Glossary

A

Access Point 
For wireless networks, an Access Point (or AP for short) is a device that relays transmissions from one wireless LAN host to another. Most APs can also be connected to a wired LAN to provide wireless LAN hosts with access to outside networks and the Internet.

Auto-Negotiation
A Protocol defined in the Ethernet standard that allows devices at either end of a link segment to advertise and negotiate modes of operation such as the speed of the link, half- or full-duplex operation and full-duplex flow control.

Auto-MDIX
A protocol which allows two Ethernet devices to negotiate their use of the Ethernet TX and RX cable pairs. This allows two Ethernet devices with MDI-X or MDI connectors to connect without using a crossover cable. This feature is also known as Auto-crossover.

 

B

Bandwidth
The maximum capacity of a network channel. Usually expressed in bits per second (bps). Ethernet channels have bandwidths of 10, 100, or 1000 Mbps.

Baud
A unit of signaling speed representing the number of discrete signal events per second and, depending upon the encoding, can differ from the bit rate.

Bit
A binary digit. The smallest unit of data, either a zero or a one.

Bit Rate
The amount of bits that can be sent per second. Usually described in units of kbps or Mbps and frequently referred to as the data rate.

Block Encoding
Block encoding is a system whereby a group of data bits are encoded into a larger set of code bits. Block encoding is used in Fast Ethernet.

Bridge
A device that connects two or more networks at the data link layer (layer 2 of the OSI model).

Broadcast
A transmission initiated by one station and sent to all stations on the network.

Bus
A shared connection for multiple devices over a cable or backplane.

 

C

Category 5
Twisted-pair cable with electrical characteristics suitable for all twisted-pair Ethernet media systems, including 10BASE-T and 100BASE-TX. Category 5 and Category 5e cable are preferred cable types for structural cabling systems.

Category 5e
An enhanced version of Category 5 cable, developed to improve certain cable characteristics important to Gigabit Ethernet operation. It is recommended that all new structured cabling systems be based on Category 5e cable; however, this cable may not be the best for use in industrial installations because of noise susceptibility.

Collision
The result of having two or more simultaneous transmissions on a common signal channel such as half-duplex Ethernet or shared Ethernet.

Collision Domain
The set of all stations connected to a network where faithful detection of a collision can occur. A collision domain terminates at a switch port.

CRC
Cyclic Redundancy Check. An error-checking technique used to ensure the fidelity of received data.

Crossover Cable
A twisted-pair patch cable wired in such a way as to route the transmit signals from one piece of equipment to the receive port of another piece of equipment, and vice versa. This allows communication between two peer devices. The opposite of a crossover cable is the straight-through cable.

CSMA/CD
Carrier Sense Multiple Access/Collision Detect. The medium access control (MAC) Protocol used in Ethernet.

D

Data Link Layer
Layer 2 of the OSI reference model. This layer passes data between the network layer and the physical layer. The data link layer is responsible for transmitting and receiving frames. It usually includes both the media access control (MAC) protocol and logical link control (LLC) layers.

Dual Homing II
Dual Homing II is the most important feature of Korenix 2nd generation Ring redundancy technology. When you want to connect multiple RSR or form redundant topology with other vendors, Dual Homing II allows you to enable RSTP (Rapid Spanning Tree Protocol) and RSR from one device at the same time. Thus you have more flexibility and standard RSTP way to construct your network topology.

 

E

Encoding
A means of combining clock and data information into a self-synchronizing stream of signals.

Error Detection
A method that detects errors in received data by examining cyclic redundancy checks (CRC) or checksum.

Ethernet
A popular LAN technology first standardized by DEC, Intel, and Xerox (or DIX) and subsequently standardized by the IEEE through the 802.3 committee.

 

F

Fast Ethernet
A version of Ethernet that operates at 100 Mbps. Although 100 Mbps is no longer the fastest data rate, this term is still used.

Fast Link Pulse
A link pulse that encodes information used in the Auto-Negotiation Protocol. Fast link pulses consist of bursts of the normal link pulses used in 10BASE-T.

Fiber Optic Cable
A cable with a glass or plastic filament which transmits digital signals in the form of light pulses at wavelengths of 850 nm (10BASE-FL and 100BASE-SX) or 1300 nm (100BASE-FX).

Flow Control
The process of controlling data transmission at the sender to avoid overfilling buffers and loss of data at the receiver.

Forwarding
The process of moving frames from one port to another in a switching hub.

