Guide To Networks Ch6 Terms

Front 1

802.1D

Back 1

The IEEE standard that describes, among other things, bridging and STP (Spanning Tree Protocol).

Front 2

802.1w

Back 2

The IEEE standard that describes RSTP (Rapid Spanning Tree Protocol), which evolved from STP (Spanning Tree Protocol).

Front 3

application switch

Back 3

A switch that provides functions between Layer 4 and Layer 7 of the OSI model.

Front 4

base I/O port

Back 4

A setting that specifies, in hexadecimal notation, which area of memory will act as a channel for data traveling between the NIC and the CPU. Like its IRQ, a device’s base I/O port cannot be used by any other device.

Front 5

best path

Back 5

The most efficient route from one node on a network to another. Under optimal network conditions, the best path is the most direct path between two points. However, when traffic congestion, segment failures, and other factors create obstacles, the most direct path may not be the best path.

Front 6

BGP

Back 6

(Border Gateway Protocol) A complex routing protocol used on border and exterior routers. BGP is the routing protocol used on Internet backbones.

Front 7

BID

Back 7

(bridge ID) A combination of a 2-byte priority field and a bridge’s MAC address, used in STP (Spanning Tree Protocol) to select a root bridge.

Front 8

BIOS

Back 8

(basic input/output system) The firmware attached to a computer’s motherboard that controls the computer’s communication with its devices, among other things.

Front 9

border router

Back 9

A router that connects an autonomous LAN with an exterior network—for example, the router that connects a business to its ISP.

Front 10

bridge

Back 10

A connectivity device that operates at the Data Link layer (Layer 2) of the OSI model and reads header information to forward packets according to their MAC addresses. Bridges use a filtering database to determine which packets to discard and which to forward. Bridges contain one input and one output port and separate network segments.

Front 11

broadcast domain

Back 11

A combination of ports on a switch (or multiple switches) that make up a Layer 2 segment. To be able to exchange data with each other, broadcast domains must be connected by a Layer 3 device, such as a router or Layer 3 switch. A VLAN is one type of broadcast domain.

Front 12

bus

Back 12

The type of circuit used by a computer’s motherboard to transmit data to components. Most new Pentium computers use buses capable of exchanging 32 or 64 bits of data. As the number of bits of data a bus handles increases, so too does the speed of the device attached to the bus.

Front 13

CardBus

Back 13

A PCMCIA standard that specifies a 32-bit interface running at 33 MHz, similar to the PCI expansion board standard. Most modern laptops are equipped with CardBus slots for connecting external modems and NICs, among other things.

Front 14

CMOS

Back 14

(complementary metal oxide semiconductor) A type of microchip that requires very little energy to operate. In a PC, the CMOS stores settings pertaining to a computer’s devices, among other things.

Front 15

CompactFlash

Back 15

The standard for an ultrasmall removable data and input/output device capable of connecting many kinds of external peripherals to workstations, PDAs, and other computerized devices. CompactFlash was designed by the CompactFlash Association (CFA), a consortium of computer manufacturers.

Front 16

content switch

Back 16

A switch that provides functions between Layer 4 and Layer 7 of the OSI model.

Front 17

convergence time

Back 17

The time it takes for a router to recognize a best path in the event of a change or network outage.

Front 18

cut-through mode

Back 18

A switching mode in which a switch reads a frame’s header and decides where to forward the data before it receives the entire packet. Cut-through mode is faster, but less accurate, than the other switching method, store-and-forward mode.

Front 19

data port

Back 19

A port on a connectivity device to which network nodes are connected.

Front 20

device driver

Back 20

The software that enables an attached device to communicate with the computer’s operating system.

Front 21

distance-vector

Back 21

The simplest type of routing protocols, these determine the best route for data based on the distance to a destination. Some distance-vector routing protocols, like RIP, only factor in the number of hops to the destination, while others take into account latency and other network traffic characteristics.

Front 22

dynamic routing

Back 22

A method of routing that automatically calculates the best path between two nodes and accumulates this information in a routing table. If congestion or failures affect the network, a router using dynamic routing can detect the problems and reroute data through a different path. Modern networks primarily use dynamic routing.

Front 23

EEPROM

Back 23

(electrically erasable programmable read-only memory) A type of ROM that is found on a circuit board and whose configuration information can be erased and rewritten through electrical pulses.

Front 24

EIGRP

Back 24

(Enhanced Interior Gateway Routing Protocol) A routing protocol developed in the mid-1980s by Cisco Systems that has a fast convergence time and a low network overhead, but is easier to configure and less CPU-intensive than OSPF. EIGRP also offers the benefits of supporting multiple protocols and limiting unnecessary network traffic between routers.

