All Course Flashcards
Application Layer (7th layer)
Interacts with application programs that incorporate a communication component such as your Internet
browser and email (provides user interface)
Bus Topology
The computers share the media (coaxial cable) for data transmission
CAT6 (category 6)
Twisted-pair cables capable of carrying up to 1000Mbps (1 gigabit) of data up to a length of 100
meters
Crossover
Transmit and receive signal pairs are crossed to properly align the transmit signal on one device with
the receive signal on the other device
CSMA/CD
Carrier sense multiple access with collision detection is the Ethernet LAN media-access method (used to
prevent collisions in wired Ethernet networks) Used in wireless networks for to reduce collisions.
Data Link Layer (2nd layer)
Layer of the OSI reference model that handles error recovery, flow control (synchronization), and
sequencing (controls which terminals are sending and receiving. Media access is controlled by the Data Link Layer
Deterministic
Access to the network is provided at fixed time intervals
Ethernet, Physical, Hardware, or Adapter Address
Other names for MAC address
Firewall Protection
Used to prevent unauthorized access to your network
Host Address
The portion of the IP address that defines the location of the networking device connected to the network;
also called the host address - Same as host number
Hotspots
A limited geographic area that provides wireless access for the public
Hub
Broadcasts the data it receives to all devices connected to its ports… it is possible for network devices to pick up a data intended for a different device… considered
a multiport repeater
IANA
The Internet Assigned Numbers Authority is the agency that assigns IP addresses to computer networks
ICMP
Internet Control Message Protocol (perform diagnostics, report errors, control the flow of data in
the network)
IEEE
Institute of Electrical and Electronics Engineers, one of the major standard-setting bodies for technological
development
Intranet
An internal network that provides file and resource sharing but ifs not accessed from the Internet
IP Address
Unique 32-bit address that identifies on which network the computer is located as well as
differentiates the computer from all other devices on the same network; they are logical addresses and can be found using the ipconfig/all command
IP Internetwork
A network that uses IP addressing for identifying devices connected to the network
ipconfig/all
Enables the MAC address information to be displayed
from the command prompt
ISP
Internet service provider
Link Integrity Test
Protocol used to verify that a communication link between two Ethernet devices has been established
Link Light
Indicates that the transmit and receive pairs are properly aligned
Link Pulses
Sent by each of the connected devices via the twisted- pair cables when data is not being transmitted to
indicate that the link is still up
Local Area Network (LAN)
Network of users that share computer resources in a limited area
MAC Address
A unique 6-byte address assigned by the vendor of the network interface card; A MAC address has two
portions. The OUI is comprised of the first 6 digits and the last half is assigned by the manufacturer.
Mbps
Megabits per second
Mesh Topology
All networking devices are directly connected to each other (fault tolerant; stations can still communicate if
some segments go down)
Multiport Repeater
Another name for a hub
Network Address Translation (NAT)
Translates the private IP address to a public address for routing over the Internet
Network Interface Card (NIC)
The electronic hardware used to interface the computer to the network
Network Layer (3rd layer)
Defines how data packets are routed in a network. Accepts outgoing messages and combines messages
or segments into packets, adding a header that includes routing information (provides a logical path for data)
Network Number
The portion of the IP address that defines which network the IP packet is originating from or being
delivered to
Organizationally Unique Identifier (OUI)
The first 3 bytes of the MAC address that identifies the manufacturer of the network hardware (ex. Network
interface card has MAC address of 00-00-86-15-7A, the OUI is 00-00-86).
