Wavelength-division multiplexing has emerged as an
important physical layer technology. Optical transmission provides a physical
layer capable of carrying bits at the speed of the order of a gigabit per
second. Optical burst switching is proposed to overcome the shortcomings of
conventional WDM deployment, such as lack of fine bandwidth granularity in
wavelength routing and electronic speed bottlenecks in SONET/SDH. In this
article, we describe an architecture for IP network over the OBS WDM
transmission core. The use of MPLS-type technique for forwarding data bursts
and the inclusion of a medium access control layer between the optical (WDM)
and IP layers are the key ingredients of the proposed architecture. In
particular, the architecture is based on provisioning MPLS paths, also called
label switched paths, of desired quality of service through the OBS WDM
transmission core. The MAC layer performs various OBS-specific functions, such
as burst assembly, burst scheduling, and offset setting/traffic shaping. While
burst assembly and burst scheduling are relatively straightforward, we point
out that the offset setting strategy has significant impact on the performance
of IP network operating over OBS WDM core. We describe a shaping scheme to set
the offset, an important system parameter for OBS,
between the successive data bursts of a given data stream (label switched path)
and their associated control packets. This scheme results in robust operation
of the network and also facilitates traffic engineering. Guidelines are
provided for implementing various IP QoS mechanisms in the optical backbone
using OBS.