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IXP400 Software
Access-Layer Components: HSS-Access (IxHssAcc) API
Programmer’s Guide IXP400 Software Version 2.0 April 2005
Document Number: 252539, Revision: 007 211
13.6.4 Packetized 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.
13.6.5 56-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.
13.7 Buffer 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.
13.7.1 Data 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.