p-Cycles have been proposed for preprovisioned 1 + N protection in optical mesh networks. Although the protection circuits are preconfigured, the detection of failures and the rerouting of traffic can be a time consuming operation. Another survivable mode of operation is the 1 + 1 protection mode, in which a signal is transmitted to the destination on two link disjoint circuits, hence recovery from failures is expeditious. However, this requires a large number of protection circuits. In this paper, we introduce a new concept in protection: 1 + N protection, in which a p-Cycle, similar to FIPP p-cycles, can be used to protect a number of bidirectional connections, which are mutually link disjoint, and also link disjoint from all links of the p-Cycle. However, data units from different circuits are combined using network coding, which can be implemented in a number of technologies, such as Next Generation SONET (NGS), MPLS/GMPLS, or IP-over-WDM. The maximum outage time under this protection scheme can be limited to no more than the p-Cycle propagation delay. It is also shown how to implement a hybrid 1 + N and 1 + N protection scheme, in which on-cycle links are protected using 1 + N protection, while straddling links, or paths, are protected using 1 + N protection. Extensions of this technique to protect multipoint connections are also introduced. A performance study based on optimal formulations of the 1 + 1, 1 + N and the hybrid scheme is introduced. Although 1 + N speed of recovery is comparable to that of 1 + N protection, numerical results for small networks indicate that 1 + N is about 30% more efficient than 1 + 1 protection, in terms of the amount of protection resources, especially as the network graph density increases.

http://home.engineering.iastate.edu/~kamal/Docs/k09.pdf

$1+{\rm N}$ Network Protection for Mesh Networks: Network Coding-Based Protection Using p-Cycles

The DARPA CORONET project seeks to develop the target network architectures and technologies needed to build next-generation long-distance IP-over-Optical-Layer (IP/OL) networks. These next-generation networks are expected to scale 10-100 times larger than today's largest commercial IP/OL network. Furthermore, DARPA has established advanced objectives for very rapid provisioning of new IP or private line connections, very rapid restoration against up to three simultaneous network failures, and future dynamic ldquowavelengthrdquo services ranging from speeds of 40-800 Gigabits per second. Besides these ambitious goals, the CORONET project seeks to establish a commercially-viable network architecture that supports both commercial and government services. In this paper, we describe the CORONET program requirements, and present our initial architectures and analysis of the early phases of this long-term project. We propose a novel 2-Phase Fast Reroute restoration method that achieves 50-100 ms restoration in the IP-Layer in a cost-effective manner, and a commercially viable OL restoration method that can meet the rapid CORONET requirements. We also estimate the magnitude of the extra capacity needed to provide dynamic wavelength services compared to that of static services, and show that the extra capacity to restore a small percentage of high priority traffic against multiple failures requires a small amount of extra capacity compared to that of single failures.

Network Design and Architectures for Highly Dynamic Next-Generation IP-Over-Optical Long Distance Networks

One of the most promising techniques of network protection i.e. p-Cycles (pre-planned, preconfigured-cycles) is reviewed in this paper. In this paper we provide a survey of the main work on p-cycles to date. The characteristics of p-cycles and various types of protection provided by them are discussed. Finally, some possible extensions or enhancements of the p-cycle concept are discussed.

p-Cycles: An overview

The concept of p-cycle (preconfigured protection cycle) allows fast and efficient span protection in wavelength division multiplexing (WDM) mesh networks. To design p-cycles for a given network, conventional algorithms need to enumerate cycles in the network to form a candidate set, and then use an integer linear program (ILP) to find a set of p -cycles from the candidate set. Because the size of the candidate set increases exponentially with the network size, candidate cycle enumeration introduces a huge number of ILP variables and slows down the optimization process. In this paper, we focus on p-cycle design without candidate cycle enumeration. Three ILPs for solving the problem of spare capacity placement (SCP) are first formulated. They are based on recursion, flow conservation, and cycle exclusion, respectively. We show that the number of ILP variables/constraints in our cycle exclusion approach only increases linearly with the network size. Then, based on cycle exclusion, we formulate an ILP for solving the joint capacity placement (JCP) problem. Numerical results show that our ILPs are very efficient in generating p -cycle solutions.

/pdf/ilp-formulations-for-p-cycle-design-without-candidate-cycle-38jnl4df9a.pdf

ILP formulations for p-cycle design without candidate cycle enumeration

We present initial network architectures and capacity-efficient design for an IP/Optical network with highly dynamic IP and wavelength services, restoration against up to 3 failures, and aggregate traffic levels that represent a 10-fold increase over today's network traffic.

