ECE 108 FIRST EXAM

interface

(Communication tasks) To communicate, a device must _____ with the transmission system.

enterprise services

(Layers of convergence) At this level, the manager deals with the information network in terms of the services it provides to support applications. The network manager needs design, maintenance, and support services related to the deployment of convergence-based facilities. Also at this level, network managers deal with the enterprise network as a function-providing system.

applications

(Layers of convergence) These are seen by the end users of a business.

exchange management

(communication tasks) Beyond the basic matter of deciding on the nature and timing of signals, there is a variety of requirements for communication between two parties that might be collected under the term _______. If data are to be exchanged in both directions over a period of time, the two parties must cooperate

addressing and routing

(communication tasks) When more than two devices share a transmission facility, a source system must indicate the identity of the intended destination. The transmission system must assure that the destination system, and only that system, receives the data. Further, the transmission system may itself be a network through which various paths may be taken. A specific route through this network must be chosen.

transmission system utilization

(communication tasks) ______ , refers to the need to make efficient use of transmission facilities that are typically shared among a number of communicating devices. Various techniques (referred to as multiplexing) are used to allocate the total capacity of a transmission medium among a number of users.

error detection and correction

(communication tasks) ______ are required in circumstances where errors cannot be tolerated. This is usually the case with data processing systems.

message formatting

(communication tasks) ______ has to do with an agreement between two parties as to the form of the data to be exchanged or transmitted, such as the binary code for characters.

network management

(communication tasks) a data communications facility is a complex system that cannot create or run itself. _____________ capabilities are needed to configure the system, monitor its status, react to failures and overloads, and plan intelligently for future growth.

security

(communication tasks) it is important to provide some measure of ____ in a data communications system. The sender of data may wish to be assured that only the intended receiver actually receives the data. And the receiver of data may wish to be assured that the received data have not been altered in transit and that the data actually come from the purported sender.

signal generation

(communication tasks) once an interface is established, _______ is required for communication. The properties of the signal, such as form and intensity, must be such that the signal is (1) capable of being propagated through the transmission system, and (2) interpretable as data at the receiver.

infrastructure

(layers of convergence) : The network and communications _______ consists of the communication links, LANs, WANs, and Internet connections available to the enterprise.

capacity, reliability, cost

(transmission line) . Much of the technical detail of how information is encoded and transmitted across a line is of no real interest to the business manager. The manager is concerned with whether the particular facility provides the required ______, with acceptable ________, at minimum _____.

pseudoternary

0 = positive or negative level, alternating for successive zeros 1 = no line signal

development of new services traffic growth at a high and steady rate advances in technology

3 different forces that drive architecture and evolution of data communications and networking facilities:

circuit switching packet switching frame relay ATM

4 alternative technologies (WAN):

faster and cheaper more intelligent networks internet, web mobility

4 notable trends (key words)

LAN

A ______ is a communications network that interconnects a variety of devices and provides a means for information exchange among those devices.

digital signal, pulse

A ______ is a sequence of discrete, discontinuous voltage pulses. Each _____ is a signal element

switched

A _______ VCC is an on-demand connection, which requires a call control signaling for setup and tearing down.

softswitch

A _______ is a general-purpose computer running specialized software that turns it into a smart phone switch. It can convert a stream of digitized voice bits into packets. This opens up a number of options for transmission, including the increasingly popular voice over IP (Internet Protocol) approach.

space division

A _______ switch is one in which the signal paths are physically separate from one another (divided in space). Each connection requires the establishment of a physical path through the switch that is dedicated solely to the transfer of signals between the two endpoints.

TSI

A _______ unit operates on a synchronous TDM stream of time slots, or channels, by interchanging pairs of slots to achieve a full-duplex operation.

virtual path connection

A ________ is a bundle of VCCs that have the same endpoints.

router

A ________ is a processor that connects two networks and whose primary function is to relay data from one network to the other on its route from the source to the destination end system

semipermanent

A _________ VCC is one that is of long duration and is set up by configuration or network management action.

nonblocking

A __________ network permits all stations to be connected (in pairs) at once and grants all possible connection requests as long as the called party is free.

HDB3

A coding scheme that is commonly used in Europe and Japan is known as the ____ code. It is the same as bipolar AMI, except that any string of four zeros is replaced by a string with 1 code violation.

network service provider

A company that provides backbone services to an Internet service provider (ISP)

internet service provider

A company that provides other companies or individuals with access to, or presence on, the Internet.

go-back-N ARQ

A form of error control wherein a station may send a series of frames sequentially numbered modulo some maximum value. The number of unacknowledged frames outstanding is determined by window size, using the sliding-window flow control technique.

Lost frame

A frame fails to arrive at the other side. In the case of a network, the network may simply fail to deliver a frame

signal spectrum

A good signal design should concentrate the transmitted power in the middle of the transmission bandwidth

high frequency

A lack of ________ components means that less bandwidth is required for transmission.

