Web OS 10.0 Application Guide44 n Chapter 2: VLANs 212777-A, February 2002VLAN ID NumbersWeb OS supports up to 246 VLANs per switch. Even though the maximum number of VLANssupported at any given time is 246, each can be identified with any number between 1 and4094.VLANs are defined on a per-port basis. Each port on the switch can belong to one or moreVLANs, and each VLAN can have any number of switch ports in its membership. Any portthat belongs to multiple VLANs, however, must have VLAN tagging enabled (see “VLANTagging” on page 44).Each port in the switch has a configurable default VLAN number, known as its PVID. The fac-tory default value of all PVIDs is 1. This places all ports on the same VLAN initially, althougheach port’s PVID is configurable to any VLAN number between 1 and 4094.Any untagged frames (those with no VLAN specified) are classified with the sending port’sPVID.VLAN TaggingWeb OS software supports 802.1Q VLAN tagging, providing standards-based VLAN supportfor Ethernet systems.Tagging places the VLAN identifier in the frame header, allowing multiple VLANs per port.When you configure multiple VLANs on a port, you must also enable tagging on that port.Since tagging fundamentally changes the format of frames transmitted on a tagged port, youmust carefully plan network designs to prevent tagged frames from being transmitted todevices that do not support 802.1Q VLAN tags.
