1.INTRODUCTION

RCUBE (Rapid Reconfigurable Router) is a low latency router (150 ns without contention) for transputing and networking applications. Designed with an internal clock of 80 MHz, it includes 8 bidirectional high speed links, 8 independent programmable routing tables (one routing table per input link), and one 8x8 non blocking crossbar switch which enables the routing of a packet from any input link to any output link. The architecture is fully parallel and the transfer of a packet between one pair of links does not affect the data rate or the latency for another packet passing through another pair of links.

It implements a wormhole flow control technique, prefix and interval routing schemes, and provides efficient supports for adaptivity.

Based on CMOS high speed links developped at BULL, it delivers a global throughput of 1 Gigabit/s per link per direction, achieving a peak global throughput of 640 Mbyte/s.

RCUBE can route packets of any length. A packet is composed of a header which is the destination address in the network, followed by a sequence of characters which compose the payload of the packet and ended by an end packet character called EP or an exceptional end of packet character called EEP (fig.1.1). The payload of the packet can be composed of data characters or any control character different from EP or EEP. A character is a 9-bit word whose most significant bit (9th in big endian coding) is used to differentiate control characters ('1') from data characters ('0').

**Figure 1.1:** Packet Format

RCUBE provides the ability to specify for each link the two following functionalities :

handling 1 or 2 character headers.
enabling a header deletion mechanism.

The technology targeted is a 3.3V, 0.5 m process. The IC can be packaged either in a 480 pads PBGA (Plastic Ball Grid Array) or a 208 pins Quad Flat Pack.

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