VPC Overview

VPC

Virtual Private Cloud (VPC) allows you to provision logically isolated virtual networks for your FlexusX instances. You can define security groups and CIDR blocks for each VPC. This facilitates internal network configuration, management, and change. You can also define rules to control communications between FlexusX instances in the same security group or across different security groups.

The private network communication rules of FlexusX instances are as follows:

In the same region of an account, multiple FlexusX instances can communicate with each other over a private network only when they are in the same VPC instead of different VPCs.
FlexusX instances created by different accounts or in different regions are located in different VPCs. They cannot communicate with each other over a private network by default.
FlexusX instances in the same region can communicate with each other through VPC Peering Connection, and those in different regions can communicate with each other through Cloud Connect.

For more information about VPC, see Virtual Private Cloud User Guide.

Network Interfaces

An elastic network interface (ENI) is a virtual network card. You can create network interfaces and attach them to your FlexusX instances to obtain flexible and highly available network configurations.

There are two types of network interfaces: primary network interfaces and extended network interfaces.

A primary network interface is created together with an instance by default and cannot be detached from the instance.
An extended network interface can be created on the Network Interfaces tab, and can be attached to or detached from an instance.

Constraints on using network interfaces are as follows:

The number of network interfaces that can be attached to a FlexusX instance is determined by the instance specifications. For details, see Instance Specifications.

**Table 1** Constraints on using different types of network interfaces
Network Interface Type	Creation	Attachment	Communication with External Networks	Communication with Public Service Zone
Primary network interface	Created along with the instance by default and cannot be created separately.	Cannot be detached from the instance.	Supported	Supported
Extended network interface	Can be created separately on the Network Interfaces page.	Can be attached to or detached from the instance.	Not supported. Policy-based routes need to be configured for external network access. For details about how to configure policy-based routes, see How Do I Configure Policy-Based Routes for an ECS with Multiple Network Interfaces?	Not supported

Extended network interfaces cannot be used to directly access Huawei Cloud services, such as Domain Name Service (DNS). You can use VPC Endpoint (VPCEP) to access these services. For details, see Buying a VPC Endpoint for Accessing Interface VPC Endpoint Services.

Billing

In the same region of an account, no additional expenditures are billed for private network access between different FlexusX instances and between FlexusX instances and other Huawei cloud servers in the same VPC. For details about the VPC billing, see Billing.

Constraints

When using a VPC, you need to plan VPCs, subnet CIDR blocks, security groups, virtual IP addresses, and elastic NICs. For details about VPC constraints, see Notes and Constraints.

Helpful Links

Operation	Description
Attaching Extended Network Interfaces to a FlexusX Instance	If your FlexusX instance requires multiple network interfaces, you can attach extended network interfaces. For details, see Elastic Network Interface Overview.
Detaching Extended Network Interfaces from a FlexusX Instance	You can detach extended network interfaces from your FlexusX instance if they are no longer needed. Only extended network interfaces can be detached from the FlexusX instance. You cannot detach the primary network interface from it.
Changing the VPC for a FlexusX Instance	This section describes how to change the VPC of a FlexusX instance.
Changing the Private IP Address of the Primary Network Interface for a FlexusX Instance	You can change the private IP address of the primary network interface for a FlexusX instance on the console.
Configuring a Virtual IP Address for a FlexusX Instance	A virtual IP address serves as a secondary IP address for a network interface. A virtual IP address can be bound to multiple cloud servers to improve server availability.