Configuration MP.11-R Installation and Management
VLAN Parameters
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VLAN Parameters
Overview
For an introduction to VLAN principles, see Virtual Local Area Networks (VLANs).
NOTE: VLANs are configurable only in Bridge mode.
VLAN Modes
Transparent Mode
Transparent mode is available on both the SU and the BSU. This mode is equivalent to NO VLAN support and is the
default mode. It is used when the devices behind the SU and BSU are both VLAN aware and unaware. The SU/BSU
transfers both tagged and untagged frames received on the Ethernet or WORP interface. Both tagged and untagged
management frames can access the device.
Trunk Mode
Trunk mode is available on both the SU and the BSU. It is used when all devices behind the SU and BSU are VLAN
aware. The SU and BSU transfer only tagged frames received on the Ethernet or WORP interface. Both tagged and
untagged management frames can access the device.
Access Mode
Access mode is available only on the SU. It is used when the devices behind the SU are VLAN unaware. Frames to and
from the Ethernet interface behind the SU map into only one VLAN segment.
Frames received on the Ethernet interface are tagged with the configured Access VLAN ID before forwarding them to the
WORP interface. Both tagged and untagged management frames can access the device from the WORP interface.
However, only untagged management frames can access the device from the Ethernet Interface.
Mixed Mode
Mixed mode is available on both the SU and the BSU. It is used when the devices behind the SU send both tagged and
untagged data. Frames to and from the Ethernet interface behind the SU can be tagged or untagged.
Tagged frames received on the Ethernet interface are compared against the SU’s trunk table, and only packets whose
VLAN ID matches the trunk table are forwarded. All other packets are dropped. Untagged traffic is forwarded without any
restrictions. If the BSU is in Mixed mode, the SU can be in Trunk, Access, Transparent or Mixed mode.
Q-in-Q (VLAN Stacking)
The Q-in-Q mechanism allows Service Providers to maintain customer-assigned VLANs while avoiding interference with
the Service Providers’ VLANs. Using the Q-in-Q mechanism, an Outer VLAN ID and Priority are added to VLAN tagged
packets on top of the existing VLAN ID, such that interference is avoided and traffic is properly routed.
NOTE: Both the Inner and Outer VLAN IDs should be present in the BSU’s Trunk table.
VLAN Forwarding
The VLAN Trunk mode provides a means to configure a list of VLAN IDs in a Trunk VLAN Table. The SU and BSU only
forward frames (between Ethernet and WORP interface) tagged with the VLAN IDs configured in the Trunk VLAN Table.
Up to 256 VLAN IDs can be configured for the BSU and up to 16 VLAN IDs can be configured for the SU (depending
upon the capabilities of your switching equipment).
VLAN Relaying
The VLAN Trunk mode for BSU operation provides an option to enable and disable a VLAN relaying flag; when enabled,
the BSU relays frames between SUs on the same BSU having the same VLAN ID.
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