OSI
Open system interconnect
OSI Model
The seven layers describing network functions
Overloading
Where NAT translates the home network’s private IP addresses to a single public IP address
Packet
Provides grouping of the information for transmission
Ping
Command used to test that a device on the network is reachable (If you can’t connect to a networked
computer, you can use the ping command to check connectivity) Used in windows in the command window
Port Address Translation (PAT)
A port number is tracked with the client computer’s private address when translating to a public address
Ports
The physical input/output interfaces to the networking hardware
Presentation Layer (6th layer)
Layer of the OSI reference model that accepts and structures the messages for the application
Private Addresses
IP addresses set aside for use in private intranets
Protocol
Set of rules established for users to exchange information
Range Extender
Device that relays the wireless signals from an access point or wireless router into areas with a weak signal
or no signal at all
RJ-45
The 8-pin modular connector used with CAT6/5e/5 cable
Service Set Identifier (SSID)
Name that is used to identify your wireless network and is used by your access point or wireless router to
establish and association
Session Layer (5th layer)
Layer of the OSI reference model that provides the control functions necessary to establish, manage, and terminate the connections (SQL and NFS technologies
are on the session layer)
SSID
Service set identifier
Star Topology
The most common networking topology in today’s LANs where all networking devices connect to a central
switch or hub, each device connects to a central point via a point-to-point link. Each device is connected to its own port
Stateful Packet Inspection (SPI)
Type of a firewall that inspects
6to4 Prefix
a technique that enables IPv6 hosts to communicate over the IPv4 Internet
Access Control Lists (ACLs)
A basic form of firewall protection
ACK
Acknowledgement packet
AES
Advanced Encryption Standard
AH
Authentication Header
Anycast Address
Is obtained from a list of addresses
ARIN
American Registry for Internet Numbers
ARP
Address Resolution Protocol, used to map and IP address to its MAC address (the destination gets the
sender’s addresses from the ARP request)
ARPAnet
Advanced Research Projects Agency network
Brute Force Attack
Attacker uses every possible combination of characters for the password
Buffer Overflow
Happens when a program tries to put more data into a buffer than it was configured to hold
CHAP
Challenge Handshake Authentication Protocol
CIDR
Classless interdomain routing
CIDR Block
The grouping of two or more class networks together; also called supernetting
Class A, B, C, D, and E
The five classes of IPv4
Classful
The IP and subnet addresses are within the same network
Connection-Oriented Protocol
Establishes a network connection, manages the delivery of data, and terminates the connection
Denial of Service (DoS)
A service is being denied to a computer, network or server
DES, 3DES
Data Encryption Standard, Triple Data Encryption Standard
Dictionary Attack
Uses known passwords and many variations (upper- and lowercase and combinations) to try to log in to
your account
Diffie-Hellman
Key generation algorithm
Directed Braoadcast
The broadcast is sent to a specific subnet
EAP
Extensible Authentication Protocol
ESP
Encapsulating Security Protocol
Firewall
Used in computer networks for protecting the network; Personal firewall software is typically based on basic packet filtering inspections where the firewall accepts or denies incoming network traffic based on information contained int he packet’s TCP or IP headers.
Full IPv6 Address
All 32 hexadecimal positions contain a value other than 0 (double colons, 32 hex characters, 128 bits)
GRE
Generic Routing Encapsulation
Hex
Hexadecimal, base 16
ICANN
The Internet Corporation of Assigned Names and Numbers
IGMP
Internet Group Message Protocol (Used for streaming media… data is passed through to the application layer
for immediate processing without error checking
IKE
Internet Key Exchange
Internet Layer
Defines the protocols used for addressing and routing data packets
IP (Internet Protocol)
Defines the addressing used to identify the source and destination addresses of data packets being delivered
over an IP network
IP Tunnel
An IP packet encapsulated in another IP packet (a secure VPN connection between two endpoints in
known as an IP Tunnel)
IPng
The next generation IP
IPsec
IP security is used to encrypt data between various networking devices (AES, ESP, and DES are security
protocols, not TKIP which is wireless protocol).
IPv4
The IP version currently being used on the Internet (Dotted decimal) Uses five classes of IP addresses, is
being replaced by IPv6. Made of up 4 bytes and octets. An octet is 8 bits. 4 make up 32 bits of an IP address.
