Ethernet cable

Inside the ethernet cable, there are 8 color coded wires.
These wires are twisted into 4 pairs of wires.
One wire in the pair is solid colored wire and the other is primarily white wire with a colored stripe.

T568A and T568B are the two color codes used for wiring eight-position RJ45 modular plugs.
Both are allowed under the ANSI/TIA/EIA wiring standards.
The only difference between the two color codes is that the orange and green pairs are interchanged.



Pin Numbering in the clip



Signals on the Pins



In straight cable pin 1 to 8 on one side is connected to pin 1 to 8 on other side

1 <--> 1
2 <--> 2
3 <--> 3
4 <--> 4
5 <--> 5
6 <--> 6
7 <--> 7
8 <--> 8

In Crossover cable Tx is connected to Rx (ie Tx+ to Rx+, Tx- to Rx-, Rx+ to Tx+, Rx- to Tx-)

1 <--> 3
2 <--> 6
3 <--> 1
4 <--> 4
5 <--> 5
6 <--> 2
7 <--> 7
8 <--> 8



In Rolled or rollver cables pin 1 to 8 on one side is connected to pin 8 to 1 on other side

1 <--> 8
2 <--> 7
3 <--> 6
4 <--> 5
5 <--> 4
6 <--> 3
7 <--> 2
8 <--> 1

If same type of devices needs to be connected cross cable is used. ie to connect PC to PC, switch to switch or router to router.

Straight cable is used if both sides of the cables are different types of devices. ie to connect PC to switch or PC to router or switch to router etc.

Gigabit Ethernet ports which support auto sensing (MDI/MDIX) doesn't require cross cable. Straight cable can be used.

Difference Between Similar Terms and Objects

To find Difference Between Similar Terms and Objects see http://www.differencebetween.net/

Clip art

Public Domain Clip Art

http://www.pdclipart.org/index.php

Hiking

Below are the Good hiking information sources

1. SF south bay and Peninsula

http://www.bahiker.com/

http://openspace.org/

2. Other sites
http://www.slackpacker.com

3. APPs
http://www.everytrail.com/ (has free mobile app to track the route)
App - http://www.everytrail.com/mobile - app available for iphone, andriod, windows mobile, blackberry

Computer Data

kilobyte (kB)	103	210
megabyte(MB)	106	220
gigabyte (GB)	109	230
terabyte (TB)	1012	240
petabyte (PB)	1015	250
exabyte (EB)	1018	260
zettabyte (ZB)	1021	270
yottabyte (YB)	1024	280

Optical basics

Optical Terminology

SM	- Single Mode fiber.
MM	- Multi Mode fiber.
WDM	- Wave length Division Multiplexing.
DWDM	- Dense Wavelength Division Multiplexing.
CWDM	- Coarse Wavelength Division Multiplexing.
OADM	- Optical Add Drop Multiplexers.
EDFA	- Erbium Doped Fiber Amplifier.
GBIC	- Giga Bit Interface Converter.
SFP	- Small Form-factor Pluggable).
O-E-O	- Optical-Electrical-Optical.
FC	- Fiber Channel.
OSNR	- Optical Signal to Noise Ratio

Optical fiber - 3 components, Core, Cladding, Coating



Fiber types - MM (Multi Mode), SM (Single Mode) (Generally SM is yellow color cable and MM is orange color cable)



Data is sent as light pulses through the optical cable.

Conventional optical networks wave lengths - 850nm, 1310nm, 1550nm.
Light source

• 850nm uses LED (Cheap, short distance)
• 1310nm uses LED or laser (Cheap, medium distance)
• 1550nm uses High quality laser(Expensive .

WDM - Wavelength Division Multiplexing.

DWDM - Dense Wavelength Division Multiplexing
In DWDM space between channels(wavelengths) is less, so needs good light source to send good signal.
DWDM uses expensive powerful lasers.
DWDM is used for long distance transmissions.

CWDM - Coarse Wavelength Division Multiplexing
In CWDM channels are spaced widely.
oesn't need powerful laser.
Used for shorter/medium distances

OADM - Optical Add Drop Multiplexers.
EDFA - Erbium Doped Fiber Amplifier (used in DWDM to Amplify the signal)

Connectors

• GBIC - Giga Bit Interface Converter
  
• SFP - Small Form-factor Pluggable) - upto 4.25 Gbits/s
• XFP - 10 gig support for dieerent protocols
• SFP+ - 10 gig Ethernet and 8 gig FC, modified/updated XFP (SFP+ is small size, low power consumption, less expensive) .

Cable Connector type - (SC, LC are widely used)

Virtual PDF printer

When you are not connected to printer and if you have webpage/coupon which can be printed only once the you need a virtual PDF printer. After installation virtual pdf printer will install a printer.

Just click print in the browser and select the virtual printer, this will create pdf file.
You can use this application to create pdf files from any application which has print option.

Some of the virtual pdf printer applications are mentioned below
bullzip (Freeware) - http://www.bullzip.com/products/pdf/info.php#download

win2pdf - Free (Free version adds a extra page at the end of the pdf document)
http://www.win2pdf.com/