Distributed health checks for gslb – Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) User Manual
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Brocade Virtual ADX Global Server Load Balancing Guide
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Enabling DNS request logging
1
Distributed health checks for GSLB
The GSLB Brocade Virtual ADX evaluates each IP address in the DNS reply based on a set of
criteria. Depending on the results of this evaluation, the GSLB Brocade Virtual ADX reorders the list
to place the “best” IP address on the top of the list. Usually, the GSLB Brocade Virtual ADX uses a
server’s health as one of the most important criteria to evaluate the server IP addresses in a DNS
reply. The GSLB distributed health check feature delegates the health-checking task, currently
carried out by the GSLB controller ADX, to the site ADX devices.
The GSLB distributed health check feature is enabled by default. With this feature enabled, the site
ADX periodically reports the health check status of all servers that are being load balanced by it to
the GSLB controller ADX. Thus, the GSLB controller ADX is not required to conduct direct health
checks for servers that are load balanced on the site ADX.
The distributed health check feature provides the following benefits:
•
Reduction of load on the GSLB controller device
•
Reduction of health check traffic from the GSLB controller
•
Increased scale due to distribution of health checks
It is not mandatory to use common GSLB health check modes (centralized versus distributed)
across all GSLB sites. The sites can slowly transition from centralized health check mode to
distributed health check mode. Refer to
“Disabling the distributed health check feature for an
on page 77 and
“Disabling or re-enabling distributed health check”
The configuration required depends on the support of the GSLB distributed health checks on the
GSLB controller and GSLB site ADX devices. Refer to
for more information.
Disabling the distributed health check feature for an individual site ADX device
If a site ADX device does not support the distributed health check feature, and if the GSLB Brocade
Virtual ADX supports the distributed health check feature, then distributed health check feature
should be disabled for that site ADX device as it does not support distributed health checking i.e.
the GSLB Brocade Virtual ADX still needs to maintain health checks for the host servers being load
balanced by that site ADX device.
To disable distributed health check feature for an individual site ADX device, enter commands such
as the following on the GSLB Brocade Virtual ADX, not on the site ADX device.
GSLB-Virtual ADX(config)#gslb site sunnyvale
GSLB-Virtual ADX(config-gslb-site-sunnyvale)#si-name 10.1.1.107
no-si-dist-health-check
TABLE 6
GSLB distributed health check configuration
Distributed health check enabled on
the site ADX device
Distributed health check disabled
on the site ADX device
Distributed health check enabled on
the GSLB controller ADX
•
No mandatory configuration
required.
•
Flashback metric disabled by
default. Do not enable.
•
Mandatory configuration
required to disable distributed
health check for this site ADX
device.
Distributed health check disabled
on the GSLB controller ADX
•
No configuration required.
•
Flashback metric enabled by
default.
Not applicable.