Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 171)

Brocade Virtual ADX Global Server Load Balancing Guide 161
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Advanced GSLB configuration for IPv6
2
IPV4 and IPV6 sticky sessions will share the same special signature. All sticky GSLB ipv6 sessions
are identified by the client IP and the following three tuples that remain the same for all sticky
sessions:
• Dst-IP: 10.0.255.0
• S-port : 7
• D-port : 8
In the example, the second and third rows show IPV6 and IPV4 sticky sessions.
Configuring DNS response parameters
Fragmentation is not supported for the GSLB Brocade Virtual ADX for IPv6.
Therefore, you must either configure an active-only policy or best-only policy or ensure that the
number of IP addresses configured in the IP list is small enough to avoid fragmentation
Configuring an active-only policy
By default, the Brocade Virtual ADX does not remove an IP address from a DNS reply even if the
address fails a health check.
You can configure the Brocade Virtual ADX to remove IP addresses from DNS replies when those
addresses fail a health check. The Brocade Virtual ADX removes the addresses that fail the check
so long as the DNS query still contains at least one address that passes the health check.
A site must pass all applicable Layer 4 and Layer 7 health checks to avoid being removed.
NOTE
If all the sites fail their health checks, resulting in all the sites being rejected by the GSLB Brocade
Virtual ADX, the Brocade Virtual ADX sends the DNS reply unchanged to the client.
The GSLB default behavior is as follows:
• In DNS proxy, the entire list of IP addresses is sent back to the client with the best IP address
selected by the GSLB controller at the top of the list. This best IP is selected in accordance with
the GSLB policy. An administrator typically configures an active-only policy, because the LDNS
may cache this response for TTL time and may round robin the IPs in this list in some cases.
• Health check in the GSLB policy is disabled. Typically administrators will not disable health
check if they are using an active-only policy.
• An active-only policy applies only to the remaining IP addresses in the IP list, not the best one.
An administrator should enable health check for best IP selection to ensure that best IP is
healthy.
To configure the Brocade Virtual ADX to remove IP addresses from DNS replies when those
addresses fail a health check, enter the following commands:
Virtual ADX(config)#gslb policy
Virtual ADX(config-gslb-policy)#dns active-only
Syntax: [no] dns active-only