Introduction and Overview


SDH is a networking protocol used mainly as a point-to-point link protocol over fibre optic links. An SDH framer is usually implemented in silicon (as a microchip) and lives on Layer 1 of the OSI Networking Layers, the physical layer. Thus, a chip that implements this type of functionality is called a PHY.

SDH is the European version of SONET, a North American standard. With the exception of terminology, the standards are almost identical.

The LINK layer device passes packets to the PHY device over a standardized interface called PL3. This SDH framer accepts packets in the PPP format over PL3 and then wraps them in HDLC before placing them in the SDH frame.

Our group embarked on this 499 project with the intent of learning VHDL, the language used most often in VLSI chip design, and the hope of expanding our knowledge of networking standards and practices. In addition to accomplishing these goals, we've learned about teamwork in a multi-designer environment.


The design of the system was broken into four main modules. Each module was implemented separately, and at the end all modules were connected. Each module was tested separately with it's own test bench before it was connected with another. Below is a general overview of the system broken into separate modules. Click on a module to get more information.