Virtual path routing for survivable ATM networks

A New Approach to Survivability of Connection Oriented Networks

“…When the primary routes are found, for assignment of backup routes the function of lost flow due to a failure of a single link can be used. Some previous authors have introduced similar approach for local rerouting strategy in [8] and formulated a problem of primary routes assignment with the objective function using the k-shortest path based rerouting.…”

“…In fiber networks a single-link failure is the most common and frequently reported failure event [8]. Therefore, in most of optimization models a single-link failure is consider as the basic occurrence.…”

“…In this section we will formulate the optimization problem of primary routes' assignment with the objective function LFN (8). Without loss of generality we assume that sets containing proposals of primary routes that conform the LDR strategy are known.…”

“…Next the assignment of connections is newly calculated in order to prepare the network for further failures. More details on the topic of ATM and MPLS survivability can be found in [1], [2], [7], [8], [9], [10].…”

“…In such networks, 100% restoration is not always possible and routes are designed to minimize effects of the failure. Authors of [8] propose to use two-step restoration, i.e upon a failure the fast restoration is executed in order to accelerate a recovery from the failure. Next the assignment of connections is newly calculated in order to prepare the network for further failures.…”