IPv6
IP version 6 (unicast, multicast, and anycast all IPv6 addresses)
ISAKMP
Internet Security Association and Key Management Protocol
L2F
Layer 2 Forwarding
L2TP
Layer 2 Tunneling Protocol
Malware
Malicious programs
MD5
Message Digest 5
Multicast Address
Data packets sent to a multicast address are sent to the entire group of networking devices, such as a
group of routers running the same routing protocol
Multicasting
When one host sends data to many destination hosts
NCP
Network Control Protocol
netstat -a -b
(a) Command used to display the ports currently open on a Windows operating system and (b) used to display
the executable involved in creating the connection or listening port
Network Interface Layer
Defines how the host connects to the network
Non-Internet Routable IP Addresses
IP addresses not routed on the Internet
Packet Filtering
A limit is placed on the information that can enter the network
Packet Sniffing
A technique in which the contents of data packets are watched (assumes that the attacker can see the
network data packets; performed using a machine attached to the network)
PAP
Password Authentication Protocol
PPP
Point-to-Point Protocol (the de facto standard in dial- up VPNs)
PPTP
Point to Point Tunneling Protocol
Prefix length notation
Another shorthand technique for writing the subnet mask except class boundaries are not being crossed
Proxy Server
Clients go through a proxy to communicate with secure systems
RIRs
Regional Internet registries, IANA-designated governing organizations responsible for IP address
allocation by geographical location
SHA-1
Secure Hash Algorithm
Social Engineering
A way for an intruder to obtain enough information from people to gain access to the network
Spoof
Inserting a different IP address in place of an IP packet’s source address to make it appear that the
packet came from another network
Stateful Friewall
Keeps track of the data packet flow
Supernets
The grouping go two or more class networks together; also called CIDR blocks
Supernetting
Allows multiple networks to be specified by one subnet mask (allows the representation of multiple networks
with one address)
SYN
Synchronizing packet
SYN ACK
Synchronizing Acknowledgement packet
TCP
Transport Control Protocol (example of a connection- oriented protocol)
Transport Layer Protocols
Define the type of connection established between hosts and how acknowledgements are sent
UDP
User Datagram Protocol; UDP is a connectionless protocol that doesn’t use acknowledgements
Unicast Address
Used to identify a single network interface address, and data packets are sent directly to the computer with
the specified IPv6 address
Virus
A piece of malicious computer code that, when opened, can damage your hardware, software, or other
files
Well-known Ports
Ports reserved by ICANN
Worm
A type of virus that attacks computers, typically proliferates by itself, and can deny service to networks
10GBASE-T
10Gbps over twisted-pair copper cable (splits the data into 4 channels of 2.5G each) Uses multilevel encoding
to reduce required bandwidth for transmission
ACR
The attention-to-crosstalk ratio measurement compares the signal level from a transmitter at the far
end to the crosstalk measured at the near end. A larger ACR indicates that the cable has a greater data capacity and also indicates the cable’s ability to handle a greater bandwidth. Essentially, it is a combined measurement of the quality of the cable. A higher ACR value (dB) is desirable.
Alien Crosstalk (AXT)
Unwanted signal coupling from one permanent link to another
Attenuation (Insertion Loss)
The amount of loss in the signal strength as it propagates down a wire or fiber strand (leakage and
resistance cause attenuation in fiber optic systems).
Balanced mode
Neither wire in the wire pairs connects to ground
Bottlenecking
Another term for network congestion
Building Entrance
The point where the external cabling and wireless services interconnect with the internal building cabling
Campus Network
A collection of two or more interconnected LANs in a limited geographic area
CAT7/7a and CAT6a
UTP cable standards that support 10GB data rates for a length of 100 meters
Color Map
The specification of which wire color connects to which pin on the connector
Cross-connect
A space where you are going to take one or multiple cables and connect them to one or more cables or
equipment
Crossover Cable
Transmit and receiver wire pairs are crossed (transmit and receive wires crossed, don’t connect to the same
pins on each end)
Crosstalk
Signal coupling in a cable
Delay Skew
This is a measure of the difference in arrival time between the fastest and the slowest signal in a UTP
wire pair
EIA
Electronic Industries Alliance
EIA/TIA 568-B
The standard that defines the six subsystems of a structured cabling system
ELTCTL
Equal Level Transverse Conversion Transfer Loss
EMI
Electromagnetic Interference
Entrance Facilities (EF)
A room set aside for complex electronic equipement
Equal Level FEXT (ELFEXT)
This measurement differs from NEXT in that the measurement is for the far end of the cable. Additionally, the LFEXT measurement does not depend on the length of the cable. This is because ELFEXT is obtained by subtracting the attenuation value from the far-end crosstalk (FEXT!!) loss
Equipment Room (ER)/Backbone Cabling
Cabling that interconnects telecommunication closets in the same building and between buildings
F/UTP
Foil over twisted-pair cabling (better security, noise immunity for EMI) It minimizes signal leakage and
provides noise immunity from EMI
FastEthernet
An Ethernet system operating at 100MBps
Full Channel
Consists of all the link elements from the wall plate to the hub or switch
Full Duplex
Computer system can transmit and receive at the same time (full duplex gigabit Ethernet uses 4 pairs)
Gigabit Ethernet / twisted pair cables
1000Mbps Ethernet; CAT6 and CAT5e rated for 1000Mbps
Horizontal Cabling
Cabling that extends out from the telecommunications closet into the LAN work area
Horizontal Cross-connect (HC)
The connection between the building distributors and the horizontal cabling to the work area or workstation
outlet-another term used for the HC is the floor distributors (FD)
Hybrid Echo Cancellation Circuit
Removes the transmitted signal from the receive signal
IEEE 802.3an-2006 10GBASE-T
The standard for 10 Gbps
Intermediate Cross-connect (IC)
Also called the building distributor (BD), this is the building’s connection point to the campus backbone.
The IC links the MC to the horizontal cross-connect (HC).
