Interlogix MCR205-1T/1S User Manual - Manual (Page 39)

IFS MCR205-1T/1S User Manual 33
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
indeed, 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 VLAN 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, in so far as VLAN 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.
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 VID 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 MCR205-1T/1S initially configures one VLAN, VID = 1, called "default." The
factory default setting assigns all ports on the MCR205-1T/1S to the "default". As
new VLAN are configured in Port-based mode, their respective member ports are
removed from the "default."
VLAN Group
This function disables or enables the IEEE 802.1Q VLAN operation mode. Press
the “Apply” button to save the latest configuration of MCR205-1T/1S.