Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 138)

122 Brocade Virtual ADX Server Load Balancing Guide
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Miscellaneous options
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Virtual ADX(config)#server virtual-name-or-ip v1
Virtual ADX(config-vs-v1)#port snmp udp-age 26
Syntax: [no] port port udp-age minutes
You can set the TCP or UDP age from 2 through 60 minutes. The default TCP age is 30 minutes. The
default UDP age is five minutes.
More specific settings override more general settings; that is, a TCP or UDP age setting for the HTTP
port will override a TCP or UDP age setting for the virtual server, which will override the global TCP
or UDP age (set with the server tcp-age or server udp-age commands).
Configuring session aging behavior
In stateful (default) mode, sessions are created when traffic flows through the Brocade Virtual ADX.
Two sessions are created for each flow: “forward” session (In Layer4 SLB, Client to VIP), and
“reverse” session (In Layer4 SLB, Real-Server to Client). These two sessions are tied together. Each
session has an associated time after which the session is marked for removal. The session age is
refreshed each time there is a new packet on the flow. The default mechanism to delete sessions is
when both forward and reverse sessions reach their age limit.
You can use the following commands to change the default session aging behavior.
To age out forward and reverse sessions independently use the following command,
Virtual ADX(config)#server one-way-session-age
Syntax: server one-way-session-age
If one session ages out, delete that session but do not delete the other session.
To delete both sessions when any of the sessions ages out use the following command.
Virtual ADX(config)#two-way-session-age-on-one-age
Syntax: server two-way-session-age-on-one-age
Configuring DNS CPU-based throttling
DNS request processing time can become very slow when CPU utilization is at a high level (90 -
95%). With this feature you can direct a Brocade Virtual ADX to reject new DNS requests when CPU
utilization goes beyond a configured threshold.
You can set DNS CPU-based throttling as shown.
Virtual ADX(config)#server throttle-on-overload 40
Syntax: [no] server throttle-on-overload cpu-percentage
The cpu-percentage variable specifies the threshold of CPU utilization when the Brocade Virtual
ADX will reject new DNS requests.
Limitation
This feature is applicable for UDP DNS only.