Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 51)

Brocade Virtual ADX Global Server Load Balancing Guide 41
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Configuring GSLB protocol parameters
1
Syntax: show gslb dns zone
Implementing the Weighted Site metric
You can configure the Brocade Virtual ADX to distribute SLB traffic among GSLB sites based on
weights configured for the sites. The weights determine the percentage of traffic each site will
receive in comparison with other sites, which may or may not have weights.
NOTE
You cannot use the Weighted Site metric if the Weighted IP metric is enabled.
NOTE
The main criteria for the Weighted Site metric is that the total number of times the GSLB selects
each domain-IP for the client request is in proportion to the relative site weights.
You assign weights to GSLB sites. Each GSLB site may consist of one or more Brocade Virtual ADXs,
but the weight is applicable to the site as a whole.
The GSLB Brocade Virtual ADX uses relative percentages in order to achieve 100% total weight
distribution, as shown in
Table 5 and Table 3 . In Table 5 , the total of the Configured Weighted Site
metrics (2nd column) is 100. The last column shows that the GSLB Brocade Virtual ADX distributes
the traffic to the IP addresses exactly as configured. In this example, traffic distribution is
straightforward because the total weight of all three GSLB sites equals 100.
Now consider the example in Table 3 . In this example, the total of the Configured Weighted Site
metrics (2nd column) does not equal 100. However, as illustrated in the last column, the GSLB
Brocade Virtual ADX uses relative percentages in order to achieve 100% total weight distribution.
By default, the Weighted Site metric is disabled. When enabled, it is placed second in the GSLB
algorithm, after the Health Check metric. You can change the metric order and enable or disable
other metrics, although we do not recommend this. For more information, refer to
“Changing the
order of GSLB policy metrics” on page 36.
TABLE 3 Example Weighted Site metric configuration
IP address Configured Weighted Site metric Relative Weighted Site metric
San Jose 15 33% (15/45 * 100)
New York 20 44% (20/45 * 100)
London 10 22% (10/45 * 100)
Total 45 100%
Virtual ADX#show gslb dns zone
ZONE: example12.com
HOST: www:
Flashback DNS resp.
delay selection
(x100us) counters
TCP APP Count (%)
* 10.10.10.200: dns v-ip ACTIVE N-AM 9 19 0 (0%)
* 10.1.1.101: dns v-ip ACTIVE N-AM 0 0 4 (100%)