With PVM-SCI it is possible to use the faster SCI transport when available but also interoperate and communicate with other cluster nodes communicating via TCP/IP for example.
References: This paper desribes the layout and implementation. Basically, a multi device snoops on SCI connections and TCP connections concurrently. If an SCI connection can not be established, the default routing with TCP is used.
For the HARNESS project
(PVM's next generation) an SCI Plug In will be provided.
With round trip latency as low as 57 usec !
