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IXP400 Software
Programmer’s Guide IXP400 Software Version 2.0 April 2005
Document Number: 252539, Revision: 007 53
Access-Layer Components:
ATM Driver Access (IxAtmdAcc) API 4
This chapter describes the Intel
®
IXP400 Software v2.0’s “ATM Driver-Access” access-layer
component.
4.1 What’s New
There are no changes or enhancements to this component in software release 2.0.
4.2 Overview
The ATM access-driver component is the IxAtmdAcc software component and provides a unified
interface to AAL transmit and receive hardware. The software release 2.0 supports AAL 5, AAL 0,
and OAM. This component provides an abstraction to the IXP4XX product line and IXC1100
control plane processors’ ATM cell-processing hardware. It is designed to support ATM transmit
and receive services for multiple ports and VCs.
This chapter describes the configuration, control, and transmit/receive flow of ATM PDU data
through the IxAtmdAcc component.
The general principle of improving performance by avoiding unnecessary copying of data is
adhered to in this component. The BSD-based buffering scheme is used.
Since AAL 0 is conceptually a raw cell service, the concept of an AAL-0 PDU can be somewhat
misleading. In the context of software release 2.0, an AAL-0 PDU is defined as containing an
integral number of 48-byte (cell payload only) or 52-byte (cell payload and cell header without
HEC field) cells.
4.3 IxAtmdAcc Component Features
The services offered by the ixAtmdAcc component are:
• Supports the configuration and activation of up to 12 ports on the UTOPIA Level-2 interface.
• Supports AAL-5 CPCS PDUs transmission service, which accepts fully formed PDUs for
transmission on a particular port and VC. AAL-5 CRC calculation is performed by hardware.
(PDUs may consist of single or chained IXP_BUFs.)
• Supports AAL-0-48 PDU transmission service, which accepts PDUs containing an integral
number of 48-byte cells for transmission on a particular port and VC. (PDUs may consist of
single or chained IXP_BUFs.)