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Warning: TRAFFIC_HUB_MODEM_CRC

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Gomes Member ★★ Offline Posts: 12 Bangladesh	Oct 28^th, 2007 at 8:25am Since last few days I'm getting WARNING on my ULC "Line card�s traffic CRC xxx above high limit of 10 within 15 seconds" Can anyone tell me how to resolve this ?
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Reply #1 - Oct 28^th, 2007 at 1:11pm

1. How many line cards are you running in that network?

2. Are they configured for Carrier groom or Freq hop?

3. If you have more than one HLC in your network are any of your other HLCs in warning? �

If not, you need to put a specan on the MHz that is configed into the line card and run a minimum trace against it and look for energy under the TDMA. �

You can also run a Line card stats query against all of the cards and look for Traffic CRC errors (compare your other cards with the card taking errors). You can view all of your line cards stats by right clicking the network level (in iMonitor) and select LINE CARD STATs. �Query ONLY your Rx cards and look for CRC errors. �

If the errors are coming from a specific remote (which they may be)...there is a procedure you can use to find the suspect VSAT. �I will wait to give you that procedure until I hear feedback on the above questions.

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« Last Edit: Oct 28^th, 2007 at 3:59pm by N/A »

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Eric Johnston

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Reply #2 - Oct 28^th, 2007 at 5:46pm

With the spectrum analyser tuned to the return link frequency you might also try zero span and look out for any abnormally shaped bursts, low level bursts, two bursts overlapping or low level cross-pol bursts.

Make tests of every remote and record the return link quality and burst timing of each.

Use a sweep time of a few seconds and single sweep manually triggered. �Keep clicking till you get a picture of something interesting.

A normal spectrum analyser display on the return link with max hold, will build up the overall envelope of your return link bursts. �Look for spectral regrowth in case one of your remote BUCs is overdriven. �Look for interference in the gaps between the return links. Follow Mike's advice regarding min hold which will find in band steady interference.

Parallel up another receiver and see if that detects the same problem but be careful that the traffic so received does not duplicate all the packets into your ethernet router system. ( been there - done that ! )

Best regards, Eric.

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« Last Edit: Oct 29^th, 2007 at 10:33am by Eric Johnston »

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Gomes Member ★★ Offline Posts: 12 Bangladesh	Reply #3 - Oct 29^th, 2007 at 4:02am 1. I've TWO ULC, TxRx - ULC1 & Stdby - ULC2 2. Configured for Carrier Grooming 3. ULC2 is Standby
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Reply #4 - Oct 29^th, 2007 at 11:01am

Run that minimum trace and look for energy underneath.

also

Are any of the other remotes in that (carrier groomed) inbound taking CRC errors?

If not, then the issue is with a specific remote.

If that is the case, I am guessing that one of the users is off peak and needs to re-aim. If you run a Network Data Snapshot at the Network level you should be able to find the culprit. Pull the stats and look at downstream and upstream SNRs.

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Gomes Member ★★ Offline Posts: 12 Bangladesh	Reply #5 - Oct 30^th, 2007 at 5:30am Warning shows most of the time (at pick hour) when one of my Remote Tx Power close to "Max. Power". But downstream and upstream SNRs are good through out the day! With SpecAn we found little Intermittent at HUB end!
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Reply #6 - Oct 30^th, 2007 at 10:52am

1. When you run a network data snapshot against the network level (by right clicking the network level and selecting network data snapshot) do you see anyone taking any errors?

2. What is the size of your FWD (Tx) carrier on that line card?
3. What is the size of the Upstream (Rx) carrier also on that line card?

4. If your upstream and downstream snrs look good, why is your remote getting close to its max power? Off peak?

That remote may be very close to saturating its BUC when it is working that hard. Something has to be causing it.

Additional questions:

What kind of remote is it?
What is its max power setting?
What is your UCP sweet spot set to (Nominal C/N)?

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Gomes Member ★★ Offline Posts: 12 Bangladesh	Reply #7 - Oct 30^th, 2007 at 11:18am 1. Yes, sometimes that remote have TDM Lost 2. Downstream 1536 3. Upstream 512 4. Only at One remote sometimes it comes to Max. Power! i. All remotes are with iDirect 3100 ii. That remote settings are Initial Power: -12 & Max. Power: -9 iii. Down C/N: 13-12 dB, Up C/N: 9-8 dB
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Ex Member Ex Member	Reply #8 - Oct 31^st, 2007 at 10:50am Everything looks good. Not seeing anything odd (with what you told me). When the CRCs are present is the remote maxed out in power (at the exact time you note it)?
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Gomes Member ★★ Offline Posts: 12 Bangladesh	Reply #9 - Oct 31^st, 2007 at 11:09am When the CRCs are present is the remote maxed out in power (at the exact time you note it)? � Ans: NO, not at the same time - gradually
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techtest Member ★★ Offline Posts: 42	Reply #10 - Jul 24^th, 2009 at 8:47am Hi All , What are the telnet commands to check current usage in i Direct modem... ie by typing that command in telnet session can we check what is uplink and downlink usage going on right now ...
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techtest Member ★★ Offline Posts: 42	Reply #11 - Jul 24^th, 2009 at 8:50am Hi All , What are the telnet commands to check current usage in i Direct modem... ie by typing that command in telnet session can we check what is uplink and downlink usage going on right now ...
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Ex Member Ex Member	Reply #12 - Jul 24^th, 2009 at 12:03pm Usage? You want throughputs or RF statistics? iSite is a better alternative than command line.
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