Networking Silicon — 82551IT
1.0
Introduction
This datasheet is applicable to the Intel® 82551IT Fast Ethernet PCI Controller, a member of the
8255x Fast Ethernet Controller family.
1.1
Overview
The 82551IT is an evolutionary addition to Intel’s family of 8255x controllers. It provides excellent
performance by offloading TCP, UDP and IP checksums and supports TCP segmentation off-load
for operations such as Large Send. The 82551IT provides an extended operating temperature in
addition to all of the same capabilities and features as the 82551ER to address applications
requiring a wider operating temperature range.
Its optimized 32-bit interface and efficient scatter-gather bus mastering capabilities enable the
82551IT to perform high speed data transfers over the PCI bus. This capability accelerates the
processing of high level commands and operations, which lowers CPU utilization. Its architecture
enables data to flow efficiently from the bus interface unit to the 3 KB Transmit and Receive
FIFOs, providing the perfect balance between the wire and system bus. In addition, multiple
priority queues are provided to prevent data underruns and overruns.
The 82551IT includes both a MAC and PHY. In also has a simple interface to the analog front end,
which allows cost effective designs requiring minimal board real estate. The 82551IT is pin
compatible with the 82559 family of controllers and is offered with software that provides
backwards compatibility with previous 8255xER controllers.
1.2
1.3
Byte Ordering
TCP and IP Internet Engineering Task Force (IETF) Request for Comments (RFCs) and literature
use big endian (BE) byte ordering. This document uses big endian ordering for all IP and TCP
frame formats. However, little endian byte ordering is used for referencing 82551IT memory
resident structures and internal structures.
References
The following documents may provide further information on topics discussed in this document.
• 10/100 Mbit Ethernet Controller Family Software Developer’s Manual. Intel Corporation.
• Advanced Configuration and Power Interface Specification, Revision 1.0. Intel Corporation,
Microsoft Corporation, and Toshiba.
• IEEE 802.3x and 802.1y Standards.
• Network Device Class Power Management Reference Specification, Revision 1.0a. AMD, Inc.
and Microsoft Corporation.
Datasheet
1
INTEL [ INTEL ]
