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Enabling fast aging for udp sessions – Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) User Manual

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Brocade Virtual ADX Server Load Balancing Guide

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Miscellaneous options

2

Allow "TCP only" or "UDP only" port definitions under virtual server

Allow similar definitions under real server also

On a Brocade Virtual ADX, when a port is defined under VIP, both UDP and TCP traffic with the port
number are enabled and passed through to the real server. This scenario is not desirable in some
cases.

As an enhancement, the user is allowed to define a TCP-only or UDP-only port so that only TCP or
UDP traffic with the specified port number can pass through. TCP-only or UDP-only traffic control
has been supported internally on a Brocade Virtual ADX, but no CLI is available for the user to
enable it.

As the enhancement, the following commands allow the user to enable or disable TCP-only or
UDP-only traffic control for a port defined under VIP.

Syntax: [no] port port tcp-only | udp-only

The command is available under VIP configuration mode.

When either TCP-only or UDP-only is configured, only TCP traffic or UDP traffic can pass through as
configured; otherwise both TCP traffic and UDP traffic can pass through. TCP-only and UDP-only are
exclusive, which means when TCP-only is configured, TCP-only and UDP-only cannot be configured
for a particular port at the same time. UDP-only will be automatically disabled if TCP-only is
configured, and vice versa.

Enabling fast aging for UDP sessions

When fast aging for UDP sessions is configured, a client request causes the Brocade Virtual ADX to
add an entry to its session table; when a response is detected, the Brocade Virtual ADX
immediately deletes the session table entry.

NOTE

Fast aging is the default behavior for the well-known DNS and RADIUS ports. To change DNS or
RADIUS to use the UDP age timer instead, refer to

“Setting TCP and UDP ages for VIPs”

on page 121.

When this feature is configured, if the Brocade Virtual ADX detects a server response to a client
request, and the response is not fragmented, the session table entry is deleted immediately. If the
response is fragmented, the Brocade Virtual ADX waits for the last fragment to arrive, forwards it to
the client, and then sends the session to the delete queue. By default, the session stays in the
delete queue for 8 seconds before being deleted. You can change the amount of time the session
stays in the delete queue to between 1 and 40 seconds.

To activate fast aging for UDP sessions for port 1234, enter commands such as the following.

Virtual ADX(config)#server virtual-name-or-ip vs1 192.168.1.2

Virtual ADX(config-vs-vs1)#port 1234 udp-fast-age

Syntax: port UDP-portnum udp-fast-age

To set the amount of time sessions for ports configured with the udp-fast-age command stay in the
delete queue before being deleted, enter the following command.

Virtual ADX(config)#server msl 2

Syntax: server msl secs

The secs variable can be from 1 to 40 seconds.