Brocade Virtual ADX Global Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 36)

26 Brocade Virtual ADX Global Server Load Balancing Guide
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Private VIPs for GSLB
1
The following commands enable DNS override on the Brocade Virtual ADX.
Virtual ADX(config-vs-dns-proxy)#exit
Virtual ADX(config)#gslb policy
Virtual ADX(config-gslb-policy)#dns override
Syntax: dns override
You must enable DNS override for the Brocade Virtual ADX to replace the address. Otherwise, the
Brocade Virtual ADX still uses the GSLB policy to select a “best” site but does not replace the IP
address with the proxy server’s address. The gslb policy command changes the CLI to the GSLB
policy configuration level.
Private VIPs for GSLB
Brocade Virtual ADX supports private Virtual IP (VIP) configurations for GSLB. GSLB support for
private VIPs enables a site Brocade Virtual ADX to communicate public VIP addresses to a GSLB
Brocade Virtual ADX, and, in effect, the GSLB Brocade Virtual ADX to recognize these IP addresses
in the DNS reply, as VIPs on the site Brocade Virtual ADX. This is accomplished by statically
mapping the private and public IP address for a VIP on the site ADX device.
Note that each time the mapping between the private IP address of the VIP and the public IP
address changes, you need to reconfigure the new public IP address for the VIP on the ADX device,
as well. Also, the GSLB IP addresses apply only to the GSLB feature. GSLB IP addresses do not
affect any other feature nor are they used by any other feature.
For example, as illustrated in Figure 3 , suppose 192.168.10.1 is the private IP address of the VIP
on ADX device B, and it is mapped to 10.95.55.23 by the firewall. On ADX device B, you would
statically map the GSLB public IP address of 10.95.55.23 for the private VIP 192.168.10.1. You
would also specify whether this public IP address is for use only by the peer GSLB ADX device A, or
if it will be used by both the peer GSLB ADX device A and ADX device B, if a local GSLB site is
present.
After statically mapping the public IP address, ADX device B will then communicate the public VIP
address, 10.95.55.23 to the peer GSLB Brocade Virtual ADX A. If GSLB ADX device A is providing
global SLB for the domain www.example2.com, where one of the IP addresses corresponding to
this domain is 10.95.55.23, then GSLB ADX device A will correctly interpret this IP address as a VIP
on the site ADX device B.
FIGURE 3 GSLB and private VIPs
Using the example in Figure 3 , suppose the configuration specifies that the public IP address will
be used by both the peer GSLB ADX device A and the site ADX device B. If ADX device B is providing
GSLB in addition to being a site ADX device, and has a local site configured, then it will also use this
public IP address of the VIP for its local site.