LCL
Longitudinal Conversion Loss
Link
Point from one cable termination to another
Main Cross-connect (MC)
Usually connects two or more buildings and is typically the central telecommunications connects point for a campus or building. It is also called the main distribution frame (MDF) or main equipment room. The MC connects to Telco, and ISP, and so on. Another term for the MC is the campus distributor (CD).
Multilevel Encoding
Technique used to reduce in the required bandwidth required to transport the data
Near-end Crosstalk (NEXT)
A measure of the level of crosstalk or signal coupling within the cable, with a high NEXT (dB) value being
desirable.
Network Congestion
A slowdown on network data traffic movement
Nominal Velocity of Propagation (NVP)
NVP is some percentage of the velocity of light and is dependent on the type of cable being tested. The typical delay value for CATD/De UTP cable is about 5.7 nsec per meter. The EIA/TIA specification allows for 548 nsec for the maximum 100-meter run for CAT5e, CAT6, CAT6, CAT6a, CAT7, and CAT7A
Power Sum NEXT (PSNEXT)
The enhanced twisted-pair cable must meet four-pair NEXT requirements, called PSNEXT testing. Basically, power sum testing measures the total crosstalk of all cable pairs. This test ensures that the cable can carry data traffic on all four pairs at the same time with minimal interference. A higher PSNEXT value is desirable because it indicates better cable performance.
Propagation Delay
This is a measure of the amount of time it takes for a signal to propagate from one end of the cable to the
other. The delay of the signal is affected by the nominal velocity of propagation (NVP) of the cable.
PSAACRF
Power-Sum Alien Attenuation Cross-talk Ratio Far-End
PSACR
Power Sum ACR uses all four wire pairs to obtain the measure of the attenuation-crosstalk ratio. This is a measurement of the difference between PSNEXT and attenuation (insertion loss). The difference is measure in dB, and higher PSACR dB values indicate better cable performance.
PSANEXT
Power-Sum Alien Near-End Crosstalk
PSELFEXT
Power sum ELFEXT that uses all four wire pairs to obtain a combined ELFEXT performance measurement. This value is the difference between the test signal level and the cross-talk measured at the far end of the cable. A higher PSELFEXT value indicated better cable performance.
Return Loss
This measurement provides a measure of the ratio of power transmitted into a cable to the amount of power
returned or reflected.
RX
Abbreviation for receive
STP
Shielded twisted pair; not good for noisy environments… blocks EMI, has metal foil placed
around the wires
Straight-through
Transmit and receive signal pairs are aligned end-to- end
Straight-through Cable
The wire pairs int he cable connect to the same pin numbers on each end.
TIA/EIA 568A
Wire color guidelines specified under the EIA/TIA568B standard (developed in 1995)
T568B
Wire color guidelines specified under the EIA/TIA568B standard
TCL
Transverse Conversion Loss
TCO
Telecommunications outlet
TCTL
Transverse Conversion Transfer Loss
Telecommunications Closet
The location of the cabling termination points that includes the mechanical termination and the distribution frames (networking equipment, patch cables, backbone cabling, patch panels)
TIA
Telecommunications Industry Association
TR
Another name for the telecommunications closet
TX
Abbreviation for transmit
Wire-map
A graphical or text description of the wire connections from pin to pin
Work Area
The location of the computers and printers, patch cables, jacks, computer adapter cables, and fiber
jumpers
Workstation or Work Area Outlet (WO)
Also called the TO (telecommunications outlet), it’s used to connect devices to the cable plant. The cable type typically used is CAT3, CAT5, CAT5e, CAT6, CAT6A, and various coaxial cables. Devices typically connected to these outlets are PCs, printers, servers, phones, television, and wireless access points.
Switch
Forwards a frame it receives directly out the port associated with its destination address (get the MAC
addresses form the data packets) Minimize unneeded data traffic, isolate portions of the network
TCP/IP
Transmission Control Protocol/Internet Protocol, the protocol suite used for internetworks such as the
Internet
ThinNet
A type of coaxial cable used to connect LANs configured with a bus topology
Token Passing
A technique where an electrical token circulates around a network-control of the token enables the
user to gain access to the network
Token Ring Hub
A hub that manages the passing of the token in a Token Ring network
Token Ring Topology / Network
A network topology configured in a logical ring that complements the token passing protocol (one failed station causes network shutdown, difficult to reconfigure, diffident to troubleshoot; each system must relay the token, if there is any failure the entire system goes down. It can be hard to determine which one it is.
