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RE: [Syslog-sec] SNMP parameters in syslog message - sequenceId



Hi,

I'm going to disagree that this should start at and rollover to 1
"because that's the way SNMP does it". 
The RFC2578 SMIv2 recommendation of starting at 1 rather than 0 is for
enumerations, not message identifiers.

The SNMP request-id does not start at 1, and roll over to 1.
>From RFC3416:
  PDU ::= SEQUENCE {
           request-id INTEGER (-214783648..214783647),

[the range used is due to the fact that the ASN.1 INTEGER type is a
32-bit signed value, not unsigned. If syslog uses unsigned encoding,
the 0..4294967295 range is fine.]

David Harrington
dbharrington@comcast.net
co-chair IETF SNMPv3 WG, concluded


> -----Original Message-----
> From: syslog-sec-bounces@www.employees.org 
> [mailto:syslog-sec-bounces@www.employees.org] On Behalf Of 
> Rainer Gerhards
> Sent: Thursday, April 14, 2005 11:27 AM
> To: syslog-sec@employees.org
> Subject: RE: [Syslog-sec] SNMP parameters in syslog message - 
> sequenceId
> 
> Tom,
> 
> thanks for the reply and the text suggestion. Changed it according
to
> your suggested text which exactly described what I wanted to 
> suggest ;)
> As a thanks, I've also change the ID to "sequenceId" - if others
> complain, I can change it back. I've now reserved 0 for special
cases,
> which means the rollover is also to 1 and not to 0.
> 
> The text now reads as follows:
> 
> ####
> 7.3.1  sequenceId
> 
>    The "sequenceId" parameter allows to track the sequence in 
> which the
>    sender sent the messages.  It is an integer that MUST be set to 1
>    when the syslog function is started	and MUST be 
> increased with every
>    message up to a maximum value of 4,294,967,295.  If that value is
>    reached, the next message must be sent with a sequenceId of 1.
> ####
> 
> Rainer 
> 
> > -----Original Message-----
> > From: Tom Petch [mailto:nwnetworks@dial.pipex.com] 
> > Sent: Monday, April 11, 2005 10:15 PM
> > To: Rainer Gerhards; syslog
> > Subject: Re: [Syslog-sec] SNMP parameters in syslog message - 
> > sequenceId
> > 
> > <inline>
> > Tom Petch
> > 
> > ----- Original Message -----
> > From: "Rainer Gerhards" <rgerhards@hq.adiscon.com>
> > To: <syslog-sec@employees.org>
> > Sent: Friday, April 08, 2005 11:24 AM
> > Subject: [Syslog-sec] SNMP parameters in syslog message 
> > (renamed subject)
> > 
> > 
> > <snip>
> > 7.3.1  sequenceID
> > 
> >    The "sequenceID" parameter allows to track the sequence in 
> > which the
> >    sender sent the messages.  It is an integer that MUST be 
> reset to 0
> >    at reboot and MUST be monotnically incremented with each
message
> >    sent.  Its maximum value is 4,294,967,295.  If that value 
> > is reached,
> >    the next message must be emited with a sequenceID of 0.
> > 
> > Uh huh. Everywhere, I look monotonic has the same, 
> > well-defined meaning which is
> > that the value only changes in one direction.  So
> > 99 77 23 5 5 5 3 3 1 -1
> > is a monotonic sequence as is
> > 1 1 1 2 2 3 3 3 5 7 68 79 123
> > To quote Merriam-Webster,
> > " having the property either of never increasing or of never 
> > decreasing as the
> > values of the independent variable or the subscripts of the 
> > terms increase
> > <monotonic functions> <a monotonic sequence>"
> > 
> > Some words change their meaning as they travel around the 
> > world but I do not
> > think this is one of them:-)
> > 
> > If you want each value to be greater than (not greater than 
> > or equal to) the
> > previous one, then I
> > think you want 'strictly increasing' but I would suggest instead
> > 'It is an integer that MUST be set to 0 when the syslog 
> > function is started and
> > MUST be increased with every message up to a maximum value of 
> > 4,294,967,295.  If
> > that value is reached, the next message must be sent with a 
> > sequenceID of 0.'
> > 
> > But I also question the use of zero; zero is special, best 
> > avoided unless really
> > wanted (as in SNMP index values and enumerations) so I 
> > suggest starting at one.
> > 
> > And I would prefer sequenceId to sequenceID (perhaps because 
> > I use so much
> > Snmp:-)
> > 
> > 
> > 
> > 
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> 


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