Nortel business policy switch 2000 User Manual page 112

112 Chapter 2 Network configuration
• Untagged frame— a frame that does not carry any VLAN tagging information
in the frame header.
• VLAN port members— a set of ports that form a broadcast domain for a
specific VLAN. A port can be a member of one or more VLANs.
• Untagged member—a port that has been configured as an untagged member
of a specific VLAN. When an untagged frame exits the switch through an
untagged member port, the frame header remains unchanged. When a tagged
frame exits the switch through an untagged member port, the tag is stripped
and the tagged frame is changed to an untagged frame.
• Tagged member—a port that has been configured as a member of a specific
VLAN. When an untagged frame exits the switch through a tagged member
port, the frame header is modified to include the 32-bit tag associated with the
PVID. When a tagged frame exits the switch through a tagged member port,
the frame header remains unchanged (original VID remains).
• User priority—a three-bit field in the header of a tagged frame. The field is
interpreted as a binary number, therefore has a value of 0 - 7. This field allows
the tagged frame to carry the user-priority across bridged LANs where the
individual LAN segments may be unable to signal priority information.
• Port priority—the priority level assigned to untagged frames received on a
port. This value becomes the user priority for the frame. Tagged packets get
their user priority from the value contained in the 802.1Q frame header.
• Unregistered packet—a tagged frame that contains a VID where the receiving
port is not a member of that VLAN.
• Filtering database identifier (FID)—the specific filtering/forwarding database
within the Business Policy Switch that is assigned to each VLAN. The current
version of software assigns all VLANs to the same FID when it is running in
the Hybrid Operational mode. This process is referred to as Shared VLAN
Learning (SVL) in the IEEE 802.1Q specification. In the Pure BPS 2000
operational mode, a VLAN may either share its filtering database with other
VLANs (SVL) or have its own filtering database, which is called independent
VLAN learning (IVL).
The default configuration settings for Business Policy Switches have all ports set
as untagged members of VLAN 1 with all ports configured as PVID = 1. Every
VLAN is assigned a unique VLAN identifier (VID) that distinguishes it from all
other VLANs. In the default configuration example shown in
incoming packets are assigned to VLAN 1 by the default port VLAN identifier
(PVID =1). Untagged packets enter and leave the switch unchanged.
208700-C
Figure 18, all