Aug 04

1000BASE-SX: A short laser wavelength on multimode fiber optic cable for a maximum length of 2 kilometers.

1000BASE-LX: A long wavelength for a “long haul” fiber optic cable for a maximum length of 10 kilometers.

100BASE-FX: 100Mbps Ethernet implementation over fiber.

100BASE-TX: 100Mbps Ethernet implementation over Category 5 and Type 1 Twisted Pair cabling.

10BASE-T: The IEEE 802.3 specification for Ethernet over Unshielded Twisted Pair (UTP) cabling.

aging: The automatic removal of dynamic entries from the Switch Database which have timed-out and are no longer valid.

ATM: Asynchronous Transfer Mode. A connection oriented transmission protocol based on fixed length cells (packets). ATM is designed to carry a complete range of user traffic, including voice, data and video signals.

auto-negotiation: A feature on a port which allows it to advertise its capabilities for speed, duplex and flow control. When connected to an end station that also supports auto-negotiation, the link can self-detect its optimum operating setup.

backbone port: A port which does not learn device addresses, and which receives all frames with an unknown address. Backbone ports are normally used to connect the Switch to the backbone of your network. Note that backbone ports were formerly known as designated downlink ports.

backbone: The part of a network used as the primary path for transporting traffic between network segments.

bandwidth: Information capacity, measured in bits per second that a channel can transmit. The bandwidth of Ethernet is 10Mbps, the bandwidth of Fast Ethernet is 100Mbps.

baud rate: The switching speed of a line. Also known as line speed between network segments.

BOOTP: The BOOTP protocol allows automatic mapping of an IP address to a given MAC address each time a device is started. In addition, the protocol can assign the subnet mask and default gateway to a device.

bridge: A device that interconnects local or remote networks no matter what higher level protocols are involved. Bridges form a single logical network, centralizing network administration.

broadcast: A message sent to all destination devices on the network.

broadcast storm: Multiple simultaneous broadcasts that typically absorb available network bandwidth and can cause network failure.

console port: The port on the Switch accepting a terminal or modem connector. It changes the parallel arrangement of data within computers to the serial form used on data transmission links. This port is most often used for dedicated local management.

CSMA/CD: Channel access method used by Ethernet and IEEE 802.3 standards in which devices transmit only after finding the data channel clear for some period of time. When two devices transmit simultaneously, a collision occurs and the colliding devices delay their retransmissions for a random amount of time.

data center switching: The point of aggregation within a corporate network where a switch provides high-performance access to server farms, a high-speed backbone connection and a control point for network management and security.

Ethernet: A LAN specification developed jointly by Xerox, Intel and Digital Equipment Corporation. Ethernet networks operate at 10Mbps using CSMA/CD to run over cabling.

Fast Ethernet: 100Mbps technology based on the CSMA/CD network access method.

Flow Control: (IEEE 802.3X) A means of holding packets back at the transmit port of the connected end station. Prevents packet loss at a congested switch port.

forwarding: The process of sending a packet toward its destination by an internetworking device.

full duplex: A system that allows packets to be transmitted and received at the same time and, in effect, doubles the potential throughput of a link.

half duplex: A system that allows packets to be transmitted and received, but not at the same time. Contrast with full duplex.

IP address: Internet Protocol address. A unique identifier for a device attached to a network using TCP/IP. The address is written as four octets separated with full-stops (periods), and is made up of a network section, an optional subnet section and a host section.

IPX: Internetwork Packet Exchange. A protocol allowing communication in a NetWare network.

LAN – Local Area Network: A network of connected computing resources (such as PCs, printers, servers) covering a relatively small geographic area (usually not larger than a floor or building). Characterized by high data rates and low error rates.

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Aug 05

Super G is Atheros’ proprietary frame-bursting, compression and channel bonding technology to improve IEEE 802.11g wireless LAN performance. The throughput transmission speed limit when using Super G is claimed to be up to 40Mbit/s-60Mbit/s at a 108Mbit/s signaling rate, which is achieved through the bonding of two 54Mbit/s 802.11g channels.

Other vendors have marketed Super G products as 108G Technology, 108Mbit/s 802.11g, and Xtreme G. Manufacturers that have licensed Super G technology from Atheros include Airlink 101, Clipsal, D-Link, Intelbras, Netgear, Nortel Networks, Planex, SMC, Sony, TRENDnet, SparkLAN, Toshiba and ZyXEL. In general, Super G products from different vendors are all interoperable in Super G mode.

Non-standard channel bonding extensions to 802.11g, such as Super G, have been criticized for creating interference on all Wi-Fi channels, potentially causing issues with other wireless devices in the band such as neighboring wireless networks, cordless telephones, baby monitors, and Bluetooth devices. However, Atheros claims that in real-world scenarios with physical separation and walls, closely located networks will not experience any interference from a Super G network.

Super G is one of several competing proprietary approaches that were developed to increase performance of 802.11g wireless devices, such as 125 High Speed Mode from Broadcom, MIMO-based extensions from Airgo Networks, and Nitro from Conexant.

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