D-Link DES-3624 - Switch - Stackable User manual - page 70
Stackable NWay Ethernet Switch User’s Guide
Figure 5-5. Data transmissions between 802.1Q-compliant Switches
In the above example, step 4 is the key element. Because the
packet has 802.1Q VLAN data encoded in its header, the
ingress port can make VLAN-based decisions about its delivery:
whether server #2 is attached to a port that is a member of
VLAN 2 and, thus, should the packet be delivered; the queuing
priority to give to the packet, etc. It can also perform these
functions for VLAN 1 packets as well, and, in fact, for any
tagged packet it receives regardless of the VLAN number.
If the ingress port in step 4 were connected to a non-802.1Q-
compliant device and was thus receiving untagged packets, it
would tag its own PVID onto the packet and use this
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Switch Management Concepts