Abstract
Optical burst switching (OBS) control architecture considers two different
models for the management of the offset time in the network. The
conventional OBS (C-OBS) introduces the offset time in soft-way by delaying
the transmission of the burst relative to its control packet in the edge
node. Another idea for an OBS architecture (E-OBS) comes from optical packet
switching world and it intends to emulate offset time by means of an
additional fiber delay unit introduced in the data path at the input port of
the nodes. Although C-OBS has attracted lots of attention, in this paper we
highlight that it possesses many difficulties that can be entirely removed
in E-OBS. Issues such as unfairness in resource reservation, efficiency and
complexity of burst scheduling, difficulty with alternative and backup
routing, and quality of service (QoS) provisioning are studied. Moreover,
E-OBS facilitates the application of several enhanced mechanisms. As an
example, in this paper we analyze a QoS application based on a preemption
window mechanism, which expands look-ahead processing window technique to
the burst preemption context. Results show that this mechanism can achieve
the performance of the conventional preemption scheme while avoiding the
well-known problem of phantom burst generation.
© 2009 IEEE
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