EIP

An elastic IP address (EIP) is a method to access a private network through a public network. 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.

Create EIP

In the navigation pane of the ZStack Private Cloud UI, choose Network Service > EIP. On the EIP page, click Create EIP. On the displayed Create EIP page, set the following parameters:

Name: Enter a name for the EIP.
Description: Optional. Enter a description for the EIP.
Select VIP: Select a VIP for the EIP. The EIP service is provided by a VIP.
To use a VIP, select one of the following methods:
- Create new IP:
  To create a new VIP, set the following parameters:
  - Network: Select a network that provides a VIP. The network can be a public network or a flat network.
  - IP Range: Optional. Specify an IP range. Note that an IPv4 public network allows you to select a normal IP range or an IP address pool.
  - Specified IP: Optional. Specify a VIP. If not specified, the system will automatically assign a VIP.
  As shown in Figure 3.
  Figure 3. Create new VIP
- Use existing VIP:
  To use an existing VIP, set the following parameter:
  - VIP: Select an existing VIP.
  As shown in Figure 4.
  Figure 4. Use existing IP

As shown in Figure 5.

Click Next. Then, the Associate VM NIC page is displayed, as shown in Figure 6.

Select the target VM instance and click OK. To cancel the operation, click Cancel. After you cancel the operation, you can associate a VM instance in EIP operations.

EIP Operations

You can perform the following operations on an EIP:

Change name and description: Change the name and description of the EIP.
Associate: Associate the EIP with a VM NIC.
Disassociate: Disassociate the EIP from a VM NIC.
Change owner: Change the owner of the EIP.
Delete: Delete the EIP. Note that the IP services provided by the EIP will also be deleted. To delete its associated VIP at the same time, select Delete VIP.
Audit: View related operations of the EIP.