First development of integrated optical packet and circuit switching node for new-generation networks

Since the underlying demand for network capacity can be satisfied only by extremely increasing transmission bit rate, processing speed, and switching capacity, it definitely will lead to increased power consumption of network nodes. Energy crisis is global crisis nowadays and it has brought up many problems. Power consumption is becoming a crucial issue in designing high-performance network devices. This paper studies the power consumption model of a kind of Optical Packet Switching (OPS) node based on Semiconductor Optical Amplifiers (SOA). Our results show that by dynamically adjusting the bias current of SOAs, the power consumption on an OPS node can be reduced considerably, especially when the traffic distribution across multiple ports is not balanced and inter-nodal distances vary. The total electrical power consumption can be cut off significantly. We also show the power consumption can be further reduced by jointly optimizing the thermoelectric cooler current.

We have proposed an optical packet and circuit integrated (OPCI) network which provides over Tbps capacity with low power consumption by optical technologies and deals with diversity of services from best-effort service to quality of service guaranteed service by packet and circuit switching schemes. Recently, we developed an integrated optical packet and circuit switch (OPS/OCS) node and constructed an OPCI ring network testbed. The integrated OPS/OCS node has a function to encapsulate Internet Protocol (IP) packets coming from client networks into optical packets. In this paper, we discuss about how to incorporate OPCI networks into current IP-based wide area networks. For the first time, we experimentally demonstrate an OPCI network testbed incorporated into a multihomed network where IP addresses are hierarchically allocated. The multihomed network provides multiple links with different characteristics such as a 100 Gbps optical packet link for high capacity and shared bandwidth services, a 10 Gbps optical path link for high quality and dedicated bandwidth services, and a 10Gbit Ethernet link for low cost services. Therefore, users can choose adequate link technologies according to application or traffic conditions. We successfully verify that high definition video data is efficiently transported by switching link technologies in the multihomed network.

Since the underlying demand for network capacity can be satisfied only by extremely increasing transmission bit rate, processing speed, and switching capacity, it definitely will lead to increased power consumption of network nodes. Energy crisis is global crisis nowadays and it has brought up many problems. Power consumption is becoming a crucial issue in designing high-performance network devices. This paper studies the power consumption model of a kind of Optical Packet Switching (OPS) node based on Semiconductor Optical Amplifiers (SOA). Our results show that by dynamically adjusting the bias current of SOAs, the power consumption on an OPS node can be reduced considerably, especially when the traffic distribution across multiple ports is not balanced and inter-nodal distances vary. The total electrical power consumption can be cut off significantly. We also show the power consumption can be further reduced by jointly optimizing the thermoelectric cooler current.

Modeling and performance analysis of a data center network (DCN) combining optical packet switching (OPS) and agile optical circuit switching (OCS) in a unified platform are presented. Hybrid optoelectronic packet routers which combine optical switching fabric and electronic buffers are used, supporting 100 Gbit/s (25 Gbit/s × 4 wavelengths) optical packets. OCS transmission is implemented by a novel “express path,” (ExP) an instant wavelength path on demand, which enables certain flows following the ExP with no packet contention, whereas ordinary OPS packets are switched with a deflection routing algorithm and buffering for contention resolution. This architecture can support OCS for large and reliability-sensitive data transferring and OPS for latency-sensitive applications. The performance of the network is investigated via numerical simulations of top-of-rack switch (ToR)-to-ToR traffic in an N-dimensional (up to 4096 node) torus topology. We have made the following observations: 1) torus topology results in high throughput and can be scaled out by increasing the dimension; 2) contention resolution between OPS and agile OCS is needed and our proposed strategies enhance the overall performance; and 3) in a lightly to moderately loaded case of OPS traffic, more than 100 ExPs can be supported simultaneously with acceptable affect on OPS.

