Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 31)

Brocade Virtual ADX Server Load Balancing Guide 15
53-1003247-01
Overview
2
Application port groups
Application groups enhance the sticky connections method by allowing you to group up to four TCP
or UDP ports with another, “primary” TCP or UDP port. When the Brocade Virtual ADX sends a client
request for the primary port to a real server, requests from the same client for a port that is
grouped with the primary port also go to the same real server. The application group method, like
the sticky method, is governed by the sticky age.
The Brocade Virtual ADX automatically sends requests for the grouped ports to the same real
server as the “primary” port, as long as the sticky timer has not expired. You must define all the
ports in an application group individually in the VIP, and you must configure all of them to be sticky.
Concurrent connections
The concurrent connection option is similar to the sticky option. However, instead of supporting
sequential connections to the same server, the concurrent connection option supports both a
primary connection and secondary connections. The connections are supported at the same time.
The primary connection is the controlling connection and dictates the resource, such as a server, to
which subsequent or secondary connections are made.
When the controlling connection is established, the server dynamically assigns a TCP or UDP port
to which the client should open subsequent or secondary connections. Subsequent connections
from that client are accepted on the server as long as the controlling connection is still active.
Figure 2 shows an example of a concurrent connection. A client initiates a session request to an
application supported on servers S1, S2, and S3. When the SLB switch receives the request, the
switch forwards the request to server S2. This forms the primary connection. Then S2 dynamically
assigns a port, 10000, to the application and forwards it to the client.
FIGURE 2 Concurrent connections in operation on an SLB network
NOTE
The method the server uses to communicate the dynamic port to the client is application-specific.