Technical data

ServerIron ADX Advanced Server Load Balancing Guide 89
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Traffic distribution based on cache server capacity
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• Within the cache server configuration:
• Set the SNMP request community string to the same as the cache server.
• Set the SNMP request oid of the cache server.
• Within the cache group configuration, set the predictor to be SNMP weighted.
The following configuration sets the SNMP request community string and OID.
NOTE
This example shows commands that are valid on the ServerIron ADX device only when it is running
the Layer 3 router image.
Syntax: [no] snmp-request community <community-string>
The <community-string> variable specifies the community string name. The string can be up to 32
characters long.
Syntax: [no] snmp-request oid <oid-index> <oid-value>
The <oid-index> variable specifies an index number for the SNMP object identifier that you are
configuring.
The <oid-value> variable specifies the SNMP object identifier for the cache server.
By default, the ServerIron ADX polls the cache server for the configured OID every three seconds.
To change the SNMP poll interval, you can use the following command.
ServerIronADX(config)# server snmp-poll 30
Syntax: [no] server snmp-poll <seconds>
The <seconds> variable specifies the poll interval for the SNMP queries sent by the ServerIron ADX
to the cache servers. The ServerIron ADX then sets the cache state based on the reply received
from the cache server.
The following configuration sets Server Cache Group 1 to use the SNMP predictor configured with
the OID index 1 with the cs100 cache server.
ServerIronADX(config)# server cache-group 1
ServerIronADX(config-tc-1)# hash-mask 255.255.255.255 0.0.0.0
ServerIronADX(config-tc-1)# cache-name cs100
ServerIronADX(config-tc-1)# predictor snmp-weighted oid 1
Syntax: [no] predictor snmp-weighted oid <oid-index>
The <oid-index> variable specifies the index number for the SNMP object identifier that you want to
use for operating SNMP weighted load sharing for this cache group. This must be the same object
identifier as that defined under the cache servers.
A typical flow for SNMP-based cache server load balancing would include the following steps.
ServerIronADX(config)# server cache-name cs100 20.20.20.100
ServerIronADX(config-rs-cs100)# snmp-request community public
ServerIronADX(config-rs-cs100)# snmp-request oid 1 1.3.6.1.4.1.14501.3.2.1.42.42.0
ServerIronADX(config-rs-cs100)# port http
ServerIronADX(config-rs-cs100)#exit