Sliding-Window Flow Control

A maintains a list of sequence numbers that it is allowed to send, and B maintains a list of sequence numbers that it is prepared to receive. Each of these lists can be thought of as a window of frames.

indication

A primitive issued by a service provider either to 1. indicate that a procedure has been invoked by the peer service user on the connection and to provide the associated parameters, or 2. notify the service user of a provider-initiated action.

confirm

A primitive issued by a service provider to acknowledge or complete some procedure previously invoked by a request by the service user.

response

A primitive issued by a service user to acknowledge or complete some procedure previously invoked by an indication to that user.

Request

A primitive issued by a service user to invoke some service and to pass the parameters needed to specify fully the requested service.

Damaged frame

A recognizable frame does arrive, but some of the bits are in error (have been altered during transmission).

multiple FSK

A signal that is more bandwidth efficient, but also more susceptible to error, is _____, in which more than two frequencies are used. In this case each signaling element represents more than one bit.

data element

A single binary one or zero (in bits)

point of presence

A site that has a collection of telecommunications equipment, usually refers to ISP or telephone company sites.

stop-and-wait flow control

A source entity transmits a frame. After the destination entity receives the frame, it indicates its willingness to accept another frame by sending back an acknowledgment to the frame just received. The source must wait until it receives the acknowledgment before sending the next frame.

end office

A switching center that directly supports subscribers is known as an _________.

inelastic traffic

A traffic that does not easily adapt, if at all, to changes in delay and throughput across an internet

1000 octets

A typical upper bound on packet length is _________. ). If a source has a longer message to send, the message is broken up into a series of packets.

offset, orthogonal

A variation of QPSK known as ________ or _____ QPSK, is where a delay of one bit time is introduced in the Q stream.

private branch exchange

A well-known application of circuit switching is the ___________, used to interconnect telephones within a building or office.

Open Systems Interconnection (OSI)

ANOTHER well-known architecture aside from TCP/IP is the _____________reference mode

Advanced Research Projects Agency

ARPA

performance, flexibility, efficiency

ATM is a connection-oriented packet-switching technology that was designed to provide the ________ of a circuit-switching network and the __________ and ____________ of a packet-switching network.

5, 48

ATM makes use of fixed-size cells, consisting of a __-octet header and a ___-octet information field.

integration

Advances in technology have led to greatly increased capacity and the concept of ________, allowing equipment and networks to work simultaneously.

fiber optic

Almost all of the long-distance telephone communications trunks within the United States and the highest speed links on the Internet consist of _______ cable. Because of its high capacity and its security characteristics, it is becoming increasingly used within office buildings and local area networks to carry the growing load of business information. The spreading use of this cable is also spurring advancements in communication switching technologies and network management architectures.

differential PSK

An alternative form of two-level PSK is _____. In this scheme, a binary 0 is represented by sending a signal burst of the same phase as the previous signal burst sent. This avoids the requirement for an accurate local oscillator phase at the receiver that is matched with the transmitter. As long as the preceding phase is received correctly, the phase reference is accurate.

nonreturn to zero inverted

An example of differential encoding, where data are represented by changes rather than levels. . The data themselves are encoded as the presence or absence of a signal transition at the beginning of the bit time. 0 = no transition at beginning of interval (one bit time) 1 = transition at beginning of interval

bandwidth

An increase in _____ allows an increase in data rate.

SNR

An increase in _____ decreases bit error rate.

bit error rate

An increase in data rate increases _________.

bipolar with 8 zeros subsititution

B8ZS stands for ________

Sequence number

Because the transport protocol is sending a sequence of segments, it numbers them sequentially so that if they arrive out of order, the destination transport entity may reorder them

Error control

Bit errors introduced by the transmission system should be corrected.

quantizing error/quantizing noise

By quantizing the PAM pulse, the original signal is now only approximated and cannot be recovered exactly. This effect is known as _______ or ________.

WANs

Changes in corporate data traffic patterns are driving the creation of high-speed ____.

voice, data

Circuit switching was designed for ______. Packet switching was designed for _______.

Combined station

Combines the features of primary and secondary. This station may issue both commands and responses.

circuit establishment data transfer circuit disconnect

Communication via circuit switching involves three phases:

Syntax

Concerns the format of the data blocks

Unbalanced configuration

Consists of one primary and one or more secondary stations and supports both full-duplex and half-duplex transmission.

Balanced configuration

Consists of two combined stations and supports both full-duplex and half-duplex transmission.

18 months

Core networking/service provider/WAN doubles every ________ months

Frame sychronization

Data are sent in blocks called frames. The beginning and end of each frame must be recognizable

transmission services

Despite the growth in the capacity and the drop in cost of transmission facilities, __________ remain the most costly component of a communications budget for most businesses. Thus, the manager needs to be aware of techniques that increase the efficiency of the use of these facilities.

