Local area networks Flashcards
what is a network?
computing devices connected with communications channel to share hardware and software resources.
what is a transmission medium?
cables/WiFi point makes transmission possible bounded or unbounded(wireless)
what is LAN?
network capabilities of group of computers near each other to share resources connected to LANs WANs and internet
what are network interface cards
to which network media can connect
what is bounded meia?
cables used as network transmission medium to carry signals between computer and peripherals.
what is bounded medium?
signals confined to medium and don’t leave.
what is bandwidth?
theoretical maximum amount of data travels along cable per unit time.
what is a twisted pair cable?
insulated strands of copper wire twisted around each other.
what do twisted pair cable prevent
electrical interference from adjacent pairs or outside sources.
what is an unshieled twisted pair cable?
several pairs copper cables covered in plastic.
why are UTPs widely used?
easy to install,expand and troubleshoot.
what are UTPs advantages and disadvantages?
cost of cabling is relatively low.
they are easy to install with simpler connections
length can’t be greater than 100 meters.
copper cables have inherent weakness.
what are copper cable weaknesses?
eavesdropping signals can be intercepted by outsiders.
Attenuation signal loses strength over distance
Crosstalk signals from 1 line interfere with signals from another line
Electromagnetic interference signals from nearby sources corrupt signal travelling.
why are fibre optic cables different?
optical fibres carry digital data singals in light pulses which means no electric impulses to steal
what do they consist of
consists of thin glass cylindrical core covered by cladding
what happens when the fibres are made from plastic?
they are easier to install but are unable to carry light pulses for long distances
what is multimode fibre?
larger core used for shorter distances.
what is single mode fibre?
smaller core for longer distances.
what are the advantages and disadvantages?
data trasmitted at high speeds
transmitted over long distance securely
used to connect segments of LAN. more expesnsive than UTP and requites experise to properly install and connect devices.
what does wireless mean?
consists of radio and microwave communication,light,visble and infrared
what is bluetooth?
wireless technology to send data over short distances and it handles data or voice transmissions at same time using little power.
what is near field communication(NFC)
wireless connection between 2 device in close proximity and it is Two-way communication and sends and receives information.
what are Radio waves?
Electromagnetic wave used in communication and data transfer. long wavelengths in Em spectrum and frequency determines distance transmitted.
what are transmission technologies?
point to point and broadcast
what is point-to-point?
directly connects 2 nodes.
what is broadcast
communication channel shred by all devices in network meaning the sender sends signal hear by mutiple parties
what is topology?
physical setup of network as in how devices are connected.
what is start topology
Cable connected to NIC in each computer and other end in port of central device which boost signal coming through using UTP cable.
what is tree topology ?
used as back bone to connect LANs.
what are the advantages and disadvantages of tree topology?
they are Easy to setup and maintain.
a problem with one computer doesn’t affect any other device.
add or removing a node does not upset the network
it is easy to extend if the switch has free ports.
it Requires large amoung of cabling to connect nodes independently switch
switch adds to cost
if the switch fails the whole network fails.
what is bus topology?
the nodes connect off a single cable with a terminator at each end to stop signals boucing out.
what the advantages and disadvantages of bus topology?
Less cable is required which reduces costs.
No switch is needed which reduces costs.
It is easy to extend the network by connection nodes to the cable.
It is difficult to trace faults because all nodes share a common cable.
Fault in main cable shuts down the whole network.
It can get congested because signals from all nodes share a cable.
what is ring topology?
the nodes are connected in a closed loop which means signals travel around in 1 direction past each computer
what is the token ring?
common network using UTp cabling to transmit electrical signals
what is a Fibre Distributed Data Interface?
It uses light instead of electric to transmit over 2 fivre optic cable rings.
what are the advantages and disadvantages of ring topology?
orderly network because every device has opportunity to transmit.
Each node duplictes data signals because there is little signal degradation
Easy to create larger network because signal boosting and fibre optic cable rings.
Malfunctioning workstations creat problem because signals pass each device
Moves,additions and device changes disrupt network
NOdes function as repeater(boost singal) which is expensive
Slower than start topology under load.
what is Hybrid topology?
combination of 2 or more different network topologies.
what are the advantages and disadvantages of Hybrid topology?
They are reliable east arror detecting and trouble shooting
Effective adapted to suti building layouts and equipment. Scalable size can easily be increased
Flexible set up to suit organisation need.
Complex in design
Costly
what is the Ethernet?
it connects nodes in LAN and WAN and enables communication through common protocalit also indicates how devices transmit,format and size data so other devices in same network segment can receive,process and recognise data.
what is INternet prococol address?
numerical lable assigned to devices connected to network
Access internet and ethernet or communicate etween devices on LAN.
What is Media Access control address?
Hardware identification number uniquely identifies devices on network and they are needed to be part of ethrenet LAN
what are Internet protocols
how data transmitted between devices and networks
How errors are controlled and reported on
How data is compressed and how sendin device indicates it finished sending and receiging device communicates received
what is the Address resolutino protocol?
Macc address linked to IP address in ARP table stored in RAM of NIC
what does the ARP table do?
The ARP table stores data from all device and know which device sent
what is Static IP address ?
Static IP addcomputer or device manyally configured to use certain IP address
what is Dynamic IP address?
the IP address changes over time
what is DHCP(DYnamic host configuration Protocol)?
takes manual work out of IP addressing and tracks used addresses to avoid conflict
how does DHCP work ?
It is provided by device at top of network
New device ask DHCP server for address and server assigns unused one
Keep record of varous device addresses.
if device goes offline it reconnects but may not have same IP address as before
what is Domain Name server (DNS)/
IT maintains directory of domain names and translates into IP addresses
what is Transmission control protocol?
