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MULTINET4 MULTI-PORT SERIAL SERVER & MANAGED SWITCH – INSTRUCTION MANUAL
OPERATIONAL GUIDE
CHAPTER 6: OPERATIONAL GUIDE
Tagged VLANs
The software supports tag-based VLAN operation. In this mode each port is either an
access (admitting only untagged frames or frames tagged with its PVID) or a trunk
(allowing all frames on the configured VLANs). Tags allow VLANs to span multiple physical
bridges.
Configure tagged VLANs using the following steps:
Z
Go to the
4.4.4.2: VLAN: VIDs
screen.
• Add a VLAN for each group.
• Click the
Apply Settings
button.
Z
Go to the
4.4.4.3: VLAN: Port Settings
screen.
• For each port that will be connected to an end device, set the
“Mode” to “Access” and select the port’s PVID.
• For each port that will be connected to another switch, set the
“Mode” to “Trunk”. This will automatically set the Tagging field to
“Yes” and enable the Prohibit field. If you want to specify VLANS to
be filtered from this trunk, do so now.
• Click the
Apply Settings
button.
6.4.3
VLANs and Serial Ports
This section describes the concept of Serial VLANs, a network design in which SCADA
traffic is segregated from other network traffic by placing it on a separate VLAN. It also
presents an example network application.
Multinet4 offers the capability of segregating serial traffic from other network traffic using
VLANs. Because the terminal server application encapsulates serial traffic in IP packets, it
cannot directly assign serial ports to a VLAN. Instead, IP addresses are assigned to VLANs
(creating virtual IP interfaces) and serial ports are in turn associated with local and/or
remote IP addresses.
Serial IP packets transmitted by Multinet4 will include an 802.1q VLAN tag if the following
two conditions are met:
1.
To reach a particular remote host, an IP packet must be sent over a virtual IP
interface.
2.
The selected physical transmission port (chosen based on VLAN assignments
and MAC learning) is configured for VLAN tagging.