Compression

Digitized video, and to a much lesser extent audio, can generate an enormous amount of traffic on a network. A streaming application, which is delivered to many users, magnifies the traffic. Accordingly, standards have been developed for producing significant savings through compression. The most notable standards are JPG for still images and MPG for video.

data frame

Each __________ includes a field that holds the sequence number of that frame plus a field that holds the sequence number used for acknowledgment

service access points (SAPs)

Each application on a computer has an address that is unique within that computer known as ________ or ports that allow the transport layer to support multiple applications at each computer

Addressing

Each layer provides services to entities at the next higher layer. These entities are referenced by means of a port, or service access point (SAP). Thus, a network service access point (NSAP) indicates a transport entity that is a user of the network service.

IP address

Each packet includes a unique numeric address of the destination host. This address is referred to as an ______, because the address is carried in an IP packet.

control unit network interface digital switch

Elements of a circuit-switching node:

24 months

Enterprise/server/LAN doubles every _____ months

signal to noise ratio data rate bandwidth

Factors affecting signal interpretation:

000+-0-+

For B8ZS, iIf an octet of all zeros occurs and the last voltage pulse preceding this octet was positive, then the eight zeros of the octet are encoded as _________.

000-+0+-

For B8ZS,iIf an octet of all zeros occurs and the last voltage pulse preceding this octet was negative, then the eight zeros of the octet are encoded as ________.

square

For a single-stage crossbar matrix, the number of crosspoints grows with the ______ of the number of attached stations. This is costly for a large switch.

zeros

For bipolar AMI, a long string of _____ would still be a problem.

transparent

For circuit-switched networks, once the circuit is established, the network is effectively ______ to the users.

nonblocking, nearly nonblocking

For data applications, there is a requirement for a _________ or "___________" (very low probability of blocking) configuration.

ones

For pseudoternary, a long string of _____ would still be a problem.

0, congestion, service data unit

For the payload type field, a value of __ in the first bit indicates user information. In this case, the second bit indicates whether ____ has been experienced. The third bit, known as the ______ type bit, is a one-bit field that can be used to discriminate two types of ATM SDUs associated with a connection.

Request Indication Response Confirm

Four types of primitives are used in standards to define the interaction between adjacent layers in the architecture.

high density bipolar 3 zeros

HDB3 stands for ______

synchronous

HDLC uses ________ transmission. All transmissions are in the form of frames, and a single frame format suffices for all types of data and control exchanges

Multimedia

Human-computer interaction involving text, graphics, voice, and video. Multimedia also refers to storage devices that are used to store multimedia content.

802

IEEE ____ is a standard that specifies the access to a LAN

IP datagram

IP appends a header of control information to each segment to form an __________________________.

32

IPv4 uses a ____-bit address to specify a source or destination

128

IPv6 includes ___-bit source and destination address fields

unipolar

If the signal elements all have the same algebraic sign, that is, all positive or negative, then the signal is _______.

0

If the value of the cell loss priority (CLP) bit is __, it indicates that a cell of relatively higher priority, which should not be discarded unless no other alternative is available.

1

If the value of the cell loss priority (CLP) bit is __, it indicates that this cell is subject to discard within the network.

piggybacking

If two stations exchange data, each needs to maintain two windows, one for transmit and one for receive, and each side needs to send the data and acknowledgments to the other. To provide efficient support for this requirement, a feature known as __________________ is typically provided

control signaling

In ATM, a mechanism is needed for the establishment and release of VPCs and VCCs. The exchange of information involved in this process is referred to as ____________ and takes place on separate connections from those that are being managed.

PSK

In ____, the phase of the carrier signal is shifted to represent data.

ASK

In ____, the two binary values are represented by two different amplitudes of the carrier frequency. It is susceptible to sudden gain changes and is a rather inefficient modulation technique. On voice-grade lines, it is typically used only up to 1200 bps. This technique is also used to transmit digital data over optical fiber.

polar

In ______ signaling, one logic state is represented by a positive voltage level, and the other by a negative voltage level.

packet switching

In a _____ network, it is not necessary to dedicate transmission capacity along a path through the network. Rather, data are sent out in a sequence of small chunks, called packets. These networks are commonly used for terminal-to-computer and computer-to-computer communications.

circuit switching

In a _______ network, a dedicated communications path is established between two stations through the nodes of the network. That path is a connected sequence of physical links between nodes. On each link, a logical channel is dedicated to the connection. Data generated by the source station are transmitted along the dedicated path as rapidly as possible. At each node, incoming data are routed or switched to the appropriate outgoing channel without delay.

datagram

In a _________ network, the packets, each with the same destination address, do not all follow the same route, and they may arrive out of sequence at the exit point.

protocol architecture

In a _____________, the modules are arranged in a vertical stack performs a related subset of the functions required to communicate with another system

switched communication network

In a _________________ , data entering the network from a station are routed to the destination by being switched from node to node.

User Datagram Protocol (UDP)

In addition to TCP, there is one other transport-level protocol that is in common use as part of the TCP/IP protocol suite: the ___________.

