DWDM Flashcards
DWDM
MANs
• Combines multiple inputs Into diff. Color single output wavelength channel.
- Fiber Trans
- Optical Networks
- Uses Colors for light Trans
- Speed problem (Chromatic Dispersion)
Access Layer Network
DSL, SONETS, Fiber Ch., Cable modems, Ethernet
Long Haul Topologies
Mesh, Ring, Pt. To Pt.
• Conn to MANs
• More bandwidth
TDM
More than 1 call can be on single line
• Increases voice traffic on single line
SONET
North America
Used in North America
• Comes in 4 inputs(OC-48), Goes out 1 output (OC-192)
SDH
Synchronous Data Heirarchy
Used Elsewhere
WDM
Increase carrying capa of fiber
- Each ch. TX @ diff Freq. / diff color
* several ch. make rainbow
Diff between WDM/DWDM
1 degree of space
DWDM has 1 degree of space between wavelengths for more capacity.
Optical AMP
Amplifies Signal / Re-Amplifies Signal
Does not re-generate / re-shape signal.
Regenerator
Re-shapes, re-times, re-TX Signal.
DWDM
Saves Money
Increases network capacity w/o expensive upgrades.
Optical Add Drop Mux
OADM
Passive - Still works w/o power. High mean time between failure (MTBF) DWDM protection
1Adv of SONET - (DCC) Data Comm. Ch.
For operations, alarms, signals info.
Fiber
Carries signal much further than copper, lower error rate, immunity to noise.
Wide Band WDM
1980’s
- 1 Fiber pair TX
* 1 Fiber pair RX
Narrow Band WDM
2 to 8 ch. of fiber used.
Dense WDM
Mid 90’s
16 to 64 Fiber Ch.
Dense WDM
Late 90’s
64 to 160 Fiber Ch.
More ch. by decreasing spacing between wavelengths
Wavelengths
nm
Represented in nm
Main job of optical fiber
Guide light/Min Loss
Guide light with min loss of signal.
100% of light that strikes surface
Is Reflected (bounces back) or Refracted (Angle is Altered)
TX Challenges of Fiber
- Attenuation
* Chromatic Dispersion
