Subject: RE: DHCP Server MIB Comments (fwd)

From: "Ralph E. Droms" <[email-masked]>
Date: Wed, 13 Jan 1999 14:50:20 -0500 (EST)

message sent to [email-masked] by [email-masked] follows.
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> > i am going on what the agentx developers have recommended to
> me.  part of
> > the agentx protocol is to pass sysUpTime to the subagents.  all
> clocks are
> > supposed to be relative to the sysUpTime.  i will reconfirm with
> > one of the
> > agentx authors on this particular issue.
>
> That would be really cool.
>
> Personally, the use of sysUpTime doesn't allow me to keep historical
> information around, which is a little distressing.  Using sysUpTime as a
> root for all future times (IE: lease expiration) works, but using it for
> things that happened in the past (IE: when was this client heard
> from last)

sysUpTime is sufficient to keep historical information.  it works as
follows:  when the management platform retrieves an object that is based on
sysUpTime it looks at the current value of the sysUpTime object and at the
current clock on the management platform. subtract the sysUpTime from the
current clock to get the time when the agent started. add to that the value
of the object that is based on sysUpTime.  you now have a time that is no
longer relative.  so for example to get the absolute time of the object
dhcpClientLastResponse:

    current_time_on_mgmt_platform - sysUpTime + dhcpClientLastResponse

(time values may need to be normalized to all be in the same units)

> brings up the question of what to do when sysUpTime resets to 0.

i agree this could be a problem, however this is a general SNMP agent
problem.  i don't think that we should try to solve this.  there have been
many long discussions on the SNMPv3 list about this.

> -Ryan