This paper introduces the architecture and the technology of the new I
SM transport network offering, which supports both fixed-length and va
riable-length packet switching. After a review of the broadband networ
king environment and the requirements it makes on the transport networ
k, the transport network node is described. The hardware and software
architecture is described, and performance figures are reported showin
g that the switch can handle a mix of traffic while sustaining maximum
throughput.