Help Center/ Cloud Container Engine/ FAQs/ Networking/ Network Planning/ What Is a Network Interface?
Updated on 2026-05-25 GMT+08:00
View PDF
Share

What Is a Network Interface?

A network interface is a virtual network card. You can create and configure network interfaces and attach them to your cloud servers (ECSs or BMSs) to build flexible and highly available networks.

Network Interface Types

  • A primary network interface is created together with an ECS instance by default, which cannot be detached from its ECS.
  • An extension network interface can be created and attached to an ECS, and can be detached from the ECS. The number of extension network interfaces that you can attach to an ECS varies by ECS flavor.

Application Scenario

  • Flexible migration

    You can detach a network interface from a cloud server and attach it to another. The interface retains its private IP address, EIP, and security group rules. This enables rapid traffic migration from a faulty server to a standby, minimizing service downtime.

  • Independent traffic management

    You can attach multiple network interfaces that belong to different subnets in a VPC to the same instance, and specify them to carry the private network traffic, public network traffic, and management network traffic of the instance, respectively. You can configure access control policies and routing policies for each subnet, and configure security group rules for each network interface to isolate networks and service traffic.

Restrictions

  • An instance and its extension network interfaces must be in the same AZ, VPC, and subnet. However, they can belong to different security groups.
  • A primary network interface cannot be detached from its ECS.
  • The number of extension network interfaces that you can attach to an ECS varies by ECS flavor.
Parent Topic: Network Planning