ZyXEL Communications ONU-2024 Series, User Manual

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ONU User’s Guide
79
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H A P T E R
8
VLAN
8.1 Overview
The type of screen you see here depends on the VLAN Type you selected in the Switch Setup
screen. This chapter shows you how to configure 802.1Q tagged and port-based VLANs.
8.1.1 What You Can Do in the VLAN Screens
• The Switch Setup screen lets you select a VLAN type ( Section 8.2 on page 82 ).
• The VLAN Status screen lets you view your VLAN’s status ( Section 8.3 on page 82 ).
• The VLAN Details screen lets you view detailed port settings and the status of a particular
VLAN group ( Section 8.3.1 on page 83 ).
• The Static VLAN screen lets you configure a static VLAN ( Section 8.3.2 on page 84 ).
• The VLAN Port Settings screen lets you configure a VLAN’s port settings ( Section 8.3.3
on page 85 ).
• The Port-based VLAN Setup screen lets you configure a port-based VLAN ( Section
8.4.1 on page 88 ).
8.1.2 What You Need to Know About the VLAN Screen
The following terms and concepts may help as you read through this chapter.
IIEEE 802.1Q Tagged VLANs
A tagged VLAN uses an explicit tag (VLAN ID) in the MAC header to identify the VLAN
membership of a frame across bridges - they are not confined to the switch on which they were
created. The VLANs can be created statically by hand or dynamically through GVRP. The
VLAN ID associates a frame with a specific VLAN and provides the information that switches
need to process the frame across the network. A tagged frame is four bytes longer than an
untagged frame and contains two bytes of TPID (Tag Protocol Identifier, residing within the
type/length field of the Ethernet frame) and two bytes of TCI (Tag Control Information, starts
after the source address field of the Ethernet frame).
The CFI (Canonical Format Indicator) is a single-bit flag, always set to zero for Ethernet
switches. If a frame received at an Ethernet port has a CFI set to 1, then that frame should not
be forwarded as it is to an untagged port. The remaining twelve bits define the VLAN ID,
giving a possible maximum number of 4,096 VLANs. Note that user priority and VLAN ID
are independent of each other. A frame with VID (VLAN Identifier) of null (0) is called a