Network Terms Flashcards
API
built-in software that programmers can use to make their programs network aware
Broadcast Address
MAC address FF-FF-FF-FF-FF-FF has never sent to a particular NIC. All systems process frame and correct system responds with its MAC address.
Define Frame
container for a chuck of data mnoving across a network; holds about 1500 bytes of data.
Define Protocol
operate at all OSI layers and are defined as sets of defined rules, regulations, standards, and procedures that enable hardware and software developers to make devices and applications
Encapsulation layer and corresponding data structure
Link = frame internet = IP packets transport = TCP or UDP datagram Application = data starts and ends here
Frame
not all networks are ethernet networks and use the ethernet pneumonic canister-type frame. IP packets fit in all sorts of ‘canisters’
Frame Structure
Recipents MAC address–>Senders MAC address–>Data–>FCS
How do NICs send data
charge on wire = 1
no charge on wire = 0
all binary
How frames are received
NIC receives frame and checks FCS, if correct it strips off data and sends to internal software
How frames are sent
NOS software in OS hands data to NIC. NIC builds frame, adds FCS, adds MAC addresses, waits until cable is clear and NIC sends to HUB. Hub copies and sends to all systems. Every NIC without correct MAC address erases it
IEEE
Institue of electronics engineer, give out MAC addresses, official term for MAC address is EUI-48 or MAC-48
IP
internet protocol (aka logical address). unique numeric identifier. 8 decimals. four 8-bit numbbers. each 8-bit number ranging from 0-255. Not burned in like MAC address but most be configured by system software
ipconfig /all
windows command for displaying physical address (MAC address)
LLC vs MAC
LLC - aspect of NIC that talks to OS, builds frames and creates CRC, also responsible for incoming frames
MAC - media access control; remembers NIC’s own MAC address and attaches to each frame then responsible for sending frames (these are the TWO SUB-LAYERS OF LAYER 2-data link layer in only with sub layers)
MAC address
media access control address; 48-bit value burned into ROM chip in NIC.
Model
simplified representation of a real thing. must have all major functions of the real item
Network Protocol
Medium/large networks. When physical MAC address won’t cut it. Network protocols creates unique identifiers in a logical addressing method for their systems AND create rules on how each system handles chopped packets, and how to send such packets between systems. (i.e. TCP/IP)
NIC
Network interface card; gives each system a unique identifer, MAC address. (operates at both layers 1 and 2; but pick 2 if cornered)
OSI
international organization for standardization
OSI Layers
Layer 1 - Physical Layer 2 - Data Link Layer 3 - Network Layer 4 - Transport Layer 5 - Session Layer 6 - Presentation Layer 7 - Application
OUI
organizationally unique address, first 6 digits of MAC address issued to NIC manufacturer by IEEE
Physical Layer
defines method of moving data between computers (cables, hubs, copper cabling, fiber optics and radio waves)
Router
magic box that makes logical addressingg possible. connects subnets. routers use IPs not MAC addresses to route data
TCP/IP network
every system has a MAC and IP address. Data is wrapped in two distinct containers (simplified).
1- Frame, outher shell which enabled data to be moved from one device to antoher
2- Packet, IP specific container that tells routers where to send data and also includes data itself
How packet is sent: 1-router stips off incoming frame; 2-reads packet to know where to send it; 3-creates a new frame and sends it on its way. (frame can be number of technologies depending on the router)
UTP
unshielded twisted pair, contains four wires that can transmit and receive data
Bus and Ring
first generation of wired networks. Bus- single cable that connects all computers in a line (needs terminators at endpoint). Ring- connect all computers with a ring of cable. Weakness.. one break, everything goes down
3 Cabling Types
Coaxial, twisted pair, fiber optic
CAT (catergory ratings for UTP)
rated in MHz, indicates highest frequency cable can handle. cat3=16/16/recognized cat5=100/100/nr cat5e=100/1000/R cat6=250/10000/R
Coaxial
contains central conductor wire surrounded by insulation material, which is then surrounded by braided metal. cable modems connect w/ rg-6 (rarely rg-59). Accessories are barrel connectors and coax splitter
Duplex fiber optic cable
Fiber optic requires two cables (sending and receiving usually bundled together in one lump cord); popular
EMI
Electromagnetic Interference; many devices generate magnetic fields, causing electric current on wire if not protected. Used in early networks w/ bayonet style connectors called BNC. Vampire taps actually pierced the cable.
