Computer network fundamental
What is the equation of number of links in mesh topology?
n(n-1)
What is the physical equation of mesh topology?
n(n-1)/2 --> the most one used
guess the term refers to the way in which a network is *laid* out physically
physical topology
In the case of video and audio, timely delivery means delivering data as they are produced, in the same order that they are produced, and without significant delay, what can we called this type of delivery?
real-time transmission
guess the type of topology each device has a dedicated point-to-point connection with only the two devices on either side of it.
ring topology
guess the word means communication at a distance
telecommunication
guess the type of topology: each device has a dedicated point-to-point link only to a central controller, usually *called a hub*. *The devices are not directly linked to one another* .
the star topology
why LANs are designed ?
to allow resources to be shared between *personal computers* or *workstations*
true or false We normally refer to the *first* as a switched WAN and to the *second as a point-to-point WAN*
true
true or false Wide Area Networks (WANs) has long distances, and it provide connectivity over large areas
true
true or false a given LAN will use only one type of transmission medium.
true
true or false about bus topology Ethernet LANs can use a bus topology
true
true or false tap is a connector that either splices into the main cable
true
true or false Local Area Networks (LANs) has short distance, and it Designed to provide local interconnectivity
true
true or false In a multipoint environment, the capacity of the channel is shared.
true because it is multi so it is shared
True or False The capacity of the channel, must be divided between the two directions.
true it may because we can send and receive at the same time so we have to divided it
can we solve problem of if the ring disable? if yes tell the solution
yes, This weakness can be solved by using a *dual ring* or a *switch capable* of closing off the break.
True or False every node in mesh topology must link (n-1) node where n= number of all nodes in mesh
true
Reliability measured in two terms, what are they?
-availability -robustness
There are four basic topologies possible, what are they?
-bus -star -mesh -ring
what are The most common LAN topologies?
-bus -star -ring
what are the two points of Switching?
-circuit-switched network -packed-switched network
Performance is often evaluated by two networking metrics, what are they?
-delay -throughput
advantages of ring topology are:
-easy to install and reconfigure. -Each device is linked to only its immediate neighbors. -To add or delete a device requires changing only two connections. -fault isolation is simplified.
the disadvantages of bus topology are:
-include difficult reconnection and fault isolation difficult to add new devices. -a fault or break in the bus cable stops all transmission
what are the Network Criteria? 3
-performance -reliability -security
The performance of a network depends on a number of factors, but including what?
-the number of users -type of transmission medium -the capabilities of the connected hardware -efficiency of the software
give some examples of transmission medium: 4
-twisted-pair -coaxial cable -fiber-optic cable -radio waves
we have many types of transmission of *Physical topology* , what are they? 3
-unicast -multicast -broadcast
disadvantages of ring topology are:
-unidirectional traffic can be a disadvantage. -In a simple ring, a break in the ring can disable the entire network.
The Effectiveness of data communication depends on what? 4
-Delivery: must deliver data to correct destination -Accuracy: must deliver data accurately -Timeliness: deliver data in a timely manner -Jitter: Variation in the packet arrival time
Security is : Data protection against corruption/loss of data, due to what? 2
-Errors -Malicious users
what are the types of networks? 4 types
-LAN -WAN -Switching -The internet
what are the key element of Protocol? 3 keys
-Syntax -Semantics -Timing
give me an examples of links:
-air -cable -optical fiber or any medium
about reliability In addition to accuracy of delivery, network reliability is measured by 3 points, what are they?
1-by the frequency of failure 2-the time it takes a link to recover from a failure 3-the network's robustness in a catastrophe
the advantages of star topology are: 2
1. star topology is less expensive than a mesh topology --> because the number of links --> so it easy to install and reconfigure. 2. If one link fails, only that link is affected. All other links remain active.(easy fault identification)
what are the disadvantages of mesh topology? 2
1. the amount of cabling and the number of I/O ports required 2. the hardware required to connect each link (I/O ports and cable) can be expensive.
what are the advantages of mesh topology? 4
1.the use of dedicated links guarantees that each connection can carry its own data load. 2.If one link becomes unusable, it does not incapacitate the entire system. 3.privacy or security. When every message travels along a dedicated line, only the intended recipient sees it. 4.point-to-point links make fault identification and fault isolation easy.
guess the type of topology: is *multipoint* . One long cable acts as a *backbone* to link all the devices in a network.
A bus topology
guess the name of connection: about bus topology is a connection running between the device and the main cable
A drop line
guess the word is a set of devices (often referred to as *nodes*) connected by communication *links*
Neatwork
guess the word is the information (data) to be communicated
Message
performance ,depend on what?
Network element
guess the type of connection: multiple recipients of single transmission
Multi-point
what is the another name of Multi-Point?
Multidrop
guess the type of connection: n single transmitter and receiver
Point-To-Point
guess the word It represents an agreement between the communicating devices
Protocol
guess the word is a set of *rules that govern data* communications
Protocol
guess the word is a set of rules that govern data communications
Protocol
guess the word is the device that *receives* the message
Receives
guess the word is the device that sends the data message
Sender
give me an example for full-duplex
Telephone network, why? because we can listen and talk at the same tame
guess the word is the physical path by which a message travels from sender to receiver
Transmission medium
guess the word provides long-distance transmission of -data -image -audio -and video information over large geographic areas that may comprise a country, a continent, or even the whole world.
