I have been assigned for my first project ever as network engineer, things seems to be going smoothly, but there's something which is not clear to me.

After configuring VLANs on the Core, IP routing is enabled, and everything going as plan, he told me to configure the port between the Core and The Perimeter Firewall on a Separate VLAN and to make it as access Port, whys that? I mean shouldn't be a trunk between Core and Firewall so that it passes VLANs to the internet?

I’m a total noob in networking, got the basic Theory knowledge but nothing practical until now.

  • 1
    it really depends of your topology, if you do all inter-vlan routing on the core, L3, switch as it seems and then route the traffic on a /30 or /31 network to the firewall then it makes sense. We need more detail to provide an accurate answer.
    – JFL
    Apr 14, 2016 at 10:36

1 Answer 1


This is general design question which all network designers may have. i will explain it very simply.

  1. if you want to apply security filtering profiles for inter VLAN routing, its good to have a trunk between core switch and router. And do the routing on firewall.

  2. If you are provides internet connectivity through firewall and you needs to filter all traffic in common manner for all VLANs, you can use different VLAN between core switch and firewall. then add default route to firewall and apply internet traffic filtering at firewall.

this two methods are depends on your requirement.


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