Westermo RedFox Series User Manual
Page 271
Westermo OS Management Guide
Version 4.17.0-0
❼ As in the previous example, each VLAN is assigned a VID; in this example
VIDs 1 (ADMIN), 2 (OFFICE) and 3 (MARKETING).
❼ Each VLAN is assigned a set of ports. (For simplicity of this example, we
have chosen to use the same port assignment on both switches.) Port 1/1
is associated (untagged) with the ADMIN VLAN, Ports 2/1-2/4 are associ-
ated (untagged) with the OFFICE VLAN, and ports 2/5-2/8 are associated
(untagged) with the MARKETING VLAN.
In addition, port 1/2, where the cable between the two switches is connected, is
associated with all three VLANs. In order for the switches to distinguish which
VLAN a packet belongs to when transmitted over a shared connection, the switch
will insert a VLAN header (VLAN tag) into the packet, which includes information
about the VLAN ID (here 1, 2 or 3). Thus, in this example port 1/2 would be
associated with VLAN 1, 2 and 3 tagged
Note
A port associated tagged on a VLAN, will send and receive tagged Ethernet
packets (i.e., Ethernet packets including a VLAN header) on that port.
Consider the case where a PC attached to port 2/1 of switch A in
trans-
mits a broadcast packet. That packet will be forwarded onto ports 2/2-2/4 of
switch A untagged, and onto port 1/2 of switch A tagged with VID 2. When the
tagged packet is received on port 1/2 on switch B, that switch can determine that
the packet belongs to VLAN 2, and will forward it onto ports 2/1-2/4 untagged.
Note
A port cannot be associated with more than one VLAN untagged. A port
cannot be associated both untagged and tagged with the same VLAN.
We refer to the VLAN with VID 1 as the switch default VLAN. Ports not associated
with any VLAN (untagged or tagged) will automatically be associated with the
default VLAN.
provides more information on the default VLAN.
For each VLAN on a switch, an associated network interface will be created. The
name of a VLAN network interface is vlan<VID>, e.g., vlan1 for VLAN 1, and
vlan100 for VLAN 100. The network interface can be assigned an IP address
(IPv4), and the switch can then be managed remotely via that VLAN. It is also
1
It is recommended that a port, which is shared between several VLANs, is associated tagged
with all those VLANs, however, it is possible to configure the port untagged on one VLAN and
tagged on all other VLANs without risk for ambiguity.
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