CS IB 3 Networks
Terms in this set (80)
two or more devices that are connected to share data and resources
local area network (LAN)
a network within a limited geographical area such as a building or small campus, usually limited to one group or organisation using its own infrastructure
virtual local area network (VLAN)
a logical group of workstations, servers and network devices that appear to be on the same LAN despite their geographical distribution. Ports share broadcast traffic and belong to the same broadcast domain. Broadcast traffic in one is not transmitted outside. This segmentation improves the overall performance of the network.
wide area network (WAN)
a network that covers a large area, often consisting of interconnected LAN's The largest one of these is the Internet, but there are many more that are not publicly accessible such as a multinational company that use one of these to connect various world wide offices
storage area network (SAN)
a high-speed network of storage devices that can be accessed by the applications running on networked servers, but not directly by the users
wireless local area network (WLAN)
"wireless network communication over short distances using radio or infrared signals instead of traditional network cabling
a computer network that uses Internet Protocol technology to share information, operational systems, or computing services within an organization.
a computer network that uses Internet Protocol technology to share information, operational systems, or computing services within an organization and to allow controlled access from outside, for specific business or educational purposes. This could be accessing a subset of the company's webpages or a subset of documents.
a global system of interconnected computer networks that use the standard protocols to create a network of networks. It is the infrastructure that other services run on.
virtual private network (VPN)
two types are remote access and site to site. Both used to establish secure connections with a remote computer network over public infrastructure, such as the Internet. An encrypted tunnel is created with either the single computer or network access server encrypting communication that is then sent, and decrypted by network access server.
hardware and software needed for VPN
network access server to encrypt/decrypt transmissions using encryption software and a pre-shared key to create the tunnel, a firewall to protect the network, and an AAA server for authentication, authorization and accounting. If being accessed by a remoter computer rather than network, the computer will need remote access client software and a pre-shared key
personal area network (PAN)
"a network that generally cover a range of less than 10 meters, using USB or FireWire technologies if wired, or Bluetooth or infrared connections if wireless. Used to transfer files including email and calendar appointments, digital photos and music.
peer-to-peer network (P2P)
a type of decentralized and distributed network architecture, often small, in which individual computers in the network act as both suppliers and consumers of resources, eg one machine takes care of Internet access, another file storage and different one printing for all of the computers on the network
Technical rules and conventions that enable compatibility and therefore facilitate communication or interoperability between different IT systems and their components. They might govern the design and use of hardware, software and the format of data.
an abstract model that describes how network communication works. It has a set of seven layers that define the different stages that data must go through to travel from one device to another over a network. Each layer has a different responsibility and different protocols working at that level
protocol is a set of agreed signals, codes and rules for data exchange between systems
a group of protocols that all work together to allow software or hardware to perform a function such as TCP/IP
exchange of signals between two device to set up communication, including agreeing transfer rate, coding alphabet, parity, interrupt procedure, and other protocol or hardware features
moving data in separate, small blocks called packets -- based on the destination address in each packet. Each packet may go a different route; its header address tells it where to go and describes the sequence for reassembly at the destination computer.
a connection is made between the two end devices, possibly through several intermediary switches. The connection lasts for as long as the data transfer, and no other devices can use the connection while the data transfer is happening.
physical, data link, network, transport, session, presentation, application
this OSI layer performs functions for the applications used by the user e.g. http
this OSI layer translates (including formatting, compression and encryption) data from programs and protocols in the application layer above it to formats that can be transmitted over networks and used by other applications on other hosts and also in the reverse direction when receiving packets. E.g.Multipurpose Internet Mail Extensions (MIME)
this OSI layer controls the connections between two computers by establishing, managing and terminatint the connections between the local and remote applications. It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures e.g. SSH
this OSI layer creates packets out of the message received from the application layer by dividing the long message into smaller messages. It controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. e.g. TCP
this OSI layer handles routing of packets across a network e.g. IPv4 or IPv6
this OSI layer deals with managing transmission. It detects and possibly corrects errors that may occur in the physical layer. It defines the protocol to establish and terminate a connection between two physically connected devices. It also defines the protocol for flow control between them. e.g. Ethernet
this OSI layer transmits 0s and 1s across the network between devices e.g. DSL
where two LANs have a private, direct connection
transfer control protocol/internet protocol (TCP/IP)
protocols that specify how data should be packetized, addressed, transmitted, routed, and received between devices on the Internet
dynamic host control protocol (DHCP)
a server that dynamically assigns an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks.
the process by which a readable message or transmission is converted to an unreadable form to prevent unauthorized parties from reading it. It uses a protocol to determine the computations to perform on the data using a key.
the result of placing each entire packet in an encrypted form within another packet before sending to add a layer of security that protects each packet on its journey over the Internet. The outer packet protects the contents from public view and ensures that the packet moves within a virtual tunnel.
two different, unrelated keys are used to encrypt and decrypt the transmission
the same key is used to encrypt and decrypt transmissions (or more precisely, where a decryption key can be easily derived from the encryption key)
a unit of data for transmission over a network that contains control information and user data, which is also known as the payload. Control information provides data for delivering the payload, for example: source and destination network addresses, error detection codes, and sequencing information.
the part of an IP packet that precedes its body and contains addressing and other data that is required for it to reach its intended destination.
