V2.0

All shields are connected to pin 1 and the AUI connector shell. Pin 4 is not used. Most Ethernet cables are built this way.

V1.0

Shielding of individual signal or power pairs is not required, since most V1.0 con-trollers and transceivers are DC-coupled. The overall AUI cable shield provides for shielding and grounding and is connected to pin 1 and the AUI connector shell.

In practice, most Ethernet V1.0 equipment uses version 2.0 cables due to cross-talk problems caused by the lack of individual shielding of the pairs in version 1.0 cables.

Wire Sizes

The three versions of AUI cables also use different wire sizes for the signal and power pairs. Table C-2 describes the wiring used by each type of transceiver cable.

Table C-2. Transceiver Cable Wire Sizes

Cable Type

Signal Pair

Power Pair

 

 

 

V1.0

AWG #22

AWG #20

 

 

 

V2.0 and IEEE 802.3

AWG #20

AWG #20

 

 

 

Non-standard “Office” cable *

AWG #24 *

AWG #24 *

 

 

 

* more flexible, but is limited to 5.0 meters in length.

Signal deterioration along the signal pairs is most likely to happen as the AUI cable approaches the maximum length of 40 meters. This signal deterioration is due to the filtering action of the cable. IEEE 802.3 AUI cables are designed to reduce this effect.

C - 4 ONline Ethernet Bridge Module Installation and Operation Guide

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3Com 5102B-EE V2.0, V1.0, Table C-2. Transceiver Cable Wire Sizes, Cable Type Signal Pair Power Pair