An important issue in the design of host-network interfaces is how much protocol processing should be done in hardware (i.e. on the network device) and how much should be done in software (i.e., on the host). THis issue is becoming increasingly important as improving network performance puts more and more stress on the end host. Recent work in this area has focused on moving one or more high-level protocols from the host to the network device. In contrast, the principal investigators propose to investigate another point on the design spectrum. --a chip that implements a collection of protocol-independent functions. The PIs have identified key functions that span multiple protocols, and plan to provide these functions in hardware. The chip, called the x-chip is an outgrowth of the PIs' work on the x-Kernel--software architecture that supports protocol implementations. One of the design philosophies of the x-Kernel has been to identify tasks that are common to all protocols, and to provide general software tools that support these tasks. The x-chip takes this philosophy one step further by moving certain aspects of the support tools into hardware. The ultimate goal is to integrate the network device and the network software infrastructure vertically.