Service definition

In addition to the protocol or protocols that operate at a given layer, standards are needed for the services that each layer provides tothe next higher layer. Typically, the definition of services is equivalent to a functional description that defines what services are provided, but not how the services are to be provided.

clocking

In differential manchester, , the midbit transition is used only to provide ________.

clocking, data

In manchester encoding, the midbit transition serves as a ______ mechanism and also as ______

media gateway, media gateway controller

In softswitch terminology, the physical-switching function is performed by a _______ and the call processing logic resides in a ________ .

manchester

In the ________ code, there is a transition at the middle of each bit period. 0 = transition from high to low in middle of interval 1 = transition from low to high in middle of interval

virtual circuit

In the __________ approach, a preplanned route is established before any packets are sent. Once the route is established, all the packets between a pair of communicating parties follow this same route through the network. In this approach, no routing decisions are required for each node.

datagram

In the ____________ approach, each packet is treated independently, with no reference to packets that have gone before.

1. Each computer on the network has a unique network address. 2. Each application on a computer has an address that is unique within that computer;

In the three-layer model, two levels of addressing are needed. 1. 2.

Semantics

Includes control information for coordination and error handling

Timing

Includes speed matching and sequencing

Source computer address

Indicates the source of this packet

quadrature PSK

Instead of a phase shift of 180°, as allowed in BPSK, a common encoding technique known as _____ uses phase shifts separated by multiples of π /2 (90°).

Control and data on same link

It is usually not desirable to have a physically separate communications path for control information. Accordingly, the receiver must be able to distinguish control information from the data being transmitted.

the same

It is usually the case that the LAN is owned by ________ organization that owns the attached devices.

ARPANET

It was the first operational packet-switching network.

switched, wireless

LANs come in a number of different configurations. The most common are ______ LANs and_______ LANs.

dc

Lack of a ______component is also desirable. With this component to the signal, there must be direct physical attachment of transmission components. Without this component, ac coupling via transformer is possible; this provides excellent electrical isolation, reducing interference.

Receive Not Ready (RNR)

Most data link control protocols also allow a station to cut off the flow of frames from the other side by sending a _________________message, which acknowledges former frames but forbids transfer of future frames.

clocking

Need to synchronize transmitter and receiver either with an external clock or sync mechanism.

synchronization

Not only must the signals be generated to conform to the requirements of the transmission system and receiver, but also there must be some form of ______ between transmitter and receiver. The receiver must be able to determine when a signal begins to arrive and when it ends. It must also know the duration of each signal element.

Addressing

On a shared link, such as a local area network (LAN), the identity of the two stations involved in a transmission must be specified

direct connection

One of the key strengths of circuit switching is that it is transparent. Once a circuit is established, it appears as a ________ to the two attached stations; no special networking logic is needed at the station.

network access point

One of several major Internet interconnection points that serve to tie all the ISPs together.

Secondary station

Operates under the control of the primary station. Frames issued by this station are called responses. The primary maintains a separate logical link with each secondary station on the line.

Streaming media

Refers to multimedia files, such as video clips and audio, that begin playing immediately or within seconds after it is received by a computer from the Internet or Web. Thus, the media content is consumed as it is delivered from the server rather than waiting until an entire file is downloaded.

Media

Refers to the form of information and includes text, still images, audio, and video.

error detection

Responsibility of a layer of logic above the signaling level that is known as data link control.

Primary station

Responsible for controlling the operation of the link. Frames issued by this station are called commands.

transmission control protocol/internet protocol

TCP/IP

timing of bits signal levels

Tasks involved in interpreting digital signal at the receiver:

customer premises equipment

Telecommunications equipment that is located on the customer's premises. It is physically attached to the "local loop" or "last mile".

stations

The devices attached to the network may be referred to as _______. These may be computers, terminals, telephones, or other communicating devices.

telephone

The most common example of circuit switching is the ______ network.

X.25

The standard used for traditional packet-switching networks is __________

48, 1

The term SDU refers to the __-octet payload of the cell. A value of __ in the first bit of the Payload Type field indicates that this cell carries network management or maintenance information.

Quality of service (QoS)

The Internet and its underlying local area and wide area networks must include a ____ capability to provide differing levels of service to different types of application traffic.

generic flow control

The _____ field does not appear in the cell header internal to the network, but only at the user-network interface. Hence, it can be used for control of cell flow only at the local user-network interface. The field could be used to assist the customer in controlling the flow of traffic for different qualities of service. In any case, this mechanism is used to alleviate short-term overload conditions in the network.

payload type

The _____ field indicates the type of information in the information field.

overhead

The ______ includes additional bits added to each packet to introduce redundancy and additional processing at the end stations and the intermediate switching nodes to detect and recover from errors.

modulation rate

The ______ is the rate at which the signal level is changed, which will depend on the nature of the digital encoding. This is expressed in baud.

duration, length of a bit

The ______ or ______ is the amount of time it takes for the transmitter to emit the bit.

