Brocade Virtual ADX Server Load Balancing Guide (Supporting ADX v03.1.00) - Manual (Page 189)

Brocade Virtual ADX Server Load Balancing Guide 173
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Layer 7 health checks
4
NNTP
The Brocade Virtual ADX waits for a message from the NNTP server:
• If the server sends a greeting message with status code 200 or 201, the Brocade Virtual ADX
sends a Quit command to the NNTP port on the real server, then resets the connection by
sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE.
• If the server does not send a greeting message with status code 200 or 201, the Brocade
Virtual ADX retries the health check up to the number of times configured (the default is two
retries). If the server still does not send the expected message, the Brocade Virtual ADX marks
the server port FAILED and removes the server from the load-balancing rotation for NNTP
service.
Performed:
• Immediately following a successful Layer 4 TCP health check
• At regular intervals, if keepalive is enabled for the port
PNM
The Brocade Virtual ADX sends a PNM file request that does not have a file name:
• If the server sends a reply containing the value "PNA", the Brocade Virtual ADX marks the port
ACTIVE.
• If the server does not send a reply containing the value "PNA", the Brocade Virtual ADX retries
the health check up to the number of times configured (the default is two retries). If the server
still does not send the expected message, the Brocade Virtual ADX marks the server port
FAILED and removes the server from the load-balancing rotation for PNM service.
Performed:
• Immediately following a successful Layer 4 TCP health check
• At regular intervals, if keepalive is enabled for the port
POP3
The Brocade Virtual ADX waits for a message from the POP3 server:
• If the server sends a greeting message that starts with “+ OK”, the Brocade Virtual ADX sends
a Quit command to the POP3 port on the real server, then resets the connection by sending a
quit and a RESET, one immediately after the other, and marks the port ACTIVE
• If the server does not send a greeting message that starts with “+ OK”, the Brocade Virtual
ADX retries the health check up to the number of times configured (the default is two retries). If
the server still does not send the expected message, the Brocade Virtual ADX marks the server
port FAILED and removes the server from the load-balancing rotation for POP3 service.
Performed:
• Immediately following a successful Layer 4 TCP health check
• At regular intervals, if keepalive is enabled for the port