Abstract: In this paper, a novel configuration is proposed for
the implementation of an almost all-optical switch architecture
called the scheduling switch, which when combined with appropriate
wait-for-reservation or tell-and-go connection and flow
control protocols provides lossless communication for traffic
that satisfies certain smoothness properties. An all-optical 2 2
exchange/bypass (E/B) switch based on the nonlinear operation
of a semiconductor optical amplifier (SOA) is considered as the
basic building block of the scheduling switch as opposed to active
SOA-based space switches that use injection current to switch
between ON and OFF states. The experimental demonstration of
the optically addressable 2 2 E/B, which is summarized for
10–Gb/s data packets as well as synchronous digital hierarchy
(SDH)/STM-64 data frames, ensures the feasibility of the proposed
configuration at high speeds, with low switching energy and low
losses during the scheduling process. In addition, it provides
reduction of the number of required components for the construction
of the scheduling switch, which is calculated to be 50% in the
number of active elements and 33% in the fiber length.
Abstract: We propose and evaluate fast reservation (FR)
protocols for Optical Burst Switched (OBS) networks. The
proposed reservation schemes aim at reducing the end-to-end
delay of a data burst, by sending the Burst Header Packet (BHP)
in the core network before the burst assembly is completed at the
ingress node. We use linear prediction filters to estimate the
expected length of the burst and the time needed for the
burstification process to complete. A BHP packet carrying these
estimates is sent before burst completion, in order to reserve
bandwidth at each intermediate node for the time interval the
burst is expected to pass from that node. Reducing the total time
needed for a packet to be transported over an OBS network is
important, especially for real-time applications. Reserving
bandwidth only for the time interval it is actual going to be used
by a burst is important for network utilization efficiency. In the
simulations conducted we evaluate the proposed extensions and
prove their usefulness.
Abstract: We propose new burst assembly schemes and fast reservation (FR) protocols for Optical Burst Switched (OBS) networks that are based on traffic prediction. The burst assembly schemes aim at minimizing (for a given burst size) the average delay of the packets incurred during the burst assembly process, while the fast reservationprotocols aim at further reducing the end-to-end delay of the data bursts. The burst assembly techniques use a linear prediction filter to estimate the number of packet arrivals at the ingress node in the following interval, and launch a new burst into the network when a certain criterion, different for each proposed scheme, is met. The fast reservationprotocols use prediction filters to estimate the expected length of the burst and the time needed for the burst assembly process to complete. A Burst Header Packet (BHP) packet carrying these estimates is sent before the burst is completed, in order to reserve bandwidth at intermediate nodes for the time interval the burst is expected to pass from these nodes. Reducing the packet aggregation delay and the time required to perform the reservations, reduces the total time needed for a packet to be transported over an OBS network and is especially important for real-time applications. We evaluate the performance of the proposed burst assembly schemes and show that a number of them outperform the previously proposed timer-based, length-based and average delay-based burst assembly schemes. We also look at the performance of the fast reservation (FR) protocols in terms of the probability of successfully establishing the reservations required to transport the burst.
Abstract: In this paper we present a signaling protocol for
QoS differentiation suitable for optical burst switching networks.
The proposed protocol is a two-way reservation scheme that
employs delayed and in-advance reservation of resources. In this
scheme delayed reservations may be relaxed, introducing a
reservation duration parameter that is negotiated during call
setup phase. This feature allows bursts to reserve resources
beyond their actual size to increase their successful forwarding
probability and is used to provide QoS differentiation. The
proposed signaling protocol offers a low blocking probability for
bursts that can tolerate the round-trip delay required for the
reservations. We present the main features of the protocol and
describe in detail timing considerations regarding the call setup
and the reservation process. We also describe several methods
for choosing the protocol parameters so as to optimize
performance and present corresponding evaluation results.
Furthermore, we compare the performance of the proposed
protocol against that of two other typical reservationprotocols, a
Tell-and-Wait and a Tell-and-Go protocol.