With optical cross connects (OXC), where 40 optical channels can be transported on a single fiber, a network element is needed that can accept various wavelengths on input ports and route them to appropriate output ports in the network - in this application two different ESM™ Embedded System Modules are used depending on the performance requirements.

The OXC needs three building blocks: fiber switching, wavelength switching and wavelength conversion. Both ESMs are equipped with communication-oriented PowerPC® processors and up to 2GB working memory. The EM4A is powered by an MPC8245 running at 300MHz clock frequency. Two Fast Ethernets and two COMs are already implemented on the ESM™. The EM3A comes with the higher-performance MPC8560 (PowerQUICC™ III) and 800MHz clock frequency. Two Gigabit and one Fast Ethernet as well as two COMs are implemented on this ESM™. All other I/O connectivity is realized on an application-specific ESM™ carrier board that has been developed by the customer himself. The additional telecom interfaces are implemented by means of IP cores in the FPGA which is located on both ESM™ modules.