PECNS

Connect types of simulations with their definitions: discrete (event). continuous. hybrid.

In a queueing system the real,unknown probability of the queue size 30 is equal to 1.23456789x10^-6. Finding this probability with the six-digit precision, i.e. 1.23456x10^-6, requires more than 10^8 measurements of the queue size. True. False.

If the interarrival time distribution is exponential then the steady-state queue size distribution is the same as queue size distribution observed by arriving jobs. True. False.

Waiting distribution is always the same as the virtual waiting time distribution. True. False.

The loss ratio may be equal to the full-buffer probability(i.e. the probability that queue size is N). True. False.

The steady-state queue size distribution depends on the variance of the service time. True. False.

Method scheduleAt() is used to schedule a message in the past. True. False.

In queueing system with finite buffer the service time is constant and equal to 10. The duration of the buffer overflow period may be 15 in this system. True. False.

simtime_t is a function returning the current simulated time. True. False.

Method empty() is used to remove all jobs from the queue. True. False.

FES is an acronym from Forward Entrance System. True. False.

How does a host that has sent TCP data know that the data was received?. A TCP acknowledgement is sent from the receiver. An ICMP echo reply is sent from the receiver. An incremented TCP sequence number is sent from the receiver. A SYN/ACK is sent from the receiver.

Which of the following best characterizes TCP versus UDP (in most cases)?. TCP is less reliable and quicker. TCP is slower, more reliable, and requires more overhead. TCP is faster, more reliable, and more streamlined. TCP is less reliable and connection-oriented.

The ISO/OSI model consists of ___ layers. three. five. seven. eight.

The TCP is a ___ protocol. reliable. connection-oriented. both a and b. none of the above.

The slice is a ___. set of allocated resources distributed across PlanetLab. set of allocated resources on a single PlanetLab node. physical location where PlanetLab nodes are located. dedicated server that runs components of PlanetLab services.

The sliver is a ___. set of allocated resources distributed across PlanetLab. slice (set of allocated resources) running on a specific node. Physical location where PlanetLab nodes are located. dedicated server that runs components of PlanetLab services.

TCP typically begins a session with: The three-way handshake of client to server with SYN set, the server response of SYN/ACK, and the client acknowledgement of ACK. The three-way handshake of server to client with SYN set,the clientresponse of SYN/ACK,and the server acknowledgement of ACK. TCP is not connection oriented so no handshake is required. A handshake consisting of the client request to the server with SYN set and a server response of a SYN.

To run the Omnet++ executable, you need an: omnetpp.ini. omnetpp.inf. omnetpp.txt. omnetpp.vec.

What is the output of the Omnet++ simulation?. The simulation results are recorded into output scaral (.sca) file. The simulation results are recorded into output vector (.vec) file. The simulation results are recorded into output vector (.vec) and output scalar (.sca) files. none of the above.

What is the function of a router?. It determines the entire route for an IP packet from source to destination host. It uses ARP to route the packet to the next hop. It uses DNS to route the packet to the next hop. It attempts to move the IP packet one hop closer to the destination.

A server port of UDP or TCP 53 is typically associated with what service?. HTTP. DNS. FTP. RPC.

A TCP flag of RESET indicates: An intention to open a new TCP connection. An intention to gracefully close and acknowledge the termination of both sides of the connection. An intention to abort a TCP connection. An intention to close the connection after all in-transit data is received.

A value of 6 in the protocol field of the IP header represents: An embedded protocol of ICMP follows the IP header. An embedded protocol of UDP follows the IP header. An embedded protocol of TCP follows the IP header. An embedded protocol of TCP precedes the IP header.

What is a typical response from a host that receives a UDP packet on a non-listening port?. A UDP reset flag set to the sender. A UDP FIN flag set to the sender. An ICMP port unreachable message to the sender. A UDP port unreachable message to the sender.

