ICS1893CFILFT datasheet(26/126 Pages) ICST

26 / 126 page

ICS1893CF, Rev. F, 03/01/07

Mar. 2007

Chapter 6 Functional Blocks

ICS1893CF Data Sheet - Release

6.2 Functional Block: Auto-Negotiation

The auto-negotiation logic of the ICS1893CF 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 ICS1893CF 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 ICS1893CF 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

ICS1893CF has the auto-negotiation process enabled and it is operating with a 10Base-T remote link

partner, the ICS1893CF 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 ICS1893CF 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 ICS1893CF 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 ICS1893CF and its remote link partner must

first both support and be enabled for Auto-Negotiation.

2. The ICS1893CF obtains the data for its FLP bursts from the Auto-Negotiation Advertisement Register

(Register 4).

3. Both the ICS1893CF and the remote link partner substitute Fast Link Pulse (FLP) bursts in place of the

Normal Link Pulses (NLPs). In each FLP burst, the ICS1893CF transmits information on its technology

capability through its Link Control Word, which includes link configuration and status data.

4. Similarly, the ICS1893CF 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 ICS1893CF and its remote link partner exchange technology capability information, the

ICS1893CF 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 ICS1893CF 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 ICS1893CF does not support this technology.)

(3) 100Base-TX (half duplex)

(4) 10Base-T full duplex

(5) 10Base-T (half duplex)

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