NAT-mode server load balancing

Figure 42: Network diagram

As shown in Figure 42, NAT-mode server load balancing contains the following elements:

NAT-mode server load balancing is implemented through the following modes:

DNAT mode

DNAT-mode server load balancing requires you to change the gateway or configure a static route for the server to send packets destined to the host through the LB device.

Figure 43: DNAT-mode server load balancing workflow

Table 10: Workflow description

Description

Source IP address

Destination IP address

1. The host sends a request.

Host IP

VSIP

2. When the LB device receives the request, it uses a scheduling algorithm to calculate to which server it distributes the request.

N/A

N/A

3. The LB device uses the DNAT technology to distribute the request, using Server IP as the destination IP.

Host IP

Server IP

4. The server receives and processes the request and then sends a response.

Server IP

Host IP

5. The LB device receives the response, translates the source IP to VSIP, and forwards the response to the requesting host.

VSIP

Host IP

SNAT mode

SNAT-mode server load balancing requires the following configurations:

As a best practice, do not use SNAT-mode server load balancing because its application scope is limited. This chapter does not provide detailed information about SNAT-mode server load balancing.

DNAT + SNAT mode

Figure 44: DNAT + SNAT-mode server load balancing workflow

Table 11: Workflow description

Description

Source IP address

Destination IP address

1. The host sends a request.

Host IP

VSIP

2. When the LB device receives the request, it uses a scheduling algorithm to calculate to which server it distributes the request.

N/A

N/A

3. The LB device uses the DNAT + SNAT technology to distribute the request, using the IP address in the SNAT address pool as the source IP and Server IP as the destination IP.

SNAT IP

Server IP

4. The server receives and processes the request and then sends a response.

Server IP

SNAT IP

5. The LB device receives the response, translates the source IP to VSIP and destination IP to Host IP, and forwards the response to the requesting host.

VSIP

Host IP