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Networking Basics

Published on October 2019 | Categories: Documents | Downloads: 10 | Comments: 0



Ethernet Basics and Network Troubleshooting Wires, switches, hubs, and what to plug where

Networking  

Communication between two or more devices. Parts required for Networking: 

Host  

Card   

Computer, networked printer, etc. Sends/receives data for network to card Every card on a network has to have a unique address Card breaks outgoing data into packets and addresses them Card receives packets addressed to it and re-assembles re -assembles packets to data

Wire  

Transmits packets across network For this discussion includes all wires, radios and devices between network cards (including hubs, switches, access points, etc.)

Wire types 

Co-Ax 

Composed of: 

10 Mb only

10Base5 “Thicknet” 

1600 ft (500 meters)

10Base2 “Thinnet” 

Core, insulation, shielding, insulation

600 ft (200 meters)

Twisted Pair  

10/100/1000 Mb 340 ft. (100 meters) between devices CAT3, CAT5, CAT5e, CAT6, CAT6e

Wire Types (cont.) 

Fiber 10/100/1000/10,000 Mb Multi-mode – Long Haul (20 km) Single-mode – “Short Haul” (3 Km) what we use Carries light, not electricity Wireless Speeds 11/7 Mb, 54/27Mb Because of encryption and connection upkeep, available bandwidth is about ½ of stated speed   

 

Common “mediums”   

InfraRed (IR) Microwave, (long distances) Radio Licensed/private Un-licensed (802.11b/g/a)  

Ethernet (Infancy) 

10Base5 – “Original Ethernet” Large Co-ax Backbone (garden hose) Terminated at ends Vampire tap, to transceiver 1600 ft. backbone 

   

“Jumper” from transceiver

to card How it works: 10 Mb/s  

One Wire… every packet

goes to every host CSMA/CD (Carrier Sense Multiple Access/ Carrier Detect) Collisions Half Duplex 

 

Ethernet (Toddler) 

10Base2 

 

  

Smaller diameter, less expensive cable shorter length 600 ft total length Get rid of the “backbone” use a “T” connector on

each card Daisy chained the whole network together Terminated on ends Still ONE WIRE Still CSMA/CD

Ethernet (Adolescent) 

10BaseT 


 

Packet is simultaneously sent out all ports If two packets come in at the same time it is a collision

Twisted pair wire The Hub is part of “The Wire”

340 feet between devices 3 hops maximum (no daisy chaining)

Server is slow/not working 

Work this with your NE!! What you *CAN* do

Step 1

Un-plug/re-plug the server’s network cables  

First Contact helpdesk/your NE. Don’t move them, plug them back in

the same place Only do one end of one cable at a time

The server will be “down” while they

are un-plugged 

Step 2 (still not working) 

Check it out, or have the network guy check it out Contact helpdesk/your NE, get server restarted

Group of computers is slow/not working 

What do they have in common? 

 All connected to same hub? 

Get a switch!!!

 All connected to same mini-switch?   

Power-cycle switch Check for loops Replace switch ($18.00 for 8 port.) Change port on IDF/MDF

Group of computers is slow/not working (cont.) 

What do they have in common? (cont.) 

 All same model/from same image?   

 

Virus/Spyware in image? Client software installed/configured wrong? OS not patched? Bad NIC driver?

Same “wing” or area 

Power cycle switches in IDF/MDF (some of these take over 3 min. to boot, so don’t just go and do

this without warning users)

Single computer is slow/not working  

Restart the computer Un-plug/re-plug/replace cables Check it’s connection at


Single computer is slow/not working (cont.) 

 

 

Change it’s port at MDF/IDF 

Don’t move other wires

Don’t “clean up” wiring!!!

If it doesn't fix it, change it back

Patches/ AntiVirus / Spyware Upgrade/Re-install NIC driver Replace NIC Force speed/duplex (gig switch, Cat5 wiring?)

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