Port Mapping (802.1Q); Q In Q/Double Tagging And Smart_Mode - Trango Systems TrangoLINK GigaPlus User Manual

higher, but there is no guarantee of prioritization when the traffic is on the same port
and the user traffic.
Q in Q Support : GigaPlus supports Q in Q, however, due to the port mapping feature
being enabled by default, the operator must disable the port mapping. See the Port
Mapping and discussion on smart_mode below for more information

Port Mapping (802.1q)

The port mapping feature is a fixed setting and provides an additional amount of data
security since traffic on the individual Ethernet ports is segmented and isolated from
traffic on other Ethernet ports. Port mapping is implemented by using fixed VLAN tags
internal to the GigaPlus link. When Ethernet traffic arrives in a port, it may be tagged or
untagged. Both tagged and untagged packets are tagged with an additional VLAN Tag
depending on which port they arrived at as follows:
GE1: GigE 10/100/1000BaseT port :VLAN ID 4091
GE2: GigE 10/100/1000BaseT port :VLAN ID 4092
GE3: GigE SFP port: VLAN ID 4093
GE4: GigE SFP port: VLAN ID 4094
At the other end of the link, the internal tags are removed and the original packets are
sent out unaltered. Essentially the GigaPlus is performing double tagging on packets
that have already been tagged.
Port mapping is active when smart_mode is "on".

Q in Q/Double Tagging and smart_mode

If the operator wishes to send packets that are already double tagged through the link,
then smart mode must be disabled. With smart_mode off, all traffic coming in on GE1
will appear at BOTH GE1 and GE2 ports on the far end. Smart_mode must be enabled
on both ends of the link and it is recommended that only one of the traffic ports GE1 or
GE2 be utilized at each end. One added benefit of smart_mode being off is that the link
can act as a media converter. Side A of the link can be copper RJ45 and side B can be
GigE fiber single or multimode. The media conversion will only work for 1000BaseT, as
the fiber interface does not support 10/100BaseT modes. It is recommended that both
ports be set to the same speed and duplex at both ends of the link.
In Band Management (IBM) with VLAN tagging will not operate with the smart mode
turned off. Out of band management and IBM with VLAN tagging off (SW V3.0) will still
be available as when Smart Mode is off.
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Trango Systems, Inc. GigaPlus User Manual Rev 3.1