Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 308)

292 Brocade Virtual ADX Server Load Balancing Guide
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Miscellaneous Layer 7 switching configurations
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clients that originally created the connections. When a client makes a request for content that is
served by a different server, the Brocade Virtual ADX closes the connection to the original server on
the server side before setting up a connection with the new server; however, the connection on the
client side can still be reused if keepalive mode is enabled on the client connections.
Default settings
By default, Brocade Virtual ADX comes enabled with HTTP 1.0 for any Layer 7 switching feature.
However, HTTP 1.0 connections are non-persistent, and therefore persistent connections or
keepalive connections are disabled by default. To support persistent connections, enable TCP
connection offload mode or keepalive mode on a virtual port. These modes are enabled at the
virtual server level.
Enabling the TCP offload mode
TCP offload mode allows a request from one connection on the client side to reuse any established
connection on the server side.
To enable persistent connection in TCP offload mode for the HTTP port on a virtual server named
"vserv1", enter the commands such as the following.
Virtual ADX(config)#server virtual-name-or-ip vserv1
Virtual ADX(config-vs-vserv1)#port http tcp-offload
Syntax: [no] port port tcp-offload [age minutes]
or
Syntax: [no] port port tcp-offload [transactions trans-num]
The age minutes variable specifies how many minutes a connection on the server side can be kept
alive. If it is not specified, by default, the keepalive time will be the same as the session age, which
can be defined globally by entering the server tcp-age minutes command or locally under the
virtual server level by entering the port port-num tcp-age minutes command.
The transactions trans-num variable specifies the maximum number of HTTP transactions that can
be completed on a connection on the server side.
If the age or transaction limit is reached, the connection on the server side is closed and a reset
packet will be sent to the server.
Graceful handling of HTTP pipelined requests
If HTTP is enabled, a client supporting persistent connection can use pipelining by allowing multiple
requests to be sent over the same connection without waiting for a response for each request. By
default, the Brocade Virtual ADX is able to handle HTTP pipelined requests. When it handles the
first of the pipelined requests, it holds the rest of pipelined requests. After the client receives the
response of the first request, the Brocade Virtual ADX handles the next pipelined request.
The Brocade Virtual ADX can be configured to handle the first request of a pipelined request
correctly and optionally send reset to the subsequent requests. This feature helps prevent
performance degradation. Reset can be enabled in keepalive mode or TCP offload mode.