# Set Up Speed and Duplex

| CAUTION: By default, Intel PRO/100 adapters are set to auto-negotiate with their link partners. Manually forcing speed and duplex should be done only by experienced network administrators.

In the default mode, an Intel PRO/100 network adapter will attempt to auto-negotiate with its link partner to determine the best setting. If no link is established with the link partner using auto-negotiation, you may need to manually configure the adapter and link partner to the identical setting to establish link and pass packets. This should only be needed when attempting to link with an older switch that does not support auto-negotiation or one that has been forced to a specific speed/duplex mode. See the instructions below for specific steps.

The settings available when auto-negotiation is disabled are:

- Auto Detect (requires a link partner set to auto-negotiate). The adapter negotiates with the link partner to send and receive packets at the highest rate. This is the default setting for the adapter. If the link partner is not set to auto-negotiate, the adapter runs at half duplex.

- 10 Mbps or 100 Mbps Full duplex (requires a full duplex link partner set to full duplex). The adapter can send and receive packets at the same time. This mode must be set manually (see the following sections).

- 10 Mbps or 100 Mbps Half duplex (requires a link partner set to half duplex). The adapter performs one operation at a time; it either sends or receives. This mode must be set manually (see the following sections).

| NOTE: If an adapter is running at 100 Mbps and half duplex, your potential bandwidth is higher than if you run it at 10 Mbps and full duplex.

## Manually Configuring Duplex and Speed Settings

If your link partner supports auto-negotiation with the NWay* standard, duplex configuration is automatic and no action is required on your part. Not all switches support auto-negotiation. Check with your network system administrator to verify whether your switch supports this feature. Most installations require manual configuration to change to full duplex.

Configuration is specific to the driver you’re loading for your network operating system. To set a specific Link Speed and Duplex mode, refer to the section below that corresponds to your operating system.

CAUTION: The settings at the switch must always match the adapter settings. Adapter performance may suffer or your adapter might not operate if you configure the adapter differently from your switch.

## Setting Link Speed and Duplex in Windows 98/NT/2000

The default setting is for auto-negotiation to be enabled. Change this only to match your link partner.

1. Double-click the Intel(R) PROSet II icon from the Control Panel.

2. Click the Advanced tab.

3. Select Link Speed and Duplex.

4. In the Link Speed and Duplex list box, click the speed and duplex mode appropriate for your adapter and its link partner.

5. Click OK.

6. Restart your computer if prompted.

## Novell NetWare*

### Setting Full Duplex in DOS, ODI, NDIS 2.01 Clients

For each adapter, edit the NET.CFG or PROTOCOL.INI file. If editing the NET.CFG file, add the following keywords to the Link Driver section. For the PROTOCOL.INI file, add these keywords anywhere:

FORCEDUPLEX 2

SPEED 100 (or 10 if 10BASE-T)

### Setting Full Duplex in NetWare Servers

For each adapter in AUTOEXEC.NCF, edit the LOAD command and add the following options (you must include the equal sign for servers):

FORCEDUPLEX=2

SPEED=100 (or 10 if 10BASE-T)

### Setting Speed

If you manually set (force) speed to 10 or 100, then both speed and duplex must be forced, and auto negotiation must be disabled. (Also be sure that the link partner settings match this.) The Autoneg parameter is ignored.

### Using Autoneg

Use the Autoneg parameter when more control is required. When this parameter is used, the Speed and Forceduplex parameters must not be specified. This parameter is a bitmap, based on the following table, that specifies which speed and duplex settings the adapter advertises to a link partner.

Setting | N/A | 100 Full | 100 Half | 10 Full | 10 Half
Value | 16 | 8 | 4 | 2 | 1

This parameter is the sum of the values of each setting to advertise. For example, to advertise 100-Full and 100-Half modes, the parameter would be set to 8 + 4 = 12.

| CAUTION: When the Speed and Force duplex keywords are used, auto negotiation is disabled. To ensure that link is established correctly, auto negotiation must be disabled on the link partner, and the link should be forced to the same speed and duplex mode used on the adapter.

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