What is Data-Link Switching ?
Data-link switching (DLSw) provides a means of transporting IBM Systems Network Architecture (SNA) and network basic input/output system (NetBIOS) traffic over an IP network. It serves as an alternative to source-route bridging (SRB), a protocol for transporting SNA and NetBIOS traffic in Token Ring environments that was widely deployed before the introduction of DLSw. In general, DLSw addresses some of the shortcomings of SRB for certain communication requirements—particularly in WAN implementations. This chapter contrasts DLSw with SRB, summarizes underlying protocols, and provides a synopsis of normal protocol operations. The three primary functions of DLSw are :
•The Switch-to-Switch Protocol (SSP) is the protocol maintained between two DLSw nodes or routers.
•The termination of SNA data-link control (DLC) connections helps to reduce the likelihood of link layer timeouts across WANs.
•The local mapping of DLC connections to a DLSw circuit.