I believe that IP/Optical integrated network solutions are working and available from a technical perspective these days. Indeed, companies have shown and tested colored optical router interface interworking with DWDM transport systems, control plane interworking for automated service set-up and network restoration, and integration of router and optical transport domains into a common network management platform. However, I think that there are other non-technical challenges that are blocking the introduction of integrated solutions.

The supporters of such an integrated approach say that network providers could achieve significant CAPEX savings if they were to adopt IP/Optical network solutions, for example, through the optical bypass of express traffic. Let me expand on this point a little more, if a packet has to travel between two locations there’s no benefit in processing it at a location in between. It’s more cost effective to perform routing at the optical level using optical add/drop multiplexers. Additional savings could even be achieved by using less transponders in the DWDM system as colored router interfaces connect directly to DWDM multiplexers and demultiplexers. Operational benefits would also come from features like the above mentioned automated service set-up and more network resilience due to additional restoration functions. Application of the latter is, for example, a scenario where restoration would be used in addition to 1+1 protection. If the protection path would fail as well in such a case the restoration feature could still restore the connection. To prove these benefits, some carriers are starting to deploy integrated solutions while others are conducting lab tests and trials.

However, I think that there are other non-technical challenges that are blocking the introduction of integrated solutions. One reason is that the life cycle of IP and transport equipment is different. Therefore network providers like to keep both domains separate in order to achieve maximum purchasing efficiency. Network management philosophies and systems are different as well. Again a reason for operating IP and transport layers in separate domains. In addition to this, price and margin structures are not equal in both industries. However, I think the most prominent reason is that IP and transport organizations are still separated at many carriers. Typically in such constellations nobody is keen to lose their power.