Figure 6 illustrates the applied port-based VLAN for LNR
service on WiMAX network infrastructure in Taiwan. Three
logical VLANs are defined and they are assigned to different
applications of e-SNG, WiTV and VoIP respectively. VoIP
(i.e. Voice over IP) is applied to provide the voice call
between e-SNG vehicle and remote TV station headend. As
the example of WiTV service, only the port numbers 3 and 4
at the switch device SW_3 of TV station headend and port
numbers 1 and 4 at the switch device SW_2 of remote site can
transmit the broadcasting packets of WiTV service because
these switch ports are designated to the same VLAN 3. Other
switch ports cannot receive and even maliciously tap the
packets of WiTV.