Topology
Architecture of a network
Transport Layer (4th layer)
Layer of the OSI reference model that is concerned with message integrity between source and destination
Uplink Port
Allows the connection of a hub or switch to another hub or switch without having to use a crossover cable
(an X label is on the uplink ports)
Virtual Private Network (VPN)
Establishes a secure network connection and is a way to protect your LAN’s data from being observed by
outsiders
Wired Network
Uses cables and connectors to establish the network connection
Wireless Network
Uses radio signal to establish the network connection… wireless signal can be incepted easier than wire
signals
Wireless Router
Device used to interconnect wireless networking devices and to give access to wired devices and
establish the broadband Internet connection to the ISP
Absorption
Light interaction with the atomic structure of the fiber material; also involves the conversion of optical power
to heat
Chromatic Dispersion
The broadening of a pulse due to different propagation velocities of the spectral components of the light pulse
(affects both single mode and multimode fibers)
Cladding
Material surrounding the core, which must have a lower index of refraction to keep the light in the core
Dense Wavelength Division Multiplex (DWDM)
Incorporates the propagation of several wavelengths in the 1550-nm range for a single fiber
Dispersion
Broadening of a light pulse as it propagates through a fiber strand (light isn’t a cause of dispersion, it is
affected by dispersion)
Dispersion Compensating Fiber
Acts like and equalizer, canceling dispersion effects and yielding close to zero dispersion int he 1550-nm region (developed to increase the transmission capacity of older cabling; allows the use of 1550nm transmission on lines that were designed for 1310nm region)
Distributed Feedback (DFB) Laser
A more stable laser suitable for use in DWDM systems
DL
Diode laser
Fiber Bragg Grating
A short strand of modified fiber that changes the index of refraction and minimized intersymbol
interference
Fiber Cross-connect
Optical patch panel used to interconnect fiber cables
Fiber, Light Pipe, Glass
Terms used to describe a fiber-optic strand
FTTB
Fiber to the business
FTTC
Fiber to the curb
FTTD
Fiber to the desktop
FTTH
Fiber to the home
Fusion Splicing
A long-term method where two fibers are fused or welded together into one piece of glass
GBIC
Gigabit interface converter (optical-to-fiber interfaced used at 1 gigabit)
Graded-index Fiber
The index of refraction is gradually varied with a parabolic profile (overcomes modal dispersion)
IC
Interconnect fibers branch exchange-item D shows the jumpers connecting the main fiber cross-connect (item
B) to the active equipment (item C)
IDC
Intermediate distribution closet
Index-matching Gel
A jellylike substance that has an index of refraction much closer to glass that to air
Infrared Light
Light extending from 680 nm up to the wavelengths of the microwaves
Isolator
An inline passive device that allows optical power to flow only in one direction
LED
Light-emitting diode
Logical Fiber Map
Shows how the fiber is interconnected and data is distributed throughout a campus (data distribution,
fiber interconnections)
Long Haul
The transmission of data over hundreds or thousands of miles
Macrobending
Loss due to light breaking up and escaping into the
cladding
Mechanical Splices
Two fibers joined together with an air gap, thereby requiring an index-matching gel to provide a good
splice
Microbending
Loss caused by very small mechanical deflections and stress on the fiber
mm
Multimode
Modal Dispersion
The broadening of a pulse due to different path lengths taken through the fiber by different modes
Mode Field Diameter
The acutal guided optical power distribution, which is typically a micron or so larger thent he core diameter;
single-mode fiber specifications typically list the mode field diameter
Multimode Fiber
A fiber that supports many optical waveguide modes; use light in the 850 nm and 1310 nm range
Numerical Aperture
A measure of a fiber’s ability to accept light
Optical Ethernet
Ethernet data running over a fiber link
Optical Spectrum
Light frequencies from the infrared on up
Physical Fiber Map
Shows the routing of the fiber but also shows detail about the terrain, underground conduit, and entries
into buildings
Polarization Mode Dispersion
The broadening of a pulse due to the different propagation velocities of the X and polarization
components of the light pulse
Pulse Dispersion
Stretching of received pulse width because of multiple paths taken by the light
Received Signal Level (RSL)
The input signal level to an optical receiver
Refractive Index
Ratio of the speed of light in free space to its speed in a given material
SC, ST, FC, LC, MT-RJ
Typical fiber connectors on the market (need to be easy to install and economical)
Scattering
Caused by refractive index fluctuations; accounts for 96 percent of attenuation loss
Single-mode Fiber
Fiber cables with core diameters of about 7-10 um; light follows a single path (use light in the 1310 nm
and 1550 nm range) Uses high-power, highly directional modulated light sources; single-mode fibers are used with lasers.
