Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 177)

Brocade Virtual ADX Server Load Balancing Guide 161
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Layer 4 health checks
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Modifying the ping interval and ping retries
The Brocade Virtual ADX automatically uses a Layer 3 health check, consisting of ICMP echo
requests (pings), to check the health of a real server. Ping is enabled by default. However, you can
modify the ping interval and the number of retries.
To modify the ping interval, enter the following command.
Virtual ADX(config)#server ping-interval 8
Syntax: [no] server ping-interval value
The value variable can be a value from 1 through 10 seconds. The default is 2 seconds.
To modify the number of times the Brocade Virtual ADX will ping a real server before changing the
server state to FAILED, enter the following command.
Virtual ADX(config)#server ping-retries 7
Syntax: [no] server ping-retries value
The value variable can be a value from 2 through 10. The default retry value is 4.
Setting the Periodic ARP Interval
You can configure the periodic ARP interval.The default interval for periodic ARPs is 20 seconds. To
configure the periodic ARP interval, use the following command.
Virtual ADX(config)#server periodic-arp-interval 14400
Syntax: server periodic-arp-interval seconds
The seconds variable specifies the ARP interval. Enter an integer from 10 to 14400.
Layer 4 health checks
When you bind a real server to a virtual server, the Brocade Virtual ADX performs either a Layer 4
TCP health check, a Layer 4 UDP health check, or a Layer 7 health check to bring up the application
port that binds the real and virtual servers. If the application port is not one of the applications that
is known to the Brocade Virtual ADX, the Brocade Virtual ADX uses a Layer 4 health check.
Otherwise, the Brocade Virtual ADX uses the Layer 7 health check for the known application type.
The Layer 4 health check can be a TCP check or a UDP check:
• TCP health check – The Brocade Virtual ADX checks the TCP port’s health based on a TCP
three-way handshake:
- The Brocade Virtual ADX sends a TCP SYN packet to the port on the real server.
- The Brocade Virtual ADX expects the real server to respond with a SYN ACK.
- If the Brocade Virtual ADX receives the SYN ACK, the Brocade Virtual ADX sends a TCP
RESET, satisfied that the TCP port is alive.