6.3.2 Forwarding Tagged/Untagged Frames

Ports can be assigned to multiple tagged or untagged VLANs. Each port on the switch is therefore capable of passing tagged or untagged frames.

To forward a frame from a VLAN-aware device to a VLAN-unaware device, the switch first decides where to forward the frame, and then strips off the VLAN tag. However, to forward a frame from a VLAN-unaware device to a VLAN-aware device, the switch first decides where to forward the frame, and then inserts a VLAN tag reflecting this port’ s default VID.

The default PVID is VLAN 1 for all ports, but this can be changed.

VLAN aware

 

 

 

 

switch

VLAN 1,2

 

VLAN 1,3

 

 

 

802.1Q

 

802.1Q

 

 

tags

 

tags

VLAN aware

switch

VLAN aware

switch

trunk VLAN 1.2.3 (802.1Q tags)

VLAN aware

switch

VLAN

 

VLAN 1,3

 

1,2,.3

 

 

802.1Q

 

(untagge

VLAN aware

 

 

 

d)

 

 

 

 

switch

 

 

 

 

 

 

 

 

 

VLAN aware

switch

WGS3 Layer 3 Switch User’s Manual

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