RFC 2114 (rfc2114) - Page 2 of 22
Data Link Switching Client Access Protocol
Alternative Format: Original Text Document
RFC 2114 DCAP February 1997 1. Introduction Since the Data Link Switching Protocol, RFC 1795, was published, some software vendors have begun implementing DLSw on workstations. The implementation of DLSw on a large number of workstations raises several important issues that must be addressed. Scalability is the major concern. For example, the number of TCP sessions to the DLSw router increases in direct proportion to the number of workstations added. Another concern is efficiency. Since DLSw is a switch-to- switch protocol, it is not efficient when implemented on workstations. DCAP addresses the above issues. It introduces a hierarchical structure to resolve the scalability problems. All workstations are clients to the router (server) rather than peers to the router. This creates a client/server model. It also provides a more efficient protocol between the workstation (client) and the router (server). 2. Overview 2.1. DCAP Client/Server Model +-----------+ +-----------+ +---------+ | Mainframe | | IP Router +- ppp -+ DLSw | +--+--------+ +-----+-----+ | Work | | | | Station | | | +---------+ +--+--+ +-------------+ | | FEP +- TR -+ DLSw Router +-- IP Backbone +-----+ +-------------+ | | | +-----------+ +---------+ | IP Router +- ppp -+ DLSw | +-----+-----+ | Work | | Station | +---------+ | DLSw Session | +-------------------------------+ Figure 2-1. Running DLSw on a large number of workstations creates a scalability problem. Figure 2-1 shows a typical DLSw implementation on a workstation. The workstations are connected to the central site DLSw router over the IP network. As the network grows, scalability will become an issue as the number of TCP sessions increases due to the growing number of workstations. Chiang, et. al. Informational
