3Com 2916-SFP User Guide - Page 100

8 CONFIGURING VLANS This section contains the following topics: ■ VLAN Overview ■ Viewing VLAN Details ■ Viewing VLAN Port Details ■ Creating VLANs ■ Modifying VLAN Settings ■ Modifying Port VLAN Settings ■ Removing VLANs VLAN Overview VLANs are logical subgroups with a Local Area Network (LAN) which combine user stations and network devices into a single unit, regardless of the physical LAN segment to which they are attached. VLANs allow network traffic to flow more efficiently within subgroups. VLANs use software to reduce the amount of time it takes for network changes, additions, and moves to be implemented. VLANs restrict traffic within the VLAN. VLAN1 is the management VLAN. You can only manage the switch through a port that is an untagged member of VLAN1. VLANs have no minimum number of ports, and can be created per unit, per device, or through any other logical connection combination, since they are software-based and not defined by physical attributes. VLANs function at Layer 2. Since VLANs isolate traffic within the VLAN, a Layer 3 router working at a protocol level is required to allow traffic flow between VLANs. Layer 3 routers identify segments and coordinate with VLANs. VLANs are Broadcast and Multicast domains. Broadcast and Multicast traffic is transmitted only in the VLAN in which the traffic is generated.