Concepts

Last updated: 2019-09-20 19:56:46

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What is an ENI?

  • ENI is a virtual network interface. Users can bind the CVM to the ENI for the connection to network. It is very useful for configuring management networks and establishing highly reliable network solutions.
  • An ENI is VPC, availability zone and subnet-specific, and can only be bound to a CVM that resides in the same availability zone as it. A CVM can be bound with multiple ENIs. The maximum number of ENIs allowed to be bound to a CVM depends on the CVM's specification.

What’s the difference between a Primary ENI and a Secondary ENI?

  • A primary ENI is assigned by the system for user, and the information cannot be modified.
  • A secondary ENI is created by user, and the information can be modified.

What are the user limits on ENI?

The maximum number of ENIs that can be bound to a CVM and that of private IPs that can be bound to each ENI vary greatly with CPU and memory configurations. For more details, please see Use Limits.

What to do if I cannot ping a EIP?

Typically, the reasons are:

  • The elastic IP is not bound to any cloud product. For binding methods, please see Binding EIPs to Cloud Products for details.
  • Security policy is invalid. Users can check whether the security policy (Security Groups or Network ACL) has taken effect.
  • Port access is disabled. Even if the bound cloud product has a security policy, but the access to the port is disabled, the port of the EIP is also inaccessible. For example: If the port 8080 is inaccessible, the port 8080 of the EIP is inaccessible either.