WANs --> wide area network
The category into which a network falls is determined by ...?
by its size
guess the word are the exchange of data between two devices via some form of transmission medium such as a wire cable.
communication
guess the word refers to information presented in whatever form is agreed upon by the parties creating and using the data
data
the advantage of bus topology is:
ease of installation
True or False (WAN) is usually privately owned and links the devices in a single office, building, or campus.
false *A local area network (LAN)* is usually privately owned and links the devices in a single office, building, or campus.
true or false Delivery mean data delivered later are useless
false *Timeliness* Data delivered later are useless
True or False In half-duplex mode both stations can transmit and receive simultaneouslyIn
false In half-duplex mode both stations can transmit and receive *but not simultaneously*
True or False LAN size is limited to a few meters.
false LAN size is limited to a few kilometers.
True or False Multi-Point connection provides a dedicated link between two devices.
false Point-To-Point connection provides a dedicated link between two devices.
true or false Switching: Connects at most two links together
false Switching: Connects *at least* two links together
True or False The star topology is used in WAN
false The star topology is used in local-area networks (LANs) and this from disadvantages of star topology
true or false Without a protocol, two devices may be connected but & communicating
false Without a protocol, two devices may be connected *but not* communicating
true or false bus uses more cabling than mesh or star topologies
false bus uses *less* cabling than mesh or star topologies
true or false we can call simplex model as duplex
false we can call Full-duplex model as duplex
true or false about performance we often need more delay and less throughput
false we often need more throughput and less delay
Today, it is very rare to see a LAN, a MAN, or a LAN in isolation; they are connected to one another. When two or more networks are connected, they become an ...?
internetwork, or internet.
the disadvantage of star topology is:
is the dependency of the whole topology on one single point, *the hub*
In a switched network, some of these nodes are connected to the end systems , what do we mean by end systems?
like computers or telephones --> *Others are used only for routing*
True or False *Switches* are devices capable of creating temporary connections between two or more devices linked to the switch
true
True or False A *node* can be a -computer -printer or any other device capable of sending and/or receiving data generated by other nodes on the network.
true
True or False In Full-duplex mode both stations can transmit and receive simultaneouslyIn
true
True or False In a mesh topology, every device has a *dedicated* point-to-point link to every other device. (dedicated means that the link carries traffic only between the two devices it connects)
true
True or False In simplex mode, the communication is unidirectional
true
True or False Multi-Point connection is one in which more than two specific devices share a single link.
true
True or False Physical topology is connection of devices
true
True or False about bus topology Nodes are connected to the bus cable by drop lines and taps
true
True or False about performance If we try to send more data to the network, we may increase throughput, but we increase the delay because of traffic congestion in the network
true
True or False about performance these two criteria(throughput & delay) are often contradictory(reverse each other)
true
True or False about point to point The entire capacity of the link *is reserved* for transmission between those two devices.
true
True or False in Half-duplex mode, the entire capacity of the channel can be utilized for each direction
true
True or False in physical topology: Two or more devices connect to a link --> two or more links form a topology.
true
True or False performance : Measured in terms of Delay and Throughput
true
True or False we can know the Failure rate of network components for reliability
true
true or false *Standards* : provide guidelines to manufacturers, vendors, government agencies, and other service providers to ensure the kind of interconnectivity necessary in today's marketplace and in international communications.
true
true or false *The switched WAN* connects the end systems, which usually comprise a router (internetworking connecting device) that connects to another LAN or WAN.
true
true or false A LAN normally covers an area less than 2 mi
true
true or false A protocol defines 1- *what* is communicated 2-*how* it is communicated 3-and *when* it is communicated
true
true or false A signal is passed along the ring in one direction, from device to device, until it reaches its destination.
true
true or false Delivery mean data must be received by only intended device or user.
true
true or false For example about Jitter, let us assume that video packets are sent every 3D ms. If some of the packets arrive with 3D-ms delay and others with 4D-ms delay, an uneven quality in the video is the result.
true
true or false Jitter mean the *uneven delay* in the delivery of audio or video packets
true
true or false LANs are distinguished from other types of networks by their transmission media and topology.
true
true or false Network security issues include implementing policies and procedures for recovery from breaches and data losses
true
true or false Network security issues include protecting data from damage and development,
true
true or false Network security issues include protecting data from unauthorized access
true
true or false Networks of a size in between are normally referred to as metropolitan area networks and span tens of miles.
true
true or false The Internet has affected people through the way they go about their business as well as the way they spend their free time.
true
true or false The full-duplex mode is used when communication in both directions is required *all* the time.
true
true or false The point-to-point WAN: is normally a line leased from a telephone or cable TV provider that connects a home computer or a small LAN to an Internet service provider (lSP)--> This type of WAN is often used to provide Internet access.
true
true or false The receives also it can be a computer, workstation, telephone handset, television
true
true or false The sender it can be a computer, workstation, telephone handset, television
true
true or false WAN can be as *complex* as the *backbones* that connect the Internet or as *simple* as a *dial-up* line that connects a home computer to the Internet.
true