Instruction Manual
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octets. All of the information originally contained in the packet is retained.
Port VLAN ID
Packets that are tagged (are carrying the 802.1Q VID information) can be
transmitted from one 802.1Q compliant network device to another with the
VLAN information intact. This allows 802.1Q VLAN to span network devices (and
the entire network, if all network devices are 802.1Q compliant).
Every physical port on a switch has a PVID. 802.1Q ports are also assigned a PVID,
for use within the switch. If no VLANs are defined on the switch, all ports are
then assigned to a default VLAN with a PVID equal to 1. Untagged packets are
assigned the PVID of the port on which they were received. Forwarding decisions
are based upon this PVID, as far as VLANs are concerned. Tagged packets are
forwarded according to the VID contained within the tag. Tagged packets are also
assigned a PVID, but the PVID is not used to make packet forwarding decisions,
the VID is.
Tag-aware switches must keep a table to relate PVID within the switch to VID on
the network. The switch will compare the VID of a packet to be transmitted to
the VID of the port that is to transmit the packet. If the two VIDs are different, the
switch will drop the packet. Because of the existence of the PVID for untagged
packets and the VID for tagged packets, tag-aware and tag-unaware network
devices can coexist on the same network.
A switch port can have only one PVID, but can have as many VID as the switch has
memory in its VLAN table to store them.
Because some devices on a network may be tag-unaware, a decision must
be made at each port on a tag-aware device before packets are transmitted –
should the packet to be transmitted have a tag or not? If the transmitting port
is connected to a tag-unaware device, the packet should be untagged. If the
transmitting port is connected to a tag-aware device, the packet should be
tagged.
Default VLANs
The Switch initially configures one VLAN, VID = 1, called "default." The factory
default setting assigns all ports on the Switch to the "default". As new VLAN are
configured in Port-based mode, their respective member ports are removed from
the "default."
Assigning Ports to VLANs
Before enabling VLANs, you must first assign each port to the VLAN group(s) in
which it will participate. By default, all ports are assigned to VLAN 1 as untagged
ports. Add a port as a tagged port if you want it to carry traffic for one or more
VLANs, and any intermediate network devices or the host at the other end of the
