Inter VLan Traffic with conditions

To set up inter-VLAN routing for your scenario, where you need to feed VLAN2 from a backup internet line in case the main line goes down, you can follow these steps:

1. Connect the backup internet line to one of the ports on your new core switches, preferably on the switch designated as the primary one.

2. Create a new VLAN for the backup internet line, let's say VLAN3. Assign an appropriate VLAN ID and IP subnet for this VLAN. For example, you can use VLAN ID 3 and subnet 192.168.3.0/24.

3. Configure the interface connected to the backup internet line on the primary switch as an access port in VLAN3. This will allow traffic from the backup line to enter the switch and be routed to other VLANs.

4. Configure inter-VLAN routing on both core switches. This will enable communication between VLANs. Ensure that the routing table is properly configured, and the default gateway points to the appropriate VLAN interface for each VLAN.

5. On the primary switch, configure a default route pointing to the main internet line (VLAN2) as the preferred path for internet traffic. This will ensure that traffic from VLAN2 uses the main line by default.

6. Configure a static route on the primary switch for VLAN2 traffic, pointing to the backup internet line (VLAN3). This static route should have a higher administrative distance (metric) than the default route to prioritize the main line.

7. Test the setup by simulating a failure on the main internet line. You can disconnect the main line temporarily to verify that VLAN2 traffic automatically switches to the backup line.

By following these steps, you can achieve the desired behavior of feeding VLAN2 from the backup internet line when the main line goes down. Keep in mind that the specific configuration steps may vary depending on the switch model and firmware version you are using. It's always recommended to consult the documentation or seek assistance from the manufacturer or a networking professional for detailed configuration guidance specific to your equipment.

Regards;

David Johnson.