ONDM 2006 Copenhagen Denmark May 22 2006 Bidirectional

ONDM 2006 Copenhagen, Denmark May 22, 2006 Bidirectional Optical Ring Network Having Enhanced Load Balancing and Protection Hagen Woesner (woesner@create-net. it) Dzmitry Kliazovich, Fabrizio Granelli, CREATE-NET University of Trento, Italy

ONDM 2006 Outline n Introduction ¨ n Last Mile and Metropolitan Networks Traffic Aggregation Core Network and node architectures ¨ MAC Protocol Candidates ¨ Resilience and Load Balancing Strategies ¨ n Comparison and Conclusions May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Last Mile Networks n n Which technology will drive Access in networks? FTTx became economically feasible ¨ n Up to 100 Mb/s per user Passive Optical Networks PON (A/B/E/GPON): total bitrate 155 Mb/s and 2. 5 Gb/s ¨ Super. PON: 10 or 40 Gb/s ¨ n n Optical transmission is required Switching inside OLT can be done electronically May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Metropolitan Area Network (MAN) n Traffic Aggregation in Metro Area ¨ Switching and Routing becomes a Communication and Computing Bottleneck! May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Traffic Aggregation Core n n Perform Distributed Switching Shared medium (bandwidth) Drop-and-Continue principle to avoid OEO conversion and corresponding processing Bidirectional Communications Ref. : A. Gumaste and I. Chlamtac, "Light-trails: a novel solution for IP-centric communication, " in Workshop on High Performance Switching and Routing (IEEE, New York, 2003). Ref. : D. Kliazovich, F. Granelli, H. Woesner, and I. Chlamtac, “Bidirectional Light. Trails for Synchronous Communications in WDM Networks”, GLOBECOM'05, St. Louis, US, December 2005. May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Traffic Aggregation Core Drop-and-Continue using Optical Couplers Bidirectional Optical Ring May 22, 2005 Hagen Woesner (woesner@create-net. it) Client Node

ONDM 2006 Traffic Aggregation Core n n n Hub-and-spoke Architecture Virtual Link Break creates Two Dual Buses on a bidirectional optical ring allowing spatial reuse Each bus is running OTDM HUB communicates at full bus speed (100 or 160 Mb/s) ¨ Client node receives/transmits in a Terminates single time slot (10 Mb/s) ¨ western bus n Downstream: point-to-multipoint downstream n Upstream: multipoint-to-point May 22, 2005 Hagen Woesner (woesner@create-net. it) Terminates eastern bus downstream

ONDM 2006 Hub Node Architecture n High-speed transmitters and receivers ¨ May 22, 2005 Implemented using Short Pulse Lasers (5 - 10 us) Hagen Woesner (woesner@create-net. it)

ONDM 2006 Client Node Architecture n Low-cost requirement ¨ May 22, 2005 Minimum number of transmitters and receivers Hagen Woesner (woesner@create-net. it)

ONDM 2006 Network Initialization n Discovery Topology ¨ n Hub goes around the ring configuring client nodes in “path-through” mode Place Virtual Link Break Assume uniform network load initially ¨ Divide ring into two equal by the number of nodes dual buses ¨ n Assign Home Channels Client node listens a certain OTDM channel in downstream ¨ Several nodes can share a single channel ¨ May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Network Communications n Point-to-multipoint Downstream reserved for reception n Multipoint-to-point Upstream requires contention resolution to ensure collision-free medium access n No node is allowed to transmit if the bus is not idle (medium sensing module) – CSMA/CA n However CSMA/CA in light trails leads to Unfairness ¨ May 22, 2005 It always favors the nodes located closer to the beginning of the upstream bus Hagen Woesner (woesner@create-net. it)

ONDM 2006 MAC Protocol Candidates n Reservation-based MAC Client sends bandwidth request in the upstream ¨ Hub computes a fair share ¨ Bandwidth is granted via downstream ¨ n Good Fairness (depends on scheduler) n Large Reservation-Grant Delay At least double propagation time between Hub and Client node ¨ Depends of the node relative position with the bus ¨ n A good candidate for constant bandwidth provisioning ¨ May 22, 2005 Example: dedicated channels for ISPs Hagen Woesner (woesner@create-net. it)

ONDM 2006 MAC Protocol Candidates n Token-rotation MAC Tokens generated by Hub in the downstream are rotated into the upstream ¨ Token detection requires optical correlator ¨ Token extraction is done using overwrite operation ¨ n Medium Access Delay tradeoffs with Round-trip propagation delay, Token rotation and Token holding time Network size defines Utilization and Performance n Backpressure Control n CSMA/CA in Medium Access ¨ Hub monitors node’s sending rates ¨ Hub sends backpressure signal to the nodes sending above a fair share ¨ n On-demand Medium Access May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Resilience and Load Balancing n Key: Shift Virtual Link Break n Single Link Failure or Node Malfunction Robustness Complete shut down of optical functionality is considered ¨ Distributed algorithm with no Hub coordination ¨ n Load Balancing between busses ¨ May 22, 2005 Triggered by Hub based on the bus utilization level Hagen Woesner (woesner@create-net. it)

ONDM 2006 Resilience and Load Balancing Tree rules of Distributed Resilience algorithm followed by nodes: 1. 2. 3. May 22, 2005 Downstream clock and no upstream clock – turn into “loopback” mode No downstream clock – join another bus by flipping optical switches. Then, send signal on the upstream Being in “loopback” switch to “path-through” upon incoming signal on the upstream Hagen Woesner (woesner@create-net. it)

ONDM 2006 Resilience and Load Balancing Link Failure CN 1 hearing clock on the downstream and no clock on the upstream closes western bus; n Being isolated CN 2 and CN 3 try to join eastern bus and send in the upstream; n CN 4 hearing an upstream signal turns off light terminator opening the downstream for CN 3 and CN 2; n May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Related Works and Comparison May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Conclusions n n Optical Network Architecture for traffic aggregation in Metropolitan Area Network (MAN) which consists of two dual buses on a bidirectional ring fiber Low-cost Client node architecture MAC candidates: reservation-based, tokenrotation or CSMA/CA with backpressure control Resilience strategy able to resolve single link break or node malfunction May 22, 2005 Hagen Woesner (woesner@create-net. it)

ONDM 2006 Thank you! May 22, 2005 Hagen Woesner (woesner@create-net. it)