A parallel IP router that uses off-the-shelf wor-kstations and interconnecting switches is presented. This router, called CORErouter-I, is a medium-grained, functionally distributed parallel system consisting of four kinds of processors for routing, routing-table searching, servicing, and line interfacing. Also discussed are issues related to the implementation of CORErouter-I, especially in terms of routing protocol processing and packet-forwarding. Performance characteristics of CORErouter-I are also clarified through several experiments performed to evaluate maximum throughput, analyze packet-forwarding time, and estimate the effect of parallel processing on the route-flapping problem.

We present a general framework with which we can evaluate the flexibility and efficiency of various replay systems for parallel programs. In our approach, program monitoring is modeled by making a virtual dataflow program graph, referred to as a VDG, that includes all the instructions executed by the program. The behavior of the program replay is modeled on the parallel interpretation of a VDG based on two basic parallel execution models for dataflow program graphs: a data-driven model and a demand-driven model. Previous attempts to replay parallel programs, known as Instant Replay and P-Sequence, are also modeled as variations of the data-driven replay, i.e. the datadriven interpretation of a VDG. We show that the demand-driven replay, i.e. the demand-driven interpretation of a VDG, is more flexible in program replay than the data-driven replay since it allows better control of parallelism and a more selective replay. We also show that we can implement a demand-driven replay that requires almost the same amount of data to be saved during program monitoring as does the data-driven replay, and which eliminates any centralized bottleneck during program monitoring by optimizing the demand propagation and using an effective data structure.