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RE: BCP and Notifications (was: snmpconf FW: MIBs for events andnotification logging)


Please note that getting a response back from an Inform does not
reliably confirm that a management application has "gotten" the
notification. There can be different implementation strategies
of how a notification receiver is implemented and how it is
connected to management applications and feeds them a stream
of notifications. Many commercial products are designed so
that a notification system is a system service that distributes
notications to clients (which are the management applications
running on the system, or even on another system).

To have "reliability", the generating system MUST log each
notification, and MUST NOT remove the log entry when it gets
back a Response (the confirmation) to an Inform. it MUST also
have the mechanism so that a receiver can determine if it
has has not received notifications, and log entries of those
notifications have been discarded from the log due to
system events such log resource limitations, or system restart
(when the log is not stored in persistent storage), etc.

On Fri, 2 Nov 2001, Randy Presuhn wrote:
> Hi -
> > Message-ID: <2413FED0DFE6D111B3F90008C7FA61FB0DDC27FF@nl0006exch002u.nl.lucent.com>
> > From: "Wijnen, Bert (Bert)" <bwijnen@lucent.com>
> > Subject: RE: BCP and Notifications (was: snmpconf FW: MIBs for events and 
> > 	notification logging)
> > Date: Fri, 2 Nov 2001 13:43:42 +0100 
> ...
> > I think the possibly more important thing to focus on is that the
> > sender of an INFORM mots probably gets a response when the 
> > notification has arrived at the destination. If not, then
> > it can decide to retry a few times, and finally it can decide
> > to save the information for anothe retrt later or for
> > a manager to pickup later.
> ...
> This makes it possible to construct what in CMIP-land is
> called a disseminator.  Think of it as a log in which
> entries persist only until their delivery to their final
> destination has been confirmed.  It really DOES give
> reliable notification, even across reboots, if one needs
> such a thing.
It's been a few years since I've read this, but if you
are saying that entries are not inserted in the log
when a notification is confirmed, then I'm not sure if
this is reliable. I'd have to look at what CMIP required
before a notification was confirmed. And if implementations
are a notification service that distributes notifications
to clients without itself first logging them, before
sending a confirmation then it is not reliable.

One subtle difference between CMIP and SNMP is that
responses for Informs in SNMP MUST be sent in a very
short time or the notification generator will resend the
Inform. This changes the implementation strategy of
the receiver.

>  Randy Presuhn          BMC Software, Inc.  1-3141

/david t. perkins