Chapter 5
Setup and Configuration
RUGGEDCOM RSG2488
User Guide
112
VLAN Concepts
Section 5.1.1
VLAN Concepts
The following sections describe some of the concepts important to the implementation of VLANs in ROS:
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Section 5.1.1.1, “Tagged vs. Untagged Frames”
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Section 5.1.1.2, “Native VLAN”
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Section 5.1.1.3, “The Management VLAN”
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Section 5.1.1.4, “Edge and Trunk Port Types”
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Section 5.1.1.5, “Ingress and Egress Rules”
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Section 5.1.1.6, “Forbidden Ports List”
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Section 5.1.1.7, “VLAN Advantages”
Section 5.1.1.1
Tagged vs. Untagged Frames
VLAN tags identify frames as part of a VLAN network. When a switch receives a frame with a VLAN (or 802.1Q)
tag, the VLAN identifier (VID) is extracted and the frame is forwarded to other ports on the same VLAN.
When a frame does not contain a VLAN tag, or contains an 802.1p (prioritization) tag that only has prioritization
information and a VID of 0, it is considered an untagged frame.
Section 5.1.1.2
Native VLAN
Each port is assigned a native VLAN number, the Port VLAN ID (PVID). When an untagged frame ingresses a
port, it is associated with the port's native VLAN.
By default, when a switch transmits a frame on the native VLAN, it sends the frame untagged. The switch can be
configured to transmit tagged frames on the native VLAN.
Section 5.1.1.3
The Management VLAN
Management traffic, like all traffic on the network, must belong to a specific VLAN. The management VLAN
is configurable and always defaults to VLAN 1. This VLAN is also the default native VLAN for all ports, thus
allowing all ports the possibility of managing the product. Changing the management VLAN can be used to
restrict management access to a specific set of users.
Section 5.1.1.4
Edge and Trunk Port Types
Each port can be configured as an edge or trunk port.
An edge port attaches to a single end device, such as a PC or Intelligent Electronic Device (IED). An edge port
carries traffic on the native VLAN.