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New Member

multiple VLANs design issue

I am having an issue in a project. There are VTS and VCS VLANs at each site and Admin Building. These two VLANs are logically separated. Please check the diagram.


1, There are VTS and VCS VLANs at each site. Hosts in VTS VLAN and VCS VLAN use Multicast to communicate and can only talk to other hosts in their own VLAN. IP addresses can not be changed. 

2,  SW05 at Site3 directly connects to an ISP router. ISP will route packets from Site 3 to other sites.

3, At Admin Building, there is an ISP router and two of my switches. SW01 and SW02.

4, At Site 1 and Site2 are two remote sites. Site 2 connects to Admin Buidling via Site1. 

Problems I have:  

By doing InterVLAN routing for VLAN 200, VLAN 201 and VLAN 202, If I use SW03 as the Layer 3 switch and create SVI on sw03 to do ip routing. The InterVLAN routing can be achieved. If so, the gateway of VLAN 200, VLAN201 and VLAN 202 is SW03.In this case, sicne the gateway is not ISP's router GW01, how can I remote access?









Everyone's tags (1)

Hi ,  Over here you need to

Hi ,

  Over here you need to have another SVI VLan Created on your SW03 (Site1) , like VLAN 100 ( for connectivity to router GW01 . 

Your Router LAN interface must be configured with IP address 

Your L3 Switch Must be configured with SVI VLAN 100 IP address

Link between Sw02 to Sw03 must be trunk link which should carry vlan 100 , vlan 200 .(microwave link)

Point default route on Sw03 towards your router LAN interface

Similalry your Router GW01 must be have reverse route for all 3 subnets pointing back to your switch ( ,, . You can do this static or dynamically via OSPF/EIGRP




New Member

Hi Sandy,I am going to use

Hi Sandy,

I am going to use all the switches as layer 2 devices. So no SVI and InterVLAN Routing on my switch.


However, on the ISP router, I will ask them to create sub interfaces and encapsulate dot1q VLAN ID.(Routing on a stick).


How do you evaluate this design?



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