Allied Telesis AT-S39 - Manual (Page 150)

Section II: Local and Telnet Management
150
There is one other thing that should be mentioned about ingress
filtering and tagged packets, and that is the priority tag. Each tagged
frame has a priority tag in it that instructs the switch as to the
importance of the frame. Frames with a high priority are handled ahead
of frames with a low priority.
Activating or deactivating ingress filtering has no effect on the switch’s
handling of priority tags. A switch will always examine a priority tag in a
tagged frame, regardless of the status of ingress filtering.
In most cases, you will probably want to leave ingress filtering activated
on the switch, which is the default. You can enable or disable ingress
filtering on a per switch basis. You cannot set this per port.
To enable or disable ingress filtering, perform the following procedure:
1. From the Main Menu, type 2 to select VLAN Menu.
2. From the VLAN Menu, type 2 to select Ingress Filtering Status. Current
status for this functionality (enabled or disabled) is displayed next to
this feature selection.The following prompt is displayed:
Enter Ingress Filtering Status (E-Enable, D-Disable)
->
3. Type E to activate ingress filtering or D to disable ingress filtering on
the switch.
4. Type S to select Save Configuration Changes.
A change to the status of ingress filtering is immediately activated on
the switch.