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There are an increasing number of ways optical network devices and IP routers can interact with each other
during a network fault. To provide continuity of service, the interactions between each component in a network
must be cooperative. Consequently, the effect of recovery processes cooperating are the network configurations
that have certain structural relationships, which can be elaborated. A conflict detector can prove that service
will be restored during a fault scenario by checking whether these structural properties hold.
We are using simulation as a method to study the coordination of recovery strategies and whether different
coordination strategies will achieve recovery goals attached to a network service. The network service carries a
traffic stream, which is injected into and extracted from a network. For multilayer recovery to complete, the
cumulative effect of device actions during a failure must be (1) a connected path between the endpoints of a
service and (2) a flow traffic delivered to a destination at a quality that matches a service level agreement.
We represent Optical and Multiprotocol Label Switching (MPLS) recovery actions as graph-maintenance
operations that change the state of a digraph. For example, the actions of forwarding traffic between an access
port and a trunk port and selecting traffic from a new trunk port and forwarding it to an access port can
be modeled as a sequence of edge additions and deletions. The state of the digraph represents the current
configuration of a multilayer network as actions of recovery are performed. In this paper, we define some
structural properties that can be observed during a simulation as the network evolves to a final state from an
initial state before a failure occurs.
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