An optical interconnection network for terabit IP routers

As data traffic increases exponentially in the Internet, a need of deploying ATM switches or IP routers with terabit/s capacity is emerging. By taking advantage of the advanced wavelength division multiplexing (WDM) technology, we propose a nonblocking WDM-based optical interconnection network (OIN) to interconnect multiple electronic router modules (RMs), where packets are stored and processed. The proposed architecture uses an input-output buffering scheme, where the OIN operates at twice the line rates to alleviate the head-of-line blocking and thus achieves close to 100% throughput. The OIN is capable of performing multicasting using the method of broadcast and select. Output port contention among the input packets is resolved by a novel ping-pong arbitration (PPA) scheme. For a 256-input packet switch, the arbitration can be completed within 11 gates delay, less than 5 ns using the current CMOS technology. We analyze the complexity of the OIN in optical components and interconnections, its power budget, and crosstalk caused by the finite ON-OFF ratio of optical switching gates. Bit error rates with respect to different ON-OFF ratios and extinction ratios are evaluated by simulations. The result shows that it is feasible to construct a 256 × 256 OIN with existing technology.