Networking Basics
Content
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
HUB
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
MDF/IDF
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?)
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
HUB
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
MDF/IDF
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?)
