Configure the core switch as the gateway and tap Create Service Network. 11 to. Probably a stupid question but when moving from a flat network to a tagged VLAN network, I know the core switch needs to have a default gateway of our firewall but what VLAN should the firewall be on (i. It's setup differently than the way I learned but besides the point. The Core is doing L3 routing for four VFR's. Other VFR's are routed on the Firewall. Routes on the Core for all. Will using the core as a gateway overburden it? Is it secure to place gateways at the access layer? After reading this article, you'll be able to determine where and how to properly deploy your gateways. 01 | First, Let's Clarify: What Is a Gateway's Purpose? Simply put: A gateway serves as a.