3Com 1000 User Manual

Also see for SuperStack 3 WEBCACHE 1000: User guide Mounting guide Release notes User guide

Contents

Virtual LANs (VLANs) 5-3VLANs and the SwitchThe Switch 1000 supports VLANs which consist ofa set of switch ports. Each switch port can onlybelong to one VLAN at a time, regardless of thedevice to which it is attached.Each Switch 1000 can support up to 16 VLANs.However, you can have more than 16 VLANs in yourentire network by connecting the 16 Switch VLANsto other VLANs using a router.The Default VLAN and Moving Ports From theDefault VLANOn each Switch, VLAN 1 is the Default VLAN of theSwitch; it has two properties:n It contains all the ports on a new or initializedSwitchn It is the only VLAN which allows an SNMP Net-work Manager to access the management agentof the unitBy default, if a device is attached to a port in theDefault VLAN and you want to move the device intoanother VLAN, you need to use the VLAN Setupscreen to place the port in that VLAN. For moreinformation about the VLAN Setup screen, refer to“Setting Up VLANs on the Switch” on page 5-8.Connecting VLANs to a RouterIf the devices in a VLAN need to talk to devices in adifferent VLAN, each VLAN requires a connection toa router. Communication between VLANs can onlytake place if they are all connected to the router. AVLAN not connected to a router is an isolatedVLAN. You need one port for each VLAN connectedto the router.Connecting Common VLANs Between SwitchUnitsIf you want to connect the VLANs on the Switch1000 with the same VLANs on another Switch unit,you can set up one link per VLAN. Alternatively,you can set up a single link for all the VLANs by cre-ating a Virtual LAN Trunk (VLT). A VLT is aSwitch-to-Switch link which carries traffic for all theVLANs on each Switch. To set up a VLT, you config-ure the port at each end of the link.VLTs can only be used for links between Super-Stack ® II Switch 1000, Switch 3000 and DesktopSwitch units. You cannot use VLTs for Switch–routerlinks.If you specify that a port on one VLAN is a VLT port,that port carries traffic for all the VLANs on theSwitch. If you then disable the VLT function on thatport, the port only carries traffic for the DefaultVLAN (VLAN 1).Using AutoSelect VLAN ModeBy default, all ports on the Switch use Port VLANMode — where each switch port is manuallyplaced in the required VLAN. The Switch allowssome ports to use another mode, AutoSelect VLANMode. In this mode, the ports are automaticallyplaced in the required VLAN by referring to a VLANServer database in 3Com’s Transcend EnterpriseManager v6.0 for Windows.