Advantages of OBS over OPS

Remove throughput limitation - Optical buffer technology has not matured enough to enable low cost manufacturing and widespread use in optical networks. Core optical network nodes are likely to either be unbuffered or have limited buffers. In such networks, delayed reservation schemes such as Just Enough Time (JET) are combined with electronic buffering at edge routers to reserve bandwidth. Using JET can create a throughput limitation in an edge router in an OPS system. This limitation can be overcome by using OBS.

Furthermore there must be a guardband in the data channel between packets or bursts, so that core optical router data planes have adequate time to switch packets or bursts. If the guardband is large relative to the average packet or burst size, then it can limit data channel throughput. Aggregating packets into bursts can reduce guardband impact on data channel throughput.

Reduce processing requirements and core network energy consumption - A core optical router in an OBS network may face reduced control plane requirements when compared to that in an OPS network, as: A core optical router in an OPS network would have to perform processing operations for every arriving packet, wherelse in an OBS network the router performs processing operations for an arriving burst which contains several packets. Therefore, less processing operations per packet are required in a OBS network core optical router compared to an OPS network. Consequently the energy consumption and potentially the carbon footprint of a core optical router in an OPS network is likely to be larger than that of an OBS network router for the same amount of data.

This advantage may be offset by the fact that an OBS network edge router is likely to be more complex than an OPS network edge router, due to the possible need for a burst assembly/aggregation and a sorting stage. Consequently energy consumption at the edge of an OBS network may be higher than in an OPS network.

July 21, 2011

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