INternet communication protocol are the rules computers follow to communicate over internet and it is used by Internet browser to connect and send or receive emails
what is a network interface card(NIC)?
physical interface or connection between computer and network cable.
what does a repeater do?
It connects network segments over long distances which boosts signal strength weakens due to attenuation.
what does a bridge do?
connects network segments to strengthen signal and forward the data packet to different segment if signel MAC address is not sending packet
what does a bridging table do?
keeps track of devices on each segment.
Wireless bridges.
connect segments in different buildings and are cheaper than fibre optic
what are advantages of bridges?
they connect unline network segments and make intelligent decisions about passing signals to next segment
what does a switch do?
connects nodes in start topology with a NIC or UTP cable connected to and switch port.
what is a router?
It is a device that connects different network segments using same protocols.
what are advantages of a router
it boosts signal and uses IP addresses to determine best path to reach destination
what do routing tables do?
they store information about connected networks to determine the quickest least but cost effective route
what is OSI model (open system interconnection)?
refernce model describinb protocol design and communication to get compatibility.
what is network communication?
sending messages between devices.
what is networking software?
strict set of rules governed by different protocols to complete task.
what does 7 layers for transmission entail ?
each has differnt hardware and software to implement specific network functions according to protocal
what is layer 7?
layer 7 is the application layer and sends data to layer 6 and to translate into binary and compress.
what is layer 6 ?
layer 6 is the presentation layer which encrypts data and corresponding layer on friend’s device decrupts
what is layer 5?
layer 5 is the seesoin layer that determines which data packets belong to which files and where to go when download files
what is layer 4?
layer 4 is the transport layer which receives data from layer 4 and breaks data into segments.
describe each segment in layer four?
each segment has source destinatnio port number and sequence number.
what is a port number
segment reaches correct application
what is a sequence number ?Q
correct order they were broken down into segments.
what is the third layer ?
the network layer and it transmits data segments between network in packet form
what is layer 2?
the data link layer it recieves packets and performs physical addressing by adding sender or receiver MAc addresses to packet
what is layer 1?
the physical layer it is hardware you are able to touch and it cnoverts binary into signeals and transmits over local media
what is a packet ?
it is created at layer3 to allow information to be exchanges between different LANs
what is the Header?
it contains instructions about data carried by the packet such as the originating IP address,Destination IP address and packet number.
what is the packet lengthe
fixed- length packets or obtain length from from header.
what does synchronisation do?
few bits help packet match up to network
what is the packet number for ?
which packet in sequence of packets.
what is a protocol?
on networks carry many tupes of information
what information does the destination address hold ?
where packet is going
what is what source address
where the packet came from
what is a payload
body or data of packet as in the actual data packet delivered to the destinatino
why is it called a fixed length packet?
because it is padded with blank information to make it the right size
what is in the trailer or footer?
contains couple of bits to tell receinving device end of packet is reached .
what is a CRC of Cyclic Redundancy Check?
it takes sum of 15 in the payload and stores result as a hexadecimal
what does the router do in the Trailer .
look at destination address in hearder a compare with lookup table to find where to send
what does the network layer do?
allows the router to send or receive data using IP address to identigy temporary address of device
what does the FCS do ?
detects errors in data transmission and than the algorithim determines if delivered data is correct.
what is VLAN or Virtual LAN?
subennetwork groups together collections of devices in LAN.
what does VLAN provide?
overall performance improvement because group devices frequently communicate.
Provides security because there is more control over devices to access each other.
And it is flexible because it is based on logical connections rather than physical
what do VLAN tags do?
allow LAN switches to distinguish between physical and logical groups of LAN ports.
what is VLAN made up of ?
4 byte field inserted between couce MAC addres and ether type field in ethernet frame.
what is wireless LAN or WLAN?
Equivalent of wired LANs without wires They are set up independently or in conunction with existing ones.
what can WLAN provide?
temporary connectoins to existing cabled network and backup to existing network and a degree of portablility.
what are some useful features of WLAN?
it can extend networks beyong cable connectivity limit and can be used easily to connect devices or extend netowrk to mobile devices in home.
what does WAP provide ?
wireless access to wired ethernet, access point pulgs into switch or wired router sends out wireless signals and encables compueters and devices to connect wirelessly and move freely
what are hotspots?
ineternet access over wireless LAN using router or WAP to link to ISP.
what does a wireless bridge do?
link to netowork segment without using cable and provides a data path between 2 segments.
what can a help with
linking 2 buildings separated by public road and logistics of laying cable prevent connection.
what does a Wi-FI router do
allows multiple connections to join same network and provide access to internet
what does a Wi-Fi router function as ?
a switch, internet router and access point.
Explain what a Wireless Mesh network can do?
It enables wireless nodes with access points to each other to share network connection accross large area.
how does WMN allow for communication?
Use common Wi-Di standards to communicate and users connecting using mobile devices.
how does WMN work ?
1 node connected to switch and shares internet conection with others creating a cloud of connectivity.
what are the advantages and disadvantages of WMN?
reduced cable cost because few nodes are wired into the network. Robust meaning if a node fails the network self-heals using another node
Easy to extend increase range by adding more nodes.
However there is an increased workload for nodes and the intitial set up it complacated
compare wifi and ethernet.
wifi has slow data transfer where as ethernet has faster. wifi has signal interference due to environmental factors whereas ethernet delivers consistent speed. WIfi data flow needs to be encrypter where as ethernet does not.wifi latency is higher than ethernet’s. wifi is east to install and deploy whereas ethernet needs infrastructure.
