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||3DES (Triple DES) is a popular private key encryption method, based on DES, an ANSI Data Encryption Standard designed by IBM in the 1970s. Triple DES, or simply 3DES is a more secure version of the DES standard that encodes text three times, as opposed to just one. Exporting DES out of the U.S. or Canada is prohibited for those who don't meet the requirements of the Bureau of Export Administration (BXA).
||802.11 is a set of specifications for implementing WLANs (wireless local area networks) developed by the IEEE. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand.
802.11 WLANs operate in the 900MHz, 2.4GHz, 3.6GHz, 5GHz, and 60GHz frequency bands.
The most widely used current revisions of the specs are 802.11n and 802.11ac, operating in the 2.4GHz and 5GHz frequency ranges.
||802.11a is a 802.11 WLAN (wireless LAN) extension that provides up to 54 Mbps in the 5GHz band. 802.11a uses an orthogonal frequency division multiplexing encoding scheme rather than FHSS or DSSS.
||802.11ac is a wireless networking standard that provide high throughput Wireless Local Area Networks (WLAN) in the 5GHz band.
Theoretically, 802.11ac has expected throughput of at least 1 Gigabit per second to all clients, and a single link throughput of at least 500 Mbps(megabits per second). This is accomplished by extending the air interface concepts embraced by 802.11n: wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256 QAM).
802.11ac range may, or may not be as far as 802.11n Wi-Fi. 802.11ac operates exclusively in 5GHz frequencies while 802.11n can also transmit and receive in the crowded, but longer range with better wall penetration 2.4Ghz frequencies.
||802.11ag (WiGig) is a draft wireless standard that operates on the unlicensed 60GHz spectrum, with theoretical multi-gigabit speeds over a distance of up to 10 meters.
The advantages of WiGig are obviously bandwidth, and that the small wavelength allows for tiny 0.5cm antennas for high gain, beam forming, TDMA, and low power consumption, making it a good match for mobile devices.
The WiGig MAC specification was published in June 2011, and the standard is currently in draft stage with the IEEE as 802.11ad. WiGig isn't necessarily meant as a replacement for 2.4GHz or 5GHz WiFi with its range of 10 meters and no propagation through walls. However, operating at 60GHz offers advantages in terms of power consumption and data rates, particularly for mobile devices.
||802.11ax is a new wireless networking standard that provides high throughput Wireless Local Area Networks (WLAN) in the 5GHz band. It is due to be publicly released in 2019.
802.11ax utilizes MU-MIMO, introduces OFDMA (improves spectral efficiency), and supports higher 1024 QAM modulation (increased throughput).
It is predicted to have a top speed of around 10 Gb/s and to achieve 4x increase to user throughput over 802.11ac due to better spectral efficiency, especially in dense deployment scenarios.
||802.11b (also referred to as Wi-Fi) is a 802.11 WLAN (wireless LAN) extension that allows up to 11 Mbps transmission, with a fallback to 5.5, 2 and 1 Mbps. Wi-Fi works in the 2.4 GHz band, uses DSSS, and is comparable to Ethernet in functionality by allowing for (somewhat) high-speed, encrypted communication.
||802.11e is a standard that defines QoS (Quality of Service) for wireless networks, to support Voice over IP, for example.
||802.11g - 802.11 WLAN (wireless LAN) extenson that provides for up to 54 MBps raw data rate (24 Mbps useful throughput) in the 2.4 GHz band. It is expected to become the next mainstream WLAN technology.
802.11g defines the use of the 802.11a OFDM modulation technique and applies it in the 2.4 GHz 802.11b frequency band. The 802.11g draft standard requires backward compatibility with 802.11b.
||802.11h is a supplement to 802.11a to make it meet European regulations on 5 GHz WLANs.
||802.11i (a.k.a. WPA2) is a standard for wireless networks (ratified by IEEE 06.2004) that was specifically designed to provide better security than 802.11a/b/g.
The 802.11i standard introduces new encryption key protocols: TKIP (Temporal Key Integrity Protocol) and AES (Advanced Encryption Standard). AES uses longer keys with a new algorigthm, and is much more processor-intensive than WEP.
802.11i is also being branded as WPA2.
||802.11j is the Japanese equivalent of 802.11h. It is a supplement to 802.11a to make it meet Japanese requlations on 5 GHz WLANs.
||802.11k - standard that addresses radio resource management to make more efficient use of WLAN resources.
||802.11n is the most current generation of Wi-Fi technology. 802.11n products can operate in either 2.4 or 5 GHz frequency bands, and are backward compatible with 802.11 a/b/g networks. 802.11n technology can deliver data rates up to 600 Mbps.
||802.11r - this standard will address fast roaming among access points.
||802.11s - standard for Mesh Wireless Networks. It aims to define a MAC and PHY for meshed networks that improve coverage with no single point of failure.
||802.15 is a standard for personal area netwroks, based on Bluetooth.
||802.16 is a family of IEEE wireless broadband standards with the trade name WiMAX.
802.16a was originally designed for fixed (non-mobile) applications only.
802.16e added mobility support potentially making WiMAX a competitor for certain 3G/4G HSPA cell-phone technologies.
802.16-2009 is the current rollup standard for both fixed and mobile wireless broadband (merges older versions of 802.16, 802.16e, 802.16f, 802.16g and P802.16i)
||802.16a (a.k.a WiMax) is WLAN specification allowing for transfer of up to 70 Mbps over as far as 30 miles.
||802.16e (Mobile WiMAX) - Mobile Broadband Wireless Access System, part of the IEEE 802.16 family of WiMAX standards.
