networks Flashcards
factors that affect the performance of networks:
-bandwidth
amount of data that can be sent and received in a given amount of time
measured in bits per sec, bit rate
-no. of users
too many users/ devices on same network can cause network to slow down if insufficient bandwidth for data
-transmission media
-error rate
-latency
how does error rate affect performance of networks
-connection
-signal quality of wireless and copper
-less reliable connections means more errors when data being transferred
-data has to be resent till correct arrival
-signal quality of wireless depends on interference and range of devices
-signal quality of copper cables depends on grade of material which reduces interference
-length of cable
what is the internet
a global connection of interconnected networks
feature of LAN
-LAN
-small geographical are
-all hardware owned by the org that uses it
-found in businesses, schools, unis
-in home: printers, PCs, smart TVs
benefits of LAN
-sharing files is easier
-share hardware (printer)
-internet connection can be shared
-can communicate with other LAN users cheaply and easily
features of WAN
-wide area
-connects LANs that r in diff geo locations
-orgs hire infrastructure from telecom companies, WAN more expensive to set up than LAN
hardware required to connect a LAN
-NETWORK INTERFACE CARD
-NETWORK INTERFACE CARD
-uses a protocol to determine how connection should work
-allow device to connect to wired or wireless network
hardware required to connect a LAN
-Wireless Access Point
(basically describe a wireless network)
-WAP
provides a link between wireless and wired networks
creates a wireless LAN that allows Wi-fi enable devices to connect to a wired network
hardware required to connect a LAN
-SWITCH
- the switch uses the NIC address on a device to route traffic
- router sends data between networks
- router needed to connect a LAN to a WAN
- router uses the IP address on a device to route traffic to other routers
copper and fibre optic cables
- connections between desktop computers and a switch are usually made w/ …………
- …………. are cheap and flexible which makes them easy to install
- longer distance networks and WAN are usually connected w/ ………….
- ………… has a higher bandwidth than ……… and suffers from less interference
- connections between desktop computers and a switch are usually made w/ UNSHIELDED TWISTED PAIR (UTP) COPPER CABLES
- COPPER CABLES are cheap and flexible which makes them easy to install
- longer distance networks and WAN are usually connected w/ FIBRE OPTIC CABLES
- FIBRE OPTIC has a higher bandwidth than COPPER and suffers from less interference
difference betw/ HUB and SWITCH
HUB: broadcasts messages to all devices on the network.
SWITCH: sends the message to the intended recipient only.
advantage and disadvantage of a full mesh network
ADVANTAGE:
- if you break any connection you can still route traffic via another route
DISADVANTAGE:
- lot more cabling and switch hardware required, adds to cost for large networking
-> can instead use partial mesh, lower amount of hardware needed
disadvantages of ethernet
-users location limited by the need for physical cable connections
-relies on lots of cables, connections , hardware = inc. in cost
features of bluetooth:
-ideal for connecting personal devices
-very short range, 10 meters
-very low power consumption compared to wi-fi
ENCRYPTION
-wireless network …… data, so it must be ……. to be secure
-this is done by scrambling the data into ……… using a ‘master key’ created from the SSID of the network and the password
-data is then decrypted by the receiver using ……., so this key is not transmitted
-wireless network BROADCAST data, so it must be ENCRYPTED to be secure
-this is done by scrambling the data into CIPHER TEXT using a ‘master key’ created from the SSID of the network and the password
-data is then decrypted by the receiver using the same MASTER KEY, so this key is not transmitted
MAC addressing is used to route
frames on a LAN
-each MAC address is unique to every network interface card
IP addressing is used to route
packets on a WAN
IPv4 VS IPv6
32 bits
128 bits
STANDARDS are a set of specifications for:
……. and ……..
w/o standards most devices wouldn’t be able to successfully communicate
-hardware
-software
what is a protocol
a set of rules that allows two devices to communicate
what is TCP (transmission control protocol)
provides error free transmission between two routers
what is IP (internet protocol)
routes packets across a WAN
(along with TCP, makes up the TCP/IP protocol stack)
what is HTTP (hypertext transfer protocol)
and HTTPS (hypertext transfer protocol secure)
-a client-server method of requesting and delivering HTML web pages
HTTPS - used when sensitive information needs to be transferred
what is FTP (file transfer protocol)
- used for sending files between a network usually on a WAN
what is POP (post office protocol)
- retrieves emails from a mail server
- removes it from the server and transfers to your device
what is SMTP (simple mail transfer protocol)
- send emails to an email server
what is IMAP (internet message access protocol)
- used by mail clients to manage remote mailboxes and retrieve email from a mail server
what is the function of a switch
-connects devices on a LAN
-receives data in frames from one device and transmits it to the device on the network w/ correct MAC address
what is the function of a router
transmits data between separate networks / across the Internet