By default, Extreme Networks switches run in 802.1Q operational mode, which means that every frame received by the switch must belong to, or be assigned to, a VLAN. The type of frame under consideration and the filter setting of the switch determines how it forwards VLAN frames. This involves processing traffic as it enters (ingresses) and exits (egresses) the VLAN switch ports as described below.
When, for example, the switch receives a frame from Port 1 and determines the frame does not currently have a VLAN tag, but recognizes that Port 1 is a member of VLAN A, it will classify the frame to VLAN A. In this fashion, all untagged frames entering a VLAN switch assume membership in a VLAN.
Note
A VLAN ID is always assigned to a port. By default, it is the default VLAN (VLAN ID = 1).The switch will now decide what to do with the frame, as described in Forwarding Decisions.
When, for example, the switch receives a tagged frame from Port 4 and determines the frame is tagged for VLAN C, it will classify it to that VLAN regardless of its port VLAN ID (PVID). This frame may have already been through a VLAN aware switch, or originated from a station capable of specifying a VLAN membership. If a switch receives a frame containing a tag, the switch will classify the frame in regard to its tag rather than the PVID for its port, following the ingress precedence rules listed below.
VLAN assignment for received (ingress) frames is determined by the following precedence:
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