ER

Untitled Flashcards Set

Distortion - Changes in the signal due to different propergations speeds  

Attenuation - Signal gets weak the farther it travels  

Inteference - something in the way  

Fiber optioc cable - easy to avoid interference into the cable  

 

  • Shared transition mediums - wired, CDSA 

    • Wireless CSSCMA  

  • Multiplexing - way of cominging multiple signals over a channel  

  • Time division multiplexing  

  • Frequency devision multiplexing  

  • Wavelength division multiplexing - specific to fiber optic 

 

Basic term  

 

Access Poiint 

SSID -wireless network name (pulling wifi up on phone 

  • Each SSID has a BSSID (layer two mac address) 

  • 3 non overlapping channels you can use in 2.4 

    • 1 

    • 6 

    • 11 

  • Gigabit ethernet - all have a maximum run distance of 100 meters, beyond should use repeaters  

  • Switches - layer 2 devices, look at mac addresses 

  • Layer 2 header as souce and destination mac address, uses to find frame 

  • Source mac address - uses that to populate its mac address table  

  • Destination mac address 

  • Types of data  

    • Analog - like a visual circle, can azoom in on the circle to get a more. Detailed measurement 

    • Digital - discrete definable values, 7 on a clock, wont get more detailed no matter how far you zoom in  

  • ISMB bands - radio frequencies we can use for our gear without getting a visit from government officials, 2.5, 6 gigahertz  

  • In a layer 2 switch, when it receives a frame with an unknown destination port, floods out to all other ports except the one it came in on  

  • Wireless networks signal to noise ratio - don’t need to know math, just power to the signal in relation to the background noise, SNR value  

  • Most common twisted pair connector - RJ45 (Ethernet connector) is the most common twisted pair connector  

  • MIMO (multiple in multiple out) wireless technology that uses multiple strings of data to increase the network capacity  

  • VLANS - how you separate devices that are on the same switch into different subnets  

  • WPA2 or WPA3 - Transition period, strongest and latest encryption method  

  • Most common cable used in enterprise data communications (or of any type) - unshielded twisted pair- (UTP) 

  • Transimission medium that has a solid central core of wire - that is coaxial cable  

  • Cables made of glass or plastic and transmits singals in the forms of light - fiber optic 

  • ARP - Address resoliton protocal - protocol devices use to find the datalink latyer of a host or router. How your device finds the mac address of something  

  • Shannon cpacity - don’t need to know firmula - used to find highest bitrate for a noisy channel, noiseless channel does not exist  

  • Mac addresses are known as the physical address-also known as the hardware address  

  • Gigabit ethernet over unshielded twtisted pair is known as 1000 based T 

    • Don’t need to memorize any of the other standards 

  • TDM WDM FDM - ethernet switch is doing time division multiplexing, all devices do it  

  • Different fiber connectors -special one that contains many strands of fiber, frequently used to any high capacity connections -MTP connectors  

  • AM vs FM radio stations  

    • AM have smaller channel wits - travel furhter distances and have worse sound quality , at a lower frequency than FM radio stations, have less space  

  • Source and destination mac address - do not change when going through a layer 2 switch  

  • 5 gigahurt spectrum has more total avaialble connection than that 2.4, 6 gigahurt spectrum has even more than the 5  

  • Data link layer - gets divided into two sub layers - LLC and the MAC  

  • WIFI is only on the 2.4, the 5, and the 6 gigahurt frequencies,  

  • however getting into point to point wireless bridges,  you can use some other frequencies  

  • Microwave ovens cause interference on the 2.4 gigahurtz band 

  • Fiber optic cabling found in backgrounds and cores  

  • Wavelength division multiplexing - multiplexing used at a phyical level in fiber optic calbe 

  •  Switching decisions happen much faster than routing decisions  

 

Essay questions  

  • Describe UTP and STP cabling  

    • UTP Unshieled twitsted pair  

    • STP shieled twitsted pair  

  • Whichi is more commonly used  

    • Unshieled twitsted pair  

  • Why shielede twitted pair, is moire expensive, bulkier, not really needed 

  • List one advantage of using 5 gigahurt specturm for wifi 

    • Faster 

    • Less interference beause 2.4 has blootooth, microwaves, wireless game controllers, less stuff in 5 gigahurts  

    • 5 times as much space for the things that are in the 5 gigahurts  

  • One adv for 2.4 

    • Reallyo nly adv is 2.4 goes a little bit further  

 

  • Two benefits for fiber optic cabling  

    • Speed, fiber optic cabeling allows for 400 gig, 800gig 

    • Distance, at least 80 km before you need a repeater  

    • Fiber optic is immune to noise  

    • Fiber optic cable can be very physically dense  

 

  • Primary duty of the phsycial layer 

    • Transmit the data in RF, look up other otions  

 

  • Know basic formula for AMPs 

    • AMPS * Volts = WATTS  

 

  • Make sure to understand why you still need a UPS  

    • Something to run your servers while your generator starts, don't want your servers to shut off