Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 230)

214 Brocade Virtual ADX Server Load Balancing Guide
53-1003247-01
Health check with content match
4
Scripted health check enhancement on real servers
When the port port-name command is configured with the content-check send option to send a
string to the server, the Brocade Virtual ADX establishes a TCP connection, and on receiving a
SYN-ACK, sends the configured string to the server. The device then waits for the server to send
ASCII text and then brings the server port up or down, based on the configured match-list policy.
In the following example, the Brocade Virtual ADX sends a SYN packet to server 10.10.1.31, port
1234. On receiving a SYN-ACK from the server, the Brocade Virtual ADX sends a TCP packet with
the data "how are you". The Brocade Virtual ADX then waits for the server. In the data of the TCP
packets sent by the server, the Brocade Virtual ADX will look for the pattern "good". If found, the
Brocade Virtual ADX marks the real server r1 port 1234 as UP; otherwise, it will mark the port as
DOWN.
Virtual ADX(config)#server real r1 10.10.1.31
Virtual ADX(config-rs-r1)#port 1234 keepalive
Virtual ADX(config-rs-r1)#port 1234 content-check m1
Virtual ADX(config-rs-r1)#port 1234 content-check send "how are you"
Virtual ADX(config-rs-r1)#exit
Virtual ADX(config)#http match-list m1
Virtual ADX(config-http-ml-m1)#up simple good
Virtual ADX(config-http-ml-m1)#default down
Syntax: [no] port port-name content-check match-list-name
Syntax: [no] port port-name content-check send "string"
NOTE
The l7-check command must be enabled in order for the Brocade Virtual ADX to send the script. If
the l4-check command is configured, the Brocade Virtual ADX will establish a TCP connection and
then send an RST.
Binary scripted health check
The scripted health check feature allows the Brocade Virtual ADX to complete 3-way TCP
handshake followed by sending an ASCII string and waiting for an appropriate response before
marking real server health. If the customer is running an application that can not interpret data in
ASCII format, this methodology will not help.
Binary scripted heath check allows the application switch to send binary data (carray format) after
doing a 3-way TCP handshake with the backend server. The Brocade Virtual ADX would then mark
the health of the server as pass or failed depending on the response content match (again in
carray format). This feature is implemented using the content-check-array option within the real
server port command as shown in the following sample configuration.
Virtual ADX(config)#server real rs1 10.1.1.1
Virtual ADX(config-rs-rs1)#port 1111 content-check-carray m1
Virtual ADX(config-rs-rs1)#port 1111 content-check-carray send “0xe1,0xe2,0xe3,
0xe4”
Virtual ADX(config-rs-rs1)#port 1111 keepalive
Virtual ADX(config)#http match-list m1
Virtual ADX(config-http-m1-m1)#default down
Virtual ADX(config-http-m1-m1)#up simple 0xca,0xcb,0xcd,0xce
Syntax: [no] port port-name content-check-carray match-list-name
The port-name variable defines the port where the binary scripted health check is performed.