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W e consider single-hop all-optical networks an which wavelength-routed connections (lightpaths) between source-destination pairs are dynamically established and torn down in response to a random pattern of arriving connection requests and connection holding times. A connection request may be blocked if n o wavelength is available on a suitable path f-rom source t o destination. FOT these networks we consider several methods for routing and wavelength assignment which combine an various ways three main principles: wavelength reservation, protectang threshold and alternate routes. The methods are evaluated and compared in two case studies. In this type of networks the traffic over lightpaths consisting of multiple links is susceptible to high blocking probabilities, which can interfere with the quality of service requirements. It is shown that some of the routing and wavelength assignment methods studied have the potential t o overcome this dijgiculty.

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Consider a swltchmg component m a packet-switching network, where messages from several incoming channels arrive and are routed to appropriate outgoing ports according to a service policy. One requirement in the design of such a system is to determine the buffer storage necessary at the input of each channel and the policy for serving these buffers that will prevent buffer overflow and the corresponding loss of messages. In this paper, a class of buffer service policies, called Least Time to Reach Bound (LTRB), is introduced that guarantees no overflow, and for which the buffer size required at each input channel is independent of the number of channels and their relative speeds. Further, the storage requirement is only twice the maximal length of a message in all cases, and as a consequence the class is shown to be optimal in the sensethat any nonoverflowing pohcy requires at least as much storage as LTRB.

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