Abstract

It is becoming increasingly important to build networks that allow easy and frequent access to bandwidth at fine granularity: at the level of TDM channels, frames and packets. We use word access to encompass such operations as circuit provisioning, monitoring, cross-connect and routing.Wavelength add-drop is the fundamental operation a node performs to enable such access. Consider the wavelength add-drop operation of Fig. 1. In 1(a), the node 3-Rs (retimes, regenerates, reshapes) wavelength λ3 and lets λ0 pass transparently.Assume that λ0 and λ3 are partially empty and hence can be used for TDM channel provisioning. To access a TDM channel on λ3, the node needs to locate the channel’s timing within the received frame. But to access a TDM channel on λ0, the node needs to drop λ0, synchronize its equipment with upstream and downstream nodes and then resume data transmission. With current add-drop techniques, all services on λ0 are disrupted while the above tasks are performed, resulting in a downtime or a hit for all TDM channels on λ0.

© 2002 Optical Society of America