Intel® IXP400 Software

Access-Layer Components: HSS-Access (IxHssAcc) API

13.6.4Packetized Disconnect

When packetized service channel is not needed any more, the function ixHssAccPktPortDisable() is called to stop the packetized service on that channel, and ixHssAccPktPortDisconnect() is called to disconnect the service.

This has to be done for each packet service channel. The client is responsible for ensuring all transmit activity ceases prior to disconnecting, and ensuring that the replenishment of the rxFree queue ceases before trying to disconnect.

13.6.556-Kbps, Packetized Raw Mode

When a packet service channel is configured for 56-Kbps, packetized Raw mode, byte alignment of the transmitted data is not preserved. All raw data that is transmitted by a device using IxHssAcc in this manner will be received in proper order by the receiver (the external PHY device, for example). However, the first bit of the packet may be seen at any offset within a byte. All subsequent bytes will have the same offset for the duration of the packet. The same offset also applies to all subsequent packets received on the service channel as well.

The receive data path is identical to the scenario described above.

While this behavior will also occur for 56-Kbps, packetized HDLC mode, the HDLC encoding/ decoding will preserve the original byte alignment at the receiver end.

13.7Buffer Allocation Data-Flow Overview

Prior to connecting and enabling ports in IxHssAcc, a client must allocate buffers to the IxHssAcc component. IxHssAcc provides two services, packetized and channelized, and the clients exchange data with IxHssAcc differently for transmitting and receiving, depending on which service is chosen.

13.7.1Data Flow in Packetized Service

Data in the time slots configured for HDLC or raw services will form packets for packetized service. IxHssAcc supports up to four packetized services per HSS port. The packetized service uses IXP_BUFs to store data, or chains IXP_BUFs together into chained IXP_BUFs for large packets.

The client is responsible for allocating these buffers and passing the buffers to IxHssAcc.

Programmer’s Guide

IXP400 Software Version 2.0

April 2005

 

Document Number: 252539, Revision: 007

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Intel IXP400 manual Buffer Allocation Data-Flow Overview, Packetized Disconnect, 13.6.5 56-Kbps, Packetized Raw Mode