Re: [ldm-users] [noaaport] Thorns amongst the roses...

• To: Gilbert Sebenste <sebenste@xxxxxxxxxxxxxxxxxxxxx>
• Subject: Re: [ldm-users] [noaaport] Thorns amongst the roses...
• From: Daniel Forrest <dan.forrest@xxxxxxxxxxxxx>
• Date: Thu, 21 Aug 2014 08:59:10 -0500

Gilbert,

> OK, everything is good with the new NOAAport, right? C/N of 18. Signal
> strength: 76. VBER: 0. Yay! But wait...
> 
> I am seeing a ton of these in our ldmd.log:
> 
> Aug 21 13:00:32 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13452198 to 13452266 [skipped 67]
> Aug 21 13:00:32 bird01 noaaportIngester[24645] WARN: Retrograde packet
> number: previous=13452270, latest=13452230, difference=4294967336
> Aug 21 13:00:32 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13452230 to 13452232 [skipped 1]
> Aug 21 13:00:32 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13452232 to 13452245 [skipped 12]
> Aug 21 13:00:43 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13452515 to 13452524 [skipped 8]
> Aug 21 13:00:43 bird01 noaaportIngester[24645] ERROR: Missing GOES fragment
> in sequence, last 37/86751 this 46/86751
> Aug 21 13:00:43 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13452524 to 13452598 [skipped 73]
> Aug 21 13:00:43 bird01 noaaportIngester[24645] WARN: Retrograde packet
> number: previous=13452598, latest=13452540, difference=4294967354
> Aug 21 13:01:07 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13453270 to 13453274 [skipped 3]
> Aug 21 13:01:07 bird01 noaaportIngester[24645] ERROR: Missing GOES fragment
> in sequence, last 115/86753 this 119/86753
> Aug 21 13:01:07 bird01 noaaportIngester[24645] WARN: Gap in packet sequence:
> 13453279 to 13453283 [skipped 3]
> 
> Is anyone else seeing this?

I recently had a similar problem using the GOES-R simulator.

Just a guess, but if the data is coming in via UDP and the data rate is
higher than it was before then it may be a case of too little kernel
buffer space.  You can try this (assuming this is Linux):

cat /proc/sys/net/core/rmem_max
cat /proc/sys/net/core/wmem_max
cat /proc/sys/net/core/rmem_default
cat /proc/sys/net/core/wmem_default

Save these values, if this doesn't help you can reset them.

echo 16777216 >/proc/sys/net/core/rmem_max
echo 16777216 >/proc/sys/net/core/wmem_max
echo 16777216 >/proc/sys/net/core/rmem_default
echo 16777216 >/proc/sys/net/core/wmem_default

And restart LDM.

If this works you can add these values to /etc/sysctl.conf.

-- 
Dan

• Follow-Ups:
  • Re: [ldm-users] [noaaport] Thorns amongst the roses...
    • From: Gilbert Sebenste
  • Re: [ldm-users] [noaaport] Thorns amongst the roses...
    • From: wxprofessor
  • Re: [ldm-users] [noaaport] Thorns amongst the roses...
    • From: Gerry Creager - NOAA Affiliate

• References:
  • [ldm-users] Thorns amongst the roses...
    • From: Gilbert Sebenste