The wavelength conversion is regarded as an effective way to resolve the optical packet contention in the wavelength domain for optical packet switching. An optical packet switching node, based on shared-per-node equipped with limited range wavelength converters and parametric wavelength converters (SPN-LP), is designed to further reduce optical packet loss probability. A novel optical packet contention resolution with priority differentiation wavelength scheduling algorithm to support quality of service (QoS) for the SPN-LP architecture is put forward in the article. The simulation results show that proposed optical packet resolution enables a good QoS differentiation, namely the high priority contending optical packet has the sufficient low packet loss probability.

We propose and implement an enhanced moving average (MA) based dynamic resource allocation method for optical packet and circuit integrated (OPCI) networks. In the OPCI networks, optical packet switching (OPS) and optical circuit switching (OCS) share the total bandwidth in a fiber by allocating separate wavelength resources to them. In this work, we leverage an exponential moving average (EMA) as an enhanced MA. Every time a signaling process for path establishment or release occurs at a node, the proposed method employs the EMA of number of in-use paths to reallocate wavelengths to OCS and OPS while the conventional method employs the absolute number of in-use paths. When the EMA reaches or becomes less than a threshold value, the dynamic resource allocation is executed. As results of simulations and a verification experiment, we show that the proposed method can reduce the amount of routing processes without suffering from blocking of path establishments in comparison to the conventional method. In addition, it is expected that the proposed method can effectively allocate vaster amount of bandwidth to OPS without suffering from the blocking and achieve better system performances for OPS.

An optical packet and circuit integrated network (OPCInet) will allow diverse services, enhanced functional flexibility, and efficient energy consumption, as optical packet switching (OPS) and optical circuit switching (OCS) links are provided on the same infrastructure. In this paper, we design and develop a control system consisting of header processing for optical packets, signaling and routing for optical path setup, and wavelength resource control and link switching between OPS and OCS for the efficient use of resources. Our onboard optical packet header processor is capable of 16-bit longest prefix matching by embedding a 0.6W (5% of TCAM technology on the same condition), 200 million search-per-second (equivalent to 100 Gbps) forwarding engine LSI, and a statistical memory LSI for retaining the statistical information of processed headers. Reactive control automatically selects a packet or circuit link according to the statistical traffic information from the header processor and works with signaling for optical paths. We present an experimental demonstration of a new control system using a previously developed OPCInet testbed.

In optical packet switching (OPS)-based data center networks (DCNs), it is preferred to set up temporal optical circuit switching (OCS) paths for large-data transmission that requires high reliability. However, inappropriate OCS path selection could severely affect the original OPS traffic. This is because an OCS path may break the network topology and cause OPS packet circulations. We propose to maintain bypassing routes for every link of the OCS path when it is established. Then, the OPS packets can bypass the OCS links by being deflected to the bypassing routes. Therefore, this method facilitates the coexistence of OCS in OPS-based DCNs. Numerical simulations demonstrate the benefit achieved by our proposal compared with non-bypassing-route scenarios.

Optical Burst Switching and Packet Switching require the adoption of suitable contention resolution mechanisms at the optical nodes due to multiple packets/bursts attempting to access the shared output channel at the same time. Contentions can be solved by exploiting the space, wavelength and time domain. The many alternatives possible call for suitable scheduling policy aiming at an optimal system performance. This paper provides an assessment of the role of key parameters for an optical packet/burst contention resolution scheme and the resulting node cost estimation in terms of CAPEX, footprint and power consumption. Feasibility tradeoffs due to limited optical buffering and wavelength conversion capability are also taken into account.

Optical burst switching (OBS) is a switching technology that can efficiently operate in the optical core network using WDM technology and can also develop the future optical internet. The OBS switching technology presents a trade-off between the two switching technologies: optical circuit switching (OCS) and optical packet switching (OPS). This switching approach increases resource utilization compared with OCS technology and avoids the technological barriers of OPS networks. In OBS networks, many packets are assembled into one data burst at the edge node and a burst header packet (BHP) is sent before the burst transmission by an offset time in order to reserve the required resources in core nodes. This can cause security issues in the network and more specifically denial of service attacks that can occur if a source node is compromised. In this paper, we study a specific denial of service attack which we refer to as "BHP flooding attack", which prevents legitimate traffics from reserving the required resources at intermediate core nodes. We also propose the design of a reconfigurable BHP flooding countermeasure module that allows to counter against this type of attacks in an OBS network.

