The emerging Broadband Integrated Services Digital Networks (BISDNs) a
re expected to be flexible, supporting a wide spectrum of services and
infrastructure applications, and responsive to evolving customer need
s. The networks are also expected to be cost-effective, supporting div
erse services on a common platform, and highly manageable, providing u
nified operations and customer control. Meeting all these expectations
represents a major challenge in the design and implementation of BISD
N networks. This paper introduces the basic structure of BISDN network
s by describing a network reference model and the BISDN Protocol Refer
ence Model. It also describes BISDN functions for signaling and call c
ontrol, network management and operations and maintenance (OAM), traff
ic management and congestion control, and network performance and qual
ity of service. The evolution of the BISDN networks is also presented,
including an example of a BISDN network interworking with service-dep
endent networks.