On Compute Cloud@Customer, networking enables you to set up virtual
versions of traditional network components.
When you work with Compute Cloud@Customer, one of the first steps is to set up a
virtual cloud network (VCN) for your cloud resources.
The infrastructure that provides the necessary services to deploy cloud workloads is
configured to operate within the network environment of your data center. During
initialization, the infrastructure's core network components are
integrated with your existing data center network design.
Virtual Network Interface Cards (VNICs)
The compute nodes in Compute Cloud@Customer have physical network interface
cards (NICs). When you create a compute instance on one of the servers, the Networking
service ensures that a VNIC is created on top of a physical interface, so that the instance
can communicate over the network. Each instance has a primary VNIC that is automatically
created and attached. The primary VNIC resides in the subnet you specify when creating the
instance. It can't be removed from the instance.
A VNIC enables an instance to connect to a VCN and determines how the instance communicates
with endpoints inside and outside of the VCN.
Instances use IP addresses for communication. Each instance has at least one private IP
address and optionally one or more public IP addresses. A private IP address enables the
instance to communicate with other instances inside the VCN. A public IP address enables the
instance to communicate with hosts outside of the cloud network environment.
Certain types of resources are designed to be directly reachable from outside the secure
Compute Cloud@Customer network environment, and therefore automatically come
with a public IP address. For example: a NAT gateway. Other types of resources are directly
reachable only if you configure them to be. For example: specific instances in your VCN.
Direct public connectivity also requires that the VCN has an internet gateway and that the
public subnet has correctly configured route tables and security lists.
The Networking service uses DHCP to automatically provide configuration information to
instances when they boot up. Although DHCP lets you change some settings dynamically, others
are static and never change. For example, when you create an instance, either you specify
the instance's private IP address or the system chooses one for you. Each time the instance
boots up or you restart the instance's DHCP client, DHCP passes that same private IP address
to the instance. The address never changes during the instance's lifetime.
The Networking service provides DHCP options to let you control certain types of
configuration on the instances in your VCN. You can change the values of these options at
your discretion, and the changes take effect the next time you restart an instance's DHCP
client or reboot the instance.
Steering Policies enable you to configure policies to serve intelligent responses to DNS
queries, meaning different answers (endpoints) may be served for the query depending on the
logic defined in the policy.