ICS1893BY-10 Data Sheet - Release
Chapter 6 Functional Blocks
6.2 Functional Block: Auto-Negotiation
The auto-negotiation logic of the ICS1893BY-10 has the following main functions:
• To determine the capabilities of the remote link partner, (that is, the device at the other end of the link
segment’s medium or cable)
• To advertise the capabilities of the ICS1893BY-10 to the remote link partner
• To establish a protocol with the remote link partner using the highest-performance operating mode that
they have in common
The design of the ICS1893BY-10 Auto-Negotiation sublayer supports both legacy 10Base-T connections
as well as new connections that have multiple technology options for the link. For example, when the
ICS1893BY-10 has the auto-negotiation process enabled and it is operating with a 10Base-T remote link
partner, the ICS1893BY-10 monitors the link and automatically selects the 10Base-T operating mode –
even though the remote link partner does not support auto-negotiation. This process, called parallel
detection, is automatic and transparent to the remote link partner and allows the ICS1893BY-10 to function
seamlessly with existing legacy network structures without any management intervention.
(For an overview of the auto-negotiation process, see Section 4.4, “Auto-Negotiation Operations”.)
6.2.1 Auto-Negotiation General Process
The Auto-Negotiation sublayer uses a physical signaling technique that is transparent at the packet level
and all higher protocol levels. This technique builds on the link pulse mechanism employed in 10Base-T
operations and is fully compliant with clause 28 of the ISO/IEC 8802-3 standard.
During the auto-negotiation process, both the ICS1893BY-10 and its remote link partner use Fast Link
Pulses (FLPs) to simultaneously ‘advertise’ (that is, exchange) information on their respective technology
capabilities as follows:
1. For the auto-negotiation process to take place, both the ICS1893BY-10 and its remote link partner must
first both support and be enabled for Auto-Negotiation.
2. The ICS1893BY-10 obtains the data for its FLP bursts from the Auto-Negotiation Advertisement
Register (Register 4).
3. Both the ICS1893BY-10 and the remote link partner substitute Fast Link Pulse (FLP) bursts in place of
the Normal Link Pulses (NLPs). In each FLP burst, the ICS1893BY-10 transmits information on its
technology capability through its Link Control Word, which includes link configuration and status data.
4. Similarly, the ICS1893BY-10 places the Auto-Negotiation data received from its remote link partner's
FLP bursts into the Auto-Negotiation Link Partner Ability Register (Register 5).
5. After the ICS1893BY-10 and its remote link partner exchange technology capability information, the
ICS1893BY-10 Auto-Negotiation sublayer contrasts the data in Registers 4 and 5 and automatically
selects for the operating mode the highest-priority technology that both Register 4 and 5 have in
common. (That is, both the ICS1893BY-10 and its remote link partner use a predetermined priority list
for selecting the operating mode, thereby ensuring that both sides of the link make the same selection.)
As follows from Annex 28B of the ISO/IEC 8802-3 standard, the pre-determined technology priorities
are listed from 1 (highest priority) to 5 (lowest priority):
(1) 100Base-TX full duplex
(2) 100Base-T4. (The ICS1893BY-10 does not support this technology.)
(3) 100Base-TX (half duplex)
(4) 10Base-T full duplex
(5) 10Base-T (half duplex)
ICS1893BY-10 Rev A 3/24/04
March, 2004
Copyright © 2004, Integrated Circuit Systems, Inc.
All rights reserved.
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ICSI [ INTEGRATED CIRCUIT SOLUTION INC ]
