Problem We need more bandwidth Data traffic doubles every 4 (up to 12) months More users connect to the Internet … And stay connected for longer times … And have better connection speeds (56kbps modem DSL & Cable modem) New applications (e.g. NAPSTER, GNUTELLA) require more bandwidth And we can expect numerous other bandwidth intensive applications Data traffic >> Voice traffic 11/7/2000 EE228A Lecture

Solution Optical Networking High speed transmission Enormous bandwidth made available WDM makes ~160 channels/wavelengths possible in a fiber Each wavelength carries about 10 Gbps Hence Tbps speeds become a reality Low bit error rates 10-9 as compared to 10-5 for copper wires High speed transmission Transparent to bit rates and modulation schemes Reconfigurability Made possible due to developments in hardware 11/7/2000 EE228A Lecture

Hardware Fiber Lasers Amplifiers (as opposed to regenerators) reduced dispersion, non linearity and attenuation loss Lasers reduced noise (both phase and intensity) 2.5 Gbps, 10 Gbps , tunability emerging made from semiconductor or fiber Amplifiers (as opposed to regenerators) make possible long distance transmissions erbium-doped fiber amplifiers transparent to bit rate and signal format have large gain bandwidths (useful in WDM systems) expensive (~$50K) 11/7/2000 EE228A Lecture

Hardware Filters Optical Add-Drop Multiplexor (OADM) with narrower spacing, wider ranges and tunability Optical Add-Drop Multiplexor (OADM) OADM 1 2 3 ’3 Optical cross-connects (OXC) route a channel from any I/P port to any O/P port can be fixed, rearrangeable, and also with  converters 11/7/2000 EE228A Lecture

Hardware … … Rigid OXC Rearrangeable OXC I/P port N I/P port 1 O/P port 1 O/P port N … 1 M I/P port N I/P port 1 … O/P port 1 O/P port N 1 M Rigid OXC Rearrangeable OXC 11/7/2000 EE228A Lecture

Hardware Wavelength () converters (WC) improve utilization of available wavelengths on links needed at boundaries of different networks all-optical WCs being developed greatly reduce blocking probabilities 3 3 2 2 WC 1 1 New request 1 3 New request 1 3 No Wavelength converters With Wavelength converters 11/7/2000 EE228A Lecture

Earlier Optical Networks SONET/SDH, ATM, FDDI … fiber as transmission medium switching, processing and routing electronically require O/E/O conversions use one wavelength only Primarily for voice traffic lots of redundancy, overhead, protection New networks should optimize for data (IP traffic) IP over WDM is emerging as the new architecture 11/7/2000 EE228A Lecture

11/7/2000 EE228A Lecture