A Cross-Layer ILP Formulation for Finding p-Cycles in All-Optical Networks

Abstract

Their high recovery speed and efficiency have made p-Cycles a premier approach to link protection. Recent research has discussed their capabilities and provided different methods for p-Cycle selection in communication networks. In this work, we consider the p-Cycle approach to resilient all-optical network design and present an ILP formulation that preconfigures pCycles in such an environment. Our proposed formulation strives to find p-Cycles that have good recovery capability in the face of physical layer impairments (PLIs) and are capacity-efficient at the same time. Our numerical results show a trade-off between these two performance measures. We evaluate the performances of different outcomes of the formulation using our accurate physical layer model. We show that applying our previously proposed cross-layer RWA algorithm, HQ, greatly improves the performance.

Implementing Protection Classes through p-Cycles in Impairment-Constrained Optical Networks

“…The ILP formulation provided in this section is a total upgrade to the formulation proposed in [2]. We partly use the same notations as our previous formulation to clearly show the upgrade in the formulation.…”

“…The network will assign the shorter available path on these two digraphs to the connection. Note that links that are on cycle are available in one direction only, but straddling links, (2,4) and (1,3), are available in both directions for connection setup.…”

“…Several ILP algorithms have been proposed to find p-Cycles without enumeration in WDM networks [8], [9], [10], but they assume that the traffic demand matrix is known and do not consider an all-optical environment with physical layer impairments. In [2] we developed an ILP formulation that applies to all-optical networks and preconfigures the p-Cycles for any dynamic traffic, with the assumption that all users have the same survivability requirement. Here we present an enhancement to the ILP algorithm to incorporate two classes of traffic with different restoration times.…”