Hi -
On Tue, Oct 29, 2019 at 10:53:49AM +0100, Martin Bjorklund wrote:
Randy Presuhn <[email protected]> wrote:
Hi -
On 10/28/2019 2:22 AM, Martin Bjorklund wrote:
....
No, in many SMIv2 objects, a zero-length value is used for optional
nodes (due to the way the protocol (SNMP) works).
This comes as a complete surprise to me. References?
I don't have any references at hand, so let me re-phrase:
No, in many SMIv2 objects, a zero-length value is used for optional
nodes.
(where "optional" means optional to set, not optional to implement)
No, for set operations DEFVAL in SMIv2 governs "missing" objects.
(RFC 1442 7.9 or any of its successors.)
The decision to define sentinel values is entirely up to the MIB
designer. Zero-length
string is a possible choice only for stuff built with OCTET STRING as
the underlying
type. But it's still a value, and in no way makes something "optional."
*Any* object/instance might appear to be "missing" for retrieval due to
the operation of
VACM or its proprietary predecessors. It's been that way since, like,
forever.
See for example RFC 1157 section 4.1.2 to get an idea how ancient this is.
Randy
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