Front 25

expansion board

Back 25

A circuit board used to connect a device to a computer’s motherboard.

Front 26

expansion slot

Back 26

A receptacle on a computer’s motherboard that contains multiple electrical contacts into which an expansion board can be inserted.

Front 27

ExpressCard

Back 27

A PCMCIA standard that allows external devices to connect to portable computers through a 26-pin interface, with data transfer rates of 250 Mbps in each direction (for a total of 500 Mbps), similar to the PCI Express expansion board specification. ExpressCard modules come in two sizes: 34 mm and 54 mm wide. Over time, PCMCIA expects the ExpressCard standard to replace the CardBus standard.

Front 28

exterior router

Back 28

A router that directs data between nodes outside a given autonomous LAN, for example, routers used on the Internet’s backbone.

Front 29

filtering database

Back 29

A collection of data created and used by a bridge that correlates the MAC addresses of connected workstations with their locations. A filtering database is also known as a forwarding table.

Front 30

firewall

Back 30

A device (either a router or a computer running special software) that selectively filters or blocks traffic between networks. Firewalls are commonly used to improve data security.

Front 31

FireWire

Back 31

A peripheral bus standard developed by Apple Computer and codified by the IEEE as the IEEE 1394 standard. Traditional FireWire connections support a maximum throughput of 400 Mbps, but a newer version supports potential throughput rates of over 3 Gbps. In addition to connecting peripherals, FireWire can be used to network computers directly in a bus fashion.

Front 32

firmware

Back 32

A combination of hardware and software. The hardware component of firmware is a ROM (read-only memory) chip that stores data established at the factory and possibly changed by configuration programs that can write to ROM.

Front 33

gateway

Back 33

A combination of networking hardware and software that connects two dissimilar kinds of networks. Gateways perform connectivity, session management, and data translation, so they must operate at multiple layers of the OSI model.

Front 34

hub

Back 34

A connectivity device that retransmits incoming data signals to its multiple ports. Typically, hubs contain one uplink port, which is used to connect to a network’s backbone. IEEE 1394 See FireWire.

Front 35

intelligent hub

Back 35

A hub that possesses processing capabilities and can therefore monitor network traffic, detect packet errors and collisions, poll connected devices for information, and gather the data in database format.

Front 36

interior router

Back 36

A router that directs data between nodes on an autonomous LAN.

Front 37

interrupt

Back 37

A circuit board wire through which a device issues voltage, thereby signaling a request for the processor’s attention.

Front 38

IRQ

Back 38

(interrupt request) A message sent to the computer that instructs it to stop what it is doing and pay attention to something else. IRQ is often used (informally) to refer to the interrupt request number.

Front 39

IRQ number

Back 39

The unique number assigned to each interrupt in a computer. Interrupt request numbers range from 0 to 15, and many PC devices reserve specific numbers for their use alone.

Front 40

IS-IS

Back 40

(Intermediate System to Intermediate System) A link-state routing protocol that uses a best-path algorithm similar to OSPF’s. IS-IS was originally codified by ISO, which referred to routers as “intermediate systems,” thus the protocol’s name. Unlike OSPF, IS-IS is designed for use on interior routers only.

Front 41

ISA

Back 41

(Industry Standard Architecture) The original PC bus type, developed in the early 1980s to support an 8-bit and later a 16-bit data path and a 4.77-MHz clock speed.

Front 42

Layer 3 switch

Back 42

A switch capable of interpreting data at Layer 3 (Network layer) of the OSI model.

Front 43

Layer 4 switch

Back 43

A switch capable of interpreting data at Layer 4 (Transport layer) of the OSI model.

Front 44

link-state

Back 44

A type of routing protocol that enables routers across a network to share information, after which each router can independently map the network and determine the best path between itself and a packet’s destination node.

Front 45

loopback plug

Back 45

A connector used for troubleshooting that plugs into a port (for example, a serial, parallel, or RJ-45 port) and crosses over the transmit line to the receive line, allowing outgoing signals to be redirected back into the computer for testing.

Front 46

memory range

Back 46

A hexadecimal number that indicates the area of memory that the NIC and CPU will use for exchanging, or buffering, data. As with IRQs, some memory ranges are reserved for specific devices—most notably, the motherboard.

Front 47

modular router

Back 47

A router with multiple slots that can hold different interface cards or other devices so as to provide flexible, customizable network interoperability.

Front 48

on-board NIC

Back 48

A NIC that is integrated into a computer’s motherboard, rather than connected via an expansion slot or peripheral bus.

Front 49

on-board port

Back 49

A port that is integrated into a computer’s motherboard.

Front 50

OSPF

Back 50

(Open Shortest Path First) A routing protocol that makes up for some of the limitations of RIP and can coexist with RIP on a network.

