Subject: Re: Inactive EP detection (was Re: [Pana] PAA-2-EP protocol requirements)

From: [email-masked]
Date: Tue, 2 Dec 2003 14:12:12 -0800

Assume that:

- PAA performs SNMP-based polling to detect inactive EPs at every 60
seconds.
   Say the last polling occured at time T.

- Some EP rebooted after T.  The reboot procedure completes before T+60.

- At the next polling time, PAA will receives response from the rebooted
EP.
  Unless there is some reboot detection mechanism, PAA will not realize
that
  the EP has been rebooted, and as a result states will not be synchronized
between EP and PAA.

I thought that PAA should get reboot counter from EP and check it in
polling procedure, and
this could be used for both inactive peer detection and reboot detection
mechanisms.
I've checked RFC3411 and there is snmpEngineBoot MIB that can be used as
the reboot counter.

On the other hand, it is also possible that EP can send SNMP trap to notify
PAA after rebooting.
This could be used for reboot detection mechanism (in passive manner) but
not for inactive peer
detection mechanism.

Yoshihiro Ohba

   hi Yoshi:

   [email-masked] a écrit:
   >    > a) Inactive peer detection:
   >    > The protocol used between PAA and EP should be able to detect
   inactive
   >    > peer within an appropriate time period. This can be achieved by
   having
   >    > both the EP and remote PAA constantly verify their connection to
   each
   >    > other via keep-alive messages: a heartbeat in fact.
   >
   >    I'm not sure how much "explicit support" we need for this from the
   >    PAA2EP
   >    protocol. There can always be ad-hoc solutions to this. For
   example,
   >    running
   >    some request-reply messages between the PAA and EP can be used as a
   >    keep-alive. I can imagine an implementation resorting to such
   techniques
   >    when the protocol does not have a dedicated facility....
   >
   >
   > Yes, some SMNP implementation can support small value (order of
   seconds)
   > for
   > miminum polling inverval.  This would be sufficient for inactive peer
   > detection, but
   > not sufficient for detecting _rebooted_ peer when rebooting can
   complete
   > within
   > SNMP polling interval. Rebooting detection is needed when EP store
   > PaC information (including accounting information) in volatile memory.
   >
   > So we might need to define some rebooting counters in SNMP MIB in
   order to
   > detect
   > rebooting peers, or if such a MIB already exists we might just specify
   the
   > use of
   > the MIB for both inactive/rebooted peer detection.

   I'm not sure to rightly understand what you mean here, please can you
   elaborate ?

   thanks in advance,
   Yacine

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