EIP

An elastic IP address (EIP) is a method to access a private network through other networks. An EIP converts the IP address of a network into the IP address of another network based on the network address translation (NAT) function.

  • The following is an example of a public EIP usage scenario in flat networks, as shown in EIP Usage Scenario in Flat Network.
    Figure 1. EIP Usage Scenario in Flat Network


    • Public networks can connect to the Internet through firewalls.
    • Private networks (flat networks) provide IP addresses for each VM instance in each compute node. Notice that these IP addresses cannot connect to the Internet by default.
    • Distributed EIP is deployed on each compute node, and can be bound to public networks or private networks separately.
  • The following is an example of an EIP usage scenario in vRouter networks or VPC networks, as shown in EIP Usage Scenario in vRouter/VPC Network.
    Figure 2. EIP Usage Scenario in vRouter/VPC Network


Definitions related to EIP:
  • Public EIP: The EIP service provided by a public VIP created from a public network.
    • An internal private network is an isolated network space, which cannot be directly accessed by the external network. A public EIP can directly associate the access to a public network with the VM IP of an internal private network.
    • A public EIP can be attached to or detached from a VM instance dynamically.
    • A public EIP can be attached to VM instances created from private networks, such as flat networks, vRouter networks, and VPC networks.
      • The EIP realized by distributed EIP can access flat networks through public networks.
      • vRouters or VPC vRouters can be used to access vRouter networks or VPC networks through public networks.
  • Flat EIP: The EIP service provided by a flat VIP created from a flat network.
    • L3 isolations exist between flat networks of different IP ranges. Therefore, these flat networks cannot be accessed directly. A flat EIP can be used to associate the access to one flat network with the VM IP created from another flat network.
    • A flat EIP can be attached to or detached from a VM instance dynamically.
    • A flat EIP can be attached to VM instances created from other flat networks.