  In this paper, we address the problem of providing survivability in elastic
optical networks (EONs). EONs use fine granular frequency slots or flexible
grids, when compared to the conventional fixed grid networks and therefore
utilize the frequency spectrum efficiently. For providing survivability in
EONs, we consider a recently proposed survivability method for conventional
fixed grid networks, known as pre-configured backup protection with sharing
(PBPS), because of its benefits over the traditional survivability approaches
such as dedicated and shared protection. In PBPS, backup paths can be
pre-configured and at the same time they can share resources. Therefore, both
short recovery time and efficient resource usage can be achieved. We find that
the existing switch architectures do not support both PBPS and EONs.
Specifically, we identify and illustrate that, if a switch architecture is not
carefully designed, several key problems/issues might arise in certain
scenarios. Such problems include unnecessary resource consumption, inability of
using existing free resources, and incapability of sharing backup paths. These
problems appear when PBPS is adopted in EONs and they do not arise in fixed
grid networks. In this paper, we propose new switch architectures which support
both PBPS and EONs. Particularly, we illustrate that, our switch architectures
avoid the specific problems/issues mentioned above. Therefore, our switch
architectures support using resources more efficiently and reducing blocking of
requests.
