Duplex support v1.1 Duplex modes for Compaq 10 and 10/100 Controllers and the NC3121 Fast Ethernet NIC ============================================================ Duplexing is a performance option that lets you choose how the controller sends and receives packets over the network. Auto. The Compaq 10/100 controllers and NC3121 Fast Ethernet NIC negotiate with the full duplex switch to send and receive packets at the highest rate. The Compaq 10-only controller supports full duplex without auto-negotiation (it must be configured manually to operate at full duplex). The switch must support auto-negotiation. If the switch does not support auto-negotiation, the controller defaults to half duplex. Note that the Compaq 10 controller does not support auto-negotiation. It does support full duplex. Full duplex (requires full-duplex switch). The controller sends and receives packets simultaneously by using a different wire to perform each function. This feature can improve controller performance by eliminating collisions. Half duplex. The controller performs one operation at a time (because send and receive lines are shared); it either sends or receives. Configuring for full duplex =========================== If you have an auto-negotiating switch (an NWay* switch), the Compaq 10/100 controller and NC3121 Fast Ethernet NIC automatically match the duplex setting at the switch. If you don't have an auto-negotiating switch, you'll need to manually configure the controller for full duplex support. The Compaq 10 controller must be manually configured for full duplex. Configuration is specific to the driver you're loading for your network operating system (NOS). See the sections for your NOS below or refer to the Installation Guide. NOTE: If you're using the Compaq 10/100 controller or NC3121 Fast Ethernet NIC, and manually configuring the controller, you must set the Speed when configuring for full-duplex support. Don't leave the Speed set to Auto. To set up the duplex mode, refer to the section below that corresponds to your operating system. For example, if you are running Windows NT on a Novell network, choose the Windows NT method below. Note that performance may suffer if your switch is not full duplex and you configure the controller to full duplex. Leave the controller on half duplex if you are not sure what type of switch you are connected to. DOS/ODI clients --------------- Edit the NET.CFG file. Add the SPEED and FORCEDUPLEX parameters under the link driver section. For example Link Driver N100ODI SPEED 100 (or 10 for 10 Mbps operation) FORCEDUPLEX 2 Windows* NT 3.51 ---------------- Use the CPQSET program: 1 Double-click the CPQSET icon in the Control Panel. 2 Click Change. 3 Set Speed on the controller to 10 or 100 (Compaq 10/100 or NC3121 Fast Ethernet NIC only). 4 Set Duplex Mode to Full. 5 Click OK until prompted to restart. Restart Windows NT. Windows* NT 4.0 --------------- 1 Double-click the Network control panel icon in the Control Panel. 2 Go to the Adapters tab and click Properties. 3 Select an controller from the list and click Settings. 4 Select a duplex mode and click OK. 5 Click OK until prompted to restart. Restart Windows NT. Windows 95 ---------- Use the CPQSET program: 1 Double-click the CPQSET icon in the Control Panel. 2 Click Change. 3 Set Speed on the Compaq 10/100 Controller or NC3121 Fast Ethernet NIC to 10 or 100. 4 Set Duplex Mode to Full. 5 Click OK until prompted to restart. Restart Windows 95. Other NDIS 2.x based clients ---------------------------- Edit the PROTOCOL.INI file. Add the FORCEDUPLEX and SPEED parameters to the N100 section. For example: [N100_NIF] ; varies depending on your NOS SPEED = 100 ; or 10 for 10 Mbps operation FORCEDUPLEX = 2 * Third-party trademarks are the property of their respective owners.