Adaption Layer Controller ALC
The MB86687 is an ATM protocol controller which autonomously terminates ATM Adaptation Layer standards Type 3/4 and Type 5. Streaming and message modes as defined for AAL 3/4 and AAL5 are supported. User data packets are transferred to and from shared data structure memory via a high speed intelligent DMA controller with a 32 bit data Bus. The device supports simultaneous segmentation and reassembly on up to 1024 virtual circuits (VCs). Shared data structures are stored in SAR memory which can be either dual-port or a partition of system memory. Segmentation packets and packets being reassembled may also be stored in dual-port memory. In addition external data structures are also stored in SAR memory and may be accessed via the DMA controller. In non-demanding applications, system memory can be used as SAR memory. The ALC device supports two transparent modes. In transparent payload mode the 48 byte ATM cell payload is received or transmitted transparently into or from SAR memory. In transparent cell mode the ATM cell is received or transmitted transparently into or from SAR memory. Other features include:
System ConfigurationsIn adapter card applications, the ALC interfaces to the Fujitsu MB86683 NTC or other device via a full duplex 8 bit wide UTOPIA compatible cell stream interface for connection to the transmission medium. In a hub or router application, the ALC connects directly to the Fujitsu MB86680 SRE for autonomous routing. In this case a programmable 0-3 byte tag can be appended to each cell. Alternatively it may be connected to a proprietary backplane architecture.
PDF documentation used to be available at: http://www.fml.co.uk/flyer/87a_fly.pdf
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