DLSw or Data Link Switching is a tunneling protocol designed to direct non-routable and non-IP protocols across IP networks. These protocols include IBM Systems Network Architecture (SNA) or NetBIOS Frames (NBF), and DLSw serves as a way of transporting SNA and NetBIOS traffic over an IP network. It enables local area network traffic to travel across a wide area network by first encapsulating the traffic in TCP packets.
DLSw was initially documented in IETF RFC 1434 in 1993 and was further expanded in RFC 1795 in 1995, and version 2 was introduced in 1997. Cisco Systems also has its proprietary extensions for DLSw known as DLSw+, which are 100% compliant with IETF RFC 1795 but include some proprietary extensions. Some organizations have started replacing DLSw tunnels with the newer Enterprise Extender (EE) protocol, which is a feature of IBM APPN on z/OS systems.
DLSw routers are known as peers, and the connection between them is called peer connections. DLSw works by creating two TCP connections between two peers, and they exchange capabilities like DLSw version numbers known by NetBIOS names.
What is the use of DLSw?
DLSw or Data Link Switching is a tunneling protocol that enables non-routable and non-IP protocols, such as IBM Systems Network Architecture (SNA) and NetBIOS Frames (NBF), to travel over IP networks.
What is DLSw+?
DLSw+ is a proprietary extension of DLSw introduced by Cisco Systems. It is 100% compliant with IETF RFC 1795 but includes some proprietary extensions that can only be used when both devices are Cisco devices.
What is Enterprise Extender (EE)?
Enterprise Extender (EE) is a protocol that allows IBM Systems Network Architecture (SNA) and NetBIOS traffic to travel over Transmission Control Protocol/Internet Protocol (TCP/IP) networks. It is a feature of IBM APPN on z/OS systems.
DLSw is an essential protocol that allows non-routable and non-IP protocols to travel over IP networks. Although there are newer protocols like EE available, DLSw still remains relevant and is widely used in organizations that use non-IP-based and non-routable protocols.