ICS1893 datasheet(41/152 Pages) ICST

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Chapter 7

Functional Blocks

ICS1893 Rev C 6/6/00

June, 2000

ICS1893 - Release

7.2.2

Auto-Negotiation: Parallel Detection

The ICS1893 supports parallel detection. It is therefore compatible with networks that do not support the

auto-negotiation process. When enabled, the Auto-Negotiation sublayer can detect legacy 10Base-T link

partners as well as 100Base-TX link partners that do not have an auto-negotiation capability.

The Auto-Negotiation sublayer performs this parallel detection function when it does not get a response to

its FLP bursts. In these situations, the Auto-Negotiation sublayer performs the following steps:

It sets the LP_AutoNeg_Able bit (bit 6.0) to logic zero, thereby identifying the remote link partner as not

being capable of executing the auto-negotiation process.

It sets the bit in the Auto-Negotiation Link Partner Abilities Register that corresponds to the 'parallel

detected' technology [for example, half-duplex, 10Base-T (bit 5.5) or half-duplex, 100Base-TX (bit

5.7)].

It sets the Status Register’s Auto-Negotiation Complete bit (bit 1.5) to logic one, indicating completion

of the auto-negotiation process.

It enables the detected link technology and disables the unused technologies.

A remote link partner that does not support the auto-negotiation process does not respond to the

transmitted FLP bursts. The ICS1893 detects this situation and responds according to the data it receives.

The ICS1893 can receive one of five potential responses to the FLP bursts it is transmitting: FLP bursts,

10Base-T link pulses (that is, Normal Link Pulses), scrambled 100Base IDLEs, nothing, or a combination of

signal types.

A 10Base-T link partner transmits only Normal Link Pulses when idle. When the ICS1893 receives Normal

Link Pulses, it concludes that the remote link partner is a device that can use only 10Base-T technology. A

100Base-TX node without an Auto-Negotiation sublayer transmits 100M scrambled IDLE symbols in

response to the FLP bursts. Upon receipt of the scrambled IDLEs, the ICS1893 concludes that its remote

link partner is a 100Base-TX node that does not support the auto-negotiation process. For both 10Base-T

and 100Base-TX nodes without an Auto-Negotiation sublayer, the ICS1893 clears bit 6.0 to logic zero,

indicating that the link partner cannot perform the auto-negotiation process.

If the remote link partner responds to the FLP bursts with FLP bursts, then the link partner is a 100Base-TX

node that can support the auto-negotiation process. In this case, the ICS1893 sets to logic one the

Auto-Negotiation Expansion Register’s Link Partner Auto-Negotiation Ability bit (bit 6.0).

If the Auto-Negotiation sublayer does not receive any signal when monitoring the receive channel, then the

QuickPoll Detailed Status Register’s Signal Detect bit (bit 17.3) is set to logic one, indicating that no signal

is present.

Another possibility is that the ICS1893 senses that it is receiving multiple technology indications. In this

situation, the ICS1893 cannot determine which technology to enable. It informs the STA of this problem by

setting to logic one the Auto-Negotiation Expansion Register’s Parallel Detection Fault bit (bit 6.4).

7.2.3

Auto-Negotiation: Remote Fault Signaling

If the remote link partner detects a fault, the ICS1893 reports the remotely detected fault to the STA by

setting to logic one the Remote Fault Detected bit(s), 1.4, 5.13, 17.1, and 19.13. In general, the reception

of a remote fault means that the remote link partner has a problem with the integrity of its receive channel.

Similarly, if the ICS1893 detects a link fault, it transmits a remote fault-detected condition to its remote link

partner. In this situation, the ICS1893 sets to logic one the Auto-Negotiation Link Partner Ability Register’s

Remote Fault Indication bit (bit 4.13).

For details, see Section 8.14.3, “Remote Fault (bit 19.13)”and Section 8.3.9, “Remote Fault (bit 1.4)”.

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