Q&A Hero

Q: With the ________ approach a bit is set in a data packet as it is forwarded by the congested node. A) forward B) binary C) credit based D) rate based

Q: _________ explicit congestion signaling approaches notify the user that congestion avoidance procedures should be initiated where applicable for traffic in the same direction as the received notification. A) Datagram B) Dynamic C) Forward D) All of the above

Q: For ________ congestion avoidance, the network alerts end systems to growing congestion within the network and the end systems take steps to reduce the offered load to the network. A) backpressure B) explicit C) implicit D) dynamic

Q: ______ is a congestion control technique. A) Choke packet B) Implicit congestion signaling C) Backpressure D) All of the above

Q: The objective of __________ is to maintain the number of packets within the network below the level at which performance falls off dramatically. A) fast restraint B) traffic management C) window management D) congestion control

Q: When a TCP entity retransmits a segment using fast retransmit it assumes that a segment was lost, even though it has not yet timed out on that segment.

Q: The size of TCP's send window can have a critical effect on whether TCP can be used efficiently without causing congestion.

Q: Token bucket is used in the Bluetooth specification.

Q: Traffic policing is concerned with traffic leaving the switch.

Q: A reservation scheme is an integral part of ATM networks.

Q: Congestion control is concerned with efficient use of a network at high load.

Q: In a rate based scheme any node along the path of the connection can reduce the data rate limit in a control message to the source.

Q: Explicit congestion signaling approaches work forward but not backward.

Q: Congestion control on the basis of implicit signaling requires action on the part of network nodes.

Q: Even if all sources can detect congestion and reduce flow on the basis of congestion, network congestion still will not be relieved.

Q: One of the things that may happen when network congestion occurs is packets are discarded.

Q: An example of a choke packet is the ICMP Source Quench packet.

Q: Backpressure is a technique for congestion control.

Q: If the rate at which packets arrive and queue up exceeds the rate at which packets can be transmitted, the queue size grows withoutbound and the delay experienced by a packet goes to infinity.

Q: Congestion is only a critical problem for certain types of switched data networks.

Q: Generally there is only one possible route connecting a source to a destination.

Q: A variety of routing algorithms have been developed for packet- switching, frame relay and ATM networks.

Q: The ________ algorithm can be stated as follows: "Find the shortest paths from a given source node subject to the constraint that the paths contain at most one link, then find the shortest paths with a constraint of paths of at most two links, and so on."

Q: The second generation routing algorithm recomputes its routing table using ________ algorithm when new information arrives.

Q: The original routing algorithm, designed in 1969, was a distributed adaptive algorithm using estimated delay as the performance criterion and a version of the ________ algorithm.

Q: The routing decision is more complex, therefore, the processing burden on network nodes increases with ________ routing.

Q: With ________, a node selects only one outgoing path for retransmission of an incoming packet. The outgoing link is chosen at random, excluding the link on which the packet arrived. If all links are equally likely to be chosen, then a node may simply utilize outgoing links in a round robin fashion.

Q: With ________, a packet is sent by a source node to every one of its neighbors. At each node, an incoming packet is retransmitted on all outgoing links except for the link on which it arrived.

Q: For ________, a single, permanent route is configured for each source-destination pair of nodes in the network. The routes only change when there is a change in the topology of the network.

Q: In a ________ network, each node will remember the routing decision that was made when the virtual circuit was established, and simply pass on the packets without making a new decision.

Q: Each node having the responsibility of selecting an output link for routing packets as they arrive is ________ routing.

Q: The term ________ refers to which node or nodes in the network are responsible for the routing decision.

Q: For internal ________ operation a routing decision is made at the time the virtual circuit is established.

Q: The ________ function seeks to design routes through the network for individual pairs of communicating end nodes so that the network is used efficiently.

Q: A generalization of the minimum-hop criterion is ________ routing.

Q: The primary function of a ________ network is to accept packets from a source station and deliver them to a destination station.

Q: ________ schemes can be categorized based on a number of factors, such as: what criterion is used to determine the best route between two nodes, what strategy is used for obtaining information needed to determine route, and whether a distributed or centralized algorithm is used.

Q: Which of the following is a drawback associated with adaptive routing?A) It may react too quickly, causing congestion producing oscillation, or too slowly, being irrelevant.B) All nodes that are directly or indirectly connected to the source node are visited.C) Because all routes are tried, at least one copy of the packet to arrive at the destination will have used a minimum hop route.D) Queue is an artificial measure of delay.