The performance of an optical switching network is mainly determined by its core node structure. An improved optical packet switching (OPS) node structure based on recirculation optical fiber delay line (FDL) and feedback tunable wavelength converter (TWC), and a specific scheduling algorithm for the node structure are presented. This switching structure supports both point-to-point and point-to-multi-points broadcasting transmission with superior capacity expansion performance. Its superiority in packet loss probability is proved by simulation.

We study the fundamental properties of the hybrid combination of optical circuit switching (OCS) and electrical packet switching (EPS) used in an ultra-high-speed local area network (LAN) of the future, where chunks of data such as those containing non-compressed super-high-definition images are frequently transmitted as well as text-based data. We assume the logical topology of the OCS network in such a LAN to be single star in which the end-to-end connections are provided through a non-blocking optical matrix switch located at the center, while a conventional modest-speed EPS-based network such as Ethernet is co-installed to function as another data plane as well as the control plane of the OCS network. We refer to queueing theory in order to understand the fundamental performances issues of OCS and packet switching, and show that the hybrid use of OCS and EPS is very preferable especially when the variance of file size is very large. Simulation results show that the hybrid configuration can significantly outperform a network based on OCS only.

Hybrid optical networks (HONs) are the combination of different switching mechanisms such as Optical Circuit Switching (OCS), Optical Burst Switching (OBS) and Optical Packet Switching (OPS). The basic idea behind HONs is to integrate the advantages of different switching mechanisms. HONs are classified into three classes as: (1) parallel hybrid optical networks, (2) integrated hybrid optical networks, (3) client-server hybrid optical networks. In this article, we describe these classes in detail and a new integrated hybrid optical network called EISM (Efficient Integration of Switching Mechanisms in all-optical networks) is introduced. The proposed EISM method could perform optimally while considering some implementation criteria; such criteria include network bandwidth utilization, implementation complexity and also the domain of network performance by combining four switching mechanisms-OCS, long-OBS, short-OBS and OPS.

In optical switching paradigm, there are three approaches; optical circuit switching, optical packet switching, and optical burst switching (OBS). OBS is a technology that takes the best features of packet switching and circuit switching by providing a flexible infrastructure for carrying IP traffic and at the same time ensuring efficient utilization of the fiber link. In this paper we propose an effective contention resolution scheme to achieve minimum burst loss at core nodes. Algorithm of zero burst loss for bimodal burst switching is extended from single node star network topology to two node star topology. Scheduling at the core node, typically an optical cross connect (OXC), is performed in two modes i.e., Mode 0 & Mode 1. Mode 0 is for burst transmission between all directly connected edge nodes whereas Mode 1 is for burst transmission through remote core node to a particular destination edge node. Synchronization of the reservation request between the core nodes is a critical task in such a topology. In order to achieve minimum burst loss, using a small length of fiber delay line in recirculation mode results in an effective strategy.

Optical packet switch with multicast capability enables a broad range of applications in next generation optical networks. In this paper, we propose a cost-effective scheme to enhance the traffic performance of our earlier reported optical wavelength-routed multicast packet switch by modifying rather than adding multicast modules in the switch. A packet scheduling technique is introduced to substantially reduce the output contention for the switch. The effectiveness of our proposed scheme in conjunction with the scheduling technique is analyzed and validated by evaluation of packet loss performance of the modified multicast packet switch through simulations. The simulation results show that the multicast packet loss probability of the modified multicast switch can be significantly reduced without increasing the number of multicast modules by our proposed scheme. This means that to achieve an acceptable level of the multicast packet loss probability, the modified multicast switch requires fewer multicast modules in comparison with our earlier reported switch.