Signamax
™
065-7921PoE 12-Port 10/100/1000BaseT/TX Web Smart PoE Switch
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VLAN-tagged frame:
An Ethernet frame, carrying VLAN tag field, contains VLAN identification without the
value of 0 and 4095, and priority information.
Priority-tagged frame:
An Ethernet frame, carrying VLAN tag field, contains VLAN identification with the value
of 0 and priority information.
Untagged frame:
An Ethernet frame carries no VLAN tag information.
VLAN Identifier:
Also referred to as VID. It is used to identify a member whether it belongs to the VLAN
group with the VID. The assignable number is 1- 4094. If VID=0, the tagged frame is a priority
packet. Both the value of 0 and 4095 also cannot be assigned in VLAN management.
Port VLAN Identifier:
VLAN identifier of a port. It also can be referred to as PVID. When an untagged frame
or a priority-tagged frame is received, the frame will be inserted the PVID of that port in the
VLAN tag field. The frame with VID assigned by a port is called PVID. Each port can only be
assigned a PVID. The default value for PVID is 1, the same as VID.
Ingress filtering:
The process to check a received packet and compare its VID to the VLAN membership
of the ingress port. The ingress filtering can be set by per port. When receiving a packet, VLAN
bridge examines if the VID in the frame’s header presents.
If the VID of the received packet presents, the VID of the packet is used. And VLAN
bridge will check its MAC address table to see if the destination ports are members of the
same VLAN. If both are members of the tagged VLAN, then the packet will be forwarded.
If the packet is an untagged or a null tag packet, the ingress port’s PVID is applied to
the packet. VLAN bridge will then look up the MAC address table and determine to which ports
the packet should be forwarded. Next, it will check to see if the destination ports belong to the
same VLAN with that PVID. If the destination ports are members of the VLAN used by ingress
port, the packet will be forwarded.
Note: VID can not be 0 or 4095.