A function of the TCP sequence number is: To associate a chronological number with each TCP segment, allowing the receiver to properly reorder the individual segments of data. To inform the sender of the next expected chronological sequence number of the TCP segment. To reassemble IP fragments. To increment the hop count on all TCP segments.

Parameters applied to the simulation may be submitted in: configuration file, e.g. *.ini. topology file, e.g. *.ned. in the simulation code *.cpp. in the other way.

The following languages are used for description of a simulation: Protel. VHDL. Proto-C. C/C++.

Results of the simulation are saved as: Arrays, lists and scalars. Vectors, scalars and animations. Vectors and scalars. Arrays, vectors and lists.

Which sequence is correct for the cSimpleModule class?. cSimpleModule(); initialize(); finish(); ~cSimpleModule();. cSimpleModule(); initialize(); ~cSimpleModule(); finish();. initialize(); cSimpleModule(); ~cSimpleModule(); finish();. initialize(); cSimpleModule(); handleEvent(); ~SimpleModule(); finish();.

The system response time is the sum of the waiting time and the service time of a job. True. False.

The waiting time distribution is always the same as the virtual waiting time distribution. True. False.

The loss ratio is never equal to the full-buffer probability (i.e. the probability that the queue size is N). True. False.

Method front() adds a message at the beginning of the queue. True. False.

Method empty() removes all messages from the queue. True. False.

FES is an acronym from Future Event Stamp. True. False.

How does a host that has scent TCP data known that the data was received?. An incremented TCP sequence number is sent from the receiver. An ICMP echo reply is sent from the receiver. A SYN/ACK is sent from the receiver. A TCP acknowledgement is sent from the receiver.

Which of the following best characterizes TCP versus UDP (in most cases)?. TCP is faster, more reliable and more streamlined. TCP is slower, more reliable and requires more overhead. TCP is less reliable and quicker. TCP is less reliable and connection-oriented.

The TCP/IP model consists of ____ layers. three. four. five. seven.

The TCP is a ____ protocol. no reliable. connection-oriented. both a and b. none of the above.

The slice is a ____. physical loction where PlanetLab nodes are located. dedicated server that runs components of PlanetLab services. set of allocated resources distributed across PlanetLab. set of allocated resources on a single PlanetLab node.

A testbed is ____. a bed that can be tested to see if it is comfortable. a platform for conducting rigorous, transparent and replicable testing of scientific theories, computational tools and new technologies. the Spirent Test Center. a dedicated server that runs components of PlanetLab services.

TCP typically begins a session with: The three-way handshake of server to client with SYN set, the client response of SYN/ACK and the server acknowledgement of ACK. The three-way handshake of client to server with SYN set, the server response of SYN/ACK and the client acknowledgement of ACK. TCP is not connection oriented so no handshake is required. A handshake consisting of the client request to the server with SYN set and a server response of a SYN.

The components of the testbed are: experimental subsystem. comfortable mattress. monitoring subsystem. wireless subsystem.

Round-trip time (RTT). is the measurement of the time taken by an object to travel a distance through a medium. is the length of time it takes for a signal to travel in one direction. specifies the latency for a bit of data to travel across the network from one communication endpoint to another. is the amount of time it takes for a signal to be sent plus the amount of time it takes for acknowledgement of that signal having been received.

What is the function of a router?. it attempts to move the IP packet one hop closer to the destination. it uses ARP to route the packet to the next hop. it uses DNS to route the packet to the next hop. it determines the entire route for an IP packet from source to destination host.

Assume that in a subway station trains arrive to the platform with random interarrival time, exponentially distibuted, on average every 10 minutes. We visit the platform every day at 12:00. On average, we have to wait 5 minutes for the train. True. False.

Assume that in a queue with infinite buffer (no loses), the arrival stream is Poisson, the service time is uniform. In such a case, the output process is Poisson. True. False.

Assume that in a queue with a finite buffer the loss ratio is 0.01, the burst ratio is 2. In such a case, the average length of the series of consecutive losses is slightly smaller than 2. True. False.

