WAGO 852-1305 Manual page 68

68 Enhanced Features
Forwarded Tagged and Untagged Frames
•
Each port on the switch is capable of forwarding tagged or untagged frames. To
forward a frame from an 802.1Q VLAN-aware switch to an 802.1Q VLAN-
unaware switch, the switch first decides where to forward the frame and then
strips off the VLAN tag. To forward a frame from an 802.1Q VLAN-unaware
switch to an 802.1Q VLAN-aware switch, the switch first decides where to
forward the frame and then inserts a VLAN tag reflecting the ingress port's default
VID. The default PVID is "VLAN 1" for all ports, but this can be changed.
A broadcast frame (or a multicast frame for a multicast group that is known by the
system) is duplicated only on ports that are subscribers of the VID (except the
ingress port itself), thus confining the broadcast to a specific domain.
• Port-Based 802.1Q VLAN
As a subscriber of a port-based VLAN, the port is assigned to a specific VLAN
independent of the user or system attached to the port. This means all users
attached to the port should be subscribers of the same VLAN. The network
administrator typically performs the VLAN assignment. The port configuration is
static and cannot be automatically changed to another VLAN without manual
reconfiguration.
As with other VLAN approaches, the packets forwarded using this method are not
transmitted to other VLAN domains or networks. After a port has been assigned
to a VLAN, the port cannot send to or receive from devices in another VLAN
without the intervention of a Layer 3 device.
The device that is attached to the port likely has no understanding that a VLAN
exists. The device simply knows that it is part of a subnet and that the device
should be able to talk to all other network subscribers by simply sending
information via the cable connection. The switch is responsible for identifying
that the information came from a specific VLAN and for ensuring that the
information gets to all other subscribers of the VLAN. The switch is also
responsible for ensuring that ports in a different VLAN do not receive the
information.
This approach is quite simple, fast and easy to manage in that there are no
complex lookup tables required for VLAN segmentation. If the "Port-to-VLAN"
connection is designed with an application-specific integrated circuit (ASIC),
performance is very good. An ASIC allows "Port-to-VLAN" mapping at the
hardware level.
WAGO-ETHERNET-Zubehör 852
852-1305 8/4-Port 100BASE-T/1000BASE-SX/LX
Manual
1.1.0