Proscend 6200-2W, User Manual

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Click the 802.1Q Tag-Based VLAN to configure the VPN Router.
In 802.1q, the VLAN information is written into the Ethernet packet itself. Each packet carries a VLAN ID (Virtual LAN
ID), called a tag. This allows VLANs to be configured across multiple switches. Note that it’s possible for VLAN tags to
be stripped by H/W and/or S/W.
When using 802.1q, four bytes are added to the Ethernet frame, of which 12 bits are used for the VLAN ID.
Theoretically, there can be up to 4096 VLANs per network.
An Ethernet packet that contains a VLAN ID is called a tagged packet. Conversely, an Ethernet packet with no VLAN ID
is called an untagged packet. Typically all packets leave untagged, unless tagged by the adapter prior to arriving at the
switch port.
Egress and Ingress Rules:
Egress rules determine which frames can be transmitted out of a port, based on the Egress List of the VLAN associated
with it. Each VLAN has an Egress List that specifies the ports out of which frames can be forwarded, and specifies
whether the frames will be transmitted as tagged or untagged frames.
Ingress rules are a means of filtering out undesired traffic on a port. When Ingress Filtering is enabled, a port
determines if a frame can be processed based on whether the port is on the Egress List of the VLAN associated with
the frame.
When an untagged packet arrives at the switch port, the switch will write a VLAN ID into the header of the frame