Q: "Given a network of nodes connected by bidirectional links, where each link has a cost associated with it in each direction, define the cost of apath between two nodes as the sum of the costs of the links traversed. For each pair of nodes, find a path with the lowest cost" is a descriptionof ________.A) least cost routingB) random routingC) fixed routingD) alternate routing

Q: Which of the following is NOT a disadvantage of the first generation routing algorithm?A) It responded slowly to congestion and delay increases and was not very accurate.B) When a node or link fails, it can no longer be used as part of a route.C) Queue length is an artificial measure of delay because some variable amount of processing time elapses between the arrival of a packet at a node and its placement in an outbound queue.D) The algorithm did not consider line speed, merely queue length.

Q: The principle conditions that influence routing decisions are ________. A) complexity and node malfunctions B) failure and congestion C) overhead and bandwidth D) route distance and amount of nodes

Q: With ________, routing decisions that are made change as conditions on the network change.A) fixed routingB) floodingC) adaptive routingD) random routing

Q: "Because all routes are tried, at least one copy of the packet to arrive at the destination will have used a minimum-hop route" is a property of________.A) fixed routingB) floodingC) adaptive routingD) random routing

Q: The disadvantage of fixed routing is ________. A) its lack of flexibility B) its simplicity C) it does not work with virtual circuits D) it does not work with datagrams

Q: With ________ the link costs used in designing routes cannot be based on any dynamic variable such as traffic. A) fixed routing B) random routing C) adaptive routing D) flooding

Q: In the case of ________ the central node typically makes use of information obtained from all nodes. A) NIS-UT B) flooding C) distributed routing D) centralized routing

Q: With ________ the routing decision is made by the source station, rather than by a network node, and is then communicated to the network. This allows the user to dictate a route through the network that meets criteria local to that user. A) source routing B) customer routing C) user routing D) station routing

Q: When the internal operation of the network is ________, a routing decision is made individually for each packet. A) datagram B) robust C) internal virtual circuit D) virtual circuit

Q: ________ is determined by whether the routing decision is made on a packet or virtual circuit basis. A) Place B) Update timing C) Decision time D) VCC

Q: The simplest criterion in the selection of a route is to choose the _______. A) network resources B) maximum hop route C) minimum hop route D) maximum nodes available

Q: If the ________ has to do with the ability of the network to deliver packets via some route in the face of localized failures and overloads. A) Correctness B) Robustness C) Efficiency D) Optimality

Q: The ________ function attempts to find the least cost route through the network. A) ABR B) management C) generic flow control D) routing

Q: ARPANET is a packet switching network that was the foundation of the present day Internet.

Q: In virtually all packet-switching networks some sort of adaptive routing technique is used.

Q: Random routing requires the use of network information.

Q: A property of flooding is all nodes that are directly or indirectly connected to the source node are visited.

Q: Fairness is a requirement for a routing function.

Q: One of the easiest design aspects of switched data networks is routing.

Q: With fixed routing there is no difference between routing for da and virtual circuits.

Q: Due to the large amounts of bandwidth available on modem networks, processing and transmission overhead is a management issue and does not impair network efficiency.

Q: Because the least-cost criterion is more flexible, it is more common than the minimum-hop criterion.

Q: The selection of a route is generally based on some performance criterion.

Q: The designer who seeks robustness does not need to cope with the requirement for stability.

Q: A key design issue in switched networks is routing.

Q: Adaptive routing algorithms typically rely on the exchange of information about traffic conditions among nodes.

Q: The earliest applications of ________ were military, where it was used for its immunity to jamming.

Q: The first type of spread spectrum developed is known as _________ .

Q: The essential idea of the ________ technique is to spread the information signal over a wider bandwidth to make jamming and interception more difficult.

Q: SC-FDMA performs a _______ prior to the IFFT operation, which spreads the data symbols over all the subcarriers carrying information and produces a virtual single-carrier structure.

Q: The signal processing for OFDM involves two functions known as fast Fourier transform and ______________ .

Q: For the IEEE 802.11a LAN standard, the OFDM scheme consists of a set of ______ subcarriers with a base frequency of 0.3125 MHz.

Q: _______ is a multiplexing technique used with spread spectrum.

Q: ________ defines subchannels that can be allocated to subscriber stations depending on their channel conditions and data requirements.

Q: The ________ reverses the FFT operation.

Q: The ________ is an algorithm that converts a set of uniformly spaced data points from the time domain to the frequency domain.

Q: _________, also called multicarrier modulation, uses multiple carrier signals at different frequencies, sending some of the bits on each channel.

Q: There are two applications of MU-MIMO: Uplink--Multiple Access Channel, MAC and __________.

Q: __________ extends the basic MIMO concept to multiple endpoints, each with multiple antennas.

Q: The two types of MIMO transmission schemes are spatial diversity and __________ .

Q: _________ antenna architecture has become a key technology in evolving high-speed wireless networks, including IEEE 802.11 Wi-Fi LANs and WiMAX.