The theme of networking in SunOS 5.8 is transport independence. Networked applications can execute without having to be tailored to a specific transport protocol.
Previous versions of the system contain sockets, TLI, and name-to-address translation functions. In SunOS 5.8 these are enhanced and work with the new network selection facility to free user applications of the details of specific protocols and address formats.
Transport independent RPC provides interfaces that let applications be free of or more closely tied to the underlying transport. It is the developer's choice to use the most appropriate level.
Applications that must adjust options or use specific addresses can still do so. But you can now write applications to be very portable over different protocol stacks.
Another important feature of SunOS 5.8 is standardized internal kernel network interfaces at the transport and link levels. At the transport level, the AT&T Transport Provider Interface is required. At the link level, the UNIX International Data Link Provider Interface is required.
Standardizing on these interfaces lets you interchange STREAMS drivers at the transport and link level with no changes to the modules or drivers communicating with them. In particular, TLI and sockets can interface to any transport provider supporting TPI, and any device driver supporting DLPI can be linked beneath the Internet Protocol (IP).