SNMP MIB: revision for last update is missing

Question

What does smilint mean when it complains about a specific line in a MIB file saying that: "revision for last update is missing"?

Answer 1

When defining an SNMP MIB, in the "MODULE-IDENTITY" section, there are four fields that should be present no matter what:

1. LAST-UPDATED
2. ORGANIZATION
3. CONTACT-INFO
4. DESCRIPTION

In addition to those, there must be at least one "revision" listed; a revision has a time stamp (the "REVISION") and a description (the "DESCRIPTION"). Each time the MIB is updated, the maintainer should add a new revision. Thus, there can be many "REVISION" and "DESCRIPTION" entries for a MIB.

Now, the value of "LAST-UPDATED" should match some revision of the MIB (hopefully the most recent one). If there is no matching "REVISION" for "LAST-UPDATED", then you will receive that error.

It is frequently the case that people mistake the "LAST-UPDATED" field for the time stamp at which the MIB was last modified; instead, it is kind of like a pointer to the most recent "REVISION" entry that has been added to the "MODULE-IDENTITY". It happens; it's safe to ignore. If it bothers you, then you can tweak the MIB file in question to have the "LAST-UPDATED" field have the same value of the latest "REVISION" listed.