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Glossary
1000BASE-SX: A short laser wavelength on multimode fiber optic cable for a maximum length of 550 meters
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.
ageing: The automatic removal of dynamic entries from the Switch Database which have timed-out and are no longer valid.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 you to automatically map 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 Ethernet/CD network access method.
Flow Control: (IEEE 802.3z) 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.
latency: The delay between the time a device receives a packet and the time the packet is forwarded out of the destination
port.
line speed:
See baud rate.
main port: The port in a resilient link that carries data traffic in normal operating conditions.
MDI - Medium Dependent Interface: An Ethernet port connection where the transmitter of one device is connected to the
receiver of another device.
MDI-X - Medium Dependent Interface Cross-over: An Ethernet port connection where the internal transmit and receive
lines are crossed.
MIB - Management Information Base: Stores a device's management characteristics and parameters. MIBs are used by the
Simple Network Management Protocol (SNMP) to contain attributes of their managed systems. The Switch contains its own
internal MIB.
multicast: Single packets copied to a specific subset of network addresses. These addresses are specified in the destination-
address field of the packet.