The Multipath Enhanced Transit Router Organization (METRO) is a flexible routing architecture for high-performance, tightly-coupled, multiprocessors and routing hubs. A METRO router is a dilated crossbar routing component supporting half-duplex bidirectional, pipelined, circuit-switched connections. Each METRO router is self-routing and supports dynamic message traffic. The routers works in conjunction with source-responsible network interfaces to achieve reliable end-to-end data transmission in the presence of heavy network congestion and dynamic faults. METRO separates the fundamental architectural characteristics from implementation parameters. Simplicity of routing function coupled with freedom in the implementation parameters allows METRO implementations to fully exploit available technology to achieve low-latency and high-bandwidth. We illustrate the effects of this implementation freedom by summarizing the performance which various METRO configurations can extract from some modern CMOS technologies. METROJR-ORBIT, a minimal instance of the METRO architecture constructed in a 1.2 /spl mu/ gate-array technology, is included.>