Hardware support for a hash-based IP traceback

The Source Path Isolation Engine (SPIE) is a system capable of tracing a single IP packet to its point of origin or point of ingress into a network. SPIE supports tracing by scoring a few bits of unique information about each packet for a period of time as the packets traverse the network. Software implementations of SPIE can trace packets through networks comprised of slow-to-medium speed routers (up to OC-12), but higher-speed routers (OC-48 and faster) require hardware support. In this paper, we discuss these hardware design aspects of SPIE. Most of the hardware resides in a self-contained SPIE processing unit, which may be implemented in a line card form factor for insertion into the router itself or as a stand-alone unit that connects to the router through an external interface.