Nortel Networks 1000ASE-XD - Manual (Page 56)

56 Chapter 2 Network configuration
209418-A
• 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.
The default configuration settings for BayStack 420 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
Figure 12 , all
incoming packets are assigned to VLAN 1 by the default port VLAN identifier
(PVID =1). Untagged packets enter and leave the switch unchanged.