Managing the Hub2-61The SmartSwitch 2000 Chassis ViewSmartSwitch 2000 firmware version 4.00.08 supports the pre-standard IEEE802.1Q draft specification for port-based VLANs.What is a VLAN?A Virtual Local Area Network (VLAN) is a logical group of devices that functionas a single Local Area Network segment (broadcast domain). Devices comprisinga VLAN may be (physically) widely separated, allowing users located in separateareas or connected to separate ports to belong to a single VLAN group. Usersassigned to a VLAN can send and receive broadcast and multicast traffic asthough they were all physically connected to a single network segment.VLAN-capable switches isolate broadcast and multicast traffic received fromVLAN groups, and contain broadcasts and multicasts from members of a VLANwithin that group.What is an 802.1Q Port-Based VLAN?Switches that support the pre-standard IEEE 802.1Q draft specification forport-based VLANs act by classifying frames into VLAN membership. Usually,VLAN classification is based on tag headers (VLAN tags) in the headers of dataframes. The tag header is inserted into the frame directly after the Source MACaddress field. A four-byte field in the tag header is used as the VLAN identifier.These VLAN tags are added to data frames by the switch as the frames aretransmitted and/or received by certain ports, and are later used to makeforwarding decisions by the switch and other 802.1Q switches. In the absence of aVLAN tag, a frame is assigned VLAN membership according to the VLANconfiguration of the switch port that receives the frame.About 802.1Q VLAN Configuration and OperationAn 802.1Q VLAN is defined by assigning it a unique identification number (theVLAN ID) and an optional name. The VLAN ID is used to identify data framesthat originate from, and are intended for, the ports assigned to the VLAN. Up to64 VLANs may be created, with VLAN IDs ranging from 2-4094. VLAN ID 1 isreserved for the Default VLAN.Ports on 802.1Q switches are assigned membership in a VLAN by associating aVLAN ID with each port on the switch. The VLAN ID is combined with the port’sidentification (e.g., device X port X) to form the Port VLAN ID (PVID).NOTEFor SmartSwitch 2000 firmware versions 4.00.08 and above, HSIM-F6 modules cannotbe installed in a SmartSwitch 2000 that is operating in 802.1Q mode.
