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Re: manager subscription model for notifications: usage survey
Excellent description of the problems with the current SNMPv3
notification distribution system, and why a change would
increase interoperability and usability!
On Mon, 1 May 2006, Juergen Schoenwaelder wrote:
> On Mon, May 01, 2006 at 08:23:33PM +0300, Romascanu, Dan (Dan) wrote:
> > Is it really much more complex to implement than the SNMP-TARGET-MIB and
> > SNMP-NOTIFICATION-MIB?
> You are right that the SNMP-TARGET-MIB and SNMP-NOTIFICATION-MIB
> basically allow subscriptions (and they are pretty complicated to use
> with all the features that went in). These MIBs, however, have two
> problems that are important if you want to use them:
> a) Notification targets can't be bound to a "session" nor are there any
> timers which cause targets to expire if the timer is not refreshed.
> Hence, garbage collection of dead dynamic subscriptions is a mess.
> This is an engineering problem which could be fixed easily by
> adding the missing capability to the standards.
> b) Most default installations are simply read-only and it typically
> requires to use the CLI to add a subscription. Given the lack of
> standards in this space, you can't really write interoperable code
> that actually works in operational networks. This is mainly a
> deployment problem and could be solved by agreeing on common access
> control setups that actually allow more useful work to happen (but
> again will take a long time to become effective).
> By introducing a subscription mechanism which uses additional protocol
> verbs rather than a writable data model, you kind of automatically
> make it much more likely that neither a) nor b) becomes a problem.
> Subscription operations make management applications that like to
> subscribe to notifications easier to write and I believe this is a
> feature and not a bug.
/david t. perkins
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