F-type connector
Used on coaxial cable it screws on, making secure connection
Fiber Optic Connectors (3 types)
ST (straight tip/bayonet)
SC (stick&click)
LC (doubletip)
Fiber Optic cable components
- Glass fiber (core piece of glass)
- Cladding (makes light reflect)
- Buffer (gives material strength)
- Insulating Jacket; most common cable is called 62.5/125 um (core/cladding size)
Fire Ratings
Three is PVC (very smokey) and Plenum (expensive but less smoke). plenum is the name of the space between ceiling and acoustical tiles. Plenum used for most runs in between floors
Hybrid
shrinking bus/star and placing in a central box. Anything that combines physical with signaling topology
HZ
Hertz; each cycle accounts for one bit of data per second. Now there is bandwidth-efficient schemes which can put more bits per signal
Mesh Topology
Wireless topology; every computer connects to each other via two or more routes
MMF vs SMF
MMF - multimode fiber; uses LED’s to send signals, wavelength is 850nm
SMF - singlemode fiber; uses lasers (eliminates modal distortion) wavelenght is 1310 or 1550nm.
Network Technology
practical application of a topology that provides a method from getting data from one computer to another. ie Ethernet and types 10baseT, 1000BaseF, etc.
Networking Standards, IEEE
Institute of electrical and electronic engineers, IEEE 802 sets standards for networking & defines frames, speeds, distances, and types of cabling. Since split into smaller subcommittes (working group) 802.3 (ethernet) and 802.11 (WLAN) among others. IEEE 1284 (parallel communication); IEEE1394 (firewire standard)
Other cables; quick and dirty connections (3)
Classic serial or RS-232 (not changed since 1969); parallel, 25pin used on some printers still; firewire (also point to point but fast 800mbps)
Partial vs Full Mesh
Full Mesh - very computer connects to every other computer. know calculations for number of connections needed. #### = y (y-1)/2. *y- number of computers
Partial Mesh - at least two machines have redundant connections.
physical vs logical topology
physical=how cables physically look.
logical=how the signals travel electronically aka signaling topology
point to multipoint
wireless network. similar to star but requires a intelligent device that helps systems converse. found in wired/wireless network
point to point
two computers connect with no need for central device. found in wired/wireless network
RG
Radio Grade; only thing that matters is OHM (how much cable resists electricity and holds electricity) most modern coax use 750ohm
RJ Connectors
Registered Jack connectors use with UTP cable. Telephones use RJ-11 (supports 2 wires); networks use four-pair wires, RJ-45 connectors
Star Topology
used a central connection box for all computers, offers fault tolerance. not as popular initially cause bus/ring cheap
Topology
Ways of connecting computers together
Twisted Pair (2 types)
Most common type in networks, cables twisted together into a common jacket.
STP - shielded twisted pair; uncommon, not usually needed except around machinery
UTP - unshielded twisted pair; most common type of cabling today.
*8 wires surrounded by thick plastic coat, aka patch cable.
10BaseFL or 10BaseF
Fiberoptic multi-mode and uses an SC or ST connector. 10 mbps, baseband, 2000 meters from hub to node, starbus, physical star, logical bus.
10BaseT
IEEE 802.3 created in 1990. Most popular networking tech in world at time, beating out appletalk and token ring. 99% used it. Consists of two machines connected to a hub. **10(stands for MB speed) base means carry on signal to diff). T stands for twisted pair. mose use UTP CAT3 or better with RJ-45.
