Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 90)

74 Brocade Virtual ADX Server Load Balancing Guide
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Multiple port binding
2
Configuration rules
Use the following rules when configuring the Brocade Virtual ADX to bind more than one virtual
server to the same real server using the same application port:
• You must configure both the real port and the alias port on the real servers. For example, if you
need to create alias port 180 so that you can bind two virtual servers to the same real server
and application port (80) on a real server, you must configure port 80 and port 180 on the real
server. Otherwise, you will not be able to completely bind all the virtual servers to the real
server. In the example below, the following real server configurations are incomplete because
neither of the real servers has both the untranslated and alias ports configured.
Virtual ADX(config)#server real-name r1 10.0.1.5
Virtual ADX(config-rs-r1)#port http
Virtual ADX(config-rs-r1)#exit
Virtual ADX(config)#server real-name r2 10.0.2.200
Virtual ADX(config-rs-r2)#port 180
Virtual ADX(config-rs-r2)#exit
• You cannot bind to both the untranslated port and the alias port in the same bind statement. In
the example below, the following bind statement is invalid.
Virtual ADX(config-vs-VIP1)#port http
Virtual ADX(config-vs-VIP1)#bind http r1 http r2 180
Here is a more detailed explanation.
When you configure SLB, one of the tasks you perform is to bind the TCP or UDP application ports
on the virtual server to their counterparts on the real server. For example, if clients will be sending
requests to port 80 (HTTP) on virtual server
www.example8.com
, but your real servers expect the
HTTP connections to arrive on port 8080 of real server R1, you must bind port 80 on the virtual
server to port 8080 on the real server.
One of the requirements is that a real server can be bound to only one virtual server using the
same TCP or UDP application port. As a result, when you bind a real server port to a virtual server
port, you cannot then bind the same real server port to a different virtual server port.
Normally, the Brocade Virtual ADX translates the IP address and application port of the virtual
server requested by the client into the real server IP address and application port that you bind to
the virtual server. However, when you disable port translation, the Brocade Virtual ADX does not
perform the translation for the application port. Instead, the Brocade Virtual ADX translates the
destination IP address in the client’s request to the IP address of a real server, but leaves the
application port in the client’s request untranslated.