3Com 3C16475BS User Manual - Page 33

Configuring VLANs 33 Option Speed Duplex Flow Control Description Sets the preferred speed and duplex mode for the port. This option is only available when autonegotiation for the port is disabled. Available speed and duplex modes include: ■ 10Mbps Half ■ 10Mbps Full ■ 100Mbps Half ■ 100Mbps Full ■ 1000Mbps Full (for ports 25 and 26 only) - See "Speed/Duplex for 1000 Mbps Connections" on page 33. When enabled, controls packet flow so that a sending device does not transmit more packets than a receiving device can process. If flow control is disabled, packets may be dropped under certain periods of high traffic loads. By default, flow control is enabled. 3 Click Apply to save your settings. To configure another port, click Port Configuration on the menu again, and then click the port number that you want to configure. Speed/Duplex for 1000 Mbps Connections You cannot preset the speed to 1000Mbps. To run a port at 1000Mbps, you must enable autonegotiation for the port. When autonegotiation is enabled, the Switch will automatically connect at 1000Mbps, providing the connected device also supports this speed. 1000Mbps connections are always full-duplex. Half-duplex connections are only available for 10Mbps and 100Mbps settings. CAUTION: Before manually setting a port to full-duplex, verify that the device connected to the port is also manually set to the same speed and duplex setting. If connecting link partners are left to autonegotiate for a link manually set on this switch to full-duplex, they will always negotiate to half-duplex, resulting in a duplex mismatch. This can result in a significant reduction in network performance. If you are unsure of how to configure the speed/duplex setting, simply enable autonegotiation for the port. You cannot modify the speed/duplex settings of ports that are members of a trunk or aggregated link. Supported SFP transceivers only operate at 1000Mbps full-duplex. Inserting an SFP transceiver into a gigabit port disables the corresponding RJ-45 port, even if no fiber cable is inserted. Configuring VLANs You can use the Switch to create VLANs to organize any group of ports into separate broadcast domains. VLANs confine broadcast traffic to the originating group and help eliminate broadcast storms in large networks. This also provides for a more secure and cleaner network environment. You can create up to 64 VLANs, add specific ports to a chosen VLAN (so that the port can only communicate with other ports on the VLAN), or configure a port make it a member of all VLANs.