Proxy Cache Connect Timeout and Parent Failover

The Netra Proxy Cache Server supports parent failover, in which, if the server's parent fails, the server switches to the next parent on its list. (See "Proxy Cascade" for a description of the table of parent and sibling proxies.) Failover occurs if the Netra Proxy Cache Server's TCP connect call fails, not if the proxy cache service's connect timeout (2 minutes, by default) is exceeded. (See "Timeouts" for a description of the Timeout for Server Connections property.)

A TCP connect call might fail because the operating system's timeout (3 minutes, by default) is exceeded or from some other cause. If the proxy cache service's timeout is shorter than the operating system's (as is true for the default case), the connect attempt is terminated before an error is returned, with the result that parent failover does not occur.

If your server experiences frequent connection timeouts when attempting to connect to a parent, you can set the proxy cache service's connect timeout to be at least 10 seconds greater than the operating system's TCP connect timeout. Alternatively, (if you have a serial connection to your server) you can reduce the operating system's timeout. To change the operating system's timeout, use the ndd command, which takes arguments in milliseconds. For example:

# ndd -set /dev/tcp tcp_ip_abort_cinterval 30000

The preceding command sets the TCP connect timeout to 30 seconds. To view the current TCP connect timeout, enter:

# ndd /dev/tcp tcp_ip_abort_cinterval