Network Router User Manual

Web OS 10.0 Application Guide

Chapter 6: Server Load Balancing

143

212777-A, February 2002

The sequence of steps that are executed in this scenario are shown in Figure 6-7:

Figure 6-7 Direct Server Return

1. A client request is forwarded to the Web switch.

2. Because only MAC addresses are substituted, the switch forwards the request to the best

server, based on the configured load-balancing policy.

3. The server responds directly to the client, bypassing the switch, and using the virtual

server IP address as the source IP address.

To set up DSR, use the following commands:

Using Direct Access Mode

When Direct Access Mode (DAM) (/cfg/slb/direct) is enabled on a switch, any client

can communicate with any real server’s load-balanced service. Also, with DAM enabled, any

number of virtual services can be configured to load balance a real service.

Traffic sent directly to real server IP addresses is excluded from load-balancing decisions. The

same clients may also communicate to the virtual server IP address for load-balanced requests.

NOTE – When DAM is enabled on a switch, port mapping and default gateway load balancing

is supported only when filtering is enabled, a proxy IP address is configured, or URL parsing is

enabled on any switch port.

Assigning Multiple IP Addresses

One way to provide both SLB access and direct access to a real server is to assign multiple IP

addresses to the real server. For example, one IP address could be established exclusively for

SLB and another could be used for direct access needs.

>> # /cfg/slb/real <real server number>/submac ena

>> # /cfg/slb/virt <virtual server number>/service <service number>/nonat ena

Internet

Layer 2 Switch

Web Switch

Server farm

Client