[mrtg] Re: RouterUptime

Christopher E. Brown cbrown at denalics.net
Wed Nov 24 14:36:52 MET 1999

On Wed, 24 Nov 1999, Tim Kennedy wrote:

> On Wed, 24 Nov 1999, Christopher E. Brown wrote:
> > 	Yes, it does.  However, the label is RouterUptime, *not*
> > RouterSNMPUptime.
> > 	If one is measuring the SNMP system, or using a SNMP
> > monitoring agent reporting SNMP subsystem uptime is a good thing.
> > However, reporting SNMP uptime as RouterUptime is not.
> > 	Reporting one as the other simply because on many systems they
> > are always the same is silly.
> You seem to be correct.  This is from rfc1213-mib.txt
>           sysUpTime OBJECT-TYPE
>               SYNTAX  TimeTicks
>               ACCESS  read-only
>               STATUS  mandatory
>               DESCRIPTION
>                       "The time (in hundredths of a second) since the
>                       network management portion of the system was last
>                       re-initialized."
>               ::= { system 3 }
> Therefore the definition of system.sysUptime is, in fact the network
> managaement susbsystem uptime, and not the host system total power on
> uptime, and should not be represented as such.

	Exactly, if the reported item was SNMPUptime or such it would
be a non issue, however the internal label is RouterUptime, and it is
reported as to suggest it is total system uptime.

	Given the label (RouterUptime), and the original use of the
software it was never an issue.  After all, since when will the snmp
uptime be different than system uptime on say a Cisco 3640?

	Also (IIRC) many network devices (routers/switches/etc) only
report sysUpTime, no reason to report host uptime if it cannot differ.

As folks might have suspected, not much survives except roaches, 
and they don't carry large enough packets fast enough...
        --About the Internet and nuclear war.

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