Smart Cluster Network (SCnet) is a high performance Virtual Interface (VI) Architecture communication system for UNIX TM systems connected with Fujitsu's Synfinity-0 System Area Network (SAN). It is the first UNIX TM VI Architecture system that achieves "Full Conformance," as defined by Intel Corp. This paper describes the design of SCnet, focusing on multiple Network Interface Card (NIC) support for load balance, inter-process protection, memory registration, and communication protocols. The paper presents the main problems faced and our solutions for them. We propose extensions needed to support the VI Architecture effectively on current systems. We evaluated the SCnet performance experimentally using a two node cluster system connected with the Fujitsu's Synfinity-0 SAN. Latency as low as 42 microseconds, and throughput as high as 108 MBytes/sec is achieved using a single NIC. When using 2 NICs per node throughput of 210 MBytes/sec is achieved.