Compared to earlier versions of WiMAX, 802.16e allows users to be on the move (such as in a car or on a train) while maintaining an active connection. As such, it can be viewed as a competitor of 3G/4G cell-phone technologies.
||802.1x is an authentication scheme based on EAP (Extensible Authentication Protocol).
||802.20 - proposal for 1 Mbps wireless metropolitan area networks.
||A-MPDU (Aggregate MAC Protocol Data Unit) and A-MSDU (Aggregate MAC Service Data Unit) are types of packet aggregation part of the 802.11n (and 802.11ac) wireless networking standards. Packet aggregation increases throughput at a potential performance penalty of increased data retransmissions.
A-MPDU aggregates packets into frames of up to 64 kilobytes. It is an alternative to A-MSDU that has more overhead, however it also causes fewer retransmissions. Because of this, A-MPDU often performs better and is preferred to A-MSDU.
||A-MSDU (Aggregate MAC Service Data Unit) and A-MPDU (Aggregate MAC Protocol Data Unit) are types of packet aggregation part of the 802.11n (and 802.11ac) wireless networking standards. Packet aggregation increases throughput by lowering header overhead, at a potential performance penalty of increased data retransmission.
A-MSDU aggregates packets into frames of up to 7935 bytes with a single MAC header and CRC. Because of that, it reduces header overhead, however it also has a potential performance penalty of increased data retransmissions. A-MPDU has higher header overhead, and causes fewer retransmissions than A-MSDU.
||A wireless access point (AP) in computer networking is a hardware device that allows wireless clients to connect to a wired network using Wi-Fi. The AP usually connects to a NAT router via a wired network, however, it can also be integrated as part of a wireless router as well.
What differentiates an access point from wireless repeaters/extenders is that it is connected via wired network to its gateway and possibly the internet.
||ad-hoc mode (a.k.a peer-to-peer mode, or Independent Basic Service Set - IBSS) in wireless networking refers to a framework in which devices or stations communicate directly with each other, without the use of an access point. Ad-hoc mode is useful for establishing a network where access points do not exist.
||ADSL (asymmetric DSL) is a type of Digital Subscriber line (DSL) that provides greater downstream(download from provider to consumer) bandwidth at the expense of lesser upstream (upload) speed.
||AES (Advanced Encryption Standard, a.k.a. Rijndael) is a symetric block cypher developed by belgian cryptographers Joan Daemen and Vincent Rijmen, that won the NIST's contest for a replacement of DES (Data Encryption Standard).
AES currently supports 128, 192 and 256-bit keys and encryption blocks, and can be extended in 32-bit multiples.
AES is used in securing wireless networks, and it is considered to be among the most secure of all commonly installed wireless encryption standards.
||AIMD (Additive Increase / Multiplicative Decrease) is the congestion control protocol used in TCP. It involves increase-by-one and decrease-to-half (per window of packets acknowledged) strategy for congestion window adjustment.
||ARP (Address Resolution Protocol) is a protocol for mapping IP adresses to MAC (Media Access Control) physical machine adresses.
ARP uses an ARP cache table to maintain a correlation and convert between each MAC address and its corresponding IP address in both directions.
ARP is used in all Ethernet/IP networks to resolve IP addresses to physical device addresses. It is not routable.
See also: RFC 826
||ARPAnet was a large WAN established in 1969, essentially the precursor to the Internet. ARPAnet was created by the US Defence Advanced Research Project Agency (ARPA) to test new networking technologies. It originally linked UCLA and Stanford, followed by the University of Utah.
||ASCII (American National Standard Code for Information Interchange) is the most common format for computer text files. In general, ASCII is the standard code for information interchange among dissimilar computers and computer programs, using a coded character set consisting of 7-bit coded characters (8 bits including parity check).
||ASIC (application-specific integrated circuit) is a microchip designed for a special application, such as such as a particular kind of transmission protocol or a hand-held computer. The term can be contrasted with general integrated circuits, such as the microprocessor and the random access memory chips in PCs.
||ASN (Autonomous System Number) is a special number assigned by IANA to identify individual networks or relatively large network segments. ASNs are primarily used with Border Gateway Protocol (BGP) routing.
BGP routing information is largely based on ASN hops, and manually configured static preferences.
Note: AS numbers are assigned in blocks by IANA to Regional Internet Registries (RIRs). The appropriate RIR then assigns AS numbers to entities within its designated area from the block assigned by IANA.
||ATA (Analog Terminal Adapter) is a device that connects an analog telephone to a VoIP network.
ATAs, usually have an Ethernet (RJ-48) jack, and an RJ-11 phone jack, and use either the SIP or IAX industry standard protocols. ATAs are also refered to as VoIP Gateways, TA (Terminal Adapter),or FXS Adapters. Some ATAs are locked to a particular VoIP provider.
||ATM (Asynchronous Transfer Mode) is a high-speed network protocol designed to support both voice and data communication. ATM is composed of 53 byte cells having 48 byte payloads, does not involve routing and is especially good for real time voice and video. DSL implementations often use ATM as the underlying data-transport protocol beneath TCP/IP.
||ATU (ADSL Transceiver/Termination Unit) is a device that provides ADSL modulation of the telephone line, os simply an ADSL modem. The device at the server side is called ATU-C (Central office), the client's device is called ATU-R (Remote).
ATU-C/R are in essence the ADSL modems that sit on both sides of the telco copper loop.
||AWG (American Wire Gauge) is a measure of the thickness of wiring - the lower the AWG number, the thicker the wire. Generally, thicker wire can carry electrical current longer distances and is less susceptible to interference.
||The part of a communications network that handles the major traffic using the highest-speed, and often longest paths in the network. On the Internet, a backbone is a set of paths that local networks connect to for long-distance interconnection.
||backdoor refers to a port/channel crackers use to access your system. As a rule, it might be easy for a skilled cracker to find a backdoor in a system that is insufficiently protected.
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