A Novel Architecture of N × N Bidirectional Reconfigurable Multiwavelength Optical Cross Connect

A novel architecture of N×N bidirectional-reconfigurable multiwavelength optical cross connect (B-RMOXC) based on tunable Fiber Bragg grating and optical circulator is proposed. B-RMOXC network is one of crucial network element for wavelength routing in dense wavelength division multiplexing system. This paper presents a high speed, power compensated bidirectional optical cross connect and verified the performance of bidirectionality with 0.8-nm channel spacing having bit rate of 10 Gbps at different transmission distances. Optical signal-to-noise ratio of 36.62 dB and 35.55 dB is achieved with acceptable Quality factor of 6.26 and 6.99 respectively for upstream and downstream at 60 km having input transmission power of −12 dBm. It is found that the data can be communicated bidirectionally to a distance of 60 km in the presence of fiber nonlinearities without optical amplifier.

Reliable multicast using remote direct memory access (RDMA) over a passive optical cross-connect fabric enhanced with wavelength division multiplexing (WDM)

It has been well studied that reliable multicast enables consistency protocols, including Byzantine Fault Tolerant protocols, for distributed systems. However, no transport-layer reliable multicast is used today due to limitations with existing switch fabrics and transport-layer protocols. In this paper, we introduce a layer-4 (L4) transport based on remote direct memory access (RDMA) datagram to achieve reliable multicast over a shared optical medium. By connecting a cluster of networking nodes using a passive optical cross-connect fabric enhanced with wavelength division multiplexing, all messages are broadcast to all nodes. This mechanism enables consistency in a distributed system to be maintained at a low latency cost. By further utilizing RDMA datagram as the L4 protocol, we have achieved a low-enough message loss-ratio (better than one in 68 billion) to make a simple Negative Acknowledge (NACK)-based L4 multicast practical to deploy. To our knowledge, it is the first multicast architecture able to demonstrate such low message loss-ratio. Furthermore, with this reliable multicast transport, end-to-end latencies of eight microseconds or less (< 8us) have been routinely achieved using an enhanced software RDMA implementation on a variety of commodity 10G Ethernet network adapters.