sm
Single mode
SONET/SDH
Synchronous optical network; protocol standard for optical transmission in long-haul
communication/synchronous digital hierarchy
STS
Synchronous transport signals
Tunable Laser
Laser in which the fundamental wavelength can be shifted a few nanometers, ideal for traffic routing in
DWDM systems
Vertical Cavity Surface Emitting Lasers (VCSELs)
Lasers with the simplicity of LEDs and the performance of lasers
XENPAK, XPAK, X2, XFP, SFP+
The ten gigabit interface adapter
Zero-dispersion Wavelength
Point where the dispersion is actually zero
Aging Time
The length of time a MAC address remains assigned to a port; length of time an IP address is assigned to a
switchport
ARP Cache
Temporary storage of MAC addresses recently contacted
ARP Table
Another name for the ARP cache
Association
Indicates that the destination address is for a networking device connected to one of the ports on the bridge (describes a wireless connection and MAC address: wireless connection has been obtained, provides the client MAC address)
AUI Port
This is a 10Mbps Ethernet port. AUI stands for “attachment unit interface.”
Auto-negotiation
Protocol used by interconnected electronic devices to negotiate a link speed (failed negotiation can cause a
link failure, not recommended for fixed data links) The link can only go as fast as the slowest link.
Auxiliary Input
Used to connect a dial-in modem into the router. The auxiliary port provides an alternative way to remotely
log in to the router if the network is down. This port also uses an RJ-45 connection
Bridge
A networking device that uses the MAC address to forward data and interconnect two LANs (easy to install) Only forwards data to the specified port, isolates the network traffic, uses MAC addresses to forward data packets. The association tells the bridge where to forward a data packet.
Bridging Table
List of MAC addresses and port locations for hosts connected to the bridge ports
Broadcast
Transmission of data by a network device to all devices connected to its ports
Broadcast Domain
Any network broadcast sent over the network will be seen by all networking devices in this domain
Broadcast Storm
Excessive amounts of broadcasts; can cause network slowdowns
Cisco Network Assistant (CNA)
A management software tool from Cisco that simplifies switch configuration and troubleshooting
Console Input
Provides a RS-232 serial communications link into the router for initial router configuration. A special cable, called a console cable, is used to connect the console input to the serial port on a computer. The console cable uses RJ-45 plugs on each end and requires the use of an RJ-45 to DB9 adapter for connecting to the COM1 or COM2 serial port
Content Addressable Memory (CAM)
A table of MAC addresses and port mapping used by the switch to identify connected networking devices
Cut-Through switching
The data packet is forwarded to the destination as soon as the destination MAC address has been read; cut through switching doesn’t read the entire frame,
just the MAC address. Low latency
Dynamic Assignment / Addressing
MAC addresses are assigned to a port when a host is connected (addresses are assigned dynamically when
using dynamic addressing)
Enterprise Network
Term used to describe the network used by a large company
Error Threshold
The point where the number of error in the data packets has reached a threshold and the switch
changes from the cut-through to the store-and- forward mode
Fast Link Pulse (FLP)
Carries the configuration information between each end of a data link (designed to operate over limited
bandwidth)
FastEthernet Port (FA0/0, FA0/1, FA0/2,…)
Naming of the FastEthernet ports on the router
Flooding
The term used to describe what happens when a switch doesn’t have the destination MAC address
stored in CAM
Gateway
Describes the networking device that enables hosts in a LAN to connect to networks (and hosts) outside the
LAN
Half-Duplex
The communications device can transmit or receive but not at the same time
Isolating the Collision Domains
Breaking the network into segments where a segment is a portion of the network where the data traffic from
one part of the network is isolated from the other networking devices
Layer 2 Switch
An improved network technology that provides a direct data connection for network devices in a LAN
Logical Address
Describes the IP address location of the network and the address location of the host in the network
Managed Switch
Allows the network administrator to monitor, configure, and manage select network features
(managed switches can be managed remotely)
Media Converter
Used to adapt a layer 1 (physical layer) technology to another layer 1 technology
Multicast
Messages are sent to a specific group of hosts on the network
Multilayer Switch (MLS)
Operates at layer 2 but functions at the higher layers
Multiport Bridge
Another name for a layer 2 switch
Network Address
Another name for the layer 3 address (routers use the network address to route packets)
Network Slowdown
Degraded network performance
Power On/Off
Turns on/off electrical power to the router
Router Interface
The physical connection where the router connects to the network; serial, ethernet, and auxiliary can all be
used to connect to the network.