10BaseT limitations
no more than 100 meters in length from hub to PC.
no more than 1024 computers (no one has that many because hubs arent that big)
Speed, 10mbps, baseband signal, starbus: physical start; logical bus topology, cat3 or better with RJ-45
568A vs 568B standards
see A plus for pictures
BPDU
Bridge protocol data unit; a special frame between switches that detects distances and changes to networks
Bridge
connects ethernet segments through uplink ports. if connecting multiple hubs, put one cable in uplink to regular port on the next hub (daisy chain)
Bridge Loops or Switching Loops
redundant connections only possible in a switched network
Bridges
acts like a repeater or hub to connect two ethernet segments, however also, filters (stop traffic from crossing one network to the next) & forwards (pass traffice from one side to the next). traffic between segments based on MAC address. Layer2 OSI and link/network of tcp/ip model. mostly used in wireless
Broadcast vs Unicast domain
Unicast - messages always go to intended recipient w/ switch. Switch sends all broadcast messages to all ports
Broadcast = switch, vs hub-based is called collision domain
Collision Domain
ethernet networks means a group of nodes can send frames at the same time resulting in collisions
connecting multiple switches
connect anyway you want, no need to daisy chain
crossover cables
one end is 568A other is 568B. you plug into regular port, not uplink
CSMA/CD
Carrier sense multiple access/ collision detection; Network access method for Etherne. Determines which computer should use a shared cable. if cable senses for 2 ms that cable is not in use, it sends. If in use, it waits. Good network has maximum of 10% collisions.
Data
contains actual payload. if its IP packet it will carry a bunch of other data like IP addresses, sequencing numbers, etc.
Diagnosing steps for hubs/switches (low-end)
- recognize problem by plugging in device and can’t connect to network
- examine switch for obvious damage
- look at link lights, not flashing, try diff port
- Look at cables, replace if needed
- replace if necessary (at emc, just reset/reboot
Ethernet
standard for a family of networking technologies that share the same basic bus topology, frame type, and network access method. Defines all issues involved with transferring data between computers. Started at Xerox, later transferred power to 802.3 IEEE
Ethernet Frame (7)
Preamble MAC address of recipient MAC address of sending system type of data data pad frame check sequence or CRC (cyclic redundancy check)
Ethernet topology
uses hybrid star-bus, used to have hub at center
FCS
Frame check sequence; ethernet term for CRC. when sending machine sends data it runs through an algorithm and attaches result (fcs). Receiving machine opens frame, uses same algorithm and compares to result. If bad, sending machine resends data
Frames
all network technologies break data into smaller pieces called frames, ethernet also. Eliminates monopolizing of wire and speeds up resending of bad data
Full Duplex ethernet
no more collisions. CSMA/CD disabled. Imagine a one-lane road being expanded to two lanes. speed limit is same. but doubles bandwidth
Full vs. half-duplex
halfduplex are nics that can only communicate in one direction at a time (ex: walkie-talkie), full-duplex can send and receive (like a telephone call)
Hub
nothing more than a repeater; reads and repeats to every other wire connected to it
MAC addresses
each NIC (or node) on an ethernet network must have unique MAC binary address (48bit)
MDI and MDIX
MDI is regular port on a hub or switch. MDIX is an uplink port
Media Converter (4 types)
interconnects ethernet types such as:
- 10BaseT and F.SMF to UTP/STP
- MMF to UTP/STP
- FIBER to COAXIAL
- SMF to MMF
Packet vs. Frame
Frames based on MAC addresses; packets are data assempled by IP protocol at layer 3 of OSI
Pad
**minimum frame size is 64bytes. If its less, sending NIC will add a padding to bring it up to 64.
Preamble
64-bit series of 0’s and 1’s that ends with 11. It basically gives receiving NIC time to realize a frame is coming. Added by sending NIC
SAT table
when switch starts to act like a hub, but then copies MAC addresses and acts like telephone operator creating on the fly connections and creates an electronic table with associated ports to MAC address
Sniffers
has NIC run in promiscuous mode reading every frame despite recipient MAC address portion of frame
STP
Spanning tree protocol; eliminates problem of accidental bridge loops, detects loops and can block loop ports state to block
Three most common issues with hubs/switches (low-end)
physical damage/ dead ports/ general flakiness
Type of data
Ethernet frame may cary several types of data. Just show very basic level like it contains IPv4 or IPv6 data (not its an email or web page, etc.)
