Nortel Networks WEB OS 212777 - Manual (Page 44)

Web OS 10.0 Application Guide
44 n Chapter 2: VLANs
212777-A, February 2002
VLAN ID Numbers
Web OS supports up to 246 VLANs per switch. Even though the maximum number of VLANs
supported at any given time is 246, each can be identified with any number between 1 and
4094.
VLANs are defined on a per-port basis. Each port on the switch can belong to one or more
VLANs, and each VLAN can have any number of switch ports in its membership. Any port
that belongs to multiple VLANs, however, must have VLAN tagging enabled (see
“VLAN
Tagging” 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, although
each 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’s
PVID.
VLAN Tagging
Web OS software supports 802.1Q VLAN tagging, providing standards-based VLAN support
for 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, you
must carefully plan network designs to prevent tagged frames from being transmitted to
devices that do not support 802.1Q VLAN tags.