31-01-2013, 11:04 AM
Fiber-Optic Networks
Fiber-Optic.ppt (Size: 1.3 MB / Downloads: 187)
Network Categories
Optical Networks are categorized in multiple ways:
All Optical (or Passive Optical) Networks Vs Optical/Electrical/Optical Networks
Based on service area
Long haul, metropolitan and access network
Wide area (WAN), metropolitan area (MAN) or local area network (LAN)
Depending on the Protocol
SONET, Ethernet, ATM, IP
Number of wavelengths
single wavelength, CWDM or DWDM
Local Area / Access Networks
Local-area networks
Interconnection on number of local terminals
Main technologies: Ethernet, Fast Ethernet, Gigabit Ethernet (better for multiple access)
Usually passive star or bus networks
Access networks
The first (or last) network segment between customer premises and a WAN or MAN
Usually owned by a Local Exchange Carrier
PON is getting popular
Fiber-copper technologies: HFC (fiber-coaxial cable) or DSL (fiber-twisted pair)
Fiber-wireless and free-space optics are also used
Metropolitan-area/regional-area networks
A MAN or RAN covers a North American metropolitan area, or a small to medium-sized country in Europe or Asia
Optical ring/mesh topologies with adequate back-up and protection
Main technologies: SONET, ATM, Gigabit & 10-Gigabit Ethernet, DWDM
Non-optical technologies: T1, T3, Frame Relay
Several LANs could be connected to MAN
Wide-Area Networks (WAN)
Long haul inter-city connections
Either government-regulated or in the public network environment
WANS originated in telephony
Main technologies: SONET/SDH, ATM, WDM
Voice circuits vs. data packets
Non-optical technologies:T1(1.544 Mb/s)/E1(2.048 Mb/s), DS-3 (44.736 Mb/s ), Frame Relay
Standards bodies include ITU-T, IETF, ATM Forum, Frame Relay Forum, IEEE
Passive Optical Networks
There is no O/E conversion in between the transmitter and the receiver (one continuous light path)
Power budget and rise time calculations has to be done from end-to-end depending on which Tx/Rx pair communicates
Star, bus, ring, mesh, tree topologies
PON Access Networks are deployed widely
The PON will still need higher layer protocols (Ethernet/IP etc.) to complete the service
Synchronous Optical Networks
SONET is the TDM optical network standard for North America (It is called SDH in the rest of the world)
We focus on the physical layer
STS-1, Synchronous Transport Signal consists of 810 bytes over 125 us
27 bytes carry overhead information
Remaining 783 bytes: Synchronous Payload Envelope