Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 66)

50 Brocade Virtual ADX Server Load Balancing Guide
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Primary and backup servers
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In addition, this feature implements the primary and backup configuration on an individual VIP
basis. You designate each backup server by changing the real server configurations. You do not
need to designate the primary servers. You enable the feature in individual VIPs for individual
application ports.
NOTE
The Brocade Virtual ADX does not differentiate between real and remote servers when the
primary-backup feature is enabled. Traffic will be load balanced among primary servers (real or
remote). When all primary servers are down, traffic will be load balanced among backup servers.
NOTE
Without the primary-backup feature enabled, traffic will be load balanced among real servers and
when all real servers are down, traffic will be sent to remote servers.
Figure 10 shows an SLB configuration that uses locally attached and remotely attached servers.
The configuration also uses some of the servers as the primary load-balancing servers while using
the other servers only as backups. Notice that one of the locally attached servers is a backup
server while one of the remotely attached servers is a primary load-balancing server.
FIGURE 10 Servers configured as primaries and backups
By default, when this feature is enabled on a VIP and all the primary servers are unavailable, a VIP
begins using the backup servers until a primary server becomes available again. When a primary
server is available, the VIP uses the primary server instead. Optionally, you can configure a VIP to
continue to use the backup servers even after the primary servers become available again.
To configure primary and backup servers, perform the following tasks.
1. Edit the configuration of each backup real server to designate the server as a backup.
NOTE
You do not need to designate the primary servers. The Brocade Virtual ADX assumes that all
servers you do not designate as backup servers are primary servers.
2. Enable use of the primary and backup servers in individual VIPs on individual application
ports. Only the VIPs and application ports for which you enable the feature use it. The other
application ports within the VIP, and the other VIPs, use the locally-attached servers
(configured using the server real-name-or-ip command) as their primary servers and the