The conventional approach of extending WDM networking from the Long-Haul/Regional network into the Metro geography typically requires a full termination of the optical capacity at the border. This is typically achieved by connecting metro service transponders into a transponder or muxponder on the long haul ROADM. While this approach provides a clean demarcation point between the networks and useful fault isolation capabilities, it does so at the increased cost of "back-to-back" transponders between the networks. This is illustrated in Scenario A.
While service providers may wish to retain the transponder demarcation point, integrated optical interfaces between Infinera DTN and ATN allow service providers to avoid a layer of line cards entirely.
Through optical layer integration between the ATN and DTN, shown in Scenario B, the same benefits of a digital demarcation point between the Metro and LH/Regional network can remain, but with additional CapEx savings at these hub locations thanks to transponder bypass. Infinera's integration architecture allows the benefits of the Intelligent Transport Network to be extended into the metro. There are three key elements to this integration: