ZyXEL ES-4124 User Guide - Page 419

Chapter 49 IEEE 802.1Q Tagged VLAN Commands where = The VLAN ID [1 - 4094]. = A name to identify the SVLAN entry. = This is the Switch port list. • Enter fixed to register the to the static VLAN table with . • Enter normal to confirm registration of the to the static VLAN table with . • Enter forbidden to block a from joining the static VLAN table with . • Enter no fixed or no forbidden to change to normal status. • Enter untagged to send outgoing frames without a tag. • Enter no untagged to tag outgoing frames. 49.3.4.1 Modify a Static VLAN Table Example The following example configures ports 1 to 5 as fixed and untagged ports in VLAN 2000. sysname (config)# vlan 2000 sysname (config-vlan)# fixed 1-5 sysname (config-vlan)# untagged 1-5 49.3.4.2 Forwarding Process Example 49.3.4.2.1 Tagged Frames 1 First the Switch checks the VLAN ID (VID) of tagged frames or assigns temporary VIDs to untagged frames. 2 The Switch then checks the VID in a frame's tag against the SVLAN table. 3 The Switch notes what the SVLAN table says (that is, the SVLAN tells the Switch whether or not to forward a frame and if the forwarded frames should have tags). 4 Then the Switch applies the port filter to finish the forwarding decision. This means that frames may be dropped even if the SVLAN says to forward them. Frames might also be dropped if they are sent to a CPE (customer premises equipment) DSL device that does not accept tagged frames. 49.3.4.2.2 Untagged Frames 1 An untagged frame comes in from the LAN. 2 The Switch checks the PVID table and assigns a temporary VID of 1. 3 The Switch ignores the port from which the frame came, because the Switch does not send a frame to the port from which it came. The Switch also does not forward frames to "forbidden" ports. 4 If after looking at the SVLAN, the Switch does not have any ports to which it will send the frame, it won't check the port filter. ES-4124 User's Guide 419