Nortel Web OS 10.0, Application Manual

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Web OS 10.0 Application Guide
Chapter 6: Server Load Balancing
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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.
N
OTE
–
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
2
Layer 2 Switch
Web Switch
Server farm
Client
1
3