Daisaku Shimazaki

Dynamic multilayer routing schemes in GMPLS-based IP+optical networks

This article presents two dynamic multilayer routing policies implemented in the photonic MPLS router developed by NTT for IP+optical generalized MPLS networks. According to IP traffic requests, wavelength paths called lambda label switched paths are set up and released in a distributed manner based on GMPLS routing and signaling protocols. Both dynamic routing policies first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. If such a path is not available, the two policies employ different procedures. Policy 1 tries to find available existing optical paths with two or more hops that connect the source and destination nodes. Policy 2 tries to establish a new one-hop optical path between source and destination nodes. The performances of the two routing policies are evaluated. Simulation results suggest that policy 2 outperforms policy 1 if p is large, where p is the number of packet-switching-capable ports; the reverse is true only if p is small. We observe that p is the key factor in choosing the most appropriate routing policy. We also describe items that need to be standardized in the IETF to effectively achieve multilayer traffic engineering.

Optimization of light-path configuration order in IP over WDM networks using fast traffic matrix estimation

We propose an algorithm for determining light-path configuration order to minimize the reconfiguration time from a disrupted state to a suboptimal state. It computes a near-optimal solution within one minute on a 1000-node network.

Multi-staged network restoration from massive failures considering transition risks

In a scenario of restoration from massive failures, a network is repaired through multiple restoration stages because availability of repair resources is limited. In a practical case, a network operator should assure the reachability of important traffic in transient stages, even as risks and/or operational overheads caused by stage transitions are suppressed. We discuss the novel problem of optimizing both traffic recovery ratio and transition risks caused by paths switching operation. We formulate our problem as linear programming, and show that it obtains Pareto-optimal solutions of traffic recovery versus transition risks. We also propose a heuristic algorithm for applying networks consisting of a few hundred nodes, and it could produce sub-optimal solutions within 4% difference from optimal solutions.

Multi-layer Traffic Engineering Experimental System in IP Optical Network

We developed distributed-controlled multi-layer traffic engineering system. There is no previous works that report the system. Therefore, we can not confirm feasibility and scalability of the system. In this paper, we report an experiment on our system consisting of Internet protocol (IP) routers and optical cross-connects (OXCs). In this system, control is provided by generalized multi-protocol label switching (GMPLS) and IP network topology and IP routes are dynamically reconfigured to suit traffic characteristics. These functions prevent traffic congestion as well as any decrease in link utilization rates. We had experiments to test behavior of the routers and OXCs depending on traffic characteristics. We cleared that the distributed-controlled multi-protocol label switching (MPLS)/GMPLS traffic engineering system was feasible and scalable by the experiments.

Latest Trends in Traffic Matrix Modeling and Its Application to Multilayer TE

We survey traffic matrix models, whose elements represent the traffic demand between source-destination pair nodes. Modeling the traffic matrix is useful for multilayer Traffic Engineering (TE) in IP optical networks. Multilayer TE techniques make the network so designed flexible and reliable. This is because it allows reconfiguration of the virtual network topology (VNT), which consists of a set of several lower-layer (optical) paths and is provided to the higher layer, in response to fluctuations (diurnal) in traffic demand. It is, therefore, important to synthetically generate traffic matrices as close to the real ones as possible to maximize the performance of multilayer TE. We compare several models and clarify their applicability to VNT design and control. We find that it is difficult in practice to make an accurate traffic matrix with conventional schemes because of the high cost for data measurement and the complicated calculations involved. To overcome these problems, we newly introduce a simplified traffic matrix model that is practical; it well mirrors real networks. Next, this paper presents our developed server, the IP Optical TE server. It performs multilayer TE in IP optical networks. We evaluate the effectiveness of multilayer TE using our developed IP Optical server and the simplified traffic matrix. We confirm that multilayer TE offers significant CAPEX savings. Similarly, we demonstrate basic traffic control in IP optical networks, and confirm the dynamic control of the network and the feasibility of the IP Optical TE server.

Traffic-driven virtual network topology reconfiguration for GMPLS network

This paper proposes a statistical traffic processing scheme that makes virtual network topology (VNT) reconfiguration depend on average traffic value for the generalized multi-protocol label switching (GMPLS) network. This scheme dynamically changes the smoothing traffic value depending on the burst characteristics of the traffic. Feasibility of this scheme is confirmed by implementing it in GMPLS routers and confirming that the system works properly in a distributed-control network

GMPLS and IP+MPLS interworking technologies - routing and signaling

When nodes that support generalized multi-protocol label switching (GMPLS) are introduced into existing networks the GMPLS nodes co-exist with conventional Internet protocol (IP) and multi-protocol label switching (MPLS) (IP+MPLS) nodes that do not support GMPLS. In this case, the GMPLS nodes must interwork with IP+MPLS nodes. This paper proposes an architecture for GMPLS and IP+MPLS interworking based on extended routing and signaling. In the extended routing, information about some nodes and links in a GMPLS network emulates information that can be understood by IP+MPLS nodes. The emulated information is advertised to the IP+MPLS network. In the extended signaling, MPLS signaling packets are forwarded to the GMPLS data plane. An MPLS label switched path (LSP) is established through a GMPLS LSP tunnel. As a result, the IP+MPLS network can interwork with the GMPLS network without upgrading the IP+MPLS nodes. We developed GMPLS prototype nodes that support this interworking architecture and show interworking experimental results.

GTEP: generalized traffic engineering protocol for multi-layer GMPLS networks

This paper proposes a generalized traffic engineering protocol (GTEP). GTEP is a protocol that permits communication between a constrained shortest path first (CSPF) engine and a generalized multi-protocol label switching (GMPLS) controller (CNTL). The latter is hosted by each GMPLS node; it handles GMPLS and MPLS protocols such as routing and signaling protocols as well as controlling the GMPLS node host. The CSPF engine provides multi-layer traffic engineering; it calculates label switched path (LSP) routes and judges whether a new lower-layer LSP should be established. GTEP functions are implemented in both the CSPF engine and GMPLS router. We demonstrate a multi-layer traffic engineering experiment conducted with GTEP.

Experiments on Multi-layer Network Virtualization towards the Software Defined Transport Network

This paper proposes a novel architecture which enables software defined networking not only at the routing layer but also at the transport layer. Proposed architecture provides multiple SDTNs with wide range of controllability level, in spite that the SDTNs coexist upon a shared multilayered network infrastructure. We have conducted a nationwide experiment where we have provided SDTNs to practical users such as broadcasting studios. Through the experiments, we have successfully verified the resource management mechanism and network control functionalities.

Generalized Traffic Engineering Protocol for Multi-Layer GMPLS Networks

This paper proposes a generalized traffic engineering protocol (GTEP). GTEP is a protocol that permits communication between a constrained shortest path first (CSPF) engine and a generalized multi-protocol label switching (GMPLS) controller (CNTL). The latter is hosted by each GMPLS node; it handles GMPLS and MPLS protocols such as routing and signaling protocols as well as controlling the GMPLS node host. The CSPF engine provides multi-layer traffic engineering; it calculates label switched path (LSP) routes and judges whether a new lower-layer LSP should be established. GTEP functions are implemented in both the CSPF engine and GMPLS router. We demonstrate a multi-layer traffic engineering experiment conducted with GTEP.