protocols should ensure that the data that is sent is accurately received. Receipt is acknowledged by the reciever and will be resent if not acknowledged within certain time(timeout)
this is managed by a protocol to avoid having the sender send data too fast for the receiver to receive and process it reliably- essential in an environment where machines of diverse network speeds communicate.
a situation in which two or more competing actions are each waiting for the other to finish, and thus neither ever does. Protocols should prevent two processes being mutually dependent.
where a node or link carries so much data that it may deteriorate network service quality, resulting in slow response times or data packet loss and the blocking of new connections. Protocols should prevent this
protocols determine how the communication will be checked for errors in the transmission e.g. cyclic redundancy checks
factors affecting network speed
connection medium (wired or wireless), hardware (switches, bridges, routers), layout and physical distance, any interference with signal, amount of traffic on network
simplest form of error checking where the number of ones in a byte is set to be either odd or even, if it received with the 1 bit changed, it will be recognised as an error
Automatic Repeat reQuest (ARQ)
"it is a method used to check data has been transmitted correctly. If the data is received correctly an acknowledgement is sent by the receiver to the senderWhen an error is detected (by e.g. paritycheck, CRC) in a packet of data or it is not received, no acknowledgement is sent by receiver.
Cyclic Redundancy Check
a method of checking for errors in data that has been transmitted.A sending device applies a 16- or 32-bit polynomial to a block of data that is to be transmitted and appends the resulting code to the block. The receiving end applies the same polynomial to the data and compares its result with the result appended by the sender. If they agree, the data has been received successfully.
data transmission speed
The speed with which data can be transmitted from one device to another. Usually measured in Mbps - Megabits per second
encoding information using fewer bits than the original representation
a type of compression that reduces bits by removing unnecessary or less important information. The original file cannot be reconstructed
compression that reduces bits by identifying and eliminating statistical redundancy. No information is lost , and the original file can be reconstructed
the overall measure of network speed - the amount of data that can be carried over a given connection in a given time (measure in Mbps etc). It depends on both the amount of data carried at once and the speed of transmission
transmission medium (plural media)
"the thing that is used to transmit the signal between two devices.
the arrangement of devices in a communication network. It can be physical or logical. Physical is the placement of the various components of a network, including device location and cable installation, while logical illustrates how data flows within a network.
A transmission medium, currently only type of this is ethernet cable. This type of medium can transfer data at high speeds over relatively short distances
a transmission medium that transmits data by sending light down extremely thin glass tubes It is extremely fast and each cable is able to contain multiple independent optical fibres and suffers less signal loss than other cables when traveling long distances. However they are extremely expensive
a connection medium that doesn't use wires
network interface card (NIC)
a computer hardware component that allows a computer to connect to a network. may be used for both wired and wireless connections.
the location of a devce on a network. version 4 uses 4 blocks of numbers 0-255 separated by full stops, version 6 uses 8 blocks of 4 hexadecimal digits separated by :
the user data that is carried by a data packet
supplemental data placed at the end of a block of data being stored or transmitted, which may contain information for the handling of the data block, or just mark its end.
used to join networks by sending packets of data across networks, towards their destination using its routing table and the ip address found in each packet header
a network device that sends packets of data to their destination within a network
wireless access point
allows wireless transmission of data between a device and the wired part of a network
wireless Network interface card (WNIC)
also known as a wireless network adapter
media acces control (MAC) address
the hardware address of a NIC that cannot be changed - 6 pairs of hexadecimal numbers that identify device and manufacturer
a combination of a wireless access point and a router
used in combination with the Lightweight Access Point Protocol (LWAPP) to manage light-weight access points in large quantities by the network administrator
Lightweight access point protocol (LWAPP)
a protocol that can control multiple Wi-Fi wireless access points at once. This can reduce the amount of time spent on configuring, monitoring or troubleshooting a large network.
MAC address filtering
only allowing access to the network to devices whose MAC addresses are on a permitted list. Quite secure but difficult to maintain an up to date list and not flexible
Service set identifier (SSID)
the name a network broadcasts to identify itself
ways of protecting a network
user id and password for network, password for device, disable SSID broadcast, block access by MAC address, use encryption (WPA2, WPA, WEP), prevent physical access, use firewall
wired equivalent privacy (WEP)
an old form of wireless encryption, which while compatible with older devices, isn't very secure
wifi protected access (WPA)
it superseded WEP as an interim measure while a more secure form of the protocol was being developed
wifi protected access v2 (WPA2)
the encryption technique that is considered best protection for networks and is available now on a wider range of devices. Use AES block cipher
Worldwide Interoperability for Microwave Access (WiMAX)
A 4G network, wireless standard originally designed to provide long range networking and broadband connectivity at 30-40 Mbps as alternative to DSL Cable, but now up to 1Gbps for fixed devices with 2nd version. Allows connection in relatively remote areas where no broadband access
used for data/internet access over a phone or mobile device up to 200Kbps
used for data/internet access over a phone/mobile device/laptop up to 100Mbps when moving e.g. on trains or 1Gbps when static
a 4G for high speed data for smartphones and mobile devices. Faster and larger capacity than 4G - as high as 300Mbps on download
future telecommunications standards beyond the current 4G standards - with larger capacity, better reliability and reducing demands on battery - but no standards exist yet
short range wireless network designed for high-bandwidth for data transfer
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