Brocade Communications Systems ServerIron ADX 12.4.00 - Manual (Page 207)

ServerIron ADX Global Server Load Balancing Guide 195
53-1002437-01
Global server load balancing for IPv6 overview
2
• If the client does not advertise EDNS0 header with a buffer larger than 512 bytes, eight IPv6
addresses per host are supported in the response.
• If the client advertises EDNS0 header with a buffer smaller than 512 bytes, forty IPv6
addresses per host are supported in the response.
GSLB for IPv6 example
Typically, GSLB for IPv6 is used to distribute IPv6 traffic to multiple sites for load balancing,
geographic proximity, or redundancy.
Figure 12 shows a deployment of IPv6 GSLB in DNS cache proxy with DNS override mode. The
GSLB controller acts as the authoritative DNS server for the www.brocade.com domain. The
domain IPs for www.brocade.com are a mix of IPv4 and IPv6 addresses. When the GSLB controller
receives DNS queries from resolvers (local DNS), it generates a response based on a configured
GSLB policy.
In this example, the GSLB controller sees that the client is geographically closer to the US site and,
therefore, directs application traffic to the closer VIP.
FIGURE 12 IPv6 GSLB configuration
5
6
Client local DNS server
sends AAAA query for
www.brocade.com.
The GSLB DNS response
www.brocade.com
. = 2001:db8::56
GSLB DNS response
www.brocade.com. = 2001:db8::56.
DNS
2
4
3 ZONE CONFIG (ip-list):
www.brocade.com
. = 192.108.22.111
www.brocade.com . = 209.157.22.210
www.brocade.com . = 2001:db8::56
www.brocade.com . = 2001:db8::ab
GSLB POLICY:
health geographic
dns best-only
GSLB SI ADX
ServerIron ADX with ADNS VIP
VIP: 2001:DB8::56 VIP: 2001:DB8::ab
Site ADX Site ADX
GSLB Site 1 (US) GSLB Site 2 (EU)
VIP: 209.157.22.210
Site ADX Site ADX
GSLB Site 3 (US) GSLB Site 4 (EU)
VIP: 192.108.22.111
1
US IPv6 client
sends DNS request
for AAAA record for
www.brocade.com .
Application traffic
US IPv6 Client (Browser)
Local DNS