Internet, 1969

The _______ evolved from the ARPANET, which was developed in _______ by the Advanced Research Projects Agency (ARPA) of the U.S. Department of Defense.

data switch

The _______ is similar to the PBX but is designed to interconnect digital data processing devices, such as terminals and computers.

data rate

The _______ of a signal is the rate, in bits per second, that data are transmitted.

virtual path identifier

The _________ constitutes a routing field for the network.

cell loss priority

The __________ bit is used to provide guidance to the network in the event of congestion.

control unit

The __________ establishes, maintains, and tears down the connection.

network interface

The ___________ element represents the functions and hardware needed to connect digital devices, such as data processing devices and digital telephones, to the network.

virtual channel identifier

The ___________ is used for routing to and from the end user.

Internet, web, associated applications

The ____________ ,the ______ and ___________ have emerged as dominant features for both business and personal network landscapes. "Everything over IP"; intranets and extranets are being used to isolate proprietary information

header error control

The ____________ field is an 8-bit error code that can be used to correct single-bit errors in the header and to detect double-bit errors

host-to-host layer, or transport layer

The ____________ or _________, may provide reliable end-to-end service, as discussed in Section 2.2, or merely an end-to-end delivery service without reliability mechanisms

peer layers

The _____________ communicate by means of formatted blocks of data that obey a protocol

physical layer

The _____________ covers the physical interface between a data transmission device (e.g., workstation, computer) and a transmission medium or network

network access layer

The _________________ is concerned with the exchange of data between a computer and the network to which it is attached

Internet Protocol (IP)

The __________________ is used at this layer to provide the routing function across multiple networks.

propagation time

The ___________________ is the time it takes for a bit to traverse the link between source and destination.

File Transfer Protocol (FTP)

The ___________________ is used to send files from one system to another under user command.

Simple Mail Transfer Protocol (SMTP)

The ______________________ provides a basic electronic mail transport facility. It provides a mechanism for transferring messages among separate hosts.

Transmission Control Protocol (TCP)

The ______________________is the most commonly used protocol to provide this functionality

encapsulation

The addition of control information to data is referred to as ____________________

transmission line

The basic building block of any enterprise network infrastructure is the ________.

time slot interchange

The basic building block of many time-division switches is the ___________ mechanism.

metallic crosspoint, semiconductor gate

The basic building block of the space division switch is a __________ or________that can be enabled and disabled by a control unit.

trunks

The branches between exchanges.

communications network

The collection of nodes is referred to as a ___________ .

protocol data unit (PDU)

The combination of data from the next higher layer and control information is known as a _______________

frames

The data are sent in a sequence of ____, each of which contains a portion of the data and some control information

Error detection

The destination detects frames that are in error and discards those frames.

Negative acknowledgment, retransmits

The destination returns a ____________ to frames in which an error is detected. The source _________ such frames.

positive acknowledgment

The destination returns a _____________________ to successfully received, error-free frames.

codec

The device used for converting analog data into digital form for transmission, and subsequently recovering the original analog data from the digital, is known as a _____.

subscribers

The devices that attach to the network.

automatic repeat request (ARQ)

The effect of __________ is to turn a potentially unreliable data link into a reliable one

physical link packet

The external network interface defines three layers:

header

The flag, address, and control fields that precede the information field are known as a __________

go-back-N ARQ

The form of error control based on sliding-window flow control that is most commonly used is called ___________________.

trailer

The frame check sequence and flag fields following the data field are referred to as a _________.

data

The fundamental purpose of a communications system is the exchange of ____ between two parties.

Damaged frame Damaged RR Damaged REJ

The go-back-N technique takes into account the following contingencies:

digital switch

The heart of a modern system is a _________. Its function is to provide a transparent signal path between any pair of attached devices

wireless

The increasing use of ______ transmission, is a result of the trend toward universal personal telecommunications and universal access to communications. The first concept refers to the ability of a person to a single account to use any communication system anytime-anywhere, ideally globally. The second refers to the ability to use one's preferred computing device in a wide variety of environments to connect to information services (e.g., to have a laptop, smart phone, or tablet that will work equally well in the office, on the street, and on an airplane, bus, or train).

Link management

The initiation, maintenance, and termination of a sustained data exchange require a fair amount of coordination and cooperation among stations. Procedures for the management of this exchange are required.

greater

The internal data rates of LANs are typically much ______ than those of WANs.

Syntax, semantics, timing

The key features of a protocol are

subscriber line

The link between the subscriber and the network, also referred to as the subscriber loop or local loop.

dc component, synchronization capability

The main limitations of NRZ signals are the presence of a ________ and the lack of _______.

binary FSK

The most common form of FSK is _____, in which the two binary values are represented by two different frequencies near the carrier frequency. It is typically used up to 1200 bps. It is also commonly used for high-frequency (3 to 30 MHz) radio transmission. It can also be used at even higher frequencies on local area networks that use coaxial cable.

ethernet

The most common switched LAN is a switched _______ LAN, which may consist of a single switch with a number of attached devices, or a number of interconnected switches.

Wi-Fi

The most common type of wireless LANs are ______ LANs.

nonreturn to zero level

The most common, and easiest, way to transmit digital signals is to use two different voltage levels for the two binary digits. 0 = high level 1 = low level

digital data, analog signal

The most familiar use of the transformation _______ to _______ is for transmitting digital data through the public telephone network.

