[Freeipmi-devel] FreeIPMI Session Management

[Anand Babu]

Keeping the session open all the time:
-------------------------------------
Why we needed this?
A way to determine if the BMC is still accessible via IPMI.

Not the right approach. Session defined by IPMI is a logical
connection. Actual transport still happens over rmcp/udp/ip in
datagram mode.

Even if you keep the session open, you will still have to send packets
in connection less mode. When you don't get response you get to know
that system is knocked out.

IPMI session requires every ~< 1 min keep alive call.
Keep alive call is nothing but re-activating the session using same
activate session call. 

Also session is a costly resource for BMC. Only 4 sessions are
allowed. Implementor may choose to support only 1 session at a given
time and still be compliant with IPMI spec.

Thats why I did not implement session_keep_alive(...) higher level
call on top of activate session. Instead a better approach is
to use the ipmi_ping call (higher level call in ipmi-wrapper.c)
to determine if the system is still accessable.
You can call ipmi_ping at regular cycles and keep an active list of
systems in a list.

And sessions are short-lived. 
  open_session (...)
  chassis_ctrl (...)
  close_session (...)
(Note: you can find these higher level calls in ipmi-wrapper.c)

Al, Jim comments?

-- 
Anand Babu
CaliforniaDigital.com
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