Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 63)

Brocade Virtual ADX Server Load Balancing Guide 47
53-1003247-01
Application port grouping
2
TCP/UDP application groups configuration example
Normally, when the Brocade Virtual ADX selects a real server for a client’s request for a TCP/UDP
port, there is no guarantee that the Brocade Virtual ADX will select the same real server for
subsequent requests from the same client. In many situations, this does not present a problem.
Even when the client is requesting the same Web page or application, if the content or service is
replicated on all the real servers, the client does not know or care which real server provides the
content or service for each request.
However, some applications may require that the client continue to use the same real server. For
example, an interactive Web site might require successive client requests to come to the same
server. Other applications might require that additional TCP/UDP applications also be on the same
real server. Some applications may even require the ability to open concurrent connections on the
client with different TCP/UDP ports dynamically assigned by the real server.
In all of these cases, the predictor (load-balancing metric) does not ensure that the client returns to
the same real server. To accommodate these types of applications, you can configure ports on a
virtual server to have the following attributes:
• Sticky connections – When you add a TCP/UDP port to a virtual server, if you specify that the
port is “sticky”, a client request for that port always goes to the same real server unless the
sticky age timer has expired. The sticky age timer ages out inactive sticky server connections.
Possible values are from 2 through 60 minutes. The default is 5 minutes. For more
information, see
“Setting the sticky age” on page 37.
• TCP/UDP application groups (using the track port function) – A “primary” TCP/UDP port is
grouped with up to four additional TCP/UDP ports. After the Brocade Virtual ADX sends a client
request for the primary port to a real server, subsequent requests from the client for ports
grouped with the primary port go to the same real server. For more information, see
“Tracking
primary ports” on page 44.
• TCP/UDP application groups (using the track group function) – Up to eight TCP/UDP ports are
grouped together. After the Brocade Virtual ADX sends a client request for any of the grouped
ports to a real server, subsequent requests from the client for ports in the group go to the
same real server. For more information, see
“Track port group function” on page 44.
NOTE
You must configure all the ports in a TCP/UDP application group to be “sticky”.
• Concurrent connections – The real server can open additional ("concurrent") TCP/UDP
sessions with the client using arbitrary TCP/UDP port numbers.
NOTE
Although the concurrent connections attribute is similar to application groups, application
groups apply to specific TCP/UDP ports that you configure on the virtual server. Concurrent
connections enable the real server to arbitrarily determine the TCP/UDP ports and assign them
to the client.