RJ-45
pins labeled 1-8, each can have a separate voltage on it. 1&2, send data; 3&6, receive data
Switch
provdes additional bandwidth, like a hub but creates point to point connection between computers w/ full bandwidth. layer 2
10GbE
10 Gibabit Ethernet
10GBaseT
works just like slower Ethernet standards
100BaseFX
SPEED = 100 mbps; SIGNAL = baseband; DISTANCE = 2 kilometers; NODE LIMIT = 1024; TOPOLOGY = star-bus, physical start, logical bus; CABLE TYPE = multimode fiber-optic cabling with ST and SC connectors
100BaseLX
long distance, uses laser, distance anywhere from 5-70 kilometers; *future of ethernet
100BaseT
originally 100BaseTX competed with…T4. TX won and was dominant by late 90’s. SPEED = 100mbps; SIGNAL = baseband; DISTANCE = 100 meters between node/nub. NODE LIMIT = 1024 nodes. TOPOLOGY = star/bus topology, physical star, logical bus. CABLE TYPE = cat5e or better with RJ-45
100BaseT NIC
auto negotiates to what switch can handle. All modern NICs are multispeed and auto-sending.
1000BaseCX
used unique twinaxial copper cable that is shielded and 150-Ohm w/ limits of 25 meters. Not too popular today
1000BaseSX
uses multimode w/ max cable length of 220-500 meters. Used LED. commonly uses LC connector. very common for peeps wanting to upgrade to gigabit ethernet.
GBIC
Gigabit interface converter. SImply pull out a gbic module that supports one flavor and plug in another
Gigabit ethernet aka 1000BaseT
today most common type of ethernet found on new NIC’s. late 1990’s, length is 100 meters.
Two Types:
1000BaseT; dominant
1000BaseX (with subcategories)
MSA’s
transceiver plugs into equipment and lets you plug in corresponding transceiver. Helps to link different types of 10GbE networks
SFF and MT-RJ
Small form factor; smaller SC connector.
MT-RJ; was the first and is still very popular with cisco. LC is a SFF connector; **most popular
100 Block aka 110-punchdown block
Connector used for back of patch panels. UTP cables connect to block with a punchdown tool. 66block used on on older telecommunications
Activity light
turns on when NIC card detects network traffic
attenuation
as signal progresses down a wire, it gets steadily weaker
Bonding
Switches that allow multiple NICS to a single machine. aka link aggregation. doubles the speed between the machine and switch
Cable Drop
location where cable comes out of the wall or workstation
Cable testers
Verify both ends of cable are terminated correctly.
CONTINUITY TESTER = cheap, insert both cables into tester
WIREMAP = more advanced, picks up shorts, crossed wires and more
MULTIMETER = works just like continuity testers
CABLE CERTIFIERS = can do NEXT and FEXT
Cable Trays
todays standards, hold wires over drop ceilings
Collision Lights
on older networks flashes when detects collision
Crosstalk
Typical UTP cable has 4 pairs of wires. Sometimes one signal can jump to another, aka crosstalk. NEXT, near-end crosstalk is when a device listens to the other three cables and measures interference. FEXT, far-end crosstalk when you listen on opposite end of cable run. Measured in DB
Demarc
connections from the outside world come into a building to a location called demarc. Dividing line of responsibility for the functioning network
Demarc Extension
Cabling that runs from NIU to customers box. For telephones the box is a multiplexer and on LAN-side is a a powerful switch w/ patch panel. That patch panel leads to every telecommunications room
Equipment Racks
central component. provides safe, stable platform for all hardware components. all are 19 inches wide but height varies
Fiber Channel Issues (3)
Attenuation - when light signal weakens over long distance
Light Leakage - when bending a fiber cable too much
Modal distortion - modes are lights being shot at different angels
Fiber testers
OTDR = optical time domain reflectometer; determines continuity and tells you exaclty where a break is
Horizontal cabling
all cables run from telecommunication to computers horizontally. Cat 5e or CAT 6 UTP better UTP. Should always be solid core.
LACP
Link aggregation control protocol; controls how multiple network devices send and receive data as a single connection
Link Lights
leds that give information about state of NIC; if its connected to a hub or switch. Link light that flickers indicate problem.
Loopback plug and loopback test
Test sends data out of the NIC and checks if it comes back. True loopback test you need the plug you put into NIC’s port.