Frame
The fundamental unit of transmission at the data link layer of the OSI model.

Full-Duplex Operation
A communication method that allows simultaneous transmission and reception of data.

 

G

Gigabit Ethernet
A version of Ethernet that operates at 1000 Mbps.

 

H

Half-Duplex Operation
A communication method in which transmissions and receptions can occur in either direction but not at the same time.

Hotspot 
Hotspot refers to a site that offers Internet access via a wireless LAN. Many hotels, restaurants, airports, and municipalities now offer free Wi-Fi access as a service for customers and visitors. 

 

I

IEEE
Institute for Electrical & Electronics Engineers. A professional organization and standards body.

IGMP Snooping
The ability of a switch to observe Internet Group Multicast Protocol (IGMP) traffic in order to learn IP Multicast group membership for the purpose of restricting multicast transmissions to only those ports which have requested them.

Internet
Worldwide collection of networks based on the use of TCP/IP network protocols.

 

J

JetBox
Korenix JetBox Series is a total solution of embedded computer. It is a RISC or X86 CPU based computer with versatile peripheral interfaces, communication capabilities and storage expansibilities. Built-in OS (Linux, WinCE, or Windows XP embedded), supporting services and daemons and providing application development tools for users to develop their own applications; these are the advantage of implementing Korenix. JetBox Software such as OS, drivers, and middleware are ready in one CF card for better system integration.

JetCard
JetCard Series uses Oxford OXmPCI954 chip, a 4-port Universal Asynchronous Receiver Transmitter, which is well-known for its high performance. Each UART channel in the JetCard offers data transmission speed up to 921.6 Kbps, and bi-directional 128-byte FIFO for each port. Deep FIFO can reduce the CPU's loading, saving CPU's resources for other important tasks. This chip also allows JetCard to be compatible with the widely-used industry standard 16C950 devices and PCI bus.

JetCon
JetCon Series offers fiber converter and serial converter, expanding network through fiber optic communication and/or serial fiber ring to extend networking distance. JetCon can be configured as Switch Converter Mode or Pure Converter Mode for your convenience.

JetNet
JetNet Series offers variety of state-of-art Managed and Unmanaged switches, which meets all customers' requests, from cost-effective to value-added. In addition, JetNet 5000 Series supports Rapid Super Ring with as low as 5 ms recovery time and wide operating temperature from -20 ~ 70oC.

JetPoE
JetPoE Series consists of Managed and Unmanaged PoE switches, delivering up to 30 watts via RJ45 cable while it transmits the data. All PoE are designed for industrial environment with wide operating temperatures, anti-shock, IP31, 1200V HiPot and fanless.

JetPort
JetPort Serial Device Server Series is a smart RS-232 or RS-232/422/485 to Ethernet serial device server. It connects the serial port devices such as card readers, measurement devices, or data acquisition terminals, over Ethernet, as if it were locally attached which meets all customers' requests such as redundant, security, I/O and multi-link functions. JetPort Series also comes with freeware such as JetPort Commander, an user-friendly utility with auto device discovery in a LAN or adding devices on the public network.

JetPortCommander
Korenix JetPort Commander is known for its abundant features, user-friendly interface and smart setup wizards. Customer can browse the JetPorts, configure services, monitor devices and group setup.
The group setup wizard includes Virtual COM Wizard, Group Setup Wizard, Group Firmware Wizard, Serial Tunnel Wizard and Group IP Wizard.

Korenix View
Korenix View is client/server architecture. Users use the client application to issue the operations and there is a server on the device to do these operations. The major difference between the Korenix View and other management tools, ex. Web, CLI, and SNMP, is that the Korenix View can configure several devices at the same time. For example, change IP address or upgrade firmware for over 30 devices at the same time is inconvenient by Web or CLI or SNMP, but it is much easier when using Korenix View to do these operations. Korenix View supports auto discovery, group IP settings, group firmware upgrade, and group configuration file backup/restore features. One more important feature is Korenix View has only one version for various operating systems, ex. Windows 95/98/ME, 2000, XP, and Linux.

 

L

LAN
Local Area Network.

Late Collision
A failure of the network in which the collision indication arrives too late in the frame transmission to be automatically dealt with by the medium access control (MAC) Protocol. The defective frame may not be detected by all stations requiring that the application layer detect and retransmit the lost frame, resulting in greatly reduced throughput.

