Cisco catalyst 6500 series Configuration Note page 123

Chapter 10 Configuring CSM Scripts
Table 10-5 Member list for the csm_env Array
Member name
realIP
realPort
intervalTimeout
openTimeout
recvTimeout
failedTimeout
retries
healthStatus
You can use the new probe probe-name script command for creating a script probe in Cisco IOS. This
command enters a probe submode that is similar to the existing CSM health probe submodes (such as
HTTP, TCP, DNS, SMTP, etc.). The probe script submode contains the existing probe submode
commands failed, interval, open, receive, and retries.
A new script script-name command was added to the probe script submode. This command can process
up to five arguments that are passed to the script when it is run as part of the health probe function.
You can also use the corresponding show module csm slot probe script name probe-name code
command. Refer to the Catalyst 6500 Series Content Switching Module Command Reference for release
3.2(1).
System Resource Usage
The Vxworks support application has 255 file descriptors that are divided across all applications, for
example, standard input and output, and any socket connections (to or from). When developing
standalone scripts, you must be extremely careful when opening a socket. We recommend that you close
a socket as soon as the operation is complete because you may run out of resources. The health
monitoring module controls the number of open sockets by way of controlling the number of actively
running scripts. Standalone scripts do not have this control.
Memory, although a consideration, is not a big limiting factor because the module generally has enough
memory available. Each script uses a 128 KB stack, and the rest of the memory is allocated at runtime
by the script.
The script tasks are given the lowest priority in the system so that the real-time characteristics of the
system remain more or less the same while executing scripts. Unfortunately, scripts having low priority
also means that if the system is busy doing non-TCL operations, all TCL threads may take longer to
complete. This situation may lead to some health scripts being terminated and the unfinished threads
marked failed. To prevent scripts being failed, all script probes should have a retry value of 2 or more.
You may want to use native CSM probes (for example, HTTP, DNS, etc.) whenever possible. The
scripted health probes should be used to support non-supported applications. The purpose is to provide
features, not speed.
TCL supports both synchronous and asynchronous socket commands. Asynchronous socket commands
return immediately without waiting for true connections. The internal implementation of the
asynchronous script version involves a much more complicated code path with many more system calls
per each such command. This condition generally slows down the system by causing some critical
OL-4612-01
Content
Suspect IP address
Suspect IP port
Configured probe interval in seconds
Configured socket open timeout for this probe
Configured socket receive timeout for this probe
Configure failed timeout
Configured retry count
Current suspect health status
Catalyst 6500 Series Content Switching Module Configuration Note
Configuring TCL Scripts
10-7