Optical Networking Best Practices Handbook

10.2. MOTIVATION AND NETWORK ARCHITECTURES

One of the key choices in the architecture of the telecom transport layer is the type, granularity, and amount of switching at this layer. In this context, switching refers to fairly static connection-oriented cross-connect functionality as opposed to more sophisticated and dynamic switching functions that occur at higher layers in the network hierarchy. As a result, both photonic (OOO) and electrical (OEO) switches are viable contenders for cross-connects [2]. In fact, these two technologies are widely regarded as competing technologies for the same transport layer applications, with photonic switching providing lower cost per bit, while electrical switching provides better manageability of connections. At best, they are considered as addressing different segments of the transport connection service market, where photonic switching addresses the high-bit-rate connection service (say, 10-Gbps connections and above), and electrical switching is considered for subwavelength connections (say, 2.5 Gbps and below). According to this rationale, if subwavelength grooming is required, it is assumed that there is no place for photonic switching. While this may be the right short-term approach to the problem, it is a better way to think of these technologies as complementary. Both of them have their function in the same network and even for the same set of services [2].

Now, let us focus on architectures for agile AONs. Such networks provide photonic ...