Low-voltage mounting bracket
outlet box that acts as a holder for the faceplate
MDF
Main distribution frame - room that holds Demarc, and telephone/LAN cross-connects.
NIC’s Types
UTP used RJ-45 connector and Fiber. Are either integrated into motherboard or inserted into 1 of 2 slots. PCI (older peripheral component interconnect) and the new PCIe expansion slot. and portable USB NICS
NIU
in private homes. DSL or modem supplied by ISP is the network interface unit that serves as demarc for responsibility.
Optical connection tester
plug end of fiber into it to see if connection is good. Hard to tell by naked eye, fiber nics dont have link lights.
Patch cable
connects ports in patch panel to switch. Typically 2-5ft UTP cables stranded
Patch panel
a box with a row of female ports in the frong and permanent connections in the back, where you install horizontal cables
Raceway
Adhere to walls so you don’t have to drill in for cabling
Run
Single piece of horizontal cabling
SmartJacks
NIUs that tell ISP is the user is connected or not and for remote troubleshooting
Solid core vs stranded core
UTP types, solid is better conductor but stiff and breaks easily. Opposite for stranded
Steps to install
Getting a floor plan; mapping runs; determine location of telecommunications room; pulling cable; making connections; connecting t path panel; testing the cable runs; NICS
Structured cable components (3)
Telecommunications room (where cables concentrate); horizontal cabling; work area
Structured cabling
set of standards used over the world to install physical cabling in safe and orderly fashion. defined by (TIA/EIA)
TDR
Time Domain Reflector; medium priced. can also tell you how long cable is and where a break occured… aka microscanner
Telecommunications Room
technically called IDF (intermediate distribution frame)
Temperature monitors & environmental monitors
monitor temperature and humidity, etc.
TIA/EIA 606
covers proper labeling and documentation of labeling, patch panels and wall outlets
Toner
helps trace cables, two separate devices used together. Tone generator (connects to cable and sends signal) and tone probe (emits a sound when placed near the cable connected) often called fox and hound.
U
Height measurement used in racks. U = 1.75 inches. device that fits in 1.75 space is called a 1U and so on. most are 1,2 or 4U
Extranet (aka DMZ)
private network that grants controlled access to users outside of the network. extension of an orgainizations intranet.
enterprise network
elements of both local and wide area networks
MAN
metropolitan area network - city or municipality
CAN
campus area network - academic or business park. typically owned or used exclusively by an entity
PAN
personal area network - two or three computers with cables and is most often seen in small or home offices
Centralized network
x
client/server network
x
peer-to-peer network
x
mixed mode network
x
topology
x
physical topology
x
logical topology
x
point-to-point connection
x
multipoint connections
x
radiated, or broadcast connection
x
physical bus topology
x
terminators
prevents signal bounce, prevents signal from bouncing back.
physical star topology
x
physical mesh topology
x
hybrid topology
x
physical tree topology
x
star-bus topology
x
star-of-stars topology
x
star-ring topology
x
logical bus topology
x
CSMA/ CD
carrier sense multiple access - collision detection
CSMA/ CA
carrier sense multiple access - collision avoidance
logical ring topology
x
logical star topology
x
multiplexer (mux)
x
802.11
IEEE standard which specifies an over-the-air interface between a wireless client and a base station or between two wireless clients
802.3
IEEE standard used to standardized Ethernet and expand it to include a wide range of cable media
A
(address record) DNS record that maps the host name to its IP address using a 32bit IPv4 address
AAAA
same as A record but IPv6 using a 128bit address
AC
alternating current; current that switches its flow back and forth in a circuit
access control
in security terms, the process of determining and assigning privileges to various resources, objects, and data
ACL
access control list - a set of data (user names, passwords, time and date, IP address, MAC address, etc) that is used to control access to a resource such as a computer, file or network
3 types of data transmission
broadcast
multicast
unicast
broadcast
1 to ALL
multicast
1 to group
unicast
1 to 1
asynchronous communication
x
synchronous communication
x
broadband fiber
multiple channels to one medium; faster but shorter distances
baseband fiber
one channel to one medium; slower but can go longer distances
modem
converts analog to digital; digital to analog; end users - transcevier