Facilities requests

The network access protocol might want the network to make use of certain facilities, such as priority.

Destination computer address

The network must know to which computer on the network the data are to be delivered.

central office

The place where telephone companies terminate customer lines and locate switching equipment to interconnect those lines with other networks.

hosts

The purpose of the Internet, of course, is to interconnect end systems, called ______; these include PCs, workstations, servers, mainframes, and so on.

small

The scope of the LAN is ______, typically a single building or a cluster of buildings.

Flow control

The sending station must not send frames at a rate faster than the receiving station can absorb them

primitives; parameters

The services between adjacent layers in a protocol architecture are expressed in terms of ________ and ________________

stop-and-wait flow control

The simplest form of flow control, known as ____________________

binary PSK

The simplest scheme uses two phases to represent the two binary digits and is known as _____.

latency

The size of TSI, in terms of the number of connections, is limited by the amount of _______ that can be tolerated. The greater the number of channels, the greater the average delay that each channel experiences. To overcome this problem, multiple TSI units are utilized.

exchanges

The switching centers in the network.

mark, space

The terms ____ and ______, for historical reasons, refer to the binary digits 1 and 0, respectively.

propagation delay

The time it takes a signal to propagate from one node to the next. This time is generally negligible.

node delay

The time it takes for a node to perform the necessary processing as it switches data.

transmission time

The time it takes for a station to emit all of the bits of a frame onto the medium is the ________________

transmission time

The time it takes for a transmitter to send out a block of data.

multiplexing, compression

The two major approaches to greater efficiency in the use of transmission services are ________ and ________.

8, 12

The virtual path identifier (VPI) is ___ bits at the user-network interface and ___ bits at the network-network interface.

switching nodes

The_________ are not concerned with the content of the data; rather, their purpose is to provide a switching facility that will move the data from node to node until they reach their destination.

Power workgroups

These groups typically consist of a small number of cooperating users who need to draw massive data files across the network. Examples are a software development group that runs tests on a new software version, or a computer-aided design (CAD) company that regularly runs simulations of new designs.

Communications/networking

This broad category refers to the transmission and networking technologies (e.g., SONET, ATM) that can support high volume multimedia traffic.

Source port

This indicates the application that sent the data.

The network access/data link layer

This layer is concerned with access to and routing data across a network for two end systems attached to the same network.

HDLC

This protocol is important for two reasons: First, it is a widely used standardized data link control protocol. Second, __________ serves as a baseline from which virtually all other important data link control protocols are derived.

Stop-and-wait ARQ Go-back-N ARQ Selective-reject ARQ

Three versions of ARQ have been standardized:

data link control or data link control protocol

To achieve the necessary control, a layer of logic is added above the physical layer, this logic is referred to as ___________________

time multiplexed switching

To connect a channel on one TDM stream (going into one TSI) to a channel on another TDM stream (going into another TSI), some form of space division switching is needed. Naturally, we do not wish to switch all of the time slots from one TDM stream to another; we would like to do it one slot at a time. This technique is known as _____________ .

multiple-stage

To overcome the limitations of a single-stage crossbar matrix, ________ switches are employed.

Primary station Secondary station Combined station

To satisfy a variety of applications, HDLC defines three types of stations, two link configurations, and three data transfer modes of operation. The three station types are:

network, intelligent

Today's _______ are more "______________", offering differing levels of quality of service (QoS) and variety of customizable services in the areas of network management and security.

segments

Transport PDUs are typically called _______________

faster and cheaper

Trend towards _________________, in both computing and communication.

Protocol specification

Two entities at the same layer in different systems cooperate and interact by means of a protocol. Because two different open systems are involved, the protocol must be specified precisely. This includes the format of the protocol data units exchanged, the semantics of all fields, and the allowable sequence of PDUs.

fiber optic, wireless

Two mediums currently driving the evolution of data communications transmission are _____ transmission and _______ transmission.

datagram, virtual circuit

Two packet switching techniques:

PCM DM

Two principal techniques used in codecs:

insert additional bits that force transitions, scrambling

Two techniques used to address the problem with a long string of 0s in the case of AMI or 1s in the case of pseudoternary. _____ is used by ISDN for low data rate transmission, while ______ is used at high data rates.

Asynchronous balanced mode (ABM)

Used with a balanced configuration. Either combined station may initiate transmission without receiving permission from the other combined station.

Normal response mode (NRM)

Used with an unbalanced configuration. The primary may initiate data transfer to a secondary, but a secondary may only transmit data in response to a command from the primary.

