Following are some sample situations and how to configure the site selection algorithm for each one on the Barracuda Load Balancer that acts as the Global Server Load Balancing (GSLB) Controller.
Disaster Recovery - Two Sites in the World
You have two sites and you want all traffic directed to one of the sites while the other is on standby and used only in the case of the failure of the first site. Create an entry for each site giving the primary site priority 1 (highest) and the backup priority 2. Make the Response Policy By Priority so that only priority is considered when directing traffic.
When a query for the address of the domain name is received, a response containing one or more IP addresses is returned. If it is operational, the primary site’s IP address will be returned first in the list and the backup site’s IP address will be second. If the primary site becomes unavailable, only the second site's IP address will be returned.
The primary site will be monitored, even after failure, so that when it becomes available then its IP address will once again be first in the returned list.
Direct Clients to Closest Data Center
You have a number of server farms that are physically located around the world, and you want clients to be directed to the closest healthy server farm. Make the Response Policy Geo IP to send client requests to the geographically nearest site. If you have a backup site, set the Failover IP address to its IP address.
Direct Clients to Specific Region
You have multiple data centers, each with region-specific content, and you want client requests from a certain region to be directed to the data center that supports that region. Make the Response Policy Region Only to associate requests with a region based on the location of the client and direct traffic to the appropriate data center.
If you have a backup site, set the Failover IP address to its IP address. Content switching rules can be used to direct HTTP traffic within the backup data center (see Directing HTTP Requests based on Content Rules).
- Barracuda Networks Knowledgebase Solution #00004306