| Term |
Description |
| 3DES |
| 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). |
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| 802.11 |
802.11 is a family of specifications for WLANs (wireless local area networks) developed by the IEEE. The most widely used current specifications are 802.11b, 802.11g, and 802.11a, in that order. All use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing.
802.11 is also an IEEE legacy standard, a WLAN providing 1 or 2 Mbps transmission in the 2.4 GHz band using either FHSS or DSSS (frequency hopping or direct sequence spread spectrum) modulaion. |
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| 802.11a |
| 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. |
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| 802.11b |
| 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. |
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| 802.11e |
| 802.11e is a standard that defines QoS (Quality of Service) for wireless networks, to support Voice over IP, for example. |
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| 802.11g |
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. |
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| 802.11h |
| 802.11h is a supplement to 802.11a to make it meet European regulations on 5 GHz WLANs. |
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| 802.11i |
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. |
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| 802.11j |
| 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. |
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| 802.11k |
| 802.11k - standard that addresses radio resource management to make more efficient use of WLAN resources. |
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| 802.11n |
| 802.11n is a proposed WLAN standard to increase the speed of 802.11a/b/g wireless networks to over 100 Mbps, while maintaining compatability. It is espected to be ratified by the end of 2006. |
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| 802.11r |
| 802.11r - this standard will address fast roaming among access points. |
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| 802.11s |
| 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. |
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| 802.15 |
| 802.15 is a standard for personal area netwroks, based on Bluetooth. |
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| 802.16 |
| 802.16 defines specifications for fixed wireless broadband. |
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| 802.16a |
| 802.16a (a.k.a WiMax) is WLAN specification allowing for transfer of up to 70 Mbps over as much as 30 miles. |
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| 802.1x |
| 802.1x is an authentication scheme based on EAP (Extensible Authentication Protocol). |
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| 802.20 |
| 802.20 - proposal for 1 Mbps wireless metropolitan area networks. |
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| A-MPDU |
A-MPDU (Aggregate MAC Protocol Data Unit) and A-MSDU (Aggregate MAC Service Data Unit) are types of packet aggregation mandatory in the 802.11n (and draft 2.0) wireless networking.
A-MPDU/A-MSDU packet aggregation is part of the 802.11n standard that increases throughput, at a potential performance penalty of increased data retransmission. |
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| A-MSDU |
A-MPDU (Aggregate MAC Protocol Data Unit) and A-MSDU (Aggregate MAC Service Data Unit) are types of packet aggregation mandatory in the 802.11n (and draft 2.0) wireless networking.
A-MPDU/A-MSDU packet aggregation is part of the 802.11n standard that increases throughput, at a potential performance penalty of increased data retransmission. |
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| ad-hoc |
| 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. |
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| ADSL |
| 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. |
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| AES |
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 usually used in WAP for protecting WLANS, and it reportedly has never been cracked. |
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| AIMD |
| 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. |
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| ARP |
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 |
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| ARPANET |
| 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. |
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| ASCII |
| 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). |
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| ATA |
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. |
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| ATM |
| 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. |
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| ATU |
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. |
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| AWG |
| 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. |
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| backbone |
| 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. |
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| backdoor |
| 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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| bandwidth |
bandwidth is the amount of data that can be carried in a given time period over a network.
More technically, bandwidth is the width of the range of frequencies that an electronic signal occupies on a given transmission medium. In digital systems, bandwidth is usually expressed as bps (bits per second), Kbps (Kilobits/second or Mbps (Megabits / second). In analog systems, it's the number of cycles of change per second, or hertz. |
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| baud |
baud is essentially the rate at which bits are transmitted over a communication link. Baud is the number of transitions (used to encode bits) that take place in one second.
However, since such single state change can involve more than a single bit of data, the term bps (bits per second) has replaced baud as a better expression of data transmission speed. |
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| BDP |
The Bandwidth*Delay Product, or BDP for short determines the amount of data that can be in transit in the network. It is the product of the availalbe bandwidth and the latency, or RTT. BDP is a very important concept in a Window based protocol such as TCP. It plays an especially important role in high-speed / high-latency networks, such as most broadband internet connections. It is one of the most important factors of tweaking TCP in order to tune systems to the type of network used.
The BDP simply states that:
BDP (bits) = total_available_bandwidth (bits/sec) x round_trip_time (sec)
or, since RWIN/BDP is usually in bytes, and latency is measured in milliseconds:
BDP (bytes) = total_available_bandwidth (KBytes/sec) x round_trip_time (ms)
What does in all mean ? The TCP Window is a buffer that determines how much data can be transferred before the server waits for acknowledgement. It is in essence bound by the BDP. If the BDP (or RWIN) is lower than the product of the latency and available bandwidth, we can't fill the line snce the client can't send acknowledgements back fast enough. A transmission can't exceed the (RWIN / latency) value, so RWIN needs to be large enough to fit the maximum_available_bandwidth x maximum_anticipaded_delay. |
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| BGP |
| BGP (Border Gateway Protocol) is a routing protocol that enables groups of routers (called autonomous systems) to communicate and share routing information establishing efficient, loop-free routes while using their own internal routing policies. BGP is commonly used within and between Internet Service Providers (ISPs). For customers, BGP allows for using unique routing policies internally, as well as connecting to multiple ISPs. The protocol is defined in RFC 1771. |
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| BIOS |
| BIOS (Basic Input/Output System) is the program which starts up your computer and communicates between the devices (such as your hard drive, keyboard, video card) and the system. BIOS is normally stored in an EPROM (Eraseable Programmable Read Only Memory) chip. |
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| bit shift |
bit shift is a binady number operation, that moves (shifts) the bits in a number to the left or right.
Each bit shifted increases/decreases the value by a power of two. Eg a shift of 1 to the left will double the value, a shift to 2 to the right will quarter it. |
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| BLEC |
| Building-focused Local Exchange Carrier |
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| Term |
Description |
Glossary