Link Integrity Test
This test verifies that an Ethernet link is connected correctly and that signals are being received correctly. This is a helpful aid but does not guarantee the link is completely functional.

Link Layer
Short for Data Link Layer. This is layer 2 on the OSI model.

Link Pulse
A test pulse sent between transceivers on a 10BASE-T link segment during periods of no traffic, to test the signal integrity of the link.

Link Segment
A point-to-point segment that connects only two devices and is "capable" of supporting full-duplex operation.

 

M

MAC
Medium Access Control. A Protocol operating at the data link layer used to manage a station's access to the communication channel.

MAC Address
A unique address assigned to a station interface, identifying that station on the network. With Ethernet, this is the unique 48-bit station address. It is also known as the physical address.

MDI
Medium Dependent Interface. The name for the connector used to make a physical and electrical connection between a transceiver and a media segment. For example, the RJ-45-style connector is the MDI for 10BASE-T and 100BASE-TX.

MDI-X
An MDI port on a hub or media converter that implements an internal crossover function. This means that a "straight-through" patch cable can be used to connect a station to this port, since the required signal crossover is performed inside the port instead of in the cable.

MIB
Management Information Base. An MIB describes a set of managed objects. An SNMP management console application can manipulate the objects on a specfic computer if the SNMP service has an extension agent DLL that supports the MIB. Each managed object in a MIB has a unique identifier. The identifier includes the object's type (such as counter, string, gauge or address), the object's access level (such as read, or read/write), size restrictions and range information.

Media Converter
A device that converts signals from one media type to that of another.

Multicast
A transmission initiated by one station and sent to many stations on the network.

 

N

NIC
Network Interface Card. Also called an adapter, network interface module, or interface card. The set of electronics that provides a connection between a computer and a network.

Node
A node is where data enters and exits a network.

 

O

OPC
Originally, OLE for Process Control. A process control communications standard for accessing process data from multi-vendor systems.

Open system authentication 
The IEEE 802.11 protocol specifies "open system authentication"" for wireless LANs that do not require any level of security. When using open system authentication to establish a communication link, the initiating station sends a randomly generated key that will be used for subsequent communications. The receiving station can accept or reject the initiating party's request. 

OSI
Open Systems Interconnection. A seven-layer reference model for networks, developed by the International Organization for Standardization (ISO). The OSI reference model is a formal method for describing the interlocking sets of networking hardware and software used to deliver network services. It is a good model, but strict compliance to the model is seldom accomplished.

OUI
Organizationally Unique Identifier. A 24-bit value assigned to an organization by the IEEE. Ethernet vendors use the 24-bit OUI they receive from the IEEE in the process of creating unique 48-bit Ethernet addresses. Contemporary Controls has been assigned a vendor OUI. 

 

P

Packet
A unit of data exchanged at the network layer. This is a much abused definition and the terms "frame" and "packet" are frequently interchanged.

Patch Cable
A twisted-pair or fiber optic jumper cable used to make a connection between a media segment and a network interface (on a station) or a network port (on a hub), or to directly connect stations and hub ports together.

PAUSE
A unique frame sent by full-duplex capable stations to indicate to the sender to slow down transmissions.

PHY
Physical Layer Device. The name used for a transceiver in Fast Ethernet and Gigabit Ethernet systems.

Physical Layer
The bottom layer in the OSI seven-layer reference model. This layer is responsible for physical signaling-including connectors, timing, voltages, and related issues. Data sent over the physical layer are termed symbols.

PoE
A solution where electrical current is run to networking hardware over the Ethernet Category 5 or higher data cabling.

Point-to-Point Technology
A network system composed of point-to-point links. Each point-to-point link connects two and only two devices-one at each end. Devices could be DTEs or DCEs, but no more than two can be connected on one link.

Port
A connection point for a cable. Repeater hubs and switching hubs typically provide multiple ports for connecting Ethernet devices.

Port Mirroring
Port Mirroring allows a switch port to monitor packets from any or all of its ports so that traffic can be analyzed.

Port Security
Prevents a switch port from learning MAC addresses. Thus, frames pass through only if their destinations are listed in the switch address look-up table. Static addresses are not affected. This feature is typically used to limit device access to a network.

Protocol
A set of agreed-upon rules and message formats for exchanging information among devices on a network.

 

Q

Quality of Service (QoS)
Some switches support QoS (per 802.1p and 802.1Q standards) whereby tagged measures, or messages received on a certain port can be assigned one of eight levels of priority. QoS can be important where time-critical applications can be impaired by data delays.

