| Configuring GSLB protocol parameters | 1 |
ServerIronADX(config)# gslb policy |
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The command in this example changes the RTT explore percentage from 5% to 10%.
Syntax: [no] round-trip-time explore-percentage <num>
The <num> parameter specifies the explore percentage and can be from
Adding static prefix cache entries
The GSLB ServerIron ADX maintains a cache of
The GSLB ServerIron ADX uses the RTT information in the prefix cache when evaluating a site using the GSLB policy. Thus, the cache entry provides the RTT information used for the RTT metric during evaluation of the GSLB policy.
When the GSLB ServerIron ADX receives RTT information from a site ServerIron ADX, the IP address of the client is compared to the prefixes in the cache. If the address fits within a network in one of the prefixes, the GSLB ServerIron ADX stores the RTT information for that site under the prefix entry. If the client address is within more than one prefix entry, the GSLB ServerIron ADX selects the entry with the longer prefix (the more exact match).
The GSLB ServerIron ADX makes a dynamic entry in the prefix cache of the length specified by the cache prefix the first time the ServerIron ADX processes a DNS query or response from that prefix. After that, each time the GSLB ServerIron ADX receives a subsequent DNS query from within that prefix, the ServerIron ADX resets the aging timer for the cache prefix entry. If a dynamic entry is not refreshed by subsequent queries, the entry ages out.
You can manually add static prefix information to the cache. For example, you can add static cache entries with longer prefix information than the dynamic cache entries to ensure that RTT information is stored under the static entries instead of dynamic cache entries with shorter prefixes. This is useful when you want to ensure that certain prefixes are always present in the cache regardless of how often the GSLB ServerIron ADX receives RTT data for them. Static prefixes do not age out.
NOTE
The GSLB ServerIron ADX uses the most exact match when more than one prefix entry can apply to the same site address. To ensure that the GSLB ServerIron ADX uses a static entry instead of certain dynamic entries for a given address, make sure prefix of the static entry is longer than the prefix for dynamic entries.
NOTE
Since RTT information is stored under individual domain names that are queried, the RTT information reported from remote ServerIron ADXs are not recorded under the static records until the GSLB ServerIron ADX receives the first DNS query or response.
To add a static prefix cache entry, enter commands such as the following:
ServerIronADX(config)# gslb policy
Syntax: static-prefix <ip-addr>/<prefix-length>
ServerIron ADX Global Server Load Balancing Guide | 55 |
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