Asynchronous response mode (ARM)

Used with an unbalanced configuration. The secondary may initiate transmission without explicit permission of the primary. The primary still retains responsibility for the line, including initialization, error recovery, and logical disconnection.

bipolar AMI

Uses more than 2 signal levels. 0 = no line signal 1 = positive or negative level, alternating for successive ones

customer

VPC establishment/release may be ______ controlled. In this case, the customer uses a signaling VCC to request the VPC from the network.

network

VPC establishment/release may be ________ controlled. In this case, the network establishes a VPC for its own convenience. The path may be network- to-network, user-to-network, or user-to-user.

nodes

We refer to the switching devices whose purpose is to provide communication as ____. These are connected to one another in some topology by transmission links.

data link

When a data link control protocol is used, the transmission medium between systems is referred to as a ___________

blocking

When a network is supporting only voice traffic, a ________ configuration is generally acceptable, because it is expected that most phone calls are of short duration and that therefore only a fraction of the telephones will be engaged at any time.

Destination port

When the destination transport layer receives the segment, it must know to which application the data are to be delivered.

RR = receive ready, or piggybacked acknowledgment

While no errors occur, the destination will acknowledge incoming frames as usual (name the acknowledgement)

REJ

With Go-Back-N ARQ, if the destination station detects an error in a frame, it may send a negative acknowledgment. What is this negative acknowledgement?

delta modulation

With ________, an analog input is approximated by a staircase function that moves up or down by one quantization level at each sampling interval.

selective reject ARQ

With ______________, the only frames retransmitted are those that receive a negative acknowledgment, in this case called SREJ, or those that time out

bit stuffing; data transparency

With the use of _____________, arbitrary bit patterns can be inserted into the data field of the frame. This property is known as _________________

virtual channel connection

_____ are logical connections in ATM and it is also the basic unit of switching in an ATM network. It is analogous to a virtual circuit.

audio

_____ generally encompasses two different ranges of sound. Voice, or speech, refers to sounds that are produced by the human speech mechanism.

LANs, MIS

_____ have been recognized by ____ as a viable and essential computing platform.

recovery

_____ techniques are needed in situations in which an information exchange, such as a database transaction or file transfer, is interrupted due to a fault somewhere in the system. The objective is either to be able to resume activity at the point of interruption or at least to restore the state of the systems involved to the condition prior to the beginning of the exchange.

mobility

______ has the potential to unleash higher performance at all business levels: personal, workgroup, and enterprise-wide. This provides compelling rationale for further business investment in wireless technologies.

quadrature amplitude modulation

______ is a popular analog signaling technique that is used in the asymmetric digital subscriber line (ADSL) and in cable modems. This modulation technique is a combination of ASK and PSK.

flow control

______ is required to assure that the source does not overwhelm the destination by sending data faster than they can be processed and absorbed.

ABM

______ is the most widely used of the three modes; it makes more efficient use of a full-duplex point-to-point link because there is no polling overhead

NRM

______ is used on multidrop lines, in which a number of terminals are connected to a host computer.

video

______ service carries sequences of pictures in time

frame relay

______ was developed to take advantage of these high data rates and low error rates. Whereas the original packet-switching networks were designed with a data rate to the end user of about 64 kbps, these networks are designed to operate efficiently at user data rates of up to 2 Mbps. The key to achieving these high data rates is to strip out most of the overhead involved with error control.

node-station, node-node

______-_______ links are generally dedicated point-to-point links. ______-______ links are usually multiplexed, using either frequency-division multiplexing (FDM) or time-division multiplexing (TDM).

compression

_______ involves squeezing the data down so that a lower-capacity, cheaper transmission facility can be used to meet a given demand.

companding

_______ is a process that compresses the intensity range of a signal by imparting more gain to weak signals than to strong signals on input. At output, the reverse operation is performed.

digitization

_______ is the process of converting analog data into digital data.

multiplexing

_______ refers to the ability of a number of devices to share a transmission facility. If each device needs the facility only a fraction of the time, then a sharing arrangement allows the cost of the facility to be spread over many users.

convergence

_______ refers to the merger of previously distinct telephony and information technologies and markets.

image

_______ service supports the communication of individual pictures, charts, or drawings.

WANs

________ generally cover a large geographical area. They often require the crossing of public right-of-ways, and typically rely at least in part on circuits provided by one or more common carriers —companies that offer communication services to the general public. Typically, this consists of a number of interconnected switching nodes.

scrambling

________ is used to replace sequences that would produce constant voltage.

checksum

________ is when the sending TCP includes a code that is a function of the contents of the remainder of the segment. The receiving TCP performs the same calculation and compares the result with the incoming code. A discrepancy results if there has been some error in transmission.

blocking

________ occurs when the network is unable to connect two stations because all possible paths between them are already in use.

Semipermanent

_________ VCCs may be used for user-to-user exchange. In this case, no control signaling is required.

TCP/IP

_________ is an Internet-based protocol suite and is the framework for developing a complete range of computer communications standards

mobility

_________ is newest frontier for ICT managers, and popular consumer devices such as the iPhone, Droid and iPad have become drivers of the evolution of business networks and their use.

external virtual circuit

_________ refers to the logical connection between two stations through the network.

Datagram

_________ sockets make use of UDP, which does not provide the connection-oriented features of TCP

time division

_________ switching involves the partitioning of a lower-speed bit stream into pieces that share a higher-speed stream with other bit streams. The individual pieces, or slots, are manipulated by control logic to route data from input to output.

