ZyXEL Communications Dimension ES-2108 Support Notes page 30

How 802.1Q VLAN works
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According to the VID information in the tag, the switch forward and filter the
frames among ports. These ports with same VID can communicate with each
other. IEEE 802.1Q VLAN function contains the following three tasks, Ingress
Process, Forwarding Process and Egress Process.
1. Ingress Process:
Each port is capable of passing tagged or untagged frames.
identifies if the incoming frames contain tag, and
belonging to a VLAN
tagged frames only, the switch port will drop all incoming non-tagged frames. If
Ingress rule accept all frame type, the switch port simultaneously allow the incoming
tagged and untagged frames:
When a tagged frame is received on a port, it carries a tag header that has a
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explicit VID. Ingress Process directly pass the tagged frame to Forwarding
Process.
An untagged frame doesn't carry any VID to which it belongs. When a
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All contents copyright (c) 2006 ZyXEL Communications Corporation.
. Each port has its own Ingress rule. If Ingress rule accept
ES-2108 Series Switch Support Notes
Ingress Process
classifies the incoming frames
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