[ Pobierz całość w formacie PDF ]

segment LANs.
Access list: A table of entries used to permit or deny traffic through a router that consists of structured
statements outlining what a router is to do with an incoming packet.
Active hub: Active hubs re-energize the signal before sending it on to its ports. Smart active hubs
intelligently direct a signal to the port on which its destination exists.
Algorithm: The process used to determine the solution to a problem. In routing, algorithms are used to
determine the best route for traffic to take to get to its intended destination.
Application layer: Layer 7 of the OSI Model. This layer defines services to application software.
ARP (Address Resolution Protocol): The protocol used to resolve physical addresses into network
addresses.
ATP/NBP (AppleTalk Transaction Protocol/Name Binding Protocol): AppleTalkÇs data transport
protocols.
Attenuation: The distance limit at which the electrical signal transmitted on a wire begins to weaken and is
no longer recognizable.
Autonomous system: A network that operates under a single set of rules that may include one or more
routing protocols.
Auxiliary password: This password is set to control access to the router on an auxiliary port.
Bandwidth: Maximum amount of data that can be transmitted over a network medium, expressed in
bits-per-second.
Binary: A number system that uses two values (0 and 1) to represent numbers in positions representing
increasing powers of 2.
Bootstrap: The bootstrap program finds a valid Cisco IOS image in the location specified by the routerÇs
configuration register and loads it to RAM.
BRI ISDN: This type of ISDN service consists of two 64 Kbps bearer (B) channels and one 15 Kbps data (D)
channel for a combined bandwidth of 144 Kbps.
Bridge: A bridge, which is a Data Link layer (Layer 2) device, works with Layer 2 protocols and Layer 2
MAC sublayer addresses to forward messages within and outside of a network segment.
Bus topology: A fundamental network topology. Using this topology, network nodes are connected to a
central cable, called a backbone, which runs the length of the network.
Cat 3: A 4-pair cable supporting bandwidth up to 10 Mbps. This cable is the minimum standard for 10BaseT
networks. Wire category (cat) standards are developed by IEEE.
Cat 5: A 4-wire cable with bandwidth up to 100 Mbps, used for 100BaseTX and ATM (asynchronous
transfer mode) networking.
256
CDP (Cisco Discovery Protocol): A proprietary Cisco protocol that is used to update information on a router
about directly connected Cisco routers, bridges, and switches.
CHAP (Challenge Handshake Authentication Protocol): An inbound authentication method that allows a
receiving device to initiate a challenge sequence, which is then modified by the requesting device before the
connection can be established
Checksum: A form of error-checking where the oneÇs complement is summed for all of the 16-bit words
that make up a TCP segment or UDP datagram.
CIR (Committed Information Rate): The minimum bandwidth committed to a customer on a circuit.
Classless Interdomain Routing (CIDR): An addressing scheme that expresses the subnet network address
in the form Ý/n,Û where ÝnÛ represents the number of bits in the network address.
Collision domain: A network segment on which networked devices share the same bandwidth and on which
message collisions may occur.
Command Line Interface (CLI): The DOS-like user interface and prompt of Cisco routers.
Configuration mode: The command line mode that is used to manually configure a router or make changes
to a routerÇs status.
Configuration-register: The location from which the IOS software is to be loaded during the boot process is
a hexadecimal value in the configuration-register.
Connectionless protocol: A connectionless protocol does not use a virtual circuit, or connection-oriented
conduit, and no error-recovery functions are included.
Connection-oriented protocol: A protocol is considered connection-oriented if it meets one of two criteria:
data is transmitted over a negotiated, established path, a virtual circuit, between two nodes, and the protocol
includes a process for error-recovery.
Console password: This password is set to control access to the router through the console port.
Convergence: When all routers on a network have the same knowledge of the network, the network is said to
have convergence.
Core layer router: Core layer routers are used to merge geographically separated networks. The focus of the
core layer is on moving information as fast as possible, most often over dedicated or leased lines.
Cost: An arbitrary routing metric value assigned by the administrator for the crossing and intersection of
networks.
CPE (Customer Premise Equipment): The equipment installed and operated from the customer end of a
frame-relay circuit.
CRC (Cyclic Redundancy Check): A calculated amount thatÇs used for error detection. It is placed into the
Data Link trailer added to the message frame before itÇs sent to the Physical layer.
Cross-connect: The connection that interconnects the workstation cabling and the network cabling. A
common method of creating network cross-connects is through a patch panel.
CSMA/CD (Carrier Sense Multiple Access/Collision Detection): The access method used on an Ethernet
network.
257
Cut-through switching: This switching method begins to forward a frame as soon as the source and
destination MAC addresses are read, typically within the first 12 bytes of an Ethernet frame. [ Pobierz całość w formacie PDF ]