Merging two Poisson processes of rates lambda1 and lambda2, respectively creates another Poisson process of rate lambda1+lambda2. True. False.

In a queuing system with losses it holds (wzór na zdjęciu): True. False.

In the M/M/1 queueing system it holds: (patrz wzór na zdjęciu): True. False.

In every queueing system with a finite buffer, the loss ratio is equal to the full-buffer probability, L=pN. True. False.

In a queueing system with no losses, the average queue size is equal to the arrival rate multiplied by the average of response time. True. False.

In some queueing systems the distribution of the waiting time can be the same as the distribution of the virtual waiting time. True. False.

Assume that transition matrix of a discrete-time Markov chain is (patrz zdjęcie). The period of this chain equals 2. True. False.

INET supports a wide class of communication networks, including. wired. wireless. mobile. ad hoc.

EtherAppClient. is a module implementing the CSMA protocol. is a module implementing an Ethernet application that only receives packets. is a traffic generator that periodically sends messages (Ethernet frames). accepts connections from EtherAppServer on a specified port.

StandardHost node contains the most common Internet protocols such as. LTE. TCP. UDP. BGP.

PhysicalEnvironment. arranges nodes in a physical environment. measures temperature of a physical environment. models the effect of a physical environment (i.e. obstacles) on radio signal propagation. defines a set of physical objects.

Ipv4NetworkConfigurator. supports manual routes and automatic routes. supports manual and automatic link configurations e.g. bandwidth, delays. assigns IPv4 addresses and sets up static routing for an IPv4 network. supports both manual and automatic address assignment.

UDPSink. listens on an UDP port and sends back each received packed to its sender. generates traffic for a UDP application. consumes and prints packets received from the UDP module. sinks UDP packets and leaves the others (e.g. TCP packets).

CSMA. stands for Computer Shared Medium Access. stands for Carrier Sense Multiple Access. is a protocol in which a node uses a token which gives transmission privilege on shared medium. is a protocol in which a node verifies the absence of other traffic before transmitting on the shared transmission medium.

To assign IP addresses to all interfaces of all hosts, from the address range 10.0.0.0 - 10.255.255.255 and netmask range 255.0.0.0 -255.255.255.25 you will use in your configuration file config = default(xml("<config>...</config>")) where ... is: <interface hosts='xx' address='10.*.*.*' netmask='255.*.*.*'/>. <interface hosts='**' address='10.x.x.x' netmask='255.x.x.x'/>. <interface hosts='xx' address='10.*.*.*' netmask='255.*.*.25'/>. <interface hosts='xx' address='10.255.255.255' netmask='255.255.255.25'/>.

Fill out the spaces in the code: <environment> <object ...1="min 130 300 0" orientation="0 0 0" ...2="cuboid 5 100 4" ...3="concrete" fill-color="203 65 84" opacity="0.8"/> </environment>. 1) shift 2) shape 3) material. 1) position 2) shape 3) material. 1) shift 2) material 3) fabric. 1) position 2) material 3) fabric.

Fill out the spaces in the code: submodules: configurator: ...1; server: ...2; router: ...3; switch: ...4;. 1) Configurator 2) Server 3) IPRouter 4) Switch. 1) Ipv4NetworkConfigurator 2) StandardHost 3) Router 4) EtherSwitch. 1) StandardConfigurator 2) StandardHost 3) IPRouter 4) Switch. 1) IP4Configurator 2) IP4Host 3) IP4Router 4) EtherSwitch.

Assume we have a discrete-time Markov chain X0, X1, X2, X3, ... The subsequence X0, X3, X6, X9, ... is a discrete-time Markov chain. True. False.

Assume that the transition matrix of a discrete-time Markov chain is (patrz zdjęcie). This Markov chain is irreducible. True. False.

Method setNumCells() sets the maximum allowed queue size in a cQueue object. True. False.

