In recent years, vehicle networks require high bandwidth due to the increasing complexity of electronic control devices for vehicles due to the demand for advanced driving aids, infotainment and V2X communication. Therefore, Ethernet protocol was introduced and vehicle gateway system was newly introduced in vehicle system. The vehicle gateway system provides an interface for continuously connecting and exchanging vehicle data in different communication environments between the Controller Area Network (CAN) protocol and the Ethernet network protocol. There are two types of data exchange in the vehicle gateway. These are direct routing and indirect routing. Vehicle gateways are connected to external networks, which can lead to security vulnerabilities. So it needs security function to ensure message integrity. Recently, vehicle manufacturers have introduced gateway systems with security features that operate to verify the integrity of messages using cipher-based message authentication codes (CMAC). But applying security functions to a gateway system introduces delays in performing security functions. Therefore, in this paper, to design stable and efficient the vehicle gateway system with security function, we have tested and evaluated the latency time that can occur according to the routing methods which are direct routing and indirect routing.