Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 169)

Brocade Virtual ADX Server Load Balancing Guide 153
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Chapter
3
Stateless Server Load Balancing
Overview
This chapter describes server load balancing configuration options that are “stateless.” Stateless
SLB does not use session table entries for the TCP or UDP sessions between the Brocade Virtual
ADX and clients or real servers.
These configuration options are useful if you want to deploy multiple Brocade Virtual ADX devices
to provide service for the same VIPs or applications, but the network topology cannot ensure that
server responses will pass back through the Brocade Virtual ADX.
NOTE
The Direct Server Return (DSR) feature allows you to deploy a single Brocade Virtual ADX in a
network where the server responses do not pass back through the Brocade Virtual ADX. Compare
the configuration example for Direct Server Return with the examples in this chapter to determine
which type of configuration is applicable to your network. Refer to
“Configuring Direct Server Return”
on page 57.
NOTE
The Brocade Virtual ADX does not support Stateless SLB with aliased ports, such as shown in the
following configuration:
server virtual-name-or-ip v3 10.176.7.23
port dns
port dns stateless
bind dns rs1 7777 real-port dns
Stateless TCP and UDP ports
You can configure a TCP application port to be stateless. When an application port is stateless, the
Brocade Virtual ADX does not create session table entries for the port. Configuring an application
port to be stateless results in the following benefits:
• The server responses for the application can use alternate paths back to the client. For
example, the Brocade Virtual ADX and real servers can be connected through a network that
provides multiple return paths to the client. Because the port is stateless, the Brocade Virtual
ADX does not assume that the application is unhealthy if the server’s response does not flow
back through the Brocade Virtual ADX.
• The Brocade Virtual ADX has more session resources available for application ports that need
them.