 7) under Priority scheduling, where red packets have priority over green packets. 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. At t=1, the number of the packet that finishes transmission is: [Choose] [Choose ] packet 6 packet 5 At t-3, the number of the packet that No packet departs at this time unit. finishes transmission is: packet 2 At t=4, the number of the packet that packet 4 finishes transmission is: packet 1 At t=2, the number of the packet that finishes transmission is: At t=5, the number of the packet that finishes transmission is: At t=6, the number of the packet that finishes transmission is: At t-7, the number of the packet that finishes transmission is: packet 3 [Chovat [Choose ] [Choose ]

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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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 Priority scheduling, where red packets have priority over green packets. 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.
Consider the same 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 round robin scheduling. Assume a round-robin scheduling cycle beings with green packets. 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).
Consider sending a file of F bits over a path of Q links. Each link transmits at R bits per second (bps). The network is lightly loaded so that there are no queueing delays. When a form of packet switching is used, the F bits are broken up into packets, each packet with L bits, of which h bits of it are header. Propagation delay is negligible. Let F = 5x104, Q = 20, R = 1 Mbps, L = 1000, and h = 10. b) Suppose the network is a packet-switched datagram network and a connectionless service is used. How long does it take to send the file?
Consider a router buffer preceding an outbound link. In this problem, you will use Little’s formula, a famous formula from queuing theory. Let N denote the average number of packets in the buffer plus the packet being transmitted. Let a denote the rate of packets arriving at the link. Let d denote the average total delay (i.e., the queuing delay plus the transmission delay) experienced by a packet. Little’s formula is N=a⋅d . Suppose that on average, the buffer contains 10 packets, and the average packet queuing delay is 10 msec. The link’s transmission rate is 100 packets/sec. Using Little’s formula, what is the average packet arrival rate, assuming there is no packet loss?
22. A datagram subnet allows routers to drop packets whenever they need to. The probability of a router discarding a packet is p. Consider the case of a source host connected to the source router, which is connected to the destination router, and then to the destination host. If either of the routers discards a packet, the source host eventually times out and tries again. If both host-router and router-router lines are counted as hops, what is the mean number of a. (a) hops a packet makes per transmission? b. (b) transmissions a packet makes? (c) hops required per received packet?
Consider a scenario in which Host A wants to simultaneously send packets to Hosts B and C. A is connected to B and C via a broadcast channel—a packet sent by A is carried by the channel to both B and C. Suppose that the broadcast channel connecting A, B, and C can independently lose and corrupt packets (and so, for example, a packet sent from A might be correctly received by B, but not by C). Design a stop-and-wait-like error-control protocol for reliably transferring packets from A to B and C, such that A will not get new data from the upper layer until it knows that both B and C have correctly received the current packet. Give FSM descriptions of A and C.
1. Below is a nested MPLS network by MTN. With the assumption that Customer 6 (C6) is connected to Router 6 (R6), execute a Dijkstra Algorithm on a Link State routing to determine the shortest path for Customer 6 to transmit packets to every other Customer/Destination connected to the rest of the Routers on the network. (a) i. Tabulate the executed iteration for the Dijkstra Algorithm using the table below. Iteration Nodes R1 R2 R3 R4 R5 R7 R8 R9 R10 0 [6] 1 [6,3] 2 [6,3,2] 3 [6,3,2,1] 4 [6,3,2,1,4] 5 [6,3,2,1,4,5] 6 [6,3,2,1,4,5,7]…
Consider the following diagram: A,B,C and D are subnets, R1, R2, and R3 are routers. Default signifies theentire rest of the internet. All 4 subnets each contain the same number of hosts.Consider the following routing table at R3: CIDR Mask Link 0.0.0.0/0 L4 128.4.6.0/24 L3 128.4.8.0/24 L5 1. If 128.4.6.0 is in A, what is the routing table at R1? 2. The ISP that owns all these networks is short on IP addresses, so theyuse a NAT router for R2. How many public IP addresses will C andD use together assuming they use as many private 10.X IP addresses asthey can? How many total public IP addresses will be used by the entirenetwork? Why doesn’t the ISP care about how many private IP addressesare used? 3. Fix R3’s routing table now that we are using NAT: 4. A node in C is given the IP address 10.0.0.1 and only sends and receivespackets on port 1234. A packet destined for this node reaches R2 witha source of (IP=128.4.6.6, Port=3000) and destination of (IP=128.4.8.0,Port=10000).…
Below is a nested MPLS network by MTN. With the assumption that Customer 6 (C6) is connected to Router 6 (R6), execute a Dijkstra Algorithm on a Link State routing to determine the shortest path for Customer 6 to transmit packets to every other Customer/Destination connected to the rest of the Routers on the network. Tabulate the executed iteration for the Dijkstra Algorithm using the table below. Iteration Nodes R1 R2 R3 R4 R5 R7 R8 R9 R10 0 [6] 1 [6,3] 2 [6,3,2] 3 [6,3,2,1] 4 [6,3,2,1,4] 5 [6,3,2,1,4,5] 6 [6,3,2,1,4,5,7]…
Below is a nested MPLS network by MTN. With the assumption that Customer 6 (C6) is connected to Router 6 (R6), execute a Dijkstra Algorithm on a Link State routing to determine the shortest path for Customer 6 to transmit packets to every other Customer/Destination connected to the rest of the Routers on the network. Tabulate the executed iteration for the Dijkstra Algorithm using the table below. Iteration Nodes R1 R2 R3 R4 R5 R7 R8 R9 R10 0 [6] 1 [6,3] 2 [6,3,2] 3 [6,3,2,1] 4 [6,3,2,1,4] 5 [6,3,2,1,4,5] 6 [6,3,2,1,4,5,7]…
1.4.12.2 End-to-end Delay. Consider again the network shown above. The links again have transmission rates of R1 = R2 = 100 Mbps (i.e., 100 x 106 bits per second), and each packet is 1 Mbit (106 bits) in size. Assume that the propagation delay is 1 msec per link. What is the end-to-end delay of a packet from when it first begins transmission at the sender, until it is received in full by the server at the end of the rightmost link. Assume store-and forward packet transmission. You can assume the queueing delay is zero. Answer choices: A. 2 x 106 msec b. 2.01 msec C. 1.1 msec D. 2.02 msec 1.4.12.3 Maximum Throughput. Consider again the network shown above. The links again have transmission rates of R1 = R2 = 100 Mbps Assume that the link R2 is fairly shared (as we've seen is done via TCP) between the two sessions. What is the maximum end-to-end throughput achieve by each session, assuming both sessions are sending at the maximum rate possible? Answer choices:…
Consider a node called A that sends packets to an adjacent node called B. To control the packet flow to node B, node A employs a credit manager scheme in which parameters C=3(credits), C_max=4(credits) and \tao=6(msec), respectively. node A has an infinite buffer to temporarily store packets. When a packet arrives at node A, node A stores the packet at the bottom of the buffer. Node A also has a single server (transmitter). As soon as the server becomes idle, the server picks up a packet at the head of the buffer, if any, and serves the packet for packet transmission time T_p as far as there remains a credit. (The packet transmission time T_p = 4 (msec).) We observed the arrival times of the first 12 packets, denoted by aA(1)⋯A(12), which were as follows: n A(n) 1 0.5 msec 2 1.0 3 1.5 4 2.0 5 4.5 6 5.5 7 6.5 8 12.5 9 13.0 10 13.5 11 14.0 12 14.6 1. Let R(n) denote the departure time of the n th packet from the buffer for n∈{1,2,...}. Find R(n) for…