Short for Data-Link Switching. DLSw is a means of tunneling Systems Network Architecture (SNA) and NetBIOS traffic over an IP network. Before the development of DLSw, SNA and NetBIOS traffic was transported via Source-Route Bridging (SRB), a protocol for transporting in token ring environments. DLSw uses Switch to Switch protocol instead of SRB between routers to create DLSw peer connections, locate resources, forward data, handle flow control and error recovery. The routers are called data link switches.