Front 51

passive hub

Back 51

A hub that simply retransmits signals over the network.

Front 52

PC Card

Back 52

A PCMCIA standard that specifies a 16-bit interface running at 8 MHz for externally attached devices. PC Cards’ characteristics match those of the ISA expansion card. And like the ISA standard, the PC Card standard suffered from its lower data transfer rates, compared to other PCMCIA standards.

Front 53

PCI

Back 53

(Peripheral Component Interconnect) A 32 or 64-bit bus that can run at 33 or 66 MHz, introduced in its original form in the 1990s. The PCI bus is the NIC connection type used for nearly all new PCs. It’s characterized by a shorter length than ISA or EISA cards, but has a much faster data transmission capability.

Front 54

PCIe

Back 54

(PCI Express) A 32- or 64-bit bus standard capable of transferring data at up to 4.26 Gbps in full-duplex transmission. PCI Express was introduced in 2002 and offers several advantages over traditional PCI. Its expansion cards can fit into older PCI slots, with some modifications to the motherboard.

Front 55

PCMCIA

Back 55

(Personal Computer Memory Card International Association) A group of computer manufacturers who developed an interface for connecting any type of device to a portable computer. PCMCIA slots may hold memory, modem, network interface, external hard disk, or CD-ROM cards. PCMCIA-standard cards include PC Card, CardBus, and the newest, ExpressCard.

Front 56

RIP

Back 56

(Routing Information Protocol) The oldest routing protocol that is still widely used, RIP does not work in very large network environments in which data may have to travel through more than 15 routers to reach their destination (for example, on the Internet). And, compared to other routing protocols, RIP is slower and less secure.

Front 57

RIPv2

Back 57

(Routing Information Protocol version 2) An updated version of the original RIP routing protocol which makes up for some of its predecessor’s overhead and security flaws. However, RIPv2’s packet forwarding is still limited to a maximum 15 hops.

Front 58

root bridge

Back 58

The single bridge on a network selected by the Spanning Tree Protocol to provide the basis for all subsequent path calculations.

Front 59

router

Back 59

A multiport device that operates at Layer 3 of the OSI model and uses logical addressing information to direct data between networks or segments. Routers can connect dissimilar LANs and WANs running at different transmission speeds and using a variety of Network layer protocols. They determine the best path between nodes based on traffic congestion, available versus unavailable routes, load balancing targets, and other factors.

Front 60

routing protocols

Back 60

The means by which routers communicate with each other about network status. Routing protocols determine the best path for data to take between nodes.

Front 61

RSTP

Back 61

(Rapid Spanning Tree Protocol) As described in IEEE’s 802.1w standard, a newer version of the Spanning Tree Protocol that can detect and correct for network changes much more quickly.

Front 62

runt

Back 62

An erroneously shortened packet.

Front 63

stand-alone hub

Back 63

A type of hub that serves a workgroup of computers that are separate from the rest of the network, also known as a workgroup hub.

Front 64

static routing

Back 64

A technique in which a network administrator programs a router to use specific paths between nodes. Because it does not account for occasional network congestion, failed connections, or device moves, static routing is not optimal.

Front 65

store-and-forward mode

Back 65

A method of switching in which a switch reads the entire data frame into its memory and checks it for accuracy before transmitting it. Although this method is more time consuming than the cut-through method, it allows store-and-forward switches to transmit data more accurately.

Front 66

STP

Back 66

(Spanning Tree Protocol) A switching protocol defined in IEEE 802.1D. STP operates in the Data Link layer to prevent traffic loops by calculating paths that avoid potential loops and by artificially blocking links that would complete a loop. Given changes to a network’s links or devices, STP recalculates its paths.

Front 67

switch

Back 67

A connectivity device that logically subdivides a network into smaller, individual collision domains. A switch operates at the Data Link layer of the OSI model and can interpret MAC address information to determine whether to filter (discard) or forward packets it receives.

Front 68

trunking

Back 68

The aggregation of multiple logical connections in one physical connection between connectivity devices. In the case of VLANs, trunking allows data from multiple VLANs to share a single interface on a switch.

Front 69

uplink port

Back 69

A port on a connectivity device, such as a hub or switch, used to connect it to another connectivity device.

Front 70

USB

Back 70

(universal serial bus) port A standard external bus that can be used to connect multiple types of peripherals, including modems, mice, and NICs, to a computer. Two USB standards exist: USB 1.1 and USB 2.0. USB 3.0 promises to be released soon. Most modern computers support the USB 2.0 standard.

Front 71

VLAN

Back 71

(virtual local area network) A network within a network that is logically defined by grouping its devices’ switch ports in the same broadcast domain. A VLAN can consist of any type of network node in any geographic location and can incorporate nodes connected to different switches.