Reliable multicast on a WDM Optical Packet Ring

Abstract

The present paper addresses multicast protection in WDM Optical Packet Rings that are currently considered for future metro network architectures. The considered architecture is optically transparent for transit traffic, which drastically limits the number of OEO conversions compared to e.g. Ethernet Packet Rings. WDM Optical Packet Rings offer huge capacity while still retaining a packet based granularity, which is not the case for ROADM based networks. Metro networks now support multicast, as IPTV services are largely deployed. Two alternate methods for implementing the traditional 1+1 and 1:1 protection mechanisms are proposed. Both rely on using the time slotted control channel to deliver failure and recovery information. The performance of the two methods are thoroughly assessed and it is shown that the transient degradation durations are always bounded by the Ring Round Trip Time, which is at least an order of magnitude less than the usual 50ms target time for protection. Moreover, using a Multicast Drop-off Point is shown to provide an almost loss free transport in case of single failure. Lastly the single ring protection schemes are extended to multi-ring architectures, relying on an MPLS-TP compatible operation mode of the WDM optical packet rings.