Day 1 Flashcards
The primary motivation for networking:
The need for people to share data and to communicate quickly and efficiently. Benefits of networking: --file sharing --electronic mail --device sharing
protocols
allow computers to establish and maintain useful communication at various levels
Local Area Network (LAN)
Small network, limited to a single connection of nodes and one or more cables contained in a building or relatively small geographic area (intranetwork)
Wide Area Network (WAN)
Links two or more separate locations and can span a relatively large geographic area. (internetwork)
Two major types of network architecture
Peer-to-peer network and Client-Server Network
Peer-to-peer network
computers connect with each other in a workgroup to share files, printers, and internet access. There is no server
Client-Server Network
There is usually a central server to which all computers logon
DoD Information Network (DODIN)
The collection of networks owned and managed by DoD
Non-Classified Internet Protocol Router Network (NIPRNet)
DoD’s unclassified but sensitive Internet Protocol Router Network
Secret Internet Protocol Router Network (SIPRNet)
DoD’s secret internet protocol router network. it is a classified tunnel carried over NIPRNet. Provides a secure transmission of data to the secret classificaiton level
Joint Worldwide Intelligence Communications System (JWICS)
DoD’s network for handling up to the top secret classified information, including Sensitive Compartmented Information (SCI). JWICS is a dedicated collection of equipment and circuits that are independent of the internet.
Network topologies
specify the geometric arrangement of the physical layout of a network
bus topology
has a series of devices, daisy chained, with successive coaxial cable and appropriate connectors and terminators
star topology
network with a concentrator/hub device that acts as a central point for all cabling
The hub is a single point of failure
Ring topology
networks connect devices in a complete ring
token ring
uses a token-passing mechanism to control which systems can transmit data over the network medium.
mesh topology
every device can connect to every other device via more than one route
partial mesh topology
consists of at least two machines with redundant connections
full mesh topology
is an organized grouping of devices where every device connects to one another
full mesh topology formula
n(n-1)/2
n= number of nodes
hybrid topology
combines the aspects of bus, star, or ring topologies into one network
point to multipoint topology
consists of multiple devices connecting to a single device in order to communicate.
computers on the network communicate with the central device but not with the other.
this differs from a star topology because a star topology computers communicate with each other.
coaxial cabling
-almost obsolete in LAN installations
network installations requiring a rugged means of cabling and delivery of cable television and internet access to residential areas still use coaxial cables.
more about coaxial cabling
coaxial cabling used in physical bus topology networks is referred to by Ethernet as “thinnet” and “thicknet”. Networking refers to it as 10Base2 and 10Base5
- 10 is the speed in Mbps at which devices operate
- Base indicates baseband transmission
- 2 and 5 indicate length in 100’s of meters for the maximum segment length
Twisted pair cabling
most popular medium for voice and data transmission in LAN’s and WAN’s.
A different number of twists per inch used for each pair reduces interference, called crosstalk, from adjacent pairs and other electrical devices
Shielded Twisted Pair (STP)
includes a wire braid inside the cladding or sheath material and a foil shielding around each wire pair.
UTP has no sheathing material or foil inner wrapper
Unshielded Twisted Pair (UTP)
UTP has no sheathing material or foil inner wrapper
CAT5 cable
most common twisted pair cabling.
supports voice and data up to speeds of 1000 Mbps
uses an RJ-45 connector
straight through cables
used to connect different networking devices to each other
crossover cables
used to connect like devices to each other
fiber optic cabling
transmits pulses of light rather than electrical signals eliminating the problem of EMI, radio frequency interference, or inductance
single mode
- made of small diameter glass fiber
- single transmission path
- higher bandwidth than multimode
- requires the use of lasers as light source
- supports longer transmission distances and higher transmission rates than multimode
- costs more to implement
multimode
- has a larger diameter core
- supports multi-propagation paths
- cheaper to implement
- provides lower bandwidth than single mode
- uses LED as light source
- used for short distance communication
Wireless Access Point (WAP)
antenna that translates between wireless and wired networks
Service Set Identifier (SSID)
designates and separates each wireless network
data transmission methods
baseband and broadband
baseband
uses only a single fixed frequency to send a signal that occupies the cable’s entire carrying capacity
broadband
carries multiple channels on a single cable, where one channel is required to send and another to receive
digital signals
carries data in a digital form using values of electrical voltage or current or as an on/off light source.
less susceptible to noise and interference
analog signals
uses a continuously varying waveform to carry data.
Digital/Telecommunications Convergence
the combination of voice, data, video, and pictures
Public Switched Telephone Network (PSTN)
the world’s largest interconnected voice-oriented public telephone networks.
almost entirely digital and includes mobile and fixed telephones
Plain old telephone service (POTS)
the original fixed-line analog telephone system
Integrated Services Digital Network (ISDN)
an international communications standard for sending voice, data and video over telephone lines.
supports data transfer rates of 64 Kbps utilizing baseband or digital signals
Digital Subscriber Line (DSL)
a modulation scheme to pack data onto copper lines or existing telephone lines.
offers data transmission speeds of up to 100 Mbps with the proper equipment and three types of service (Asymmetric DSL, Symmetric DSL, Very High Bitrate DSL)
Asymmetric DSL
(ADSL) allows for faster downstream data rates than upstream rates
Symmetric DSL
(SDSL) Supports same data rates for upstream and downstream transfers
Very High Bitrate DSL
(VDSL) provides up to 100 Mbps upstream and downstream speeds
Asynchronous Transfer Mode (ATM)
high speed network technology designed for use on both LANs and WANs.
It is connection-oriented and uses a dedicated circuit between switches.
supports data, voice, and video in real time using 53-byte fixed length cells
Synchronous Optical Network (SONET)
a high-speed, digital networking standard that specifies data rates over fiber-optic connections.
uses a baseband signal, providing for synchronous communications.
Partnered with ATM where ATM is the underlying signalling technology, while SONET is the overlying communications standard.
Footprint
the area on the earth that the satellite signal strikes regardless of orbit type
geostationary orbit
satellite appears to hang motionless over a point on the equator.
enables the satellite to be visible or accessible from roughly 30 to 40 percent of the Earth’s surface
elliptical/non-geostationary orbit
provides wider coverage than geostationary orbit.
apogee-the orbit point farthest from Earth
perigee-the orbit point closest to the Earth.
more than satellite is needed in order to provide 24/7 coverage
Very Small Aperture Terminal (VSAT)
networking services such as data, voice, video, and fax transmissions are delivered using geostationary satellites.
work in a mesh or star topology
VSAT mesh topology
communications go from the VSAT to satellite and then directly to the destination VSAT
VSAT star topology
communications must go through a hub station
VSAT configurations
point-to-point, point-to-multipoint, and multipoint-to-point
point-to-point
communications occur between two or more earth stations.
uses mesh topology
point-to-multipoint
one transmitter and multiple receivers.
uses star topology
multipoint-to-point
multiple transmitters and one receiver acting as a hub.
uses star topology