To compute the end-to-end diverse path in multi-domain networks is still a challenging topic puzzled both the network
industry and the network academy. Although the existing Path Computation Element (PCE)-based simultaneous scheme
performs minimum blocking rate, the computation complexity and communication overhead are high. In this paper, an
enhanced PCE-based simultaneous scheme is proposed to decrease the computation complex and communication
overhead. Analysis and simulation show the effectiveness of the proposed scheme.
KEYWORDS: Network security, Network architectures, Internet, Data communications, Roads, Failure analysis, Photonics, Current controlled current source, Basic research
Recently, several distributed attacks based on local information have been emerged threating network security. The
coordinated attack is one of the most destructive attacks, with an important property to identify the next-step target
through coordinating all crashed nodes. It has been ignored in most of existing researches that the crashed nodes network
size will become larger and larger along with the coordinated attack, which makes the coordinated attack crash each
node in the same time virtually impossible. In this work, we propose R.C.H strategy, which removes a fraction of
crashed hub nodes to improve network robustness against the coordinated attack. The simulation shows that R.C.H
strategy is highly contribute to degrade efficiency of the coordinated attack by means of the larger cluster diameter of the
crashed node network, which provides some insights for the future research on enhancing robustness of complex
communication networks.
This paper measures and optimizes the network survivability based on average distance. A method is proposed to design
a network with constrained minimum average distance and to reduce the computation complexity based on adjacency
matrix. This paper studies the optimization of simple connected graph with arbitrary nodes and links under degree limit.
There may have several networks with minimum average distance in our method. So we choose the optimal network
from them by the network performance analysis under random failure.
To improve robustness for the complex network, this paper propose a novel probabilistic approach to allocate
redundancy links based on nodal degree, i.e. preferential allocation, inverse preferential allocation, and hiding
redundancy links (HRL) strategy. We find that allocating redundancy links can efficiently improve robustness of
networks to tolerate the coordinated attack. Especially, I-I case, which both source node and destination node are chosen
by inverse preferential allocation, performs the best. Furthermore, we investigate the effects of HRL strategy under the
coordinated attack, and the simulation shows that HRL strategy can achieve the better performance than never. More
interestingly, the relationship between threshold of crash and the number of redundancy links appears to achieve
nonlinear by the HRL strategy. Therefore, a small fraction of redundancy links is highly contributed to improve the
tolerance attack dramatically. This paper provides an insight on improving network robustness to tolerant the coordinated
attack by allocating redundancy links.
This paper proposes a network anomaly detection method based on catastrophe theory. The network anomaly detection model based on catastrophe theory is constructed by utilizing the catastrophe characters of the cusp catastrophe model in catastrophe theory and analyzing the properties of network data included normal and abnormal data. The simulation demonstrated that with the anomaly detection algorithm, this model could detect the network anomaly not only timely, but also detect precisely.
Bandwidth-on-Demand (BoD) services are characteristic of dynamic bandwidth provisioning based on customers'
resource requirement, which will be a must for future networks. BoD services become possible with the development of
make-before-break, Virtual Concatenation (VCAT) and Link Capacity Adjustment Scheme (LCAS). In this paper, we
introduce BoD services into L1VPN, thus the resource assigned to a L1VPN can be gracefully adjusted at various
bandwidth granularities based on customers' requirement. And we propose a dynamic bandwidth adjustment scheme,
which is compromise between make-before-break and VCAT&LCAS and mainly based on the latter. The scheme
minimizes the number of distinct paths to support a connection between a source-destination pair, and uses make-beforebreak
technology for re-optimization.
New concepts of horizontal protection and half-mesh topology for survivability design in multicast optical virtual private
networks are presented. All issues mentioned in this paper are expected to form targets for further investigations.
Generalized Multi-Protocol Label Switching (GMPLS) appears as a promising candidate to implement the control plane
for next-generation optical networks. In GMPLS-based wavelength division multiplexing (WDM) optical networks,
existing resource reservation protocol (RSVP) may fail to setup a multicast Label Switched Path (LSP) with high
probability, since multiple destinations in one multicast session may reserve different wavelengths and result in
reservation collision at branch nodes. In this work, we extend the existing GMPLS RSVP signaling protocol and propose
an efficient scheme to set up optical multicast LSP and avoid wavelength resources collision, called Last-hop Label Set
(LLS) scheme, by introducing a new object called Last-hop Label Set object in Resv message. Once the setup of a
multicast LSP fails caused by wavelength reservation collision at a branch node, the branch node can re-reserves a new
wavelength according to the Last-hop Label Set object within Resv messages. The numerical results indicate that the
proposed LLS scheme offers lower blocking probability compared to the existing GMPLS signaling scheme.
A ring based optical virtual private network (OVPN) employing contention sensing and avoidance is proposed to deliver
multiple-to-multiple group-multicast traffic. The network architecture is presented and its operation principles as well as
performance are investigated. The main contribution of this article is the presentation of an innovative group-multicast
capable OVPN architecture with technologies available today.
