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Re: comments on version 2 of protocol draft
On Wed, Mar 03, 2004 at 11:01:57AM -0800, Wes Hardaker wrote:
> Picking an example at random, the ipCidrRouteTable from SNMP contains
> the routing table (I actually wasn't even sure till I looked that it
> contained a suitable set of default values). There are defaults for
> ifIndex, route age, next hop as, and the 5 metrics... Thats roughly
> half the columns. How often have you needed to specify all 5 metrics
> when defining a new route. If you send every new route entry with all
> the parameters, I bet you'd find that you'd roughly double your data
> since many of those parameters to most frequently be the default. Go
> look at a real existing large routing table and do the math on it and
> let me know what you get numerically.
Despite the fact that we should not mix protocol issues with payload
issues, I think it is important to stress that the SMIv2 DEFVAL clause
has this nice wording which says that the specified value "may be used
at the discretion of an agent."
The consequence of this is that you cannot rely on the defaults and
thus you (a) specify all values when you create a row or (b) create
a row without specifying the defaults and you use a subsequent get
to see whether the defaults are what you expected to be, potentially
followed by an additional set operation...
[I think the real reason for DEFVALs in the SMIv2 is again this stupid
484 byte message size constraint for the holy default transport.]
/js
P.S. Shall we move this thread to the SNMPv3 list so that we can use
this list to do real work? ;-)
--
Juergen Schoenwaelder International University Bremen
<http://www.eecs.iu-bremen.de/> P.O. Box 750 561, 28725 Bremen, Germany
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