ICS1893AGILF datasheet(35/135 Pages) ICST

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Chapter 7 Functional Blocks

ICS1893AG, Rev. A 04/14/05

April, 2005

ICS1893AG Data Sheet - Preliminary

7.2.1 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 ICS1893AG 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 ICS1893AG and its remote link partner must

first both support and be enabled for Auto-Negotiation.

2. The ICS1893AG obtains the data for its FLP bursts from the Auto-Negotiation Advertisement Register

(Register 4).

3. Both the ICS1893AG and the remote link partner substitute Fast Link Pulse (FLP) bursts in place of the

Normal Link Pulses (NLPs). In each FLP burst, the ICS1893AG transmits information on its technology

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

4. Similarly, the ICS1893AG 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 ICS1893AG and its remote link partner exchange technology capability information, the

ICS1893AG 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 ICS1893AG 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 ICS1893AG does not support this technology.)

(3) 100Base-TX (half duplex)

(4) 10Base-T full duplex

(5) 10Base-T (half duplex)

Table 7-1 shows an example of how the selection process of the highest-priority technology takes

place.

6. To indicate that the auto-negotiation process is complete, the ICS1893AG sets bits 1.5 and 17.4 high to

logic one. After successful completion of the auto-negotiation process, the ICS1893AG

Auto-Negotiation sublayer performs the following steps:

a. It sets to logic one the Status Register’s Auto-Negotiation Complete bit (bit 1.5, which is also

available in the QuickPoll register as bit 17.4).

b. It enables the negotiated link technology (such as the 100Base Transmit modules and 100Base

Receive modules).

c. It disables the unused technologies to reduce the overall power consumption.

Table 7-1. Example of Selection Process of Highest-Priority Technology

If Register 4 Has These

Technologies:

If Register 5 Has These

Technologies:

Resulting Highest-Priority Common

Technology from Auto-Negotiation

Sublayer

(3) 100Base-TX half duplex

(1) 100Base-TX full duplex

(3) 100Base-TX half duplex

(4) 100Base-T full duplex

(3) 100Base-TX half duplex

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