Network design and architectures for highly dynamic next-generation IP-over-optical long distance networks

The enabling technology for supporting IP centric traffic over optical transport networks evolves as the amount of traffic grows. In this paper, we first review a recently proposed concept called light trails. Light trails can enable high speed provisioning, accommodate multigranularity traffic, support high data rates and offer a good candidate for carrying IP traffic over optical networks. Next, we focus on light trail design. We propose a two-step approach for solving the light trail design problem. The first step is called traffic matrix preprocessing, it divides single long hop paths into several shorter paths that satisfy the hop-length constraint. In the second step, the light trail design problem is formulated as an integer linear programming (ILP) optimization problem. The results obtained from our experiments show that the resulting light trail network has high wavelength utilization.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1161&context=ece_conf

Optimal light trail design in WDM optical networks

Achieving both high capacity efficiency and fast restoration speed is a primary goal of survivable design in WDM network. The p-cycle method aims to benefit from the fast restoration of ring-like protection and high capacity efficiency of mesh protection. In this paper, we first present a p-cycle based method to deal with dynamic traffic in survivable WDM network design. In this method, we first find an optimal set of p-cycles for the given network topology. Next, we propose three routing strategies for accommodating dynamic requests upon their arrival time. The performance of our p-cycle based design using different routing strategies are compared with that of the shared backup path protection (SBPP). The results show that proposed p-cycle based design method performs better than SBPP in dense networks. Whereas SBPP performs better than the p-cycle based design in sparse networks.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1151&context=ece_conf

A p-cycle based survivable design for dynamic traffic in WDM networks

In this paper, we consider the problem of survivable network design in traffic groomed optical WDM mesh networks with sub-wavelength capacity connections. In typical survivable network designs, individual sessions are provided either full protection or no protection. We consider a quality of protection (QoP) framework where a connection is provided partial protection, i.e. when a link failure occurs on the primary path, the protection bandwidth provided on the backup path is less than or equal to the primary bandwidth. Each connection request specifies the primary bandwidth and a minimum backup bandwidth required. The network will guarantee at least the minimum backup bandwidth and, if capacity is available, higher backup bandwidth up to the primary path's bandwidth. The advantage of such a model is that it can reduce backup capacity requirements based on connection needs leading to lower blocking probability and lower network costs. We consider two scenarios: (i) a network with static traffic and formulate the problem of providing partial protection in groomed networks as an integer linear program (ILP); and (ii) a network with dynamic traffic that is analyzed using discrete-event simulation models. The results quantify the gain in blocking probability for different partial protection scenarios.

On partial protection in groomed optical WDM mesh networks

Due to power considerations, it is possible that not all wavelengths available in a fiber can be used at a given time. In this paper, an analytical model is proposed to evaluate the blocking performance of wavelength-routed optical networks with and without wavelength conversion where the usable wavelengths in a fiber is limited to a certain maximum number, referred to as wavelength usage constraint. The effect of the wavelength usage constraint is studied on ring and mesh-torus networks. It is shown that the analytical model closely approximates the simulation results. We also evaluate the performance of the first-fit wavelength assignment algorithm and compare its performance with the random wavelength assignment algorithm through simulation. It is observed that increasing the total number of wavelengths in a fiber is an attractive alternative to wavelength conversion when the number of usable wavelengths in a fiber is maintained the same.

Performance Analysis of WDM Optical Networks with Wavelength Usage Constraint

The recently proposed light trail architecture offers a promising candidate for carrying IP centric traffic over optical networks. In this paper, we first give a brief introduction to the light trail architecture, then focus on the optimal design of survivable light trail optical network. Two protection schemes, namely connection based protection and link based protection, that can achieve 100% protection against single link failure are proposed and compared. The survivable light trail design problem using connection based protection model is formulated as an integer linear programming (ILP) optimization problem. The numerical results obtained from solving our ILP formulation are presented and show that the design achieves high wavelength utilization as well as 100% protection again single link failure.

Jing Fang

Papers

Optimal light trail design in WDM optical networks

A p-cycle based survivable design for dynamic traffic in WDM networks

On partial protection in groomed optical WDM mesh networks

Performance Analysis of WDM Optical Networks with Wavelength Usage Constraint

On survivable design in light trail optical networks