Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 169)

Brocade Virtual ADX Global Server Load Balancing Guide 159
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Advanced GSLB configuration for IPv6
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To return the same IP address for a client that has sent requests previously, the GSLB controller
must save the following information:
• Client IP address/prefix
• Domain name the client requested
• Selected IP address for the request
This information is saved in a session table when the sticky GSLB persistence is enabled, and the
GSLB controller creates a sticky session for each client within the session table. Each session has a
special user type and source port or destination port number to distinguish from other sessions.
When a new request enters the system, the GSLB controller searches for the client IP and domain
name pair. If a match is found, the previously selected IP address will be returned.
To ensure the selected IP is still valid for the request, the GSLB controller checks for the following
conditions to be true before it returns the reply:
• Selected IP still belongs to the requested domain
• Selected IP is still active
Enabling sticky persistence for IPv6
Sticky persistence for IPv6 addresses is implemented as a GSLB policy, and it can be applied
globally or on per-host basis.
To enable GSLB globally for all domains, enter commands such as the following on the GSLB
controller:
SLB-Ctrl-Virtual ADX(config)#gslb policy
SLB-Ctrl-Virtual ADX(config-gslb-policy)#sticky
To enable Sticky GSLB for a specific host, enter commands such as the following on the GSLB
controller:
SLB-Ctrl-Virtual ADX(config)#gslb-host-policy test
SLB-Ctrl-Virtual ADX(config-gslb-host-policy-test)#sticky
SLB-Ctrl-Virtual ADX(config)#gslb dns zone example1.com
SLB-Ctrl-Virtual ADX(config-gslb-dns-example1.com)#host-info www gslb-policy test
This example defines a host policy, then applies that policy to the specific host www. The sticky is
one function within the host policy.
Syntax: [no] sticky
No special CLI commands need to be issued on the site ADX device.
Specifying sticky session prefix lengths
To create sticky for a specific group (subnet) of clients, configure a different prefix length for that
group. Once configured, the GSLB controller will ensure that DNS clients within the same subnet
will be served the same IP address in the GSLB response so long as the IP address belongs to the
domain and is active.
By default, the Brocade Virtual ADX creates sticky sessions for every IPv6 DNS client with a prefix
length of 128 bits. The ipv6-prefix-length parameter enables you to specify an alternative prefix
length.