ServerIron ADX Global Server Load Balancing Guide 81
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Weighted distribution of sites with hash-based persistence 1
Configuring weights for domain IP addresses
Weighted Hash-based GSLB persistence enables the user to distribute the hash buckets for the
domain in proportion to the weights configured for the domain IP addresses. Use the following
command line interface to configure weights for the domain IP addresses.
ServerIronADX(config)# gslb dns zone gslb.com
ServerIronADX(config-gslb-dns-gslb.com)# host www http
ServerIronADX(config-gslb-dns-gslb.com)# host www ip-hash-weight 20.20.1.80 10
ServerIronADX(config-gslb-dns-gslb.com)# host www ip-hash-weight 30.30.1.80 20
Syntax: host-info <host-name> ip-hash-weight <IPaddress> <weight>
•The <host-name> parameter specifies the host name.
•<IP address> is the IP address for which you are assigning a hash weight.
•<weight> is a value from 0 to 100. The default value is 1. A weight of 0 implies that the client IP
will not be allocated any hash buckets. A weight of 0 can be used to designate a domain IP as
backup.
NOTE
The aggregate of the hash weights for all the IPs for a domain does not have to add up to 100.
When user configures a hash weight of zero for a domain IP, no hash buckets are allocated to this
domain IP. If the hash buckets for this domain does not have any other healthy IPs, then the best IP
address among all the healthy IPs including the IP with hash weight of zero, will be selected based
on the remaining GSLB metrics. So user can configure a domain IP to be used as a backup IP by
configuring a weight of zero for this IP address.
Disabling rehash on introduction of new IP addresses or state change from down to healthy
You can disable rehash on the introduction of a new IP address or change of IP address state from
down to healthy. Persistence that occurs when rehashing is performed is prevented. The trade-off
is the new IP address will not be included in the hash table.
To disable rehash, enter commands such as the following:
SLB-ServerIronADX(config)# gslb policy
SLB-ServerIronADX(config-gslb-policy)# hash-persist persist-rehash-disable
Syntax: hash-persist persist-rehash-disable <time-out>
The <time-out> parameter specifies the number of seconds before an IP address is removed from
the hash table when that IP becomes down. The default is 5 seconds.
Disable rehash when weight for an IP is changed
When user changes the hash weight configured for an IP in the domain, GSLB controller will
automatically rehash the hash table for that domain. You can disable this rehash on weight
configuration change with the following command.
Use the following command line interface to disable rehashing on weight change for global GSLB
policy.
ServerIronADX(config)# gslb policy