IP over WDM network docx

IP over WDM network Fang Yu 294 Class Presentation Outline  History of WDM networks  Current Internet: Multi-layer protocol stack between IP and WDM layers  Future: IP directly over WDM  Challenge  Virtual Topology Reconfiguration  Multi-layer routing  One proposal: Optical Burst Switching technologies History  In the late 70s  First fiber based optical transmission system  Before 1995  Mostly a single high-speed optical channel  All multiplexing done in electrical domain(TDM)  50Mb/s to 10Gb/s data services  After 1995  WDM allows simultaneously transmitting multiple high-speed channels on different frequencies (Up to 160 wavelengths today)  40G per λ (OC768)  Total link capacity = 160 λ *40G =6.4 Tbps Current Typical Protocol Stacks IP ATM SONET WDM N e t w o r k P h y s i c a l D a t a l i n k N e t w o r k SONET ATM IP D a t a l i n k D a t a l i n k N e t w o r k WDM Proprietary (20-400 Gb/s) OTS OTS OTS OTS OTS OTS (OTS: Optical Transport System) Transport Layer Model “Packet” “Packet” “Packet” “Packet” 1/0 DCS 1/0 DCS 1/0 DCS 1/0 DCS 4E 4E 4E 4E 3/1 DCS 3/1 DCS 3/1 DCS 3/1 DCS 3/3 DCS Layer (DACS III) DACS III DACS III DACS III DACS III ATM/IP ATM/IP ATM/IP ATM/IP DS1 (1.5 Mb/s) DS3 (45 Mb/s) DS3 (45 Mb/s) OC48+ (2.5+ Gb/s) ADM ADM ADM ADM ADM ADM ADM Fiber Conduit/ Sheath 3/1 DCS Layer SONET ADM Layer Core ATM/IP Layers Service Layers Media Layer LA CHCG LA LA LA LA LA LA PHNX PHNX PHNX CHCG CHCG CHCG CHCG CHCG Wavelength Path Crossconnect Wavelength Mux Section Crossconnect Hard- Wired Disadvantage of Current Multi- layer Protocol Stack  Inefficient  In IP over ATM over SONET over WDM network, 22% bandwidth used for protocol overhead  Layers often do not work in concert  Every layer now runs at its own speed. So, low speed devices cannot fill the wavelength bandwidth.  When detecting of failure, different layers compete for protection  Optical layer detects failure almost immediately, restores error in 2us to 60ms  SONET layer detects failure in 2.3–100 us, restores error in 60 ms Disadvantage of Current Multi- layer Protocol Stack (Cont)  Functional overlap: So many layers are doing the same thing  Routing  Protections  Slow speed  Electronic devices can not catch the transmission speed available at optical layer  Latencies of connection Historical Reason for Multi-layer  SONET over WDM  Conventional WDM deployment is using SONET as standard interface to higher layers  IP over ATM  IP packets need to be mapped into ATM cells before transporting over WDM using SONET frame  OEO conversions at every node is easier to build than all optical switch Electronic Network Electronic Network Electronic Network Electronic Network O/E/O O/E/O O/E/O O/E/O O/E/O O/E/O Optical Core E/O E/O E/O E/O Simplified Protocol Stacks? IP Frame Relay ATM SONET WDM IP WDM WDM-aware Electronic layer Current Typical Protocol Stack Simplified Protocol Stack IP Directly Over WDM?  Establish high-speed optical layer connections (lightpaths)  IP routers connected through lightpaths rather than fiber A B C D E W a v e l e n g t h c r o s s c o n n e c t L i g h t p a t h s I P r o u t e r [...]... Current IP over ATM over SONET over WDM network is inefficient and redundant Future IP directly over WDM network    Advantages  Less latency  Automatic provisioning  Higher bandwidth utilization Challenge of packet directly over WDM network  Optical buffer Optical burst switch is one of the proposed techniques to IP over WDM network Reference          John Strand, “Optical Networking and IP. .. Strand, “Optical Networking and IP over Optical”, Feb 4, 2002 Kumar N Sivarajan, IP over Intelligent Optical Networks”, Jan 5, 2001 Gaurav Agarwal, “A Brief Introduction to Optical Networks”, 2001 Yang Lihong, “Optical Burst Switching”, CMU networking seminar presentation Vincent W S Chan, “Optical Networks: Technology and Architecture” Eytan Modian, WDM- Based Packet Networks”, IEEE Communication Magazine,...Challenge for IP over WDM network  WDM- aware Electronic layer        Reconfiguration and load balancing Protection and restoration Optical flow switching Network management/control Cross-layer optimization Reconfigurable (within milli-seconds) OXC Wavelength Converters 3 2 3 2 WC... a long way to go……………………… Various Optical Switching Technologies Optical Burst Packet Switching  Retrospect the goal of IP over WDM:    Avoid electronic bottlenecks Decrease the cost by simplifying the multiple layer architecture OBS is one proposal of how to realize such a network Optical Burst Switching  Resources are allocated using one way reservation      Sender sends a request Sender... Fixed Routing 0.1 0.01 Reconfigurable Routing X6 WDM ring, 20 nodes one transceiver/node call BW = 1 wavelength 0.001 0.01 0.02 0.03 0.04 Call arrival rate 0.05 Multi-layer Routing   IP layer routing is the bottleneck of present Internet Solution: Routing long duration flows at lower layers User 1 Router 1 Network control Router 2 User 2 Router 3 WDM layer • • • Conventional packet routing Optical... light-paths in WDM network by   Changing the light path connectivity between electronic switches Tuning of the transmitter wavelength and the frequency-selective-switches A B A B C D C D Virtual Topology Reconfiguration(Cont.)  Enable network to dynamically response to changing of traffic pattern  Load balancing  Efficiency Issues:    Time scale of changes Triggered by what mechanisms IP routing... IEEE Journal on selected areas in communications, October 2000 Eytan Modiano, Aradhana Narula-Tam, “Survivable lightpath routing:a new approach to the design of WDM- based networks”, IEEE JSAC,April 2002 R Ramaswami and K N Sivarajan, Optical Networks: A Practical Perspective, San Francisco: Morgan Kaufmann, 1998 . IP over WDM network Fang Yu 294 Class Presentation Outline  History of WDM networks  Current Internet: Multi-layer protocol stack between IP and WDM layers  Future: IP directly over WDM  Challenge  Virtual. Multi-layer  SONET over WDM  Conventional WDM deployment is using SONET as standard interface to higher layers  IP over ATM  IP packets need to be mapped into ATM cells before transporting over WDM using. of Current Multi- layer Protocol Stack  Inefficient  In IP over ATM over SONET over WDM network, 22% bandwidth used for protocol overhead  Layers often do not work in concert  Every layer