Routing Table
Keeps track of the routes to use for forwarding data to its destination
Secure Address
The switch port will automatically disable itself if a device with a different MAC address connects to the
port
Serial Port (S0/0, S0/1, So/2,…)
Naming of the serial ports on the router
Serial Ports
Provides a serial data communication link into and out of the router, using V.35 serial interface cables
Store-and-Forward
The entire frame of data is received before any decision is made regarding forwarding the data packet
to its destination
Switch Latency
The length of time a data packet takes from the time it enters a switch until it exists
Translation Bridge
Used to interconnect two LANs that are operating two different networking protocols
Transparent Bridge
Interconnects two LANs running the same type of protocol
Wire Speed Routing
Data packets are processed as quickly as they arrive
Access Point
A transceiver used to interconnect a wireless and a wired LAN (looks at the SSID to determine if the data
packet is intended for its network)
Ad Hoc
Another term used to describe an independent network
Backscatter
Refers to the reflection of the radio waves striking the RFID tag and reflecting back to the transmitter source
Basic Service Set (BSS)
Term used to describe an independent network
Beacon
Used to verify the integrity of a wireless link
BWA
Broadband wireless access
CSMA/CA
Carrier sense multiple access/collision avoidance
DSSS
Direct sequence spread spectrum
Extended Service Set (ESS)
The use of multiple access points to extend user mobility (allows a wider range of wireless signals using
roaming)
FHSS
Frequency hopping spread spectrum
Hand-off
When the user’s computer establishes an association with another access point
Hopping Sequence
The order of frequency changes
Inquiry Procedure
Used by Bluetooth to discover other Bluetooth devices or to allow itself to be discovered
ISM
Industrial, scientific, and medical
Last Mile
The last part of the connection from the telecommunications provider to the customer
MIMO
A space-division multiplexing technique where the data stream is split into multiple parts called spatial
streams (uses space-division multiplexing to transmit different data streams in parallel)
NLOS
Non-line-of-sight
OFDM
Orthogonal frequency division multiplexing
Paging Procedure
Used to establish and synchronize a connection between two Bluetooth devices
Pairing
When a Bluetooth device is set up to connect to another Bluetooth device
Passkey
Used in Bluetooth Security to limit outsider access to the pairing
Piconet
An ad hoc network of up to eight Bluetooth devices
Pseudorandom
The number sequence appears random but actually repeats
Radio Frequency Identification (RFID)
A technique that uses radio waves to track and identify people, animals, objects, and shipments (full speed
tollbooths, tracking shipments, border crossings) Parameters that define an RFID system is frequency of operation, power, and protocol
RADIUS
Remote Authentication Dial-In User Service (prevents unauthorized users to connect to the network as well as preventing users form connecting to rogue access
points)
Roaming
The term used to describe a user’s ability to maintain network connectivity as he moves through the
workplace
Site Survey
Performed to determine the best location(s) for placing the access point(s) to provide maximum RF coverage
for the wireless clients (conducted both inside and outside)
Slotted Aloha
A wireless network communications protocol technique similar to the Ethernet protocol
Transceiver
A transmit/receive unit
U-NII
Unlicensed National Information Infrastructure
Wi-Fi
Wi-Fi Alliance(md) and organization that tests and certifies wireless equipment for compliance with the
802.11x standards
WiMAX
A broadband wireless system based on the IEEE 802.16e standard (30 miles max range)
WLAN
Wireless local area network
WPA
Wi-Fi Protected Access
The Transport Layer (4th layer)
The transport layer protocols in TCP/IP are very important in establishing a network connection, managing the delivery of data between a source and destination host, and terminating the data connection (TCP and UDP are the only protocols on the Transport layer).
HTTP Port Number
80
Bluetooth
Operates in the 2.4 GHz band; 802.11n, 802.11b, 802.11g (802.11a operates in the 5Gz range)
Core size of multimode cables
62.5
Patch Cable
Used to make the physical connection to the wall plate
Stretching of a received pulse is due to
Pulse-dispersion and Multiple paths taken by the light waves
EIA/TIA568-B.2 and 568-2.1
specify the cabling components and transmission of copper cabling hardware
10.10.20.250
Example of a private IP address, a nonroutable Internet IP address, Class A address
Antivirus software
Signatures or definitions contain traits of the specific virus or worm
MAC address filtering
Only devices with specified layer 2 addresses will be allowed to access the network… lets you specify which
devices can connect to the network
10101010
Provide MAC functions to allow users to connect to each other; provides 802.11 MAC layer functions
Cisco LEAP
User must provide the correct password
Router Routing tables
Keep track of the addresses needed to route data. Contains addresses of adjacent routers and the
networks that they can reach. It also includes the metric and method of learning the route. Use the ip route command to the the routing table.