Fill spaces in the code: network #1 { #2: submod1: Node; submod2: Node; #3: submod1.port --> submod2.port; }. 1. Network 2. nodes 3. topology. 1. Module 2. networks 3. topology. 1. Topology 2. submodules 3. connections. 1. Network 2. submodules 3. connections.

Fill spaces in the code: void FFGenerator::#1(cMessage *msg) { #2 *m = new #2("cPackage"); m->setBitLength(par("msgLength")); #3(m, "out"); scheduleAt(simTime() + deltaT, sendMessageEvent); }. 1. handleMessage 2. cMessage 3. send. 1. handleMessage 2. cPackage 3. send. 1. handleEvent 2. cMessage 3.receive. 1. handleEvent 2. cPackage 3. receive.

Tovisually aggregate many network elements into a single element, the following elements are used: Netmask. Subnet. Toolbox. Scenario.

Uzupełnij kod: compmodule #1 { submodules: submod1:#2; submod2: #2; #3: submod1.port --> submod2.port; }. 1. Network 2. Submodule 3. topology. 1. Module 2. Submodule 3. topology. 1. Module 2. Submodule 3. connections. 1. Network 2. Node 3. connections.

Uzupełnij kod: FFGenerator::#1(cMessage *msg) { #2 *m = new #2("packet"); m->setBitLength(par("msgLength")); #3(m, "out"); scheduleAt(simTime() + deltaT, sendMessageEvent); }. 1. receiveMessage 2. cMsg 3. send. 1. handleMessage 2. cMessage 3. Send. 1. handleEvent 2. cMessage 3.Receive. 1. handleEvent 2. cMsg 3. Receive.

Do wyswietlania przebiegów czasowych wykorzystujemy w Omnecie klase: cLongHistogram(). cProcessDisplay(). c0utVector(). cStdDev().

Metoda pobierajace wynik (dana) do histogramu cDoubleHistogram() to: collect(). take(). record(). set(). żadna z powyższych.

FES (lub FEL) w Omnecie to: Kolejka zawierająca zdarzenia przyszłe. Kolejka zawierająca zdarzenia, które już wystapiły od początku symulacji. Tablica zawierająca wszystkie moduły symulatora. Tablica zawierająca wszystkie połączenia miedzy modułami.

Mamy system kolejkowy, w którym czas pomiędzy zadaniami jest wykładniczy ze średnia 1. Zamieniamy rozkład czasu pomiędzy zadaniami na jednostajny uniform(0.1, 1.1), pozostawiając resztę systemu bez zmian. W nowym systemie średnia długość kolejki będzie: Większa niż poprzednio. Mniejsza niż poprzednio. Nie zmieni się.

ARP protocol: maps a network layer protocol address to a data link layer hardware. is used to provide secure connections across the Internet. is used to resolve IP address to the corresponding Ethernet address. is used to automatiaclly provide IP addresses to network computers.

Using the Spirent Test Center and Spirent devices we can. generate UDP traffic. emulate hosts. emulate routers. emulate bridges.

The Stream Block is a. "summary" definition, it can represent a single stream in a single port, or 1000s of streams across 100s ports. Spirent chassis. router. single stream on a single port.

The DUT is a. device under test. device UDP traffic. driver urgent transfer. Spirent Test Center interface.

Assume we have a queuing system with the following parameters: the interarrival time distribution = exponential(1), the service time distribution = uniform(0,2), the buffer size N = 10. In this system, it is possible to lose 7 arriving jobs in a row (one after another). True. False.

FES is an acronym from Future Event Set. True. False.

In a queueing system with a finite buffer it holds: X= lambda(1-L)R. True. False.

In a queueing system with a finite buffer it is possible to compute the burst ratio, if we know only the loss ratio and the buffer size. True. False.

In a queueing system with a finite buffer it is possible to compute the empty system probability, if we know only the system load and the loss ratio. True. False.

In a queueing system with a finite buffer the service time is constant and equal to 2. The duration of the buffer overflow period may be 1 in this system. True. False.

