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20050519: LDM sequencing

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  • Subject: 20050519: LDM sequencing
  • Date: Thu, 19 May 2005 12:24:54 -0600
Michael,

>Date: Thu, 19 May 2005 12:53:41 -0500
>From: Michael McEniry <address@hidden>
>Organization: University of Utah
>To: Steve Emmerson <address@hidden>
>Subject: 20050519: LDM sequencing

The above message contained the following:

> > That's correct.  A downstream LDM will establish a connection to the
> > top-level, upstream, LDM server for an ISALIVE inquiry if the downstream
> > LDM hasn't received anything in one minute.  To prevent this, an
> > upstream LDM sends an empty packet to the downstream LDM every 30
> > seconds.
> 
> This is the NULLPROC message, right?

Correct.

> If the downstream 
> processes keep sending ISALIVE, does that mean that the 
> upstream processes aren't sending NULLPROC?

Well... it certainly means that the downstream LDM isn't receiving 
NULLPROC-s.  The upstream LDM should be sending them.

> Might it be version related?

No.  All versions of LDM-6 do this.

> They occasionally need to reconnect, but there are missing 
> products at other times. According to ntpdate -q, the system 
> clocks are off by 0.025 sec. Is that skew too large?

That amount should be OK.

Regards,
Steve Emmerson
LDM Developer