ZyXEL Communications ES-2048 - Manual (Page 44)

ES-2000 Series Switch Support Notes
All contents copyright (c) 2006 ZyXEL Communications Corporation.
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untagged frame is received, Ingress Process insert a tag contained the PVID
into the untagged frame. Each physical port has a default VID called PVID
(Port VID). PVID is assigned to untagged frames or priority tagged frames
(frames with null (0) VID) received on this port.
After Ingress Process, all frames have 4-bytes tag and VID information, and
then go to Forwarding Process.
2. Forwarding Process:
The Forwarding Process decides to forward the received frames according to
the Filtering Database. If you want to allow the tagged frames can be
forwarded to certain port, this port must be the egress port of this VID. The
egress port is an outgoing port for the specified VLAN, that is, frames with
specified VID tag can go through this port. The Filtering Database stores and
organizes VLAN registration information useful for switching frames to and
from switch ports. It consists of static registration entries (Static VLAN or
SVLAN table) and dynamic registration entries (Dynamic VLAN or DVLAN
table). SVLAN table is manually added and maintained by the administrator.
DVLAN table is automatically learned via GVRP protocol, and can't be created
and upgraded by the administrator.
The VLAN entries in Filtering Database have the following information:
1. VID: VLAN ID
2. Port: The switch port number
3. Ad Control: Registration administration control. There are 3 type of ad
control, including forbidden registration, fixed registration and normal
registration.