Re: queries to only one table

On 15 February 2011 09:32, Egor <[email protected]> wrote:
> when I use snmpwalk <params> myMibModule::FirstTable, it's returned values
> from FirstTable, but it makes another queries to SecondTable.

Just to clarify - does the command display anything from the SecondTable?
Or is the output as expected?


If the output is correct, but your concern is that the agent receives a final
request for the first entry in the SecondTable (which is then discarded),
then that is perfectly normal.   It's inherent in the way that walking an
SNMP table works.

To understand what, you need to remember that snmpwalk is simply a
wrapper round a sequence of GETNEXT requests, and that these will
move seamlessly from once column to the next, and from one table to
the next.   The GETNEXT request has no concept of the "context" of
the request - it's asked to get the next value that the agent knows about,
so that's what it does.

Remember also that the 'snmpwalk' command doesn't know what the
next result will be.   So it doesn't know when it's received the last value
in the table.   The only way that it knows when it reaches the end of
the table is by asked for "the next value", and gets an answer that it's
not interested in.   It discards that answer and stops.
   That's what you are probably seeing here.



Of course, if snmpwalk *is* displaying results from the second table,
then that's a more serious problem.   But simply sending "one extra"
request is perfectly normal.

Dave

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