https://medium.com/google-cloud/using-a-multi-nic-vm-to-connect-vpcs-in-google-cloud-d84aa533538

Cloud Load Balancing supports proxying traffic to external backends outside Google Cloud. To define an external backend for a load balancer, you use a resource called an internet network endpoint group (NEG). You can use this type of deployment when you want to serve content from an external backend, but you want your Google Cloud…

An SLI is a service level indicator—a carefully defined quantitative measure of some aspect of the level of service that is provided. Most services consider request latency—how long it takes to return a response to a request—as a key SLI. Other common SLIs include the error rate, often expressed as a fraction of all requests received, and system throughput,…

Policy-based routes let you specify a next hop based on the packet’s protocol and source IP address in addition to the destination IP address. In this case, traffic is redirected to an internal passthrough Network Load Balancer which enables the insertion of appliances such as firewalls into the path of network traffic as policy-based routes…

Every VPC network uses a scalable, distributed virtual routing mechanism. There is no physical device that’s assigned to the network. Some routes can be applied selectively, but the routing table for a VPC network is defined at the VPC network level. Each VM instance has a controller that is kept informed of all applicable routes…