Layer 1 VPN (L1VPN) extends the notion of VPN to the optical domain to provide virtually dedicated circuit like leased
lines, so that the security is more enhanced. Despite their secure gains from channel isolation, VPNs still suffer fragilities
resulting from link-failures or node-failures. Extensive activities on survivability designs for wavelength-routed optical
networks are proposed, including various protection and restoration schemes, but concerns on network edge are rare.
Dual-homing is an effective skill to achieve survivability gains for L1VPNs. There are two dual-homing mode:
Active/Standby mode and Load-Sharing mode In this paper, we investigate the problem of PE assignment, which is the
key of dual-homing design and is NP-hard. We formulate it as an integer programming problem, and propose heuristic
solutions. Simulation results show that the proposed solutions work in a correct and effective way and the Load-Sharing
mode has higher bandwidth efficiency than Active/Standby mode.
This paper proposes a three-layer service model in optical networks. It utilizes diversity design and service shift
mechanisms. Both the analysis and simulation results demonstrate this model can effectively promote the survivability of
IP networks.
As bandwidth-intensive and time-sensitive streams applications such as high-definition television (HDTV) get popular, there rises a demand of supporting multicast communication directly at optical layer on next-generation optical networks. The multicast-capable optical cross-connect (MC-OXCs) is the necessary device to implement multicasting at optical layer. The functional building blocks for MC-OXC are light splitters (space splitters) or multi-wavelength converters (frequency splitters). The space splitter has no wavelength conversion capability, whereas the frequency splitter has limited fanout, decreased optical signal-to-noise ratio and also is expensive. We therefore proposed a tradeoff architecture called joint multicasting capable optical cross-connect (jMC-OXC) integrating both space splitters and multi-wavelength converters. In this paper, we investigate the network performance and the physical transmission performance on the jMC-OXC architecture by dynamic simulation and experimental demonstration. Three simulation schemes are designed and the results show that the network performance of the jMC-OXCs with limited multi-wavelength converters can obtain a close performance to that with full multi-wavelength converters. A prototype of jMC-OXC is examined and its bit error rate (BER) performance is tested after passing the multi-wavelength converters.
The multicast capability of a multicast-capable optical add/drop multiplexer (MC-OADM) is analyzed and the dynamic network performance on the WDM ring employing such MC-OADMs is investigated. The MC-OADM multicast scheme can provide more multicast services while consume less resources in comparison with that of the normal OADM ring without multicast capability.
We analyze the multicast capability of a multicast-capable optical add/drop multiplexer (MC-OADM) and investigate the dynamic network performance of the MC-OADM ring in comparison with that of the normal OADM ring without multicast capability. The simulation results show that the multicast scheme using MC-OADMs provides more multicast services and occupies fewer resources.
The emerging broadband real-time streams applications require the supporting networks to provide multicasting communication at optical layer. The multicasting capable optical cross-connect (MC-OXCs) is the necessary device to implement multicasting at optical layer. The functional building blocks for MC-OXC are light splitters, which can be space splitters or multiwavelength converters (frequency splitters). The space splitter has no wavelength conversion ability, while the frequency splitter has limited fanout, decreased optical signal-to-noise ratio and also is expensive. We proposed a tradeoff architecture called joint multicasting capable optical cross-connect (jMC-OXC) integrating both space splitters and frequency splitters in our previous work. This paper further studies the network performance in terms of member blocking ratio for the jMC-OXC architecture. Three simulation schemes are designed and the results show that the network performance of the jMC-OXCs with limited frequency splitters can obtain a close performance to that with full frequency splitters.
A translucent multicasting scheme based on sparsely placed signal re-generable translucent multicasting capable optical cross connect (tMC-OXC) nodes is proposed to provide signal-quality guaranteed multicasting services. We propose a tMC-OXC architecture capable of transparent unicasting and electronic multicasting. The electronic multicasting devices are also used to regenerate the impaired signals. A regeneration weight based MC-OXC nodes placement
strategy is designed to construct the translucent network. We propose two multicasting tree construction algorithms to evaluate the performance of the proposed translucent network, where the selected MC-OXC nodes serve as core nodes (we call them hub nodes). Our study shows that no more than 30% nodes need to be equipped with electronic multicasting and electronic 3R regeneration capability, having more than 30% nodes with regeneration capability only slightly enhances the network performance.
From element automatic control view, we propose a configuration algorithm for three-level cross-connects in data plane to handle with bypass, grooming and local add/drop traffic of fiber-level, band-level and wavelength-level by a abstract bipartite graph of MG-OXC and bandwidth utilization spectra graph. The configuration algorithm is evaluated by computer simulation as well as validated by experiment on our flexible Multi-functional Optical Switching Testbed (MOST).
To solve the scalability and flexibility issue in current optical network testbeds, a Multi-functional Optical Switching Testbed (MOST) has been built. Benefiting from design of modular hardware and layered software, network experiments of scalability and complicated node architecture can be made based on it. The hardware and software structure of the MOST system is explicitly analyzed in the article and demonstrations of a 12-node ASON and shared wavelength conversion ASON on MOST are also reported.
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