User`s manual

Chapter 1 Overview
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Figure 1-9 Example of Port-Based VLAN Function
1.6.3.7 Support for 802.1Q Tag-Based VLAN Switching
VLAN tags carry additional information that can be used to identify VLAN
membership and priority. Such tags can therefore be used to differentiate among a
variety of traffic in accordance with the VLAN number (identifier – ID) and priority
(preferred QoS).
The information needed to specify the handling of frames in accordance with their
VLAN ID is given in a VLAN switching table, which contains the forwarding rules.
One rule must be defined for each VLAN ID to be processed: any frame with VLAN
Ids not appearing in the table is ignored (discarded upon ingress). The maximum
number of rules that can be defined is 64.
A forwarding rule specifies two types of information:
 The ports that participate in the forwarding of frames with the corresponding
VLAN ID. Any rule can include a single external (LAN) port – LAN 1 or LAN 2.
Rules must also be defined to include VLANs switched only among VCG
groups, and for the management VLAN, when management VLAN tagging is
enabled.
 The handling of frame tags. The available selections include:
 Unmodified: the port transfers the tags of the frames forwarded to it
without any change. Therefore, untagged frames egress the port as
untagged frames, and tagged frames egress the port as tagged frames.