In a queueing system with a finite buffer the service time is constant and equal to 10. The duration of the buffer overflow period may be 15 in this system. True. False.

In a queueing system with losses it holds: : L = 1 - (1-p0)/p. True. False.

In a queueing system with Poisson arrivals the average queue size distribution observed at arbitrary times is the same as when observed at arrival times. True. False.

In an open Jackson network, for every queue it holds: Xi=(1-p)/p?. True. False.

In some queueing systems with a finite buffer, the loss ratio is equal to the full-buffer probability: L=p_N. True. False.

The queue size distribution observed just before arrival times is the same as the queue size distribution observed just after departure times. True. False.

The uniform distribution has the memoryless property. True. False.

Application nodes. maintain the set of network interface (e.g. eth0, wlan0) in the network node. are often modeled as compound modules containing separate modules for queues, classes MAC, and PHY protocols. are represented by compound modules which are connected to the network layer protocol other network interfaces in the wired case. model the user behavior as well as the application program (e.g. browser), and the application layer protocol (e.g. HTTP).

CSMA/CA. stands for Computer Shared Medium Access with Collision Avoidance. stands for Carrier Sense Multiple Access with Collision Avoidance. is used to improve the performance of the CSMA. is a protocol which a node verifies the absence of other traffic before transmitting on the shared transmission medium.

1. cModule 2. cBaseModule 3. cChannel. 1. cModule 2. cComponent 3. cSimpleChannel. 1. cComponent 2. cModule 3. cChannel. 1. cUnit 2. cModule 3. cSimpleChannel.

INET supports. nodes mobility. simulation visualization. external frameworks. Javascript plugins.

Ipv4RoutingTable. supports manual routes and automatic routes. supports manual and automatic link configurations e.g. bandwidth, delays. stores a routing table. supports both manual and automatic routes assignment.

TcpBasicClientApp. accepts any number of incoming TCP connections. sends back the messages that arrive to it. is a client for a generic request-response style protocol over TCP. communicates with a server sessions.

The sliver is a ___. set of allocated resources distributed across PlanetLab. slice (set of allocated resources) running on a specific node. set of allocated resources on a single PlanetLab node. physical location where PlanetLab nodes are located. dedicated server that runs components of PlanetLab services.

Using the Stream Block Editor of the Spirent Test Center we can define. the Ethernet frame. the UDP header. the IPv4 header. the gateway in the UDP header. the destination MAC address in UDP header.

Which are predefined geographical (?) scales of network topologies. world. enterprise. campus. office.

Which topics were NOT covered by twelve pdf manuals available on the Platform?. TCP. WiFi. LTE. Queuing disciplines.

Fill out the spaces in the code network = WiredNetworkExample *.numClients = 10 #number of clients in network *.client[*].numApps = i #number of applications on clients *.client[*].app[0].typename = “...1” #client application type *.client[*].app[0].connectAddress = “...2” #destination address *.client[*].app[0].connectPort = 1000 #destination port *.server.app[0].typename = “...3” #server application type *.server.app[0].localPort = 1000 #TCP server listen port. 1. TcpClientApp 2. TCPServerApp 3. TCPSinkAPP. 1. TcpSessionApp 2. server 3. TCPEchoAPP. 1. UDPApp 2. client 3. UDPSink. 1. TcpSessionApp 2. server 3. TCPSinkAPP.

Fill out the spaces in the code network WiredNetworkExample { submodules: configurator: ...1; radioMedium: ...2; host: WirelessHost; accessPoint: ...3; … }. 1. Ipv4NetworkConfigurator 2. Ieee80211ScalarRadioMedium 3. AccessPoint. 1. Ipv4RoutingTable 2. Ieee80211ScalarRadioMedium 3. AccessPoint. 1. Ipv4NetworkConfigurator 2. RadioMedium 3. Ieee80211AccessPoint. 1. Ipv4RoutingTable 2. RadioMedium 3. Ieee80211AccessPoint.