 

R

Rapid Super Ring (RSR)
The most common industrial network redundancy is to form a ring or loop. Typically, the managed switches are connected in series and the last switch is connected back to the first one. In such connection, you can implement Korenix Super Ring and Rapid Super Ring technology.

Rapid Spanning Tree
Newer version of Spanning Tree Protocol that is backward compatible while providing a faster recovery time.

Rate Limiting
The ability of a switch to limit the throughput of particular ports on the switch. Used to prevent certain ports from consuming all the bandwidth.

RJ-45
An 8-pin modular connector used on twisted-pair links.

 

S

SC
Subscriber Connector. This is a type of fiber optic connector used in 100BASE-FX fiber optic media systems. The connector is designed to be pushed into place, automatically seating itself.

Segment
A cable made up of one or more cable sections and connections joined together to produce the equivalence of a continuous cable.

Shared key authentication 
Shared key authentication uses a secret key that each station belonging to the network must use in order to communication with other stations on the network. 

Slot Time
A unit of time used in the medium access control (MAC) Protocol for Ethernet.

SNMP
Simple Network Management Protocol. The de facto standard for switch management. A familiarity with MIB objects is necessary to manage a switch with an SNMP management program. SNMP is not necessarily limited to TCP/IP networks.

SMTP
Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server. This is why you need to specify both the POP or IMAP server and the SMTP server when you configure your e-mail application.

Spanning Tree Protocol
A link management protocol providing path redundancy and preventing network loops by defining a tree to span all switches in a network. It forces redundant data paths into a standby (blocked) state. If a path malfunctions, the topology is reconfigured and the link reestablished by activating the standby path.

SSID 
An SSID (Service Set Identifier) is essentially the name of the wireless network. Each computer and access point connected to a particular wireless LAN must be configured with the same SSID.

Star Topology
A network topology in which each station on the network is connected directly to a hub.

 

T

TIA-568A and TIA-568B
Two standards used to define RJ-45 pin connectors and wire color-coding schemes.

Topology
The physical layout of a network.

Transceiver
A combination of the words transmitter and receiver. A transceiver is the set of electronics that sends and receives signals on a media system. Transceivers may be internal or external. Sometimes called a MAU.

Trunking
Two or more ports grouped together as one logical path to increase bandwidth between a switch and a network node when a single path cannot handle the traffic. Loops are avoided because specific paths are designated. Often a single link is designated for flooding broadcasts and packets of unknown destination. Trunks can provide redundancy to critical devices.

Twisted-Pair Cable
A multiple-conductor cable whose component wires are paired together, twisted, and enclosed in a single jacket. A typical Category 5 twisted-pair segment is composed of a cable with four twisted pairs contained in a single jacket. Each pair consists of two insulated copper wires that are twisted together.

V

VLAN
Virtual Local Area Network. A LAN that maps stations on a basis other than location such as by department, user type or application. Managing traffic, workstations, and bandwidth can be easier with a VLAN and improve network efficiency.

 

W

Web Server
A computer or device that serves up Web pages. By installing server software into a computer or device and connecting it to a network, it can become a Web server. Every Web server has an IP address and possibly a domain name.

WEP 
Wired Equivalent Privacy, or WEP for short, is designed to provide wireless LANs with the same level of security provided by a wired LAN. WEP was specified as part of IEEE 802.1b, and although it can be compromised in a relatively short time (typically one to two weeks) with software tools available on the Internet, WEP is often used as a first line of defense against eavesdroppers.

WPA 
Wi-Fi Protected Access, or WPA for short, is the security standard introduced to fix problems with WEP. WPA uses dynamic keys, Extensible Authentication Protocol to secure network access, and Temporal Key Integrity Protocol (TKIP) to ensure that data is transmitted securely. 
  
Wi-Fi 
Strictly speaking, Wi-Fi, which is short for Wireless Fidelity, is the same as IEEE 802.11b (compare this with Ethernet, which is often used in place of IEEE 802.3). Wi-Fi is a trademark owned by WECA (Wireless Ethernet Compatibility Alliance). Products that carry the Wi-Fi mark are guaranteed to be compatible with each other, even if they are produced by different manufacturers.

WLAN 
WLAN stands for Wireless Local Area Network. A WLAN uses radio waves to transmit data from one station to another, as opposed to the more common method of using electrical signals transmitted over copper wire networks.