If an Operator decides to deploy Multi-layer protection using both IP/MPLS and Optical domain, he faces a number of challenges: IP/MPLS and Optical control planes work separately in transport networks; they are, usually, disjoint and do not communicate with each other. IP/MPLS circuits are provisioned as one of the services for optical layer with no co-ordination between them. While the “disjoint” protection strategy may work.but it is NOT a very efficient way in the long run.
Operators who chooses to adopt a pure IP+ Optical protection/restoration model (in comparison to other models that include OTN as intermediate layer) should consider the following three things:
- Tight Integration between IP/MPLS and Optical Control Plane: For the model to bring down CAPEX and resource efficiency, there should be a tight integration between the NMS (Network Management System) of IP/MPLS and that of Optical domain, resulting in seamless integration. When fiber cut happens, how different layers would react and in which order, shall follow a proper sequence. IP/MPLS should know the optical resources and routes through GMPLS NNI+ interface enabling it to make better routing decisions.The signaling between the two layers can better optimize resources and informed decisions on when and which protection should come into play, once fiber cut happens.
- IPoDWDM. If operators choose a pure IP and Optical path(with no OTN switching layer) the IPoDWDM option makes sense. This will, further, bring down transponders’ cost. Otherwise, adding an overlay of back to back ports (grey ports of router to transponder on DWDM) can make the cost of lambda high.
- Organizational Structure: Last but not the least, operator must look into its own organizational structure. Operator should align its own organizational structure with its planned technological integration. Most importantly, if transport and IP departments are separate entitites, it is time to look closely at reorganization . As “Transport” and “IP” merge as technology, organisational structure should follow suit. Therefore, one department that plans and operates both IP and Transport makes sense in such cases. The model of having combined network protection/restoration strategy only works if there is a tight integration between the structure, processes, operations and management of both transport and IP groups. This has been found to have worked successfully in those organisations where there is one group that is responsible for the transport and IP part. Operators should align their department strategies keeping in view these changes in networks today.