Stream sockets

__________ make use of TCP, which provides a connection-oriented reliable data transfer.

wireless networks

__________ provide advantages in the areas of mobility and ease of installation and configuration.

datagram packet

__________ switching does not require a call setup. Thus, for short messages, it will be faster than virtual circuit packet switching and perhaps circuit switching.

ATM, cell relay

__________, sometimes referred to as ________, is a culmination of developments in circuit switching and packet switching. It can be viewed as an evolution of frame relay and circuit switching. It is designed to work in the range of 10s and 100s of Mbps, and in the Gbps range. It can offer a constant-data-rate channel even though it is using a packet-switching technique. Thus, it extends circuit switching to allow multiple channels with the data rate on each channel dynamically set on demand.

multiprotocol label switching (MPLS)

___________ has reduced the role for ATM. It is a layer-2 connection-oriented packet-switching protocol that, as the name suggests, can provide a switching service for a variety of protocols and applications, including IP, voice, and video.

TCP/IP

___________ is a result of protocol research and development conducted on the experimental packet-switched network, ARPANET, funded by the Defense Advanced Research Projects Agency (DARPA)

Raw sockets

____________ allow direct access to lower-layer protocols, such as IP.

Secure Shell (SSH)

____________ provides a secure remote logon capability, which enables a user at a terminal or personal computer to log on to a remote computer and function as if directly connected to that computer

Error control

____________ refers to mechanisms to detect and correct errors that occur in the transmission of frames.

Information (I-frames)

_____________ frames _____________carry the data to be transmitted for the user (the logic above HDLC that is using HDLC).

asynchronous transfer mode

_____________ is a switching and multiplexing technology that employs small, fixed-length packets called cells. A fixed-size packet was chosen to ensure that the switching and multiplexing function could be carried out efficiently, with little delay variation.

meta-signaling

______________ channel is a permanent channel, probably of low data rate, that can be used to set up VCCs that can be used for call control. It can also be used to set up a user-to-network or user-to-user signaling virtual channel.

Supervisory frames (S-frames)

______________ provide the ARQ mechanism when piggybacking is not used.

Stop-and-wait ARQ

_________________ is based on the stop-and-wait flow control technique outlined previously. The source station transmits a single frame and then must await an acknowledgment (ACK). No other data frames can be sent until the destination station's reply arrives at the source station.

Retransmission after timeout

____________________ is when the source retransmits a frame that has not been acknowledged after a predetermined amount of time.

differential manchester

_____________________ has the added advantage of employing differential encoding. always a transition in middle of interval 0 = transition at beginning of interval 1 = no transition at beginning of interval

Unnumbered frames (U-frames)

_______________provide supplemental link control functions.

Flow control

a technique for assuring that a transmitting entity does not overwhelm a receiving entity with data.

B= R (d/V)

bit length of a link formula

internet layer

cases where two devices are attached to different networks, procedures are needed to allow data to traverse multiple interconnected networks

subnetworks

constituent networks are usually referred to as _____________

applications enterprise services infrastructure

convergence in terms of a three-layer model of enterprise communications:

applications, computers, networks

distributed data communications can be said to involve three agents:

signal spectrum clocking error detection signal interference and noise immunity cost and complexity

encoding schemes (5):

cells

fixed-length packets

TCP/IP protocol suite

foundation of the internet

acknowledgment frame

if a station has data to send and an acknowledgment to send, it sends both together in one frame, saving communication capacity. Of course, if a station has an acknowledgment but no data to send, it sends a separate __________________________, such as RR or RNR

text

information that can be entered via a keyboard and is directly readable and printable

network access layer, transport layer, application layer

it appears natural to organize the communication task into three relatively independent layers:

transport

it makes sense to collect those mechanisms (for providing reliability ) in a common layer shared by all applications; this is referred to as the _________ layer

server farms

multiple centralized servers

Physical layer Network access/data link layer Internet layer Host-to-host, or transport layer Application layer

name the 5 TCP/IP Layers

B8ZS

same as bipolar AMI, except that any string of eight zeros is replaced by a string with 2 code violations. It is commonly used in North America and it is based on a bipolar AMI.

protocol

set of rules or conventions

baud

signal elements per second

application layer

the _____________ contains the logic needed to support the various user applications.

application

the ______________ layer contains the logic needed to support the various user applications

network access protocol (NAP)

the _________________________ appends a network access header to the data it receives from the transport layer, creating a network access PDU, typically called a packet.

20

the header format for TCP, has a minimum of ____ octets

high level data link control (HDLC)

the most important example of a data link control protocol

Error detection code

the sending transport entity may include a code that is a function of the contents of the segment. The receiving transport protocol performs the same calculation and compares the result with the incoming code. A discrepancy results if there has been some error in transmission. In that case, the receiver can discard the segment and take corrective action

transport header

the transport layer appends a _______________, containing protocol control information

ASK FSK PSK

three basic encoding or modulation techniques for transforming digital data into analog signals:

frames

variable-length packets