Subject: Re: [netmod] Y45 again

From: Randy Presuhn <[email-masked]>
Date: Thu, 2 Apr 2015 12:27:51 -0700 (GMT-07:00)

Hi -

>From: Martin Bjorklund <[email-masked]>
>Sent: Apr 2, 2015 12:00 PM
>To: [email-masked]
>Cc: [email-masked]
>Subject: Re: [netmod] Y45 again
...
>> >Right.  But it also means that a SNMP manager has no idea what values
>> >an SNMP agent supports for a particular instance of a particular object
>> >(well it has *some* idea).  The only reason we are having such
>> >problems with Y45 is that we have created a requirement on ourselves
>> >that a client should be able to determine what the server supports
>> >from what it advertises.
>> 
>> I think there's a little more to it than that.
>> The transaction model also makes not knowing exactly
>> what configuration a given instance is capable
>> of supporting a much bigger deal in the Netconf world
>> than it is in the SNMP world.
>
>Can you elaborate?

SNMP does configuration in little spurts.  With each PDU,
one knows whether the change was accepted or not, and
recovery strategies have to be formulated at a microscopic
level. 

With Netconf, the good thing is that you can deliver an entire
configuration for validation.  That's the bad thing, too.
If parts of the managed resource are constrained in ways
beyond what is explicit in the model (we can think of
the presences of some less-capable versions as being an
example of that) and we can't find out about that limitation
until a new configuration is validated, we will have invested
a lot more effort before we learn that we have to fall
back on "plan B".  One would hope that easy-to-implement
microscopic recovery strategies would be possible, but
I suspect that watching them in action on the wire would
be pretty ugly.

Randy