Cells in frames: ATM over legacy networks

Cells in frames is a technology developed at Cornell University in conjunction with members of the CIF Alliance which provides a mechanism for running complete ATM protocol stacks, along with service quality guarantees, on legacy, frame-based networking hardware such as Ethernet or token ring. The CIF protocol also provides for the use of variable-length ATM packets, potentially reducing the cell tax overhead frequently identified as an inefficiency in the ATM cell format. Because CIF provides access to the full ATM stack, it can be thought of as a frame-based PHY layer. In this paper we will discuss the rationale for developing cells in frames, the protocol and frame format, and our experience with the technology. We will pay particular attention to performance, particularly in the contexts of desktop operating systems such as MacOS and Windows 95/NT and of multimedia data transport. While CIF has received some attention in the literature, this paper presents the first published results of a CIF implementation.