Maximum length for multimode fiber optic cable
2000 meters or 2 km
Wired networks
Can have data rates as high as 100Gbps
no ip directed-broadcast network command
Prevents networks from becoming intermediate sites for network attacks. On a Cisco router prevents a
network form becoming an intermediate site for a network attack
Hexadecimal equivalent of 1011
B = 1011 = 11
Serial Interface
Used to create a T1 connection; sometimes has a built-in CSU/DSU
802.11 technologies
Don’t use visible light; use FHSS, DSSS, infrared
Secure a wireless home network
Turn on encryption; turning on WEP, WPA or WPA-2 will encrypt the data
Class C usable IP network addresses
192.0.0.0 - 223.255.255.255 (there are 24 network bits; the first three octets are used with 24 bits total)
150.25.191.255
broadcast address for 150.25.151.68 with a mask of 255.255.192.0
How many wire pairs are used for gigabit Ethernet
4: all 4 wire pairs are used for transmission at 1 Gbps speeds
Wireless security guidelines
Use firewalls, turn on access point security features. Technology in any frequency band may be used and
3rd party tools must be used end-to-end.
Network Segment
A segment is associated with each networking device; the networking link between 2 LANs
Intrusion detection
the monitoring of data packets passing through the network to catch potential attacks; the monitoring of
data packets passing through the network to catch ongoing attacks. The first issue of intrusion is Social Engineering.
Private IP address
Cannot be used on the Internet, only Intranets
OC-3 bit rate
155.52 Mbps
UTP wire pair length difference
can be due to poor manufacturing, can be due to inconsistent twists, cause the cable not to be certified… cable testing will reveal these issues. The inconsistent length can cause failure if one wire is over 100 meters while the others are not. Due to the difference in the cable twists for each wire pair.
255.255.255.224
Expressed as a /27 using CIDR notation because there are 27 1s in the subnet mask
192.168.55.0 dived into multiple subnets, need at lest 30 host ID’s in each subnet; maximum number of subnets you could have?
8: Class C address and we must use 5 bits for our hosts (2 to the 5th -2 = 30 hosts). That leaves 3 bits to use for subnets. 2 to the 3rd = 8 subnets.
Probing
Indicators of repeated attempts to make connections to certain machines
Core
Carries the light signals in a fiber optic cable
Static assignment
MAC address that has been manually assigned
SMTP Port Number
25
Router
Interconnect LANs; routers know where to send packets coming into or leaving the LAN; router ports
commonly refereed to as interfaces which provide the physical connection to the network
Ethernet (DIX) frame after the Preamble
Destination address, Source address, Type/Length, Data, Pad, FCS
Fiber optic communication system
Source, cable, connectors, photodiode… the link may have splices but it must have connectors
255.255.252.0
Expressed as /22 using CIDR notation becasue there are 22 1s in the subnet mask
Well-known ports
ICANN reserves these ports for particular protocols
SYN Flood
Attackers send SYN packets to set up virtual connections that use up the connection buffer…
denial-of-service attack characterized by using all connections available on a computer
How many usable host IP addresses are provided: network IP address of 192.168.12.0 and a subnet
mask of 255.255.255.252
2
Telnet Port
23
DSL Modem
Used to connect to a broadband network through your telephone connection only. Broadband modems can
connect using cable or telephone technology.
Physical Architecture of a computer network
Topologies, A physical topology is the actual layout of the network.
SLA ID
Used to identify subnets in an IPv6 address
802.11u
802.11x standard increases security by incorporating user authentication, not 802.11u
Correct order sequence of packets that are sent to set up a virtual TCP connection
The three-way handshake is used to create virtual TCP connections: SYN, SYN-ACK, ACK
802.11g advantage
Compatible with 802.11b, high speed
What tools are needed to make a UTP cable?
Crimping Tool and strippers are used to terminate UTP cables
FTP Port Number
21
Layered Protocol Specifications
Multi vendor interoperability, easier to develop, easier to learn; Multivendor engineering not a benefit because doesn’t specify how it should work, just what it needs to be able to do.
Designing a LAN
- document all devices 2. develop and addressing scheme, physically connect devices and configure
devices to communicate
With an address of 197.15.22.31 and a subnet mask of 255.255.255.224 how many bits have been borrowed to create a subnet?
- 224 = 11100000, 3 bits on
Light detector characteristics
Responsitivity, response speed